r:::=~~---... ~ DIVISION OF NATURAL RtSOURCES' ANO ENVIRONMENT U. i. AUSTIN REC'D MAY 0 9 fS1S REFER TO H ......-........•....................•...• andle.......... Read & Return File D1L£e. . .... ?2..-14=...-.-~~.~--~~~­EFFECT OF VEHICULAR AND PEDESTRIAN TRAFFIC ON BApKSHORE VEGETATION AND DUNE DEVELOPMENT Beach Impact Study, Padre Island National Seashore Final Report for Contract CX 700040146 E. W. Behrens R. L. Watson P. D. Carangelo W. H. Sohl H. S. Finkelstein INTRODUCTION Purpose of Study -Padre Island National Seashore is located on one of the longest barrier islands in the world. These barrier islands exist in a fragile equilibrium between the natural erosional and depositional forces by which they were built. Even a seemingly insignificant ehange in any of the processes which built the island may signal an imbalance leading to its destruction by the same natural system which built it. Development and increased usage of the barrier islands of our coastal states has involved intentional modification of coastal sediment transport systems in order to serve short term goals, often with the result being the initiation of long term cumulative erosion. Such changes can also be initiated acci­dentally and with no prior intention solely through excessively high human usage. It is important to note, that a very minor change in the stability of a barrier island may result in severe long term damage even though the changes ·are occurring so slowly as to be difficult to detect over a short study period. The purpose of this study is to determine if the rapidly increasing vehicular and ' . pedestrian traffic on the beaches of the Padre Island National Seashore is adversely affecting the long term stability of the vegetated foredune system. The Natural Seawall -A barrier island system such as. P~dre Island is composed of the following major physiographic elements in dynamic equilibrium with each other; shoreface, beach, foredune system, vegetated barrier flats, back island dunes, wind tidal flats and lagoon (Fig. 1). The stability of each of these is to a large extent controlled by the stability of the zone immediately seaward II .,, .. COAST ·. SHORE SHORE­ . .' ~ r ~ ~ FACE ·~, . I I / .. LAGUNA VEGETATED FORE DUNES Tl DAL BACKSHORE FORE IGULF OF I' MADRE SHORE MEXICO FLAT BARRIER · FLATS VEGETATED J WIND SHADOW DUNE LONGSHORE w·EST ll EAST t; BARS 40. .. DIAGRAMMATIC PROFILE OF €) . 20 PAOR£ ISLAND -·-------------··-. -­ .05 . I 0 I FIGURE 1 MILES APPROXIMATE SCALE (ADAPTED FROM MILLING a BEHRENS 1966) ,-, 3 and windward of it. Of these physiographic elements, the vegetated foredune ridge plays a major role. From 1900 to 1972 twenty-seven hurricanes have made landfalls on the Texas coast (Brown, et al., 1974). With a hurricane expected on the Texas coas~ once every 2.5 years, the presence of a high, continuousAwell vegetated foredune ridgeAto~ serve as a natural seawallAis a most valuable asset. According to r.V Bodine (1969) Padre Island can e~pect a storm tide or surge of six feet once in 10 years, eight feet once in 25 years, and 10 feet once in 100 years. Wave run-up from storm waves may add significantly to the effective water level. Such flood levels are sufficient to flood and wash over low portions of the islandJdestroying roads and structures in their path and depositing large amounts of beach dune and shoreface sediment in the lagoon. After passage of the storm, outwash from the lagoon may flood over low parts of the island and cut new channels through the beach and dune ridge where it has been breached. "Sand dunes near the beach not only protect against high water and waves, but also serve as stockpiles to feed the beach. Sand accumulating on the seaward slope of a dune will extend or build the dune toward the shoreline. This sand, once in the dune, (1) may be returned to the beach by a severe storm and thus nourish the beach. Figure 2 is a schematic diagram of storm wave attack on the beach and dune. As shown, the initial attack of storm waves is on the beach berm fronting the dune. When the berm is eroded, waves (9 attack the dune. If the wave attack lasts long enough, the dune can be overtopped by waves with resultant lowering of the dune crest. Much of the sand eroded from the berm and dune is transported directly offshore and deposited in a bar formation. This process ·'( ') . J M.H.W~--­ Profile A ... Normal wove oclion i I I ~ M.H.W;.. ___ ____o-Af tet storm .,au a'ftoek, normal won ocllon I t rt Figure 2 Schematic Diagram of Storm Wave Attack on Beach and Dune (after· sPM, 1973 ppg. 5-23) ·' . 5 not only. helps to dissipate incident wave energy during a storm, but offshore deposits will normally be transported back to the beach by swells after the storm. Onshore winds transport the sand from the beach toward the f oredune area and the dune building pro­ceeds on another natural cycle. This dune building, however, is generally at a.very slow rate unless supplemented by fences or vegetation" (SPM, P. 5-21, 1974). In addition to serving as a vital seawall to protect the interior of the barrier island, and a sand reservoir to reduce storm damage, the foredune ridge provides a unique environment for a wide variety of plant and animal life. A manmade seawall can serve many of the functions of the natural dune line, but it is expensive, not aesthetically pleasing, is seldom fronted by a beach, does not repair itself between storms, and provides a poor habitat for the fauna and flora of the foredune system (Plate 1, Appendix B). Preliminary Observations -For five miles to the south of the northernmost beach access road to just south of Malaquite Beach in the Padre Island National Seashore, the beach is completely closed to all vehicular traffic. The juxtaposition of areas of heavy and no vehicular traffic provides some striking observations . on the co~parative development of vegetation with resulting sand accumulation seaward of the foredune ridge on the backshore (Fig. 3)o In the area where no traffic is allowed, the vegetation line extends 70 ft. farther seaward than where vehicular traffic is allowed (Plate 1, Appendix B). This new vegetation (developed since Hurri­cane Celia, August 3; 1970) is serving as an effective organic baffle and is beginning to form small, and increasingly stabilized dunes. The result is to rebuild the storm destroyed portions of the foredune ridge and extend it further seaward. GULF OF lllEXICO :·· ••••••••••••••• ·:-.:·......_··::. •••••••• ··.-.-.:-: :·. •1~...........-••••• -· •• -........ -· •• ••• .... • • • • • ...... , .. •. ..... . . • •.• • . . • • • . • • • ··1 • • ..... . •. . • .. .. ••.•.• -.. .• . . . . • . •.• • • . ....:.·:.... ··"··. ... ~···......:-...·..··~ .. ..........·... ............~:.....·.......... ....:.-:.,............. I SWASH TOP . I (LOW TI DE) I I NORTH I I . . BERM CREST I (NORMAL HIGH TIDE) • e It.••• • • • • • • • • • e e • • • e e • e e • e e • e • e • e • e e • • e e eee • • • • e .1. • • • • e VEGETATION LINE VEHICLES ALLOWED 0 . _J 0 c:t > z 10 0 8 t­ <( I-. 6 en - 4 > · w 2 > I-0 <( _J LI.I a:: 10 8 • 6 4 2 0 (ADAPTED FROM McATEE a DRAWE 1974) DRIVING ONLY ·I ---NOT RAF PEDTRAF -----VEHTRAF . --. --------........., • :··-~, "' ' . ----, /,,,, ' _,,, \. '-----·---­ PEDESTRIAN BACK SHORE NOTRAF _,. / PEDTRAF ;'/./ . " \ ----· VEHTRAF ..,, ~ "" ~ ~ ~ ~ ~ ~------............. ____ r "' PEDESTRIAN· FORESHORE "' NOT RAF • PEDTRAF ----· VEHTRAF ' 10 due to various types of pedestrian and vehicular traffic in the time period since Hurricane Celia (August 3, 1970). ·Objective two is to use these comparisons to indicate possible long term trends. Repeated future vegetation and topographic surveys at each of these sites can be used to verify or modify the apparent trends in the stability of the backshore and foredune area. Sites NOTRAF, VEHTRAF, and PEDTRAF are identical with transects 2, 3 and 4 of McAtee (1974) enabling the data of both studies to be combined in analyzing the long term effects of beach traffic on foredune stability. Research Methods -At each of the four study sites a pair of concrete and steel monuments was erected along a range line perpendicular to the local shoreline. This enables the survey crew to measure exactly the same profile line during each survey in order to accurately measure small amounts of erosion or accretion. During each survey, elevations are determined every 10 feet along the range line. A level loop including the stations at NOTRAF, PEDTRAF, and VEHTRAF has been closed~ so that those three stations are all relative to the same datum. The datum is approximately mean sea level as determined from local water level and a tide gage located at the Corpus Christi Water Exchange Pass. The datum for SHELL is also approximately mean sea level and was determined in the same fashion, but was not tied in to the other three stations by a level loop because of the distance involved. The study areas were profiled monthly from April 1974 through July 1974 and bimonthly thereafter. During the fall and winter study periods, qualitative vege­tative data was collected at each of the four study sites during each survey. The species present in each zone of each study area were noted as well as their effectiveness in sand stabilization and trapping. During November 1974 detailed maps of the vegetation at NOTRAF and VEHTRAF were compiled in