From the foothills to the crest: landscape history of the southern Manzano Mountains, central New Mexico, USA since 1800

In ~1800, after abandoning the area for about 120 years, Hispanic settlers reoccupied the eastern Manzano Mountain region. Livestock, particularly sheep introduced by these early residents, and later cattle brought in by Anglo-American settlers in the late 19th century, modified forest structure and composition. By the early 1900s, extensive commercial logging exacerbated the effects of overgrazing. Coupled with fire suppression, a much different landscape exists today than 200 years ago. First account records such as travel diaries, and more importantly, the field notes of the US Public Land Survey System document the increasing effect of human agency on this locale. Analysis of US Forest Service grazing allotment files revealed much of the area suffered from overgrazing early in the 20th century. By 1880, dense underbrush had replaced the forest understory of grasses and forbs in much of the area. Logging, spurred by railroad construction’s need for lumber and crossties, removed much of the open stand ponderosa pine timber, especially from the eastern side of the range. Because of fire suppression since ~1900, forest density has increased considerably. Fuel loads are high and the danger of catastrophic fire is now a real danger in many areas. Furthermore, fire suppression resulted in the decline of mountain meadows that periodic but low intensity fire helped maintain. Dense stands of coniferous forest now intercept substantial amounts of precipitation resulting in less groundwater recharge and a decline in stream flow. Livestock overgrazing removed surface vegetation such as grass and forbs fostering arroyo cutting and surface erosion. Livestock damage riparian habitat and areas around springs and cienegas by trampling, selective grazing, and fecal contamination. Moreover, facilities associated with livestock production such as corrals and water points cause serious local disturbance and landscape degradation. Animal trails to and from these areas intensify soil erosion and vegetation damage. Recreation activities and facilities, and subdividing surrounding private lands into “ranchettes” for suburban residents are creating additional pressure on the Manzano Mountain region. Unchecked or uncontrolled these newer factors may exceed the landscape degradation effects of earlier more traditional uses.