Grass-Shrub Competition in Arid Lands: An Overlooked Driver in Grassland–Shrubland State Transition?
Grass-Shrub Competition in Arid Lands: An Overlooked Driver in Grassland–Shrubland State Transition?
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DOI：
10.1007/s10021-018-0290-9
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发表时间：
2018-08
期刊：
影响因子：
3.7
通讯作者：
Nathan A. Pierce;S. Archer;B. Bestelmeyer;D. James
中科院分区：
文献类型：
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作者：
Nathan A. Pierce;S. Archer;B. Bestelmeyer;D. James
传统的干旱土地状态转换模型强调干扰机制和非生物反馈的变化，促进草地退化为灌木林，而生物的相互作用，如竞争和促进往往被忽视。在这里，我们进行了一项实验，以确定灌木是否有一个积极的，中性的，或负面的影响，草，如果这些相互作用可能发挥作用，在草地灌丛状态transition.Prosopis glandulosashrub邻居5米内的Bouteloua eripodagrass补丁保持完整（对照）或杀死叶面除草剂，草性能的指标进行了评估超过5年。我们没有看到灌木促进草的证据。相反，草ANPP积极响应灌木清除在所有年份，但更是在年平均降雨量以上。草分配到营养繁殖和草斑块的大小也增加了灌木邻居被删除。这些结果表明，生物干扰灌木草加强和放大放牧和干旱引起的非生物反馈在草地灌木过渡。因此，灌木对草的影响应被认为是荒漠草原状态转换的关键过程。
Traditional models of state transition in arid lands emphasize changes in disturbance regimes and abiotic feedbacks that promote the degradation of grassland into shrubland, whereas biotic interactions like competition and facilitation are often overlooked. Here, we conducted an experiment to determine whether shrubs have a positive, neutral, or negative effect on grasses and if these interactions may play a role in grassland–shrubland state transition.Prosopis glandulosashrub neighbors within 5 m ofBouteloua eriopodagrass patches were left intact (controls) or killed with foliar herbicide, and metrics of grass performance were evaluated over 5 years. We saw no evidence of shrub facilitation of grasses. Instead, grass ANPP responded positively to shrub removal in all years, but more so in years with above-average rainfall. Grass allocation to vegetative reproduction and grass patch size also increased when shrub neighbors were removed. These results demonstrate that biotic interference by shrubs upon grasses reinforce and magnify grazing- and drought-induced abiotic feedbacks during grassland–shrubland transitions. Shrub effects on grass should therefore be considered a key process in desert grassland state transitions.