1. Resilience—the capacity of an ecosystem to recover from disturbance—is a popular concept but quantitative empirical studies are still uncommon. This lack of empirical evidence is especially true for semi‐arid ecosystems in the face of the combined and often confounding impacts of land use and climate changes.
2. We designed a methodology to disentangle vegetation responses to land‐use exclusion and weather variability, and piloted it at the southern extreme of the Gran Chaco forest, the most extensive seasonally dry forest in South America. We established 16 pairs of neighbouring fenced and unfenced plots in four ecosystem types resulting from different long‐term land‐use regimes under the same climate and on highly similar soil parental material. From lower to higher land‐use intensity, related with logging and livestock grazing and trampling, these types were: primary forest (no land use in the last 50 years), secondary forest, closed species‐rich shrubland and open shrubland. In each plot we monitored plant species composition during the first 5 years following land‐use exclusion, and evaluated the resilience as the rate of change of vegetation towards the primary forest, considered as the reference ecosystem.
3. We found that during the first 5 years of exclusion and despite the high rainfall, only grass cover in the secondary forest showed positive resilience (recovery towards the reference ecosystem). The rest of the variables in the other ecosystem types showed either no significant change (null resilience) or even transitioned away from the reference state (negative resilience).
4. Synthesis. The lack of detectable recovery after 5 years of exclusion suggests that (a) long‐term land use, even at lower intensities, has affected the sources of resilience of this ecosystem; (b) rainy periods do not necessarily speed up recovery as suggested in the literature; and (c) study designs should incorporate the variation of the reference ecosystem in order to differentiate the effect of land use from other factors in a context of climate change. Although still confined to the early post‐disturbance stages, our findings suggest that recovery of these systems may be slower and more complicated than predicted in the literature on the basis of space‐for‐time substitutions.

中文翻译：

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半干旱查科森林恢复初期的低回弹力-来自野外试验的证据

1. 复原力（生态系统从干扰中恢复的能力）是一个流行的概念，但是定量的经验研究仍然很少见。面对土地利用和气候变化的综合影响，而且常常是混杂的影响，这种缺乏经验证据的情况对于半干旱生态系统尤其如此。
2. 我们设计了一种方法，以区分植被对土地利用排斥和天气变化的响应，并在南美洲最广泛的季节性干旱森林格兰查科森林的南部极端进行了试验。我们在四种气候系统类型中建立了16对相邻的围栏和无围栏地块，这些围栏是在相同的气候和高度相似的土壤亲本材料下，由于不同的长期土地使用方式而产生的。从低到高的土地利用强度，与伐木，牲畜放牧和践踏有关，这些类型是：原始森林（过去50年没有土地利用），次生森林，物种丰富的灌木丛和开放灌木丛。在每个土地上，我们都在土地使用排除后的头5年内监测植物物种组成，
3. 我们发现在排斥的前5年中，尽管降雨很高，但仅次生林中的草皮显示出正的复原力（恢复到参考生态系统）。其他生态系统类型中的其余变量显示无明显变化（零弹性），甚至从参考状态过渡（负弹性）。
4. 综合。排除5年后缺乏可检测到的恢复，这表明（a）即使在较低强度下的长期土地使用也影响了该生态系统的复原力来源；（b）阴雨时期不一定像文献所建议的那样加快恢复速度；（c）研究设计应纳入参考生态系统的变化，以便在气候变化的背景下将土地利用的影响与其他因素区分开来。尽管仍局限于扰乱后的早期阶段，但我们的发现表明，这些系统的恢复可能比文献中基于时空替换的预测更慢，更复杂。