Patterning of vegetation in drylands is a consequence of localized feedback mechanisms. Such feedbacks also determine ecosystem resilience—i.e. the ability to recover from perturbation. Hence, the patterning of vegetation has been hypothesized to be an indicator of resilience, that is, spots are less resilient than labyrinths. Previous studies have made this qualitative link and used models to quantitatively explore it, but few have quantitatively analysed available data to test the hypothesis. Here we provide methods for quantitatively monitoring the resilience of patterned vegetation, applied to 40 sites in the Sahel (a mix of previously identified and new ones). We show that an existing quantification of vegetation patterns in terms of a feature vector metric can effectively distinguish gaps, labyrinths, spots, and a novel category of spot–labyrinths at their maximum extent, whereas NDVI does not. The feature vector pattern metric correlates with mean precipitation. We then explored two approaches to measuring resilience. First we treated the rainy season as a perturbation and examined the subsequent rate of decay of patterns and NDVI as possible measures of resilience. This showed faster decay rates—conventionally interpreted as greater resilience—associated with wetter, more vegetated sites. Second we detrended the seasonal cycle and examined temporal autocorrelation and variance of the residuals as possible measures of resilience. Autocorrelation and variance of our pattern metric increase with declining mean precipitation, consistent with loss of resilience. Thus, drier sites appear less resilient, but we find no significant correlation between the mean or maximum value of the pattern metric (and associated morphological pattern types) and either of our measures of resilience.

中文翻译：

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定量监测萨赫勒地区图案植被的恢复力

旱地植被模式是局部反馈机制的结果。这种反馈也决定了生态系统的复原力——即从扰动中恢复的能力。因此，植被的图案被假设为弹性的指标，即斑点的弹性不如迷宫。以前的研究已经建立了这种定性联系并使用模型对其进行了定量探索，但很少有人对可用数据进行定量分析来检验假设。在这里，我们提供了定量监测图案植被恢复力的方法，这些方法应用于萨赫勒地区的 40 个地点（先前确定的和新发现的混合）。我们表明，根据特征向量度量现有的植被模式量化可以有效区分间隙、迷宫、斑点、和最大程度的新型斑点迷宫，而 NDVI 则不然。特征向量模式度量与平均降水相关。然后，我们探索了两种衡量弹性的方法。首先，我们将雨季视为一种扰动，并检查随后的模式衰减率和 NDVI 作为可能的弹性度量。这表明腐烂速度更快——通常被解释为更大的弹性——与更潮湿、植被更多的地点相关。其次，我们去除了季节性周期的趋势，并检查了残差的时间自相关和方差，作为可能的弹性度量。我们的模式度量的自相关和方差随着平均降水量的下降而增加，这与恢复力的丧失一致。因此，较干燥的地点似乎弹性较差，