order to better understand the function of each species in sand stabilization. A similar map was compi~ed in SHELL during December. These maps are repre­sentative of the individual localities and broadly representative of each traffic usage level for the fall and early winter months. RESEARCH RESULTS Individual Site Characteristics -SHELL -Study site SHELL is located 8.3 miles south of the four wheel drive sign in the Little Shell portion of the shell beaches. The shell beaches in Little Shell are composed of up to 80 percent shell material. They are the result of landward deflation of the finer grained terrigenous s~nd with the shell .supply due to a convergence in littoral drift (Watson, 1971). The study site SHELL is very . different from the three other sites located north of the shell beaches where the shell accumulation in the beach sediment averages less than one percent. Due to the coarse nature of the shell beaches, the foreshore is steeper than the foreshore at the other study sites (Fig. 6). Also the storm berm is somewhat higher, probably due to higher runup of the waves on the steeper profile beaches. The backshore slopes down markedly in the landward direction from the berm crest, with the lowest elevation on the beach occurring just in front of the vegetation line. Shell content decreases and sediment firmness increases from the berm crest to the low point of the backshore (Watson, 1971). The main beach road is just in front of and truncating the vegetation line and tends to limit further seaward growth of vegetation except in isolated clumps (Plate 1, Appendix B). There is very little active movement of sand by wind action in the shell beaches as compared with the terrigenous sand beaches of the other study sites. After reworking of the beach by waves associated with high water levels, wind action deflates the finer grained terri­genous sediment leaving the beach covered with a coarser shell N ---..0 ....:­ '+­ '-' _J U) aJ ~ Ow f- SHELL w ---4-17-74 ->~ ---5-20-74 f­ -----7-3 -74 <( -6 -6 7-26-74 _J -··-··-·· 10-2-74 WN \ 0:: --11-8-74 ·. 0 00 \ \ ', -------I -28-75 ·.,. o-··~~ _J '-" ·~ WO 6~·'·~ \ \ -.;\ FIGURE 6 ~ "-o-o...___o' N '-50 0 50 100 150 200 250 300 350 400 DISTANCE OFFSHORE (ft.) 14 pavement. As the shell material cannot be transported by wind, the beach becomes very stable and new dune growth may proceed slowly. Profile Changes -Note that the only significant change in the profiles landward of the berm crest at SHELL is a growth of less than one.foot of the small vegetated dune near the seaward limit of vegetation (Fig. 6). The volume of sediment in cubic feet per foot of beach above -5 ft. relative to Mean Sea Level has been measured for two segments of the profile: from the base of the foredune to the seaward limit of vegetation; and from the seaward limit of vegetation to the berm crest. A plot of these volumes demonstrates the stability of the shell beach area (Fig. 7, and Table 1). Vegetation -The vegetation between the dune base and the seaward limit of growth was mapped during December 1974 (Fig. 8) .. The profile line is marked by the front range and back range locations in the center line of the map (+BR and +FR). Note that the vegetation is sharply truncated near the front range by the vehicle road. The dominant dune building and sand arresting plants in shell are Uniola paniculata, Croton punctatus, Ipomoea pes-caprae, I. stolonifera, and Cassia fasiculata. Uniola is the primary dune builder and stabilizer in this area and is capable of rapid upward growth and is stimulated by moderate sand deposition. In addition to the pressure of vehicular traffic on the backshore limiting its development there, the coarse shell beach probably is very poor at retaining moisture producing an exceptionally harsh environment. However, isolated clumps of Uniola are found as far seaward as the berm crest (Plate 2, Appendix B). Once SHELL DECEMBER 1974 feet 10 0 10 20 ~Uniolo panicu/ata Ill Croton punctatus b] lpomoea pes-caprae • lpomoea stolonifera ~Cassia fasiculata APPROXIMATE ELEVATION IN FEET ABOVE M SL 6 6 ·~ FIGURE 8 I ·~!~'~~~·;;' --~ 17 TABLE 1 Volume of Sand Accumulation Cubic Ft/Ft of Beach Above -5.Ft. MSL . Foredune to Edge of Foredune to Edge of Edge of Vegetation Edge of VegetationVegetation to Berm Vegetation to Berm NOTRAF 0-160' 160'-220' PEDTRAF 0-170' 170'-200' 4/17/74 1804 600 4/17/74 2072 306 5/20/74 1800 616 5/20/74 1984 304 7/3/74 1802 604 7/3/74 2024 320 7/26/74 1830 608 7/26/74 2052 308 10/2/74 1800 602 10/2/74 2030 310 11/8/74 1872 624 11/8/74 2062 316 1/28/75 1868 602 1/28/75 2086 334 VEHTRAF 0-110' 110'-210' SHELL 0-90' 90'-200' 4/17/74 1564 1028 4/17/74 1104 . 1216 5/20/74 1568 1034 5/20/74 1100 1220 7/3/74 1570 1030 7/26/74 1576 -1024 7/26/74 1110 1220 10/2/74 1636 . 1046 10/2/74 1110 1222 11/8/74 1652 1062 11/13/74 1110 1234 1/28/75 1630 1068 1/28/75 1124 1232 18 established they rapidly accumulate a small dune of finer grained terrigenous wind blown sand which is better able to retain moisture than the surrounding coarser shell material. The presence of these isolated wind shadow dunes suggests that in the absence of additional pressure from vehicular traffic that the vegetation might be more.widespread on the backshore (Plate 2, Appendix B). \ I. pes-caprae and I. stolonifera are present in the vegetated area either on otherwise bare sand or associated with less dense stands of Uniola. The I. stolonifera is le·ss salt tolerant than I. ~­caprae and tends to grow in the landward portion of the vegetated zone. Croton occurs in small dense patches accumulating low oval and circular wind shadow dunes. _Cassia appears to be the least salt tolerant and ·usually occurs in the most landward sections of the vegetated area. It is often found on the lee sides of small dunes and in other protected locations. Note that attime of mapping Cassia was an important plant relative to it's abundance and estimated cove~age. Yet die off in winter leaves Oenothera drummondit asanimportant sand arrestor-accumulator. It is more widespread on the backshore at these times than Cassia would normally be. It should be noted that even though the presence of coarser beach sediment may inhibit plant growth and definitely does reduce the rate of sand·transporxby wind, the dunes within the area of shell ~ beaches are very well stabilized. The berm of the shell beaches is on the order of one foot higher than the berm of the terrigenous beaches. This would indic~te that the yegetation on the backshore seaward of the dunes is subject to less frequent wave attack and inundation by sea water, providing a longer period for growth and healing between damaging inundation. 19 Individual Site Characteristics -The following three study sites VEHTR~F, NOTRAF, and PEDTRAF are virtually identical with regard to sediment type, wave action, and other environmental variables and differ only with regard to the type and intensity of vehicular and pedestrian traffic. As there is considerable variability within each traffic usage type, the detailed data from each study site can be considered to broadly characterize each locality but not represent all of the variability present in each area. VEHTRAF -Study site VEHTRAF is located 1.5 miles south of the beach access road just south of Malaquite Beach. It was selected as a beach area subject to very heavy vehicular traffic and moderate to heavy pedestrian usage (Fig. 5). It is similar to Transect 4 of McAtee (1974). Note that there is greater mobility of the terrigenous sand throughout the profile at this locality than at SHELL (Fig. 9). VEHTRAF is characterized by a low berm with a very gently landward sloping backshore which is subject to heavy vehicular traffic. At the study site there is a very well developed new vegetated dune growing between the base of the foredune ridge and the backshore area travelled by cars (Plate 3, Appendix B). Its height has increased by about two feet during the study period (Fig. 9). The boundary between the vegetation and the area of vehicular traffic is about 110' seaward of the foredune ridge. The profile segment from the base of the foredune to the seaward limit of vegetation showed a net accumulation of about 70 cubic feet of sediment per foot of beach while the zone from the vegetation line to the berm crest showed a net accumulation of about 40 cubic feet per foot of beach (Fig. 10, Table 1). N .--.... 0 .,.; ­ '+­ ........., _J CJ) CX> ~ 0 I-<.O VEHTRAF w ---4-17-74 > -q­ --5-20-74 i­ ----7-3-74 <{ -A-A 7-26-74 _J -··-··-·· I0-2-74 WN a::: -0-o 11-8-74 ----------I -2 8-75 ....J Wo FIGURE 9 N 1-50 0 50 100 150 200 250 300 350 400 DISTANCE OFFSHORE (ft) 0 :c 0 (.) ~ <( w "~ m 0 0 0 0 al 0 <( C\J VEGETATION LINE Q TO BERM CREST z 0 <( 0 CJ) . . ,,,,,,,.,......-. LL . /···· 0 .......-......