Resilience and alternative stable states after desert wildfires

Improving models of community change is a fundamental goal in ecology and has renewed importance during global change and increasing human disturbance of the biosphere.  Using the Mojave Desert (southwestern USA) as a model system, invaded by non-native plants and subject to wildfire disturbances, we examined models of resilience, alternative stable states, and convergent-divergent trajectories for 36 years of plant community change after 31 wildfires in communities dominated by the native shrubs Larrea tridentata or Coleogyne ramosissima.  Perennial species richness on average was fully resilient within 23 years after disturbance in both community types.  Perennial cover was fully resilient within 25 years in the Larrea community, but recovery was projected to require 52 years in the Coleogyne community.  Species composition shifts were persistent, and in the Coleogyne community, the projected compositional recovery time of 550 years and increasing resembled a deflected trajectory towa...

优化群落变化模型是生态学的核心研究目标之一，在全球变化加剧、人类对生物圈的干扰愈发严重的当下，这一目标的重要性愈发凸显。本研究以受外来植物入侵且易受野火干扰的美国西南部莫哈韦沙漠为模式系统，针对以本土灌木三齿拉瑞阿（Larrea tridentata）和黑果木（Coleogyne ramosissima）为优势种的群落，基于31场野火后36年的植物群落变化数据，检验了恢复力、备选稳定态（Alternative Stable States）以及趋同-趋异轨迹相关模型。两类群落的多年生植物物种丰富度均在干扰后23年内实现完全恢复。三齿拉瑞阿群落的多年生植物盖度可在干扰后25年内实现完全恢复，而黑果木群落的盖度恢复预计需要52年。物种组成的变化呈现持续性特征；在黑果木群落中，预计的组成恢复时长达550年且仍在增加，这一趋势类似偏转轨迹向……