Foodwebs based on unreliable foundations: spatiotemporal masting merged with consumer movement, storage, and diet
Foodwebs based on unreliable foundations: spatiotemporal masting merged with consumer movement, storage, and diet
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DOI：
10.1002/ecm.1381
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发表时间：
2019-07-17
影响因子：
6.1
通讯作者：
Tomasek, Bradley
中科院分区：
文献类型：
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作者：
Clark, James S.;Nunez, Chase;Tomasek, Bradley
肥果树代表着一种脉冲资源，既支持又破坏了消费群体的稳定。虽然可靠的资源平均来说是丰富的，并且在时间和空间上的变化有限，但桅杆是不稳定的和局部性的，这种差异在整个食物网中都是分叉的。理论的发展是为了评估桅杆的时空结构如何与消费者互动，这些消费者利用替代宿主，在空间广泛觅食，并在时间上储存储备。我们推导出资源供给的时空物种协方差，并将其与消费者的时空饮食广度或范围相结合。通过Mast推理和预测(MASTIF)实现了与数据的直接连接，MASTIF是一种状态空间自回归模型，适用于种子诱捕器和树冠观测，并在完全不确定的情况下预测树冠内和森林地面上的资源可用性。可以将资源分数分配给每个消费者-栖息地组合，这些组合整合了高平均供应相对于差异成本的好处。随着消费者范围的扩大，不可靠资源的波动性从差异成本转变为平均收益。消费者在树冠上觅食(树栖节肢动物和啮齿类动物、鸣禽)会体验到寄主树木之间的时空协变性。森林地面上的消费者(种子和立枯病真菌、节肢动物、啮齿动物、地面筑巢的鸟类、哺乳动物)反而通过扩散经历了这种协方差的重新分配。对于缺乏流动性的消费者来说，在丰年之后以断断续续的出生队列的形式进行的人口存储对于人口的持久性非常重要。此外，消费者还通过饮食广度来弥补波动性。根据寄主树种在饮食中的主导控制策略，栖息地根据消费者范围和寄主的时空协变之间的不一致而对消费者进行不同的限制。增加或减少饮食项目的影响可以用标准误差(SE)规则或添加的饮食项目的收益与差异成本相平衡来衡量，这两者都取决于现有的饮食、新宿主的丰度和消费者的觅食范围。结果从资源的角度根据栖息地支持野生动物和其他消费者的能力对栖息地进行排名。结果由Mastif直接与数据相关联，具有完全的不确定性。
Mast-fruiting trees represent a pulsed resource that both supports and destabilizes consumer populations. Whereas a reliable resource is abundant on average and with limited variation in time and space, masting is volatile and localized, and that variability ramifies throughout food-webs. Theory is developed to evaluate how the space-time structure of masting interacts with consumers who exploit alternative hosts, forage widely in space, and store reserves in time. We derive the space-time-species covariance in resource supply and combine it with the space-time-diet breadth of consumers, or ambit. Direct connection to data is made possible with Mast Inference and Forecasting (MASTIF), a state-space autoregressive model that fits seed-trap and canopy observations and predicts resource availability within the canopy and on the forest floor with full uncertainty. A resource score can be assigned to each consumer-habitat combination that integrates the benefits of a high mean supply weighed against the variance cost. As the consumer ambit increases, the volatility of an unreliable resource shifts from a variance cost to a mean benefit. Consumers foraging in the canopy (arboreal arthropods and rodents, song birds) experience space-time covariance between host trees. Consumers on the forest floor (seed and damping-off fungi, arthropods, rodents, ground-nesting birds, mammals) experience instead a redistribution of that covariance by dispersal. For consumers lacking mobility, demographic storage in the form of episodic birth cohorts following mast years is important for population persistence. Consumers additionally compensate volatility with diet breadth. Depending on the dominant masting strategies of host tree species in the diet, habitats differentially limit consumers depending on the misalignment between consumer ambit and spatiotemporal covariance of hosts. The impact of adding or subtracting a diet item can be gauged with the standard error (SE) rule or the benefit of an added diet item balanced against the variance cost, both of which depend on the existing diet, the abundance of the new host, and the consumer's foraging ambit. Results rank habitats by their capacities to support wildlife and other consumers from a resource perspective. Results are connected directly to data, with full uncertainty, by MASTIF.