_ ·' -~·~·· ....,,,,,,­ 0 w 0 :E 0 :::> .... ­ _J 0 0 > 0 O'> r--­ 0 C.O N (X) (X) - I .C\J (\J I I C\J I I .0 I ~ lO ~ DATE 1974-75 FIGURE 10 22 A map of the area surrounding VEHTRAF shows the dominance of rather high, steep Uniola dunes (Fig. 11). Note that I. ~­caprae is a pioneer in vegetating the seaward slope of the vege­tated area, but is severely truncated by automobile traffic and cannot propagate seaward of the edge of the dunes (Plate 3, Appendix B). I. stolonifera is common primarily landward in the vegetated zone where it is more protected from salt spray and inundation. Croton forms numerous small wind shadow dunes and Cassia is common in the lee slopes and other protected areas. Again Cassia tends to disappear in winter till middle summer to be replaced by Oenothera in sand arresting importance. Relative to much of the immediately adjacent beach, the study area in VEHTRAF has some of the optimally-developed new dunes and vegetation seaward of the main foredune ridge. Many other parts of the immediate area have almost no development of vegetation or new accreting dunes seaward of the main dune line. These areas are often used for parking, camp sites and campfire locations, which inhibit the development of vegetation seaward of the foredune·ridge. Individual Site Characteristics -PEDTRAF -The study site PEDTRAF is located between the campground and the observation tower just north of Malaquite Beach. It is closed to vehicular traffic, but is subject to heavy pedestrian usage from campers ' walking between the Malaquite Beach facilities and the campground. This site is similar to Transect 3 of McAtee which was located at the north end of the camping area. The vegetation line at PEDTRAF is located about 170 ft. seaward of the base of the foredune ridge. ·'":.· •;•. 3 :::;~ ,.(' J I >l a ~ ,i:··~~·. ·=· 10 l~i; ·•,.~~-X::r~~11:~~~:~~~·~~,xi:~i~~ii' ()~'. n 0n0 n" ~,o<[ · ••• -:. ·-,. ,.1.. :: •• 0o, ~:: '~ h6'b'(izy • ••• fi 9 •:•: '...__. · · Jo88f rG/i o"'t> • ~'booo~' 9 oO ·=·· ;·: 9 4 ~, 0 .:::r ·.··:. ,,~;i::; •:fcY,Prc l • • ·~ ·.: :~t. CJ) :E oco 1­w PEDTRAF 'b-.. ->~ --4-17-74 t­ --5-20-74 \'-··-~-==-,A~<( -----7-3-74 ' ·. ----~~ _J ' \ --~-6 -A-& 7-26-74 o, '.WN a:: J -0 -··-··-I0-2-74 o'° _J -0 11-8-74 w 0 . --------1-28-75 FIGURE 12 N -50 0 50 100 150 200 250 . 300 350 400 DISTANCE OFFSHORE {ft.) 0 ......... 0 ::c (..) C\J <3: w 0 en . 0 ,,,.. ..... 0 '+­rt>' C\J +­ .... ........ .. 0 _J 0 CJ) m ·~ .. lO 0 0 CX)lJJ > 0 0 CD <( 0 lO . Cl z <( 0 CJ) \ 0 v, v LL 0 0 . W 0 ~ rt) :::> _J 0 0 > 0 -I • ' ... DUNE_BASE TO VEGE·TATION LINE PEDTRAF VEGETATION LINE --TO BERM · CREST ····""""""' ...._.........._..... -----~ ····~ .........._.... -, i. ...._ C\J r--0 rt) <.O N CX) I I C\J I C\J C\l I I ('... I 0 I v ('... lO DATE 1974-75 FIGURE 13 foot wide vegetated zone seaward of the foredune ridge extending to the high tide line. Growth of Uniola at the high tide line has produced an irregular line of small, but growing wind shadow dunes (Fig. 14; Plate 4,Appendix B). The vegetated zone is 160 ' ft. wide, and the unvegetated beach seaward of the vegetation extends about 30 to 60 ft. to the berm crest .. The new dunes \ growing seaward of ~he for~dune ridge are low and scattered, but the area is well vegetated with a very diverse plant community (Plat~ 5, Appendix B). There has been little net gain in sediment within the vegetated area during this study (Fig. 15, Table 1). This is probably due to ~he very narrow source area for ·sediment (the dry beach seaward of the vegetation) and the stability of the sand within the well vegetated backshore. Similarly, there has been little net change in the amount . of sand accumulated in the zone between the vegetation line and the berm crest (Fig. 15,· Table 1). The lack of either erosion or accumulation suggests that both zones are well stabilized. Detailed mapping of the vegetation at NOTRAF showed three distinct zones of vegetation trending roughly parallel with the beach seaward of the foredune ridge (Plates 5 & 6, Appendix B). No more than two .zones were mapped at the other study sites. Species diversity was high with 10 dominant species present rather than only five (Fig. 16). The most seaward zone is popu­lated by Uniola, Sesuvium portulacastrum, and Ipomea pes-caprae. These halophytes are capable of rapid upward and lateral growth and are resistant to occasional salt water· inundations by exceptionally high tides. The individual Uniola ?lumps forming N ~o -+-­ '+-­ ....._ _J U)OO ~ 0 J--(.0 w >v J-­ 0 m <( Cl z <{ CJ) LL q 0 w ~ :::> _J 0 > a> 0 0 ~ 0 0 . 0 0 DUNE BASE TO VEGETATION LINE NOTRAF VEGETATION LINE T.O BERM CREST ---.__..._. ....~. ....~~....___,,,,..... .......,,,; ··. ' 1'· 1---F;~URE 15 I NOTRAF NOVEMBER 1974 feet Q Fimbrisfylis coroliniono ~N.,;"f 10 ~ ~ Ill . []. II ­ IJ Ill 0 10 20 30 Unio/o poniculola Croton puncfolus /pomoea pes-coproe Ipomoeo slolonif•ro Sporfino po/ens Sporobolus virginicus Ponicum omorum Sesuvium pw q­ t­<{ _J w C\I 0:: .....J Wo FIGURE 17 N I -50 200 250 300 350 400 OFFSHORE (ft) C\I -I \ \ \ / -\ • BERM CREST \ ~ 0 i ' \ I EDGE OF '+-­ ..__... \ \ (\ I ' . _J Cf) CX> ~ 0 t-(D w > ~j I­ gN~ _J I WO I FIGURE 18 N I -50 0 50 100 150 200 250 300 350 400 DISTANCE OFFSHORE (ft) 36 edge of vegetation at SHELL and at VEHTRAF is far inshore of the berm crest, while it nearly coincides with the berm crest at PEDTRAF and NOTRAF. Further, vegetated sand storage at VEHTRAF is in the form of a single high dune just seaward of the foredune ridge, while at PEDTRAF and VEHTRAF vegetated sand storage occupies a much wider zone of numerous small dunes extending nearly to the berm crest and high tide line. Comparison of the volume of sand accumulated in the vegetated portion of the backshore of each of the study sites indicates that greatest stabilized storage occurs at PEDTRAF, followed in order by NOTRAF, VEHTRAF, and SHELL (Fig. 19). However, the mean ele­vation above Mean Sea Level for vegetated backshore of each of the study sites is greatest at VEHTRAF, followed by SHELL, PEDTRAF, and NOTRAF (Fig. 20, Table 2). The very high mean elevation at VEHTRAF is due to the rapid upward growth of .the new dune supplied by sand from the wide unvegetated foreshore. Although the mean elevation ·or the vegetated portion of the backshore at PEDTRAF and NOTRAF is lower, the total stabilized sand storage is considerably higher than at VEHTRAF because the vegetated zone is much wider -than at _VEHTRAF where it is truncated by vehicular traffic. Further, it is likely that if there is sufficient time before the occurrence of the next major storm that the elevation .,, of the vege~ated portions of NOTRAF and PEDTRAF will rise as high or higher than those at VEHTRAF considerably increasing the volume of vegetated sand storage. Upward gr-owth at VEHTRAF may be limited by the steepness of resulting slopes, while seaward growth is limited by vehicular traffic. The volume increase of the vegetated ,.._. 0 0 :c (.) C\J <{ w 0 . ·JD 0 0 +-I (\j '+-I I'>" +­ ..... ........­ ,.. 0 0 ....J m Cl) ~ 0 lO 0 CX> w > 0 0 lO m tO <{ Cl z 0 <( tn Cl) lO LL 0 0 w lO ~ :::> ..J 0 0 lO > 0 -I ~·~EDTRAF ' • "' NOTRAF ___, /,_..-'--..,VEHTRAF / / .... ----------/ . DUNE BASE TO VEGETATION LINE ................................ SHELL . . ....~. ............... : ·'·\ I'-lO (X) 0 rt) C\I (X) C\I C\I I I C\I · I I I 0 lO l'-I'­ DATE 1974-75 I . ! FIGURE 19 0 • - ,...__ .... ...... ~ 0 • 0 _J CJ) ~­ 0 . en w <., > 0 '37 CD 0. <( (X) z 0 0 -.. t-I'­<( '> ·w _J 0 • w (0 z 0 <{ • w LO ::? 0 • ~ ._,,.... /"" ',, VEHT RAF / ) . . ------------/ --~/ • ..• .-~ . -. . " ' . . SHELL . ........ .. ·····...........•···•····•········•·········· PEDTRAF NOT RAF DUNE BASE TO' . VEGETATION LINE r--0 (0 C\J I C\J C\J I I C\J I . I I Q ­ v tO r--f'... DATE I 9 7 4 -7 5 _ ·---_ . _____ l I FIGURE 20 Foredune to Vegetation NOTRAF 4/17/74 6.2' 5/20/74 6.25' 7/3/74 6.26' 7/26/74 6.4' 10/2/74 6.2' 11/8/74 6.7' 1/28/75 6.26' VEHTRAF 4/17/74 9.2' 5/20/74 9.2' 7/3/74 9.2' 7/26/74 9.3' 10/2/74 9.'8' 11/8/74 10.0' 1/28/75 9.8' TABLE 2 Mean Elevation Above 0.0 MSL Edge of Vegetation to Berm PEDTRAF 5.0' 4/17/74 5.2' 5/20/74 5.06' 7/3/74 5.1' 7/26/74 5.0' 10/2/74 5.4' 11/8/74 5.03' 1/28/75 SHELL 5.3' 4/17/74 5-3' 5/20/74 5-3' 5.2' 7/26/74 5.5' 10/2/74 5.6' 11/13/74 5.7' 1/28/75 39 Edge of Foredune to Vegetation Vegetation to Berm 7.1' 5.2' 6,~ 6' 5.1' 6.9' 5.6' 7.0' 5.2' 6.9' 5.3' 7.1' 5.5' 7.27' 6.13' 7.2' 6.0' 7.2' 6.0' 7-3' 6.0' 7.3' 6.1' 7.3' 6.2' 7. 5' .. 6.2' I / 40 , portion of the backshore from April 74 to January 75 at NOTRAF has been nearly as great as at VEHTRAF (Table 1, Fig. 19). If we look at the unvegetated portion of the backshore from the vegetation li~e to the berm crest we find that the greatest totally unstabilized sand storage occurs at SHELL (due to the very high berm and wide unvegetated backshore) followed by VEHTRAF, . \ NOTRAF, and PEDTRAF (Fig. 21). With the exception of SHELL, this portion of the backshore at each of the study sites averages about 5 to 5.5 ft. above mean sea level (Fig. 22). The greater storage in the .unvegetated portion at VEHTRAF is indicative of the greater width of unstabilized sand produced by vehicular traffic. Effective Sand Storage Above Hurricane Beach. -One of the most important functions of vegetated sand storage seaward of the foredune line is as a reservoir of sand to nourish the beach during . severe storms. This serves a dual function. The eroding beach is provided with a sand supply and as long as that sand supply lasts, I the main foredune . line is not attacked. The potential sand storage above a hurricane beach can be estimated if the slope of the hurri­cane beach is known and if the hurricane storm surge water level is known. We will assume a storm surge level of six feet (10 year storm) and a hurricane foreshore slope of 1.9 ft/100 ft. Davis (1972) measured beach profiles at Mustang Island, Texas before and after Hurricane Fern and determined a slope of 1.9 ft./100 ft. Fern was a very small storm. Mason (personal communication) determined a post storm slope of 2.8 to 3.5 ft. for Hurricane Celia on Matagorda Peninsula. Assuming a slope of 1.9 ft./100 ft. with erosion to 'the base of the foredune ridge at an elevation of 6 ft., the storage .