Data from: Time since disturbance affects colonization dynamics in a metapopulation

1. Disturbances are widespread in nature and can have substantial population-level consequences. Most empirical studies on the effects of disturbance track population recovery within habitat patches, but have an incomplete representation of the recolonization process. Additionally, recent metapopulation models represent post-disturbance colonization with a recovery state or time-lag for disturbed (“focal”) patches, thus assuming that recolonization rates are uniform. 2. However, the availability of colonists in neighboring “source” patches can vary, especially in frequently-disturbed landscapes such as fire-managed forests that have a mosaic of patches that differ in successional state and undergo frequent local extinctions. To determine how time since disturbance in both focal and neighboring source patches might affect metapopulations, we studied the effects of time since fire (TSF) on abundances of a specialist palmetto beetle within and between fire management units in Apalachicola National Forest, Florida. 3. We measured beetle abundances at three distances from the shared edge of paired units, with units ranging from 0-64 months since fire and the difference in time since burning for a focal-source pair ranging from 3-58 months. 4. Soon after fire, beetle abundances within management units were highest near the unit edge, but this pattern changed with increasing TSF. Between paired units, the more recently-disturbed (“focal”) unit’s beetle abundance was positively related to source unit abundance, but the shape of this relationship differed based on focal unit TSF and the units’ difference in time since burning. 5. Results suggest that both focal and source habitat history can influence recolonization of recently-disturbed patches and that these effects may persist over years. Thus, when predicting metapopulation dynamics, variation in habitat characteristics should be considered not only for patches receiving colonists, but for patches supplying colonists as well.

1. 干扰在自然界中广泛存在，可对种群产生显著的种群水平效应。当前绝大多数关于干扰效应的实证研究均聚焦于生境斑块（habitat patch）内部的种群恢复过程，但对再定居（recolonization）过程的刻画仍不够完整。此外，近期的集合种群（metapopulation）模型将受干扰的“核心”斑块（focal patch）的灾后拓殖（colonization）过程描述为恢复状态或时间滞后，进而默认再定居速率均一。
2. 然而，邻近“源斑块”（source patch）中的拓殖者（colonist）可获得性并非恒定，在火管理森林这类频繁受扰的景观中尤为明显——这类景观的斑块镶嵌体（patch mosaic）具有各异的演替状态（successional state），且频繁发生局域灭绝（local extinction）。为探明核心斑块与邻近源斑块的火后时间（time since fire, TSF）如何影响集合种群动态，我们以佛罗里达州阿巴拉契科拉国家森林的火管理单元（fire management unit）为研究对象，探究了火后时间对一种专食性棕榈甲虫种群丰度的影响，同时分析了单元内部与单元间的甲虫丰度变化。
3. 我们在成对火管理单元的共享边界处设置了三个采样距离梯度，所有采样单元的火后时间跨度为0~64个月，且每对核心-源单元的火烧时间差范围为3~58个月。
4. 火烧后初期，火管理单元内部的甲虫丰度在单元边界处达到峰值，但这一分布模式随火后时间增加发生改变。成对单元之间，受干扰时间更短的“核心”单元的甲虫丰度与源单元丰度呈正相关，但该相关关系的具体形式随核心单元的火后时间以及单元间火烧时间差发生变化。
5. 研究结果表明，核心斑块与源斑块的生境历史均可影响新近受扰斑块的再定居过程，且这类效应可持续数年之久。因此，在预测集合种群动态时，不仅需要考虑接收拓殖者的斑块的生境特征变异，也需纳入提供拓殖者的斑块的生境特征变异。