Department of Biological Sciences and Program in Ecology, Evolution, and Behavior, Boise State University, Boise, Idaho 83725 USA.
Department of Integrative Biology, University of Wisconsin-Madison, 451 Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706, USA.
Ecol Appl. 2019 Mar;29(2):e01850. doi: 10.1002/eap.1850.
Conservation and restoration projects often involve starting new populations by introducing individuals into portions of their native or projected range. Such efforts can help meet many related goals, including habitat creation, ecosystem service provisioning, assisted migration, and the reintroduction of imperiled species following local extirpation. The outcomes of reintroduction efforts, however, are highly variable, with results ranging from local extinction to dramatic population growth; reasons for this variation remain unclear. Here, we ask whether population growth following plant reintroductions is governed by variation at two scales: the scale of individual habitat patches to which individuals are reintroduced, and larger among-landscape scales in which similar patches may be situated in landscapes that differ in matrix type, soil conditions, and other factors. Quantifying demographic variation at these two scales will help prioritize locations for introduction and, once introductions take place, forecast population growth. This work took place within a large-scale habitat fragmentation experiment, where individuals of two perennial forb species were reintroduced into eight replicate ~50-ha landscapes, each containing a set of five ~1-ha patches that varied in their degree of isolation (connected by habitat corridors or unconnected) and edge-to-area ratio. Using data on individual growth, survival, reproductive output, and recruitment collected one to two years after reintroduction, we developed models to forecast population growth, then compared forecasts to observed population sizes, three and six years later. Both the type of patch (connected and unconnected) and identity of the landscape to which individuals were reintroduced had effects on forecasted population growth rates, but only variation associated with landscape identity was an accurate predictor of subsequently observed population growth rates. Models that did not include landscape identity had minimal forecasting ability, revealing the key importance of variation at this scale for accurate prediction. Of the five demographic rates used to model population dynamics, seed production was the most important source of forecast error in population growth rates. Our results point to the importance of accounting for landscape-scale variation in demographic models and demonstrate how such models might assist with prioritizing particular landscapes for species reintroduction projects.
保护和修复项目通常通过将个体引入其原生或预测范围的部分地区来开始新的种群。这些努力可以帮助实现许多相关目标，包括生境创造、生态系统服务提供、辅助迁移以及在当地灭绝后重新引入濒危物种。然而，重新引入工作的结果高度可变，结果从局部灭绝到种群急剧增长不等；这种变化的原因仍不清楚。在这里，我们询问植物重新引入后种群增长是否受两个尺度的变化控制：个体被重新引入的个体栖息地斑块的尺度，以及在基质类型、土壤条件和其他因素不同的景观中可能位于类似斑块的较大景观尺度。在这两个尺度上量化人口变化将有助于确定引入的优先地点，一旦引入发生，就可以预测人口增长。这项工作是在大规模生境破碎化实验中进行的，在该实验中，两种多年生草本植物的个体被重新引入到八个重复的 50 公顷景观中，每个景观都包含一组五个 1 公顷的斑块，这些斑块的隔离程度（通过生境走廊连接或不连接）和边缘面积比不同。利用重新引入后一到两年收集的个体生长、存活、繁殖输出和繁殖数据，我们开发了预测种群增长的模型，然后将预测与三到六年后的实际种群大小进行比较。个体被重新引入的斑块类型（连接和不连接）和景观身份都对预测的种群增长率有影响，但只有与景观身份相关的变异是随后观察到的种群增长率的准确预测因子。不包括景观身份的模型预测能力有限，这表明在这个尺度上的变异性对于准确预测至关重要。在用于模拟种群动态的五个人口统计率中，种子生产是预测种群增长率的最主要误差源。我们的结果表明了在人口统计模型中考虑景观尺度变化的重要性，并展示了这些模型如何帮助为物种重新引入项目确定特定景观的优先级。
