Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA. Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya.
Science. 2015 Feb 6;347(6222):651-5. doi: 10.1126/science.1261487.
Self-organized spatial vegetation patterning is widespread and has been described using models of scale-dependent feedback between plants and water on homogeneous substrates. As rainfall decreases, these models yield a characteristic sequence of patterns with increasingly sparse vegetation, followed by sudden collapse to desert. Thus, the final, spot-like pattern may provide early warning for such catastrophic shifts. In many arid ecosystems, however, termite nests impart substrate heterogeneity by altering soil properties, thereby enhancing plant growth. We show that termite-induced heterogeneity interacts with scale-dependent feedbacks to produce vegetation patterns at different spatial grains. Although the coarse-grained patterning resembles that created by scale-dependent feedback alone, it does not indicate imminent desertification. Rather, mound-field landscapes are more robust to aridity, suggesting that termites may help stabilize ecosystems under global change.
自组织的空间植被模式广泛存在，并已使用植物与水之间的尺度相关反馈模型进行了描述，这些模型适用于均匀基质。随着降雨量的减少，这些模型会产生一个具有特征性的模式序列，植被越来越稀疏，然后突然崩溃为沙漠。因此，最终的点状模式可能为这种灾难性的转变提供早期预警。然而，在许多干旱生态系统中，白蚁巢通过改变土壤性质来产生基质异质性，从而促进植物生长。我们表明，白蚁引起的异质性与尺度相关反馈相互作用，从而在不同的空间粒度上产生植被模式。尽管粗粒模式类似于仅由尺度相关反馈产生的模式，但它并不表明即将发生荒漠化。相反，土丘-田野景观对干旱更为稳健，这表明白蚁可能有助于稳定全球变化下的生态系统。
