2003 Prescribed Burn Effect on Chihuahuan Desert Grasses and Shrubs at the Sevilleta National Wildlife Refuge, New Mexico: Species Composition Study (2004-present)

Disturbance from fire can affect the abundance and distribution of shrubs and grasses in arid ecosystems. In particular, fire may increase grass and forb production while hindering shrub encroachment. Therefore, prescribed fires are a common management tool for maintaining grassland habitats in the southwest. However, Bouteloua eriopoda (black grama), a dominant species in Chihuahuan Desert grassland, is highly susceptible to fire resulting in death followed by slow recovery rates. A prescribed fire on the Sevilleta National Wildlife refuge in central New Mexico in 2003 provided the opportunity to study the effects of infrequent fires on vegetation in this region. This study was conducted along a transition zone where creosote bushes (Larrea tridentata) are encroaching on a black grama grassland. Before and after the fire, above ground plant productivity and composition were monitored from 2003 to present. Following the prescribed fire, there were fewer individual grass clumps and less above ground grass cover in burned areas compared to unburned areas. This decrease in productivity was primarily from a loss of B. eriopoda. Specifically, B. eriopoda density and cover were significantly lower following the fire with a slow recovery rate in the five years following the fire. Other grasses showed no such adverse response to burning.火灾干扰可改变干旱生态系统中灌木与草本植物的丰度与分布格局。具体而言，火烧可提升草本植物与非禾本科草本植物（forb）的生产力，同时抑制灌木入侵。因此，受控火烧（prescribed fire）是美国西南部维持草原生境的常用管理手段。然而，奇瓦瓦沙漠草原的优势种——黑格兰马草（Bouteloua eriopoda，black grama）对火灾极为敏感，受火后会大量死亡且恢复速率缓慢。2003年，新墨西哥州中部的塞维利塔国家野生动物保护区实施了一场受控火烧，为探究低频火烧对该区域植被的影响提供了研究契机。本研究开展于一处过渡带内，该区域中三齿拉雷亚灌木（Larrea tridentata）正入侵黑格兰马草草原。自2003年至今，研究人员持续监测了火烧前后的地上植物生产力与群落组成。与未火烧区域相比，火烧区域的草本簇数量与地上草本盖度均有所下降。该生产力下降主要源于黑格兰马草的种群损失。具体而言，火烧后黑格兰马草的密度与盖度均显著降低，且在火烧后的五年内恢复速率缓慢。其余草本植物则未出现此类针对火烧的负面响应。