(ft.3/ft. beach) at each of the sites from the ,....., :c 0 () 0 <( ro w CD ·' ...................... SHELL ••••••••••••••••••••••L.. ••••• +-0 'I-0 SO" +-C\J 't­ '"""' ...J 0 CJ) 0 ::E " ,,-------VEHTRAF . ~ lO ---------__,,,,, *""" . 0 ' .. .. WO VEGETATION LINE >o ·o TO BERM CREST CD 0 <( 0 Cl l'­ z ~o 0 NOTRAF LL tD 0 PEDTRAF 0 w ·o ~ ro ::> _J 00 >0 C\J I'­ 0 ro -«> C\l co ex>C\l I ~ . I I C\II lO ~ I'-· 0 -· I DATE 1974 -75 FIGURE 21 lO • !'-­ VEGETATION . LINE .,....... .,._ ..... 0 -......-• TO BERM .CREST !'-­ ...J (/) LO • ~ <.O ..... , .... ·SHELL w . . .....>.:..... P E D T R' A F w • 'NOTRAF lO ...J lLJ lO .. 0 .z • a> C\J C\I I I C\I ... I I ~ lO' !'--!'---o -I - DATE 1974-75 FIGURE 22 43 foredune to the berm is as follows: 4/17/74 1/28/75 gain PEDTRAF 514 586 72 NOTRAF 330 382 52 VEHTRAF 330 434 104 Note that the total storage increases with increasing beach \ traffic and that the annual increase in total storage increases with increasing traffic. This suggests that increased beach traffic may be beneficial. However, if we look at the vegetated storage which is much more resistant to erosion and thus will better protect the main dune line instead of both the vegetated and un­ vegetated storage we see a different picture. The vegetated storage· (ft.3/ft. beach) above our hypothetical hurricane beach surface is as follows: 4/17/74 1/28/75 gain PEDTRAF 426 484 5,8 NOTRAF 278 328 50 VEHTRAF 190 264 74 Note that the stabilized, vegetated storage above our hypothetical storm beach is much greater at PEDTRAF and NOTRAF than at VEHTRAF • .. Further, if there is sufficient time for accumulation before the onset of the next severe storm, the well vegetated storage at NOTRAF and at PEDTRAF will increase. Supporting Data from Other Localities -We made a field trip to all accessible beaches in Texas to the north of Padre Island. At the north end of Galveston Island, we encountered adjacent beaches which were closed to vehicular traffic and open to vehicular traffic (Fig. 23). Note that as with NOTRAF and VEHTRAF, that N --.. 0 +-= ­ '+­ ....__ EAST BEACH 2-5-75 _J (f) co ~ Ow r-­w I j ~ \• ~. ~ v~ ·~-·' ,~· \ <( _J w Ni GALVESTON a:: _J W o-1 -•-•­ FIGURE 23 C\J I -50 0 50 100 150 200 250 300 350 400 450 DISTANCE OFFSHORE {ft.) 45 vehicular traffic has limited the seaward advance of vegetation and reduced the amount of vegetated sand storage. The relatively high (10 ft.) dune at t~e left end of the profile is the main dune line. The deep saddle in the traffic beach profile is due to a dune buggy road along the length of the dune ridge at that location (Plate 6, Appendix B) . CONCLUSIONS Effect of Vehicular Traffic -It is difficult to fully assess the impact of vehicular traffic in the shell beaches as there are no areas in the shell beaches closed to vehicular traffic for comparison. However, vehicular traffic in the shell beaches truncates the seaward propagation of pioneer plants at the prominent "road" at the lowest part of the backshore. Many of the small Uniola clumps further seaward on the backslope of the berm have been severely damaged by automobile traffic (Plate 1, Appendix B). However, the impact of vehicles on the backshore may have little long term effect -on the stability of the main foredune :··ridge in the shell beaches· because the beaches are well stabilized by the shell pavement on the surface. · Vehicular traffic has pronounced effect on the ~errigenous beaches of North Padre Island. The traffic limits the seaward propagation of backshore vegetation and thus reduces the vegetated sand storage on the beach (Plates 1 and 2; Appendix B). The wide unvegetated sand beach produced by the traffic provides a source for windborn sand to be blown into the remaining, narrow, vegetated backshore. This produces rapid vertical growth and a harsh envi­rorunent, greatly limiting plant species diversity, and probably eliminating some animal habitats which would be present with more diverse plant communities. The narrow, vegetated backspore of the area subject to vehicular traffic may be less stable with respect to storm erosion due to lower diversity and poorer deve­lopment of sand binding plants. The many re-entrants through this narrow zone make direct wave attack on the main foredune line \ probably early in .the development of a storm. Effect of Pedestrian Traffic -The effect of pedestrian traffic on the backshore is certainly far less damaging than vehicular traffic. It appears that. there is little difference in the location of the vegetation line in areas subject to fairly heavy pedestrian traffic as compared with an area with virtually no traffic of any kind. This suggests that pedestrian usage at 1974 levels may be continued without serious damage to the c environment. Presumably at some more intensive usage level dune · vegetation will be adversely affected. Possible Management Practices -The plant community growing on the backshore ~ill develop best_ in the absence of any human traffic and particularly in the absence of vehicular traffic. Closing the beach to public access is not a logical alternative. However, since pedestrian traffic is far less damaging than vehicular traffic it would be best to provide access to the beach * while restricting driving on the backshore· by vehicular traffic. The best long term approach would be that suggested by McAtee (1974) and practiced by the Island Beach State Park in New Jersey (personal communication, 1975). Construction of roads and parking lots behind the main foredune line with boardwalks or designated 47 paths to provide beach access would stop damage by vehicles on · the beach. This would also increase the aesthetic beauty of the beach and remove a significant accident hazard. It would be best accomplished by the construction of very numerous small parking lots in order to spread out the beach users to reduce the impact of large concentrations of pedestrians at individual sites. A \ second, but less desirable alternative would be to restrict driving on the beach to near and seaward of the natural vegetation line. As the natural vegetation line approaches the high tide line and is inundated by unusually high tides driving would be considerably more difficult than with the entire beach available. In addition, . this practice would concentrate vehicular traffic on the upper foreshore which is an area of high recreational value. This would increase the accident hazard due to beach driving. The last alter­native is to make no management changes and continue to allow unrestricted beach driving. This may result in long term damage. If this policy is followed, the re-entrants in the backshore vegetation where there are no backshore dunes present should be fenced off and closed to automobiles so that the narrow vegetated zone which is present on some of the backshore can at least become - continuous and shelter the main dune line from instantaneous attack during severe storms. Recommendations for Future Research -Study of the differences between vegetative development and sand accumulation on the backshore at sites experiencing heavy traffic and sites with no traffic should continue at least until after the next severe tropical storm. This should demonstrate the relative effectiveness of the backshore vegetation and resulting sand accumulations in protecting the main 48 dune line from storm attack on beaches with and without vehicular traffic. The effect of a storm surge shou~d be put in the context of the spectrum of storm tides to which this coast is exposed and in the context of the spectrum of climatic conditions occurring here. That is, a long range continuation of this study is necessary to determine the natural variability of plant cover that corresponds to the range of rainfalls from drought to wet which this area normally experiences (about 10-50 inches annually). Continuing the study over such a span of conditions is necessary to answer questions such as: does a small storm tide during drought conditions do as much damage as a large tide during wet conditions; and what are the specific differences in plant cover and diversity under drought to wet conditions? It would be highly desirable to establish some additional study sites to further evaluate differing usage levels. Such experiments might_include either closing a portion.of beach to vehicular traffic landward of the high tide line. This section of beach should be adjacent to a beach with unrestricted vehicular traffic and, if possible, also adjacent to a beach with no vehicular traffic. This experiment might most easily be accompllshed by running a fence south along the edge of vegetation at the north end of the now closed section of beach for about a mile. This would allow vehicular traffic to operate at the berm crest and on the foreshore and would open that section of beach to heavier pedestrian usage, but would protect the backshore vegetation from vehicular traffic. A long term monitoring study could then assess the differences between heavy traffic, limited tr~ffic, and no traffic. The limited traffic might increase the rate of wind erosion of the foreshore and cause the protected vegetated back­shore to build up faster. Alternatively, the additional blowing sand might provide a harsher environment and reduce the total amount of vegetation and the species diversity of the backshore. Future studies should be made quarterly, rather than bimonthly. Seasonal sampling should be quite adequate to determine long term trends. It would be desirable to increase the number of transects in each usage level of beach in order to obtain a more representative sample of the effect of differing types of traffic. Existing information should be used to prepare educational materials for park use and perhaps for local school use to help park visitors understand the multifaceted role of the foredunes in barrier island stability and ecosystem diversity. 