Colorado State University, Department of fish, Wildlife, and Conservation Biology, Fort Collins, Colorado 80523-1474, USA.
Ecology. 2012 Apr;93(4):858-67. doi: 10.1890/11-1515.1.
Despite the importance of habitat in determining species distribution and persistence, habitat dynamics are rarely modeled in studies of metapopulations. We used an integrated habitat-occupancy model to simultaneously quantify habitat change, site fidelity, and local colonization and extinction rates for larvae of a suite of Great Plains stream fishes in the Arikaree River, eastern Colorado, USA, across three years. Sites were located along a gradient of flow intermittency and groundwater connectivity. Hydrology varied across years: the first and third being relatively wet and the second dry. Despite hydrologic variation, our results indicated that site suitability was random from one year to the next. Occupancy probabilities were also independent of previous habitat and occupancy state for most species, indicating little site fidelity. Climate and groundwater connectivity were important drivers of local extinction and colonization, but the importance of groundwater differed between periods. Across species, site extinction probabilities were highest during the transition from wet to dry conditions (range: 0.52-0.98), and the effect of groundwater was apparent with higher extinction probabilities for sites not fed by groundwater. Colonization probabilities during this period were relatively low for both previously dry sites (range: 0.02-0.38) and previously wet sites (range: 0.02-0.43). In contrast, no sites dried or remained dry during the transition from dry to wet conditions, yielding lower but still substantial extinction probabilities (range: 0.16-0.63) and higher colonization probabilities (range: 0.06-0.86), with little difference among sites with and without groundwater. This approach of jointly modeling both habitat change and species occupancy will likely be useful to incorporate effects of dynamic habitat on metapopulation processes and to better inform appropriate conservation actions.
尽管栖息地对物种分布和存续至关重要，但在研究复合种群时，很少对栖息地动态进行建模。我们使用综合栖息地-占有模型，在美国科罗拉多州东部的阿里卡里河，连续三年同步量化了一系列大平原溪流鱼类幼虫的栖息地变化、地点忠诚度以及局部定居和灭绝率。这些地点位于流间歇性和地下水连通性的梯度上。各年的水文学特征不同：第一年和第三年相对湿润，第二年干旱。尽管水文学存在差异，但我们的结果表明，地点适宜性每年都在随机变化。对于大多数物种，占有概率也与前一年的栖息地和占有状态无关，这表明地点忠诚度较低。气候和地下水连通性是局部灭绝和定居的重要驱动因素，但地下水的重要性在不同时期有所不同。对于物种而言，在从湿润到干旱条件的转变期间，地点灭绝的概率最高（范围：0.52-0.98），地下水的影响在未受地下水补给的地点更为明显，这些地点的灭绝概率较高。在这一时期，以前干燥的地点（范围：0.02-0.38）和以前湿润的地点（范围：0.02-0.43）的定居概率相对较低。相比之下，在从干旱到湿润条件的转变期间，没有任何地点变干或保持干燥，从而导致较低但仍然很高的灭绝概率（范围：0.16-0.63）和较高的定居概率（范围：0.06-0.86），具有和不具有地下水的地点之间几乎没有差异。这种同时对栖息地变化和物种占有进行建模的方法，可能有助于纳入动态栖息地对复合种群过程的影响，并更好地为适当的保护行动提供信息。