50 REFERENCES Bodine, B. R. 1969. Hurricane surge frequency estimated for the Gulf coast of Texas. U.S. Army Corps of Engineers Coastal Engineering Research Center Memo. 26, 32 pp. Brown, L. F. Jr., R. A. Morton, J. H. McGowen, C. W. Kreitler and W. L. Fisher. 1974. Natural Hazards of the Texas Coastal Zone, Bureau of Economic Geology, The University of Texas at Austin. Davis, R. A. Jr. 1971. Beach changes on the central Texas coast associated with Hurricane Fern, September 1971. Contri. Mar. Sci., 16: 89-98. Mason, C. 1975. Personal communication; (Oceanographer, Special Projects Branch, U.S. Army Corps of Engr., Coastal Engineering Research Center). McAtee, J. W. and D. L. Drawe. 1974. A preliminary study of human impact on the vegetation and microclimate of the beach and foredunes on Padre Isla~d National Seashore; Transactions of the Southwest Region Natural Science Conference, National Park Service, November 19-21, 1974. Milling, M. E. and E. W. Behrens. 1966. Sedimentary structures of beach and dune deposits, Mustang Island, Texas. ' Publ. Inst. Mar. Sci., 11: 135-148. · Shore Protection Manual (SPM), 1973. U.S. Army Corps of Engineers Coastal Engineering Research Center, Volumes I, II and III. Watson, R. L. 1971. Origin of shell beaches, Padre Island, Texas. Jour. Sed. Petr., 41(4): 1105-1111. APPENDIX A SPECIES DISTRIBUTION AND FUNCTION, BACKSHORE VEGETATION PADRE ISLAND NATIONAL SEASHORE . \ _ _ _____ _ .__~ .... l zto:: ' ,..... ? -.. .,,.... --< Species Amaranthus gregii Beach Amaranth Andropogon gZomeratus Bushy Bluestem Baaopa monnieri Water Hyssop Cassia fasiauZata var. ferrisiae Partridge Pea CroptiZon divariaatum var. hirteZZum Scratch Daisy Croton punatatus Beach Tea Cyperus poZystaahos Cedar Sedge Eragrostis oxyZepis Red Lovegrass APPENDIX A Beach Vegetation, Padre Island National Seashore Characterization Function Habitat Remarks Annual Thick Succulent Herb Prostrate or upright Low Embryonic Dune former Low Areas-Berm, Berm Crest Appears in most seaward locations back 10 15' from vegetation line. Unimportant as d former, stabilizer. March-Dec. Perennial Bunch grass -Upright bunches ?Soil stabilizer Low Areas to intermediate heights Often grows in clumps, usually a character istic plant of th~ barrier flats behind foredune ridge. In dense stands it may be stabilizer, adapted to relatively sterile disturbed sites. Sept.-Dec. Perennial Aquatic Low deflation zones between foreshore & high foredunes Common along coast in depression, swales a flats and along shores (Jones 1975). Frese indicates fresh ground water. Associated w FimbristyZis caroZiniana at "NoTraf." Apri Nov. Annual Woody Herbacous Shrub Erect & prostrate ?Sand/Wind Arrestor Low and inter­mediate heights somewhat pro­tected spots Cassia appears in lower areas associated w fresh water areas or protected spots. Foun on higher dunes also but the more exposed less erect and robust. Seems to appear in areas/zones which tend toward stabilizatio June-Dec. Annual Intermediate heights Frequent along the coast in openings or on island dunes (Jones 1975). Found at "NoTra among UnioZa & Spartina back from vegetati line. Aug.-Nov. Perennial Woody-based Erect Dune former Sand/Wind Arrestor Intermediate heights & fore­dune crests An abundant dune species. Often seen in de shrub forms with no other species within i area of coverage except for Ipomoea's & Un but stems are not often mixed. March-Dec. all year. Annual ?We~k Sand Binder Low deflation Not a dune former or stabilizer but does b Scapose Herb areas dunes in fore­ sand somewhat. Indicates fresh soil moistu A plant commonly found on barrier flats. Low deflation Noted as a range grass. Not an important Perennial ?Weak Sand Binder areas to some-dune species. May afford binding character Grass what intermediate tics in dense growths. Sept.-Dec. ''--~-1-.L­ -.;:----_ --.... ---~ ,.., ~ ~ -.,.. t> :.... ~.,,-5'f ii -5'WiiMC# ........____-...C.< · ?'.":; , APPENDIX A (cont.) Eragrostis speatablis Perennial Purple Lovegrass Bunch grass Erigonium myrionaatis Perennial Running Fleabane Prostrate Creeping Erigonium multiflorum Annual or Biennial Wild Buckwheat Fimbristylis aaroliniana Perennial Scapose Herb Heterotheaa subaxillaris Perennial Camphorweed Ipomoea pes-aaprae Perennial Goatfoot Morning-Glory Vine Railroad Vine Thick Stems & Leathery leaves Ipomoea stolpnifera Perennial Fiddle leaf Vine Morning-Glory Thick Stems & Beach Morning-Glory Leathery leaves . Oenothera drummondii Perennial Beach Evening Primrose Erect with spreading stems ?Weak Sand Binder ?Weak Sand Binder Sand Binder/Stabi­lizer Sand Arrestor temporary binder Sand Arrestor temporary binder Pretty Flower ...__.~ as with E. As with E. oxylepis oxyZ.epis Low deflation A weak rhizome system of surface runners may areas, swales in afford binding characteristics in dense foredunes growths. Grows abundantly in low areas of fresh soil moisture. Feb.-Dec. and earlyspring. Intermediate Encountered in protected or less exposed areas heights of fore­with Spartina & Uniola at "NoTraf" back from dunes vegetation line. Not a salt tolerant plant. Found all over barrier islands, backdunes & barrier flat hummocks. Sept.-Dec. Low deflation Not a dune former and characteristic of areas barrier flats. Encountered at "NoTraf" at base of high dune. Roots are thick and scaled indicating a binding function. Sept~-Dec. Intermediate A showy composite at intermediate heights. In heights more protected areas. One of the first plants to-reappear in the spring. April-Nov. Beach face,berm, Usually in exposed areas subject to blowing berm crest,dune~ sand and salt spray. A xerophytic haloplayte dune crests important as a pioneer and sand arrestor. Can be found along foredune face but not among fresh soil water areas. May-Dec. Intermediate Like I. pes-aaprae this plant, rooting at the heights & crests nodes, and with it__.§ robust character arrests sand and temporarily stabilizes it. I. stonoi­fera prefers less haline soils than I. pes­aaprae and is not found on the berm. April­Dec. Intermediate Often a conspicuous bloomer. This plant heights(protecte~ becomes somewhat woody with age and the to lower heights spreading upright stems can temporarily accumu­ late sand. March-Dec. APPENDIX A (cont.) Panicum amarum Bitter Panicurn Panicum portoricense Paspalum monostachyum Physalis visaosa Dune Ground Cherry Senecio riddellii Ragwort Sesuvium portulasaastrum Sea Purslane Spartina patens Marshray Cordgrass Perennial Grass Annual Grass Perennial Grass Perennial Ascending & spreading stems Perennial Perennial Succulent Xerophytic­Halophyte Perennial Grass Dune former and Stabilizer ?Sand Binder Embryonic dune former Dune former­stabili z er Intermediate When in dense stands this Panicum is an heights, crests excellent sand binder stabilizer and dune of low dunes former and is used extensively for such purposes. It however is not an important floral member at any study sites and is present only as a solitary stand at "NoTraf." Sept.-Nov. Intermediate Found at rear of low foredunes in protected heights spots. Not important here due to low frequency. Occasional on sandy soils. Sept.­Oct. Low deflation Paspalum may be an effective sand binder areas when growing in dense stands due to its deep root/rhizome system. It prefers a fresh water environment and is an abundant member of the barrier flat flora. After a fire it is one of the first plants to reappear. Sept.-Nov. Intermediate Often an abundant dune species returning heights,low dune~ early in late winter and spring. Found in dunes most locations but more often in open, more stable sands and protected areas. March-Nov. Intermediate On foredunes as clumps on protected, rela­heights in tively stable, lee faces of the dunes. This protected(lee) species is one of the first plants to return areas only in late winter and early spring(Feb). Oct.­ Nov. and throughout. Berm,berm crest, Sesuvium can be found overall in low occas­ low moist areas sionally inundated areas but its development and occurence is greatest at the vegetation line (NOTRAF) or where saltwater can reach it Berm-berm crest. April-Dec. Intermediate This very coarse grass is frequent in salty heights to dune soils and is abundant on the barrier flats. crests. Low areas May-Nov. with saline/fresh soils -W<· ..-"irt T This species grows at the vegetation line at "NoTraf" ; intermediate zones and back ranges. Ge: .erally occurs in saline soils along coast. Often confused with DistiahyZis sp. Sept.-Nov. Like Amaranthus gregii in location and functiono Not abundant at survey sites and not important except as a pioneer.May-Dec Dominant species of dunes, crest and inter­ ·mediate heights. Forms low dunes at vegetation edge at "NoTraf" and other non-traffic areas. July-Sept. This plant grows in exposed ·sites at med­ ian heights to higher elevations in relatively exposed, sterile soils. Often encountered in areas at dune base. Not salt tolerant. May-Nov., or throughout. Sporobolus virginiaus Seashore Dropseed Tidestromia Zanuginosa Rat's Ear Uniola paniauZata Sea Oats Euphorbia ammannioides Spurge APPENDIX A (cont.) Perennial Grass Annual Prostrate spreading Perennial Grass Annual ·Prostrate or trailing stems Dune Stabilizer Embryonic dune former Dune former, stabilizer, wind/ sand arrestor Not specific prefers a low relatively moist habitat and is salt tolerant as well as fresh tolerant At berm,berm crest,slightly back Berm,dune faces, dune crests Intermediate heights, open sites " --~--:::.:__:-~-~~-.:._-::-~:::.":.-------~~:::=-..=._=:::::---·---;-.--:~·--..... '1 I I, , JI I • • ~ -• U .. ~l.-.i •. ~ ,, J, L• ....-..-... .• TABLE 3 Species present at each study site. j ------·--· ~~ j • ~-• ' I • ) j I • ~ ---­ j , TABLE 3 (cont.) "' Species Senecio .. riddellii ...:I ...:I µ.:i ~ (/) ? ~ c::t: p:; 8 ~ µ.:i > x J.l:.i c::t: p:; 8 0 µ.:i p.. x ~ ~ p:; 8 0 z x Sesuvium portulacastrum x x x Spartina patens x x x Sporobolus virginicus x x x Tidestromia lanuginosa x x Uniola paniculata x x x x "' I APPENDIX A Transect vegetation itemization and density parameters by transect 1) plants grouped as types with most abundant in each group listed first 2) family NOTRAF 28/10/75 Species Grasses: Spartina patens Sporobolus virginicus Uniola paniculata Paspalurn rnonostachyurn Eragrostis oxylepis Leptolorna cognaturn Panicurn arnarum *Fimbristyli~ castanea Centrus incertus Chloris petraea Forbs: Ipornoea stolonifera Oenothera drurnmondii Erigeron myrionactis Tidestroernia lanuginosa Euphorbia ammanoides cassia fasiculata Sesuvium portulacastrum Croton punctatus Ipomoea pes-caprae **Amaranthus greggii Heterotheca subaxillaris Physalis viscosa Phyla nodiflora Ambrosia psilostachya Cyperus esculentus Cyperus spp. *less than .3% **less than 1.1% ~ M2 QUADRAT Family Grarninae Grarninae Grarninae Grarninae Grarninae Grarninae Grarninae Grarninae Grarninae Grarninae Convolvulaceae Onagraceae Compositae Arnaranthaceae Euphorbiaceae Leguminosae Aizoceae Euphorbiaceae Convolvulaceae Arnaranthaceae Cornpositae Solanaceae Verbenaceae Compositae Cyperaceae Cyperaceae NOTRAF 10...:28-75 ~ M2 QUADRAT Density Composition 410' FoliarTransect Species # Ind. %Foliar 210' Foliar to 0 MSL 2.4 Uniola paniculata 17 .015 .085 .041 Spartina patens 689 .61 3.45 1. 68 Sporobolus virginicus 104 .09 .52 .25 Paspalum monostachyum Croton punctatus 33 .03 .17 .080 Erigeron myrionactis 97 .085 . . 49 .236 Tidestroemia lanuginosa 131 .115 .66 .319 Oenothera drummondii 17 .015 .. ·• 085 .041 I. stolonifera 37 .03 .185 .090 I. pes-caprae 3 .003 .015 .007 Heterotheca subaxillaris 2 • 002 .01 .005 Cyperus esculentus 1 .001 .005 .002 Total =1131 = 5.675 = 2.751 200' 380' 2.0 Uniola paniculata 21 .OS --.105 -.055 Spartina patens 253 .64 1. 265 .666 Sporobolus virginicus 7 .02 .035 .018 Paspalum monostachyum 10 .025 .OS .026 Erigeron myrionactis 17 .04 .085 .045 Tidestroemia lanuginosa 15 .04 .075 .039 Oenothera drummondii 36 .09 .18 .095 I. stolonifera 29 .07 .145 .076 I. pes-caprae 8 .04 .02 .021 Amaranthus greggii 2 .oos .01 .oos Total = 398 = 1. 990 = 1.046 220' 415' 1.6 Uniola paniculata 35 .11 --.16 -.08 Spartina patens 40 .12 .18 .10 Sporobolus virginicus 21 .06 .095 .OS Tidestroemia lanuginosa 36 .11 .16 .09Oenothera drummondii 42 .13 .19 .10 I. stolonifera 58 .18 . • 26 .14 Cassia fasiculata 47 .14 • 21 .11 Euphorbia ammanoides 49 .15 .22 .12Total = 328 = 1.475 = .79 - NOTRAF 10-30-75 ~ M2 QUADRAT Density Composition 480' Foliar Transect Species # Ind.· %Foliar 240' Foliar to 0 MSL - 1. 2 Uniola paniculata 1 .001 .004 .002 Spartina patens 209 .32 .87 .43 Sporobolus virginicus 69 .11 .29 .14 Paspalum monostachyum 8 .01 .03 .02 Eragrostis oxylepis 13 .02 .as .03 Leptoloma cognatum 1 .001 .004 .002 Chloris petraea 1 .001 .004 .002 Fimbristylis castanea 12 .02 .OS .02S Erigeron myrionactis 48 .07 .20 .10 Tidestroemia lanuginosa 22 .03 .09 .04S Oenothera drummondii 87 .13S .36 .18 I. pes-caprae 7 .01 .03 .01 I. stolonifera 43 .07 .18 .09 cassia fasiculata 7 .01 .03 .01 Euphorbia ammanoides S2 .08 •22 .11 Phyla nodiflora 2 .003 .008 .004 Sesuvium portulacastrum S9 .09 .25 .12 Cyperus esculentus 3 ~DOS .01 .006 Total = 644 = 2.680 = 1. 326 200' 400' 0.8 Uniola paniculata 38 .11 -.19 -.09S Spartina patens 67 . 20 .33 .167 Croton punctatus 9 .03 .04S .022 I. pes-caprae 1 .003 .oos .002 I. stolonifera 117 .3S .S8S . 292 Euphorbia ammanoides 103 .31 .SlS .257 Phyla nodiflora 1 .003 .oos .002 Total = 336 = 1.670 = .837 200' 480' 0.4 Uniola paniculata 1 .003 -.oos -.002 Spartina patens 48 .16 .24 .1 Sporobolus virginicus 6 .02 .03 .012 Panicum amarum 3 .01 .015 .006 NOTRAF 10-30-75 (cont.) ~ M2 QUADRAT Density Composition 480' Foliar Transect Species # Ind. %Foliar 200' Foliar to 0 MSL 0.4 Croton punctatus 12 .04 .06 .025 Oenothera drummondii 98 .34 .49 .20 I. pes-caprae 15 .as .075 .03 I. stolonifera 55 .19 .275 .114 Sesuvium portulacastrum 53 .18 .09 .110 Total = 291 = 1. 28 = .599 NOTRAF 10-7-75 ~ M2 QUADRAT Transect Species 800 s Uniola paniculata Sporobolus virginicus Croton punctatus Tidestroemia lanuginosa Oenothera drummondii I. pes-caprae I. stolonifera Sesuvium myrionactis Total = 620 s Uniola paniculata Sporobolus virginicus Paspalum monostachyum Centrus incertus Panicum amarum Tidestroemia lanuginosa Oenothera drummondii I. stolonifera Erigeron myrionactis Cassia f asiculata Ambrosia psilostachya Amaranthus greggii Cyperus esculentus Total = Composition # Ind. % Foliar 59 28 .21 .10 271 13 9 68 6 79 9 .OS .033 .250 .022 .291 .033 43 .11 9 .022 49 .123 5 .012 12 .03 6 . .015 47 .118 85 .214 9 .022 113 • 285 9 .022 8 .020 1 .002 396 Density 345 1 Foliar 190' Foliar to 0 MSL .31 .17 .147 .08 . 068 .04 .047 .026 .357 .197 .031 .017 .415 .22 .047 .026 = 1.422 = 0.776 190'--.122 330'--.130 .047 .027 .257 .148 .026 .015 .063 .036 .031 .018 .247 .14 .447 • 257 .047 .027 .594 .342 .047 .027 .042 .024 .005 .003 = 2.778 = 1.194 NOTRAF 10-6-75 -k M2 QUADRAT Density Composition 330' Foliar Transect Species # Ind. % Foliar 210' Foliar to 0 MSL 580 s Uniola paniculata 1 .006 .005 .003 Spartina patens 4 .025 .019 .012 Leptomoma cognatum 19 .120 .090 .057 Tidestroemia lanuginosa 15 .095 .071 .045 Oenothera drummondii 17 .107 .081 .051 I. stolonifera 95 .601 .452 • 288 Cassia fasiculata 1 .006 .008 .003 Sesuvium myrionactis 6 .038 .028 .018 Total ·= 158 = .754 = .933 230' 360' 400 s Uniola paniculata 1 .002 -.004 -.003 Sporobolus virginicus 23 .057 .1 .064 Paspalum monostachyum 26 .065 .113 .072 Eragrostis oxylepis 5 .012 .022 .014 = .239 = .153 ' Oenothera drummondii 39 .097 .169 .11 I. stolonifera 239 .597 1.04 .664 I. pes-caprae 13 .033 .056 .036 Erigeron myrionactis 32 .08 .139 .089 Sesuvium myrionactis 22 .ass .096 .061 Total =400 = 1.5 = .960 220' 360' 2008 Uniola paniculata 45 • 20 -.20 --.125 Sporobolus virginicus 40 .18 .18 .111 Eragrostis oxylepis 18 .08 .08 .OS Croton punctatus 26 .12 .12 .072 Tidestroemia lanuginosa 22 .10 .10 .061 Oenothera drurhmondii 3 .01 .01 .008 I. stolonifera 63 • 28 .28 .175 Sesuvium myrionactis 5 .02 .02 .138 Total = 222 = .9945 = .740 NOTRAF Preliminary Date 10-3-75 Composition Transect Species # Ind. % Foliar 0 Uniola paniculata 42 .12 Spartina patens 98 •28 Sporobolus virginicus 2 .005 Paspalum monostachyum 48 .14 Eragrostis oxylepis 15 .04 Leptomoma cognatum 6 .02 Fimbristylis castanea 6 .02 Croton punctatus 2 .005 Erigeron myrionactis 58 .17 Tidestroemia lanuginosa 1 .003 Oenothera drummondii 7 .02 I. pes-caprae 2 .oos I. stolonifera 36 .10 cassia fasiculata 8 .02 Physalis viscosa 1 .003 Sesuvium myrionactis 4 .01 Amaranthus greggii 2 .005 Cyperus esculentus 1 .003 Cyperus unk. #3 8 .02 Total = 347 ~ M2 QUADRAT Density 360' Foliar 196' Foliar to 0 MSL •21 .116 .5 • 272 .01 .006 .24 .133 .08 .041 .03 .017 .03 .017 .01 .006 .30 .161 .oos .003 .04 .020 .01 .OQ6 .18 .10 .04 .02 .oos .003 .02 .011 .01 .006 .oos .003 .04 .022 = 1. 765 = .963 m = 2.019 m = 1.089 Tot. 24.2225 13.068 Tot. VEHTRAF Grasses: Forbs: ,'( 0. 2% ** 0.1% 28/10/75 Species· . Spartina patens Uniola paniculata *Panicum amarum Ipomoea stolonifera Croton punctatus cassia f asiculata Ipomoea pes-caprae Tidestroemia lanuginosa Oenothera drummondii Euphorbia ammanoides **Sesuvium portulacastrum ~ M2 QUADRAT Family Graminae Graminae Graminae Convolvulaceae Euphorbiaceae Leguminosae Convolvulaceae Amaranthaceae Onagraceae Euphorbiaceae Aizoceae 2 VEHTRAF 10-28-75 ~ m QUADRAT Composition Density 360' Foliar Transect Species #Ind. % Foliar 150' Foliar to 0 MSL 2.3 Uniola paniculata 7 .08 .046 .019 Spartina patens 4 .05 .266 .011 Croton punctatus 11 .13 .073 .03 I. stolonifera 47 .55 .31 .13 Sesuvium portulacastrum 3 .03 .02 .008 Euphorbia ammanoides 8 .095 .053 .02 Tidestroemia lanuginosa 4 .05 .026 .011 Total = 84 = .794 = .229 230' . 360' 2.0 Croton punctatus 45 .21 .195 .125 I. pes-caprae 1 .005 .004 .003 I. stolonifera 107 .50 .465 .30 Oenothera drummondii 55 .26 .24 .15 Tidestroemia lanuginosa 4 .02 .02 .01 Total = 212 = .92 = .59 200' 390' 1.7 Uniola paniculata 1 .004 .05 .002 Spartina patens 91 .39 .455 .23 Croton punctatus 84 .36 .42 .21 I. stolonifera 37 .16 .185 .09 I. pes-caprae 2 .01 : .01 .005 Tidestroemia lanuginosa 17 .07 .085 .04 Total = 232 = 1.120 = .577 VEHTRAF 10-28-75 (cont.) \ m2 QUADRAT Transect Species Composition #Ind. % Foliar 240' Density420' Foliar Foliar to 0 MSL 1.4 Uniola paniculata 18 .05 .075 .04 Croton punctatus I. stolonifera I. pes-caprae Cassia fasiculata 90 34 10 237 .23 .09 .02 .61 .375 .14 .04 .21 .08 .02 Total = 389· = 1.62 = .91 VEHTRAF le; m2 QUADRAT Transect Species Composition #Ind. %Foliar 110' Density 410' Foliar Foliar to 0 MSL 1.0 (10-23-75) Croton punctatus I. stolonifera 50 103 .33 .67 .45 .94 .12 .25 Total = 153 = 1.39 = .37 170' 360' 0.6 (10-23-75) Uniola paniculata I. stolonifera I. pes-caprae Cassia fasiculata 49. 55 35 4 .34 .. 38 .24 .03 .28 .32 .21 .02 .136 .152 .097 .01 Total = 143 = . 83 = .395 240' 385' lOOON (10-8-75) Spartina patens I. stolonifera I. pes-caprae Tidestroemia lanuginosa 17 33 24 5 .215 .42 .30 .06 .071 .14 .10 .021 .044 .085 .062 .013 Total = 79 = .332 = .204 220' 420' 800N (10-8-75) I. stolonifera Tidestroemia lanuginosa 41 16 . 72 .28 .19 .07 .09 .038 Total = 57 = •33 = .164 VEHTRAF ~ m2 QUADRAT Composition Density 430' Foliar Transect Species #Ind. %Foliar 235' Foliar to 0 MSL 600 N (10-8-75) Uniola paniculata Croton punctatus I. stolonifera Cassia fasiculata 14 112 59 28 .065 .525 .28 .13 .06 .48 .25 .12 .03 .26 .13 .065 Total = 213 = .91 = . 485 210' 430' 400N (10-8-75) Spartina patens Panicum amarum Croton punctatus I. stolonifera I. pes-caprae Tidestroemia lanuginosa 101 4 7 99 1 41 . 40 .02 .03 .39 .004 .16 . 48 . .019 .03 .47 .005 .195 .23 .009 .016 .23 .002 .09 Total = 253 = 1.20 = . 57 185' 370' 200N (10-9-75) Uniola paniculata Spartina patens Croton punctatus I. stolonifera Cassia fasiculata Tidestroemia lanuginosa Total = 13 70 9 145 5 9 251 .05 .28 .03 .58 .02 .035 .07 .38 .05 .78 .03 .05 = 1.36 = .035 .189 .02 .039 .013 .02 .316 VEHTRAF Transect Species 0N Uniola paniculata (10-9-75) Croton punctatus I. stolonifera I. pes-caprae Cassia fasiculata Euphorbia amrnanoides Total ~ m2 QUADRAT Composition Density 350' Foliar #Ind. % Foliar 190' Foliar to 0 MSL 36 .17 .19 .10 2 .009 .01 .006 108 .502 .57 .31 40 .19 .21 .11 21 .097 .11 .06 8 .. 04 .04 .02 = 215 = 1.13 = .606 m = 1.015 m -= • 4·61 Total 12.184 Total 5.54 SHELL 21/10/75 Species Grasses: Uniola paniculata Forbs: Cassia fasiculata Heterotheca subaxillaris Ipomoea stolonifera Croton punctatus Ipomoea pes-caprae PEDTRAF 9/10/75 Species Grasses: Paspalum monostachyum Uniola paniculata Sporobolus virginicus Schizachyrium scoparius Forbs: cassia f asiculata Croton punctatus Ipomoea stolonifera Sesuvium portulacastrum Tidestroemia lanuginosa Euphorbia amrnanoides Amaranthus greggii Oenothera drumrnundii Ipomoea pes-caprae 1­ 4 M2 QUADRAT Family Graminae Leguminosae Compositae Convolvulaceae Euphorbiaceae Convolvulaceae ~ M2 QUADRAT Family Graminae Graminae Graminae Graminae Leguminosae Euphorbiaceae Convolvulaceae Aizoceae Amaranthaceae Euphorbiaceae Amaranthaceae Onagraceae Convolvulaceae SHELL ~ m2 QUADRAT Composition Density 340' Foliar Species #Ind. % Foliar 203' Foliar to 0 MSL 10-21-75 Uniola paniculata 33 27 .163 .097 Croton punctatus 7 6 .034 .021 Cassia fasiculata 40 33 .197 .118 Heterotheca subaxillaris 32 26 .153 .094 I. pes-caprae 1 .8 .005 .003 I. stolonifera 9 7 .044 .026 = .596 = .359 Total 122 PEDTRAF 222' 10-9-75 Uniola paniculata 39 6.5 .18 none Paspalum monostachyum 60 10 .27 none Schizachyrium scoparius 1 .2 .005 none Sporobolus virginicus 4 .1 .02 none Croton punctatus 124 21 .56 none Cassia fasiculata 169 28 .76 none Oenothera drummundii 24 4 .11 none .I. pes-caprae 6 1 .03 none I. stolonifera 47 8 .21 none Euphorbia ammanoides 31 5.2 .14 none Amaranthus greggii 27 4.5 .12 none Tidestroemia lanuginosa 32 5.4 .14 none S. portulacastrum 33 5.5 .15 none Total 597 = 2.695 NOTRAF 28/10/75 POINT FRAME Grasses: Forbs: * less than .5% ** less than 1.2% Species Uniola paniculata Spartina patens Sporobolus virginicus Paspalum monostachyum Eragrostis oxylepis *Leptoloma cognatum Panicum amarum Centrus incertus Oenothera drummundii Ipomoea stolonifera Cassia fasiculata Tidestroemia lanuginosa . Croton punctatus Erigeron myrionactis Sesuvium portulacastrum Ipomoea pes-caprae **Euph9rbia ammanoides Ambrosia psilostachya Amaranthus greggii Cyperus sp. Family Graminae Graminae Graminae Graminae Graminae Graminae Graminae Graminae Onagraceae Convolvulaceae Leguminosae Amaranthaceae Euphorbiaceae Compositae Aizoceae Convolvulaceae Euphorbiaceae Compositae Amaranthaceae Cyperaceae NOTRAF 10-28-75 POINT FRAME Transect 2.4 Species Uniola Spartina Sporobolus Pasp. mono. # Ind. 2 28 3 4 Composition· %Foliar %Basal .01 .08 •21 .02 .03 %Ground .oos 210' Foliar .01 .14 .015 .02 Density Basal Ground .oos .oos 410' Foliar to 0 MSL .oos .068 .007 .010 Tidestroemia Croton Oenothera Erigeron I. stolonifera AL~ BG* GL* 12 7 5 7 5 62 173 12 .09 .OS .04 .as .04 .46 .53 .15 .23 .02 .005 .02 .90 .06 .057 .033 .025 .033 .025 .31 .035 .Ol .015 .015 .oos .015 .865 .06 .029 .017 .012 .017 .012 .151 = .668 = .328 2.0 Uniola Spartina Oenothera Erigeron I. stolonifera AL* BG* GL* 5 27 4 5 l so 169 5 .os .30 .04 .as .01 .54 l.O .006 .97 .03 -200' .025 .135 .02 .025 .005 .25 .025 .025 .845 .025 380'-.013 .071 .010 .013 .003 .132 = .325 = .242 NOTRAF Transect Species 1. 6 Uniola Spartina Sporobolus Tidestroemia Cassia Euphorbia Oenothera I. stolonifera AL* BG* GL* *AL = aerial litter; BG = # Ind. 25 2 1 2 12 4 6 7 43 187 7 bare ground; 10-28-75 (cont.) Composition % Foliar %Basal %Ground .24 .02 .14 .oos .01 .14 .005 .02 .28 .oos .12 .04 .06 .14 .oos .07 .28 .01 .42 .94 .035 GL = ground litter 220' Foliar .11 .01 .004 .01 .OS .02 .03 .03 .195 = .459 POINT FRAME Density Basai Ground .004 .004 .004 .004 .01 .004 .01 .01 .85 .03 415' Foliar to 0 MSL .060 .DOS .002 .DOS .029 .010 .014 .017 .104 = .468 NOTRAF 10-30-75 POINT FRAME Composition · Density 240' 480' Foliar Transect Species # Ind. %Foliar %Basal %Ground Foliar Basal Ground to 0 MSL 1.2 Uniola 3 .04 .0125 .006 Spartina 12 .16 .11 .009 .OS .01 .01 .025 Sporobolus 6 .08 .os .004 .02 .004 .004 .012 Eragrostis 2 .03 .01 .004 Tidestroemia 8 .11 .03 .017 Euphorbia 4 .07 .os .004 .02 .004 •004 .008 Oenothera 9 .12 .28 .01 .04 .02 .01 .019 Erigeron 4 .OS .17 .009 .02 .01 .01 .008 I. pes-caprae 1 .01 .004 .002 I. stolonifera 2 .03 .33 .03 .01 .02 .02 .004 Sesuvium 2 .03 .01 .004 AL* 21 • 28 .08 .044 BG* 212 .93 .85 GL* 1 .004 .004 = .306 = .153 200' 4QQT - 0.8 Uniola 30 .30 .25 .oos .15 .01 .DOS .075 Spartina 4 .04 .02 .01 Croton 3 .03 .015 .007 Euphorbia 11 .11 .375 .011 .06 .015 .01 .027 I. stolonifera 21 .21 • 375 .011 .11 .015 .015 .052 AL* 32 .32 .16 .080 BG* 175 . 938 . .875 GL* 8 .042 .04 = .515 = .234 NOTRAF 10-30-75 (cont.) POINT FRAME Composition Density I 200' 480' Foliar Transect Species # Ind. %Foliar %Basal %Ground Foliar Basal Ground to 0 MSL 0.4 Uniola 3 .06 .015 .006 Spartina 3 .06 .015 .006 Croton 5 .10 .025 .010 Euphorbia 1 .02 .005 .002 Oenothera 16 .31 .428 .017 .08 .015 .015 .033 I. pes-caprae 3 .06 .015 .006 I. stolonifera 5 .10 .428 .017 .025 .015 .015 .010 Sesuvium 3 .06 .143 .006 .015 .005 .005 .006 AL* 12 .235 .06 .025 BG* 163 .953 .815 GL* 1 .006 .015 = .255 = .104 *AL =aerial litter; BG -bare ground; GL =ground litter NOTRAF 10-7-75 POINT FRAME Transect Species # Ind. Composition · %Foliar %Basal %Ground 200' Foliar Density Basal Ground 345' Foliar to 0 MSL 800 s Uniola Sporobolus 30 2 .33 .02 .6 .02 0.15 0.01 .015 .015 .087 .006 Oenothera I. stolonifera I. pes-caprae Sesuvium AL* 11 3 1 l · 43 .12 .03 .01 .01 .47 .2 .2 .01 0.055 0.015 0.005 0.005 0.215 .005 .005 .005 .005 .032 .009 ,003 .003 .125 BG* GL* 140 19 .85 .11 .70 .095 = .455 = .265 190' . - 330'- 620 s Uniola Panicum Sporobolus Centrus 22 1 1 0 .. 16 .01 .01 0 .10 .10 .20 .006 .006 .006 .116 .005 .oos 0 .005 .005 .01 .005 .005 .oos .067 .003 0 Tidestroemia cassia Oenothera Ambrosia I. stolonifera AL* 0 34 9 2 3 68 0 .24 .06 .01 .02 .49 .20 .40 .,006 .02 0 .179 .005 .001 .002 .036 .01 .02 .005 .016 0 .103 .027 .006 .009 .206 B3* GL* 144 13 .88 .08 .76 .04 = . 349 = .422 NOTRAF Transect 59a s Species Cyperus Tidestroemia Cassia Oenothera I. stolonifera AL* BG* GL* * AL = aerial litter; BG = 3 .as .014 1 .a2 .oos 3 .as .a14 25 .43 . 40 .al .119 14 .24 • 6a .a3 .067 12 • 21 .057 98 .90 7 .a6 = c279 bare ground; GL =ground litter .009 .003 .ao9 .076 .042 .036 ia-7-75 (cont.) POINT FRAME # Ind. Composition %Foliar %Basal %Ground 2ia' Foliar Density Basal Ground 330' Foliar to 0 MSL .009 .oos .a14 .014 .47 .03 = .17S NOTRAF POINT FRAME Composition Density Transect Species # Ind. % Foliar %Basal %Ground 230' Foliar Basal Ground 360' Foliar to 0 MSL 400 s Eragrostis 1 .03 .004 .003 Oenothera Erigeron I.stolonifera I.pes-caprae Sesuvium AL* 8 0 16 2 6 2 .23 .46 .06 .17 .06 .14 •29 •29 .21 .07 .005 .005 .009 .014 .005 .035 .069 .009 .026 .009 .009 .017 .017 .013 .004 .004 .004 .013 .009 .004 .022 .044 .006 .017 .006 BG* GL* 172 35 .80 .16 .75 .15 = .152 = .093 220'- 360'- 200 s Uniola Sporobolus 9 2 .15 ~03 .125 .008 .041 .009 .004 .004 .025 .006 Tidestroemia Croton Oenothera I. stolonifera AL* 6 14 6 4 19 .10 .23 .10 .07 .32 .125 .625 .125 .008 .024 .008 .027 .064 .027 .018 .086 .004 .023 .004 .004 .014 .004 .017 .039 .017 .011 .053 BG* GL* 108 10 .87 .08 .490 .045 •30 .03 = .272 = .168 NOTRAF Transect 0 Species Uniola Spartina Eragrostis Paspalum Leptoloma Tidestroemia cassia Oenothera Erigeron I. stolonifera Amaranthus AL* BG* GL* *AL = aerial litter; BG = # Ind. 33 11 2 10 2 1 15 1 7 8 1 87 178 23 bare ground; Composition %Foliar %Basal .185 .06 .01 .06 .44 .01 .005 .08 .005 .04 .04 .005 .49 .11 .33 .11 GL = ground litter %Ground .02 .005 .01 .005 .855 .11 Total 196' Foliar .168 .056 .010 .Q51 .010 .005 .076 .005 .036 .041 .005 .444 = .907 4.942 POINT FRAME Density Basal Ground 360' Foliar to 0 MSL .02 .020 .092 .031 .006 .028 .005 .015 .005 .005 .010 .oos .006 .003 .042 .003 .019 .022 .003 .242 .908 .117 .494 .064 = .557 Total 2.171 ~;;:., VEHTRAF 23/10/75 POINT FRAME Grasses: Forbs: ,."l. 0% ,."* •5% Species Uniola paniculata Spartina patens ,t:Panicum amarum Ipomoea stolonifera Croton punctatus Cassia f asiculata Ipomoea pes-caprae Tidestroemia lanuginosa Oenothera drummundii **Euphorbia ammanoides Family Graminae Graminae Graminae Convolvulaceae Euphorbiaceae Leguminosae Convolvulaceae Amaranthaceae Onagraceae Euphorbiaceae VEHTRAF 10-23-75 POINT FRAME Transect 2.3 Species Uniola Spartina #Ind. 1 2 Composition %Foliar %Basal %Ground .05 .2 .01 .09 150' Foliar •.007 .013 Density Basal Ground .007 .007 360' Foliar to 0 MSL .003 .005 I. stolonifera Tidestroemia AL* 10 0 8 .48 0 .38 . 4 . 4 .01 .01 .067 .05 .• 013 .013 .007 .007 .02 BG* GL* 92 1 .96 .01 .61 .007 = .137 = . 058 230' 360 1 2.0 I. stolonifera Croton Oenothera AL* 10 6 6 1 .43 .26 .26 .04 .44 .44 .11 .05 .025 .01 .04 .03 .03 .004 .02 .02 .004 .02 .009 .004 .03 .02 .02 .003 BG* GL* 69 2 .88 .025 .3 .009 = .104 = . 073 200' 390' 1.7 Spartina 6 .14 .003 .015 I. stolonifera Croton AL* 1 28 7 .02 .67 .17 .67· .33 .01 .01 .005 .14 .035 .01 .. 005 .005 .005 .002 .072 .018 BG* GL* 98 0 .98 .00 .049 0 = .183 = .107 VEHTRAF 10-23-75 (cont.) POINT FRAME Transect Species #Ind. %Foliar %Basal %Ground 240' Foliar Density Basal Ground 420' Foliar to 0 MSL 1.4 Uniola 12 .11 .05 .028 I. stolonifera Croton Cassia AL* 3 32 37 24 .03 .30 .34 .22 .57 .43 .03 .01 .13 .15 .10 .016 .012 .016 .008 .007 .076 .080 .057 BG* GL* 123 8 .90 .06 .51 .03 = .44 = .256 110' 410' 1.0 Uniola 2 .05 .02 .005 I. stolonifera Croton AL* 21 13 6 .50 ,31 .14 .78 .22 .04 .01 .19 .12 .054 .06 .02 .04 .009 .051 .032 .015 BG* GL* 93 5 . 90. .05 = .384 = .103 170' 360 1 o.6 Uniola 17 .24 . 2 .007 .10 .012 .006 .047 I. stolonifera I. pes-caprae Cassia AL* BG* GL* 9 11 · 8 26 111 7 .13 .15 .11 .37 .4 . 4 .03 . . 02 .88 .055 = .05 .06 .05 .15 . 41 .023 .023 .023 .018 .65 .04 = .025 .030 .022 .072 .196 *AL=aerial litter; BG=bare ground; GL=ground litter VEHTRAF 10-8-75 POINT FRAME Transect Species #Ind. Composition % Foliar %Basal %Ground 240' Foliar Density Basal Ground 385' Foliar to 0 MSL lOOON Spartina 1 .06 .22 .01 .004 .008 .004 .002 I. stolonifera I. pes-caprae AL* 3 11 2 .18 .65 .12 .22 .56 .01 .04 .012 .096 .008 .008 .021 .004 .021 .008 .028 .005 BG* GL* 105 11 .85 .09 .437 .046 = . 07 = .043 220' 420' SOON I. stolonifera Tidestroemia AL* 8 1 1 .80 .10 .10 . 75 . 25 .03 .01 .036 .004 .004 .014 .004 .009 .004 .019 .002 .002 BG* GL* 66 .96 .30 = .044 = .023 235' 430' 600N Uniola 9 .12 .038 .021 I. stolonifera Croton Cassia AL* 5 37 17 6 .07 .50 .23 .08 .25 . 75 .02 .02 .021 .157 .072 .025 .013 .038 .013 .013 .012 .086 .039 .014 BG* GL* 99 16 .82 .13 .421 .068 = .313 = .171 VEHTRAF 10-8-75 (cont.) POINT FRAME Composition Density 230' 430' Foliar Transect Species #Ind. %Foliar ~ Basal %Ground Foliar Basal Ground to 0 MSL 400N Spartina 3 .11 .013 .007 Panicum 1 .035 .004 .002 I. stolonifera 9 .32 .82 .06 .039 .039 .030 .021 Croton 4 .14 .09 .01 .017 .004 .004 .009 Tidestroemia 9 .32 .09 .01 .039 .004 .004 .021 AL* 2 .07 .009 .005 BG* 91 .87 .396 GL* 5 .05 .022 = .121 = .065 185' 370' 200N Uniola 4 .10 .022 .011 Spartina 5 .12 .027 .013 I. stolonifera 23 .56 .90 .055 .124 .049 .032 .062 Croton 1 .02 .10 .009 .005 .005 .005 .003 Tidestroemia 1 .02 .005 .003 AL* 7 .17 .038 .019 BG* 98 .91 .53 GL* 3 .03 .016 = .221 = .111 *AL=aerial litter; BG=bare ground; GL=ground litter VEHTRAF 10-9-75 POINT FRAME Composition Density 190' 350' Foliar Transect Species #Ind. %Foliar %Basal %Ground Foliar Basal Ground to 0 MSL ~ Uniola 18 .37 .08 .01 .09 .005 .005 .051 I. stolonifera 12 .25 .25 .01 .06 .015 .02 .034 I. pes-caprae · 9 .19 .67 .03 .05 .042 .01 .026 Cassia 4 .08 .02 .011 Euphorbia 2 .04 .01 .006 AL* ·3 .06 .015 .008 BG* 122 .96 .64 GL* 0 = .245 = .136 Total 2.672 Total 1. 342 *AL=aerial litter; BG=bare ground; GL=ground litter SHELL Grasses: PEDTEl\F Grasses: 21/10/75 Species Uniola paniculata Heterotheca subaxillaris cassia fasiculata Croton punctatus Ipomoea pes-caprae 9/10/75 Species Paspalum monostachyum Uniola paniculata cassia fasiculata Croton punctatus Tidestroemia lanuginosa Amaranthus greggii Ipomoea stolonifera Euphorbia ammanoides Ipomoea pes-caprae Sesuvium portulacastrum Oenothera drummundii POINT FRAME Family Graminae Compositae Leguminosae Euphorbiaceae Convolvulaceae POINT FRAME Family Graminae Graminae Leguminosae Euphorbiaceae Amaranthaceae Amaranthaceae Convolvulaceae Euphorbiaceae Convolvulaceae Aizoceae Onagraceae SHELL POINT FRAME Composition Density 340' Foliar Species #Ind % Foliar % Basal %Ground 203' Foliar Basal Ground to 0 MSL 10-21-75 Uniola paniculata 4 8 50 1 .019 .015 .005 .012 Croton punctatus Cassia fasiculata I. pes-caprae Heterotheca subaxillaris AL* 3 6 1 11 25 6 12 2 22 50 17 33 1 1 .015 .030 .005 .054 .123 .005 .010 .005 .005 .015 .018 .003 .032 .074 BG* GL* 1 85 96 1 .42 .005 Total = .246 = . 030 = .154 PEDTRAF 222' (NONE) 10-9-75 Uniola paniculata Paspalum monostachyum 9 10 5 6 20 .5 . o.41 .045 .009 .004 Tidestroemia lanuginosa Croton punctatus Cassia fasiculata Euphorbia ammanoides Oenothera drummundii I. pes-caprae I. stolonifera Amaranthus greggii S. portulacastrum AL* BG* GL* Total 17 27 56 5 1 4 6 8 4 21 184 3 10 16 33 3 .5 2 4 5 2 12.5 30 20 20 10 1.0 1.0 .5 .5 95 1.5 = .076 .122 .25 .023 .005 .018 .027 .036 .018 .095 .756 .014 .009 .009 .004 .009 .009 .004 .004 .83 *AL=aerial litter; BG=bare ground; GL=ground litter APPENDIX B Beach elevations, widths, and volumes to MSL PADRE ISLAND NATIONAL SEASHORE Avg. Elevations/transect (to O'MSL) Ave. Ave. Ave. Bare Veg. Transect Veg. Bare Totl. Trans. Beach El. Veg. El. Beach El. Distance Distance Vol. Vol. Vol. Not. 0 4.72 6.39 2.63 200' 360' 1278 421 1699 Not. 2008 5.19 6.72 2.80 220' 360' 1478 392 1870 Not. 400S 4.72 6.01 2.45 230' 360' 1382 319 1701 Not. 580S 5.18 6.61 2.68 210' 330' 1388 322 1710 Not. 6208 5.12 7.27 2.2 190' 330' 1381 308 1689 Not. 8008 4.75 6.40 2.47 190' 345' 1216 383 1599 Not. .4 mi. 4.46 6.34 2.26 200' 370' 1268 384 1652 Not. .8 mi. 4.99 7 .. 32· 2.66 200' 400' 1464 532 1996 Not. 1. 2 mi. 4.20 5.96 2.44 240' 480' 1430 586 2016 Not. 1. 6 mi. 4.42 6.55 2.01 220' 415' 1441 392 1833 Not. 2. 0 mi. 4.34 6.24 2.22 200' 380' 1248 400 1648 Not. 2.4 mi. 4.59 6.71 2.37 210' 410' 1409 474 1883 m = 4.72 6.54 2.43 209' 378' 1365 409 1779 = . 33 = .43 = .23 = 15.6 = 43 = 90 = 84 = 135 Veh~ 0 5.18 7.64 2.26 190' 350' 1452 362 1814 Veh. 200N 5.19 7.80 2.58 185' 370' 1443 477 1920 PADRE ISLAND NATIONAL SEASHORE (cont.)I Trans. Ave. Beach El. Ave. Veg. El. Ave. Bare Beach El. Veg. Distance Transect Distance Veg. Vol. Bare Vol. Totl. Vol. Veh. 400N 5.16 7.20 3.22 210' 430' 1512 708 2220 Veh. 600N 5.68 8.42 2.38 235' 430' 1979 464 2443 Veh. SOON 4.10 5.82 2.21 220' 420' 1280 442 1722 Veh. lOOON 4.87 6.24 2.61 240' 385' 1498 378 1876 Veh. .6 mi. 5.86 8.22 3.74 170' 360' 1397 711 2108 Veh. 1. 0 mi. 4.63 8.71 3.14 110' 410' 958 942 1900 Veh. 1.4 mi. 6.15 8.25 3.35 240' 420' 1980 603 2583 Veh. 1. 7 mi. 6.28 8.92 3.50 200' 390' 1784 665 2449 Veh. 2.0 mi. 4.78 6.35 2.01 230' 360' 1461 261 1722 Veh. 2.3 mi. 4.61 7.17 2.78 150' 360' 1075 584 1659 m = 5.21 7.56 2.81 196' 391' 1485 550 2035 = •67 = 1.02 = . 56 = 40 = 30 = 313 =189 = 319 Shell. 4.91 7.39 4.02 90' 340' 665 1005 1670 Pedtraf. - 7.04 - 220' - 1549 ST. Not. Not. Not. Not. Not. Not. Not. Not. Not. Not. Not. Not. Veh. Veh. Veh. Veh. Veh. Veh. Veh. Veh. Veh. Veh. Veh. Veh. Shell Sand Storage above "hurricane beach" 0-Berm. 0-Veg. Volume Volume Veg .-Berm. 0 466 372 94 200S 461 460 1 400S 351 351 0 5SOS 6S9 654 35 620S 970 S54 124 SOOS 722 676 46 .4 mi. 73S 710 439 .s S92 S92 0 1.2 64S 2S4 364 1. 6 2S9 216 73 2.0 432 432 0 2.4 736 31S 41S m= 616 = 214 m= 51S = 229 m = 133 0 6Sl 549 132 200N 644 611 33 400N 1077 565 512 600N 946 557 3S9 SOON 737 217 520 lOOON S33 241 -592 • 6 mi. 927 662 265 1.0 656 435 221 1.4 12S3 194 10S9 1.7 1065 -60 1125 2.0 1132 -531 1663 2.3 670 -131 SOl 200 532 207 325 Pedtraf. 265 906 702 204 m = 1007 m = 410 = 2S5 ffi·= 656 APPENDIX C Beach Profiles September -October 1975 0 s s s s s 10 8 ..... 6 w ~ I 800 s w LL. 4 2 0 0 100 200 300. 400 500 FEET 10 . 100 200 300 400 500 FEET 1000 N VEHTRAF I 0/ 9 /7 5 800 N 600 N 400 N 10 200 N 8 I-6 w w u.. 4 0 N 2 0-------------------_..._____________ 0 100 200 300 400 500 FEET 10 8 )-6 lJJ lJJ 4 LL. ... ..__ 2 0 0 100 200 300 400 500 FEET SHELL 21/ 10/75 '', _,__ PEDTRAF 9/ 10/75 " .. ... ' . ' .(J · , ' . .··.. ~) ' ·.. ... ... .. . , ' ..... .__ ,, __,_ 10 8 t-6 w w l.1...' 4 2 o--_...___.___...____._________________..__.... 0 I 00 200 300 400 500 FEET