LTER Cross-site: Collaborative Research - Assessing the Geographic and Temporal Consistency of Life History and Demographic Patterns: A Long-term, Multi-site Comparison

莫里斯生态学家越来越多地理解自然系统中空间变异性的重要性，这一认识导致了LTER网络的创建。然而，令人惊讶的是，我们仍然对个体物种人口学的空间差异知之甚少，这造成了应用生态学和基础生态学知识的重大差距。缺乏全面的人口研究，涵盖了相当大的地理范围内的多个人口，这造成了两个普遍的问题。首先，种群生物学家被迫从单个经过充分研究的种群中发现的种群动态和生活史模式推断出发生在物种范围遥远部分的种群动态和生活史模式。这种外推在保护生物学、比较生活史分析和气候变化预测中是司空见惯的，目前对个体物种的人口学中实际存在多少空间差异知之甚少。第二个问题是什么设定了物种的范围限制。虽然气候的生理影响通常是众所周知的，但由于缺乏大规模的人口研究，人们不太清楚种群动态在范围界限附近是如何变化的，因此，较差的人口表现与其他拟议的因素，如集合种群动态，在多大程度上决定了物种的分布界限。因此，我们几乎没有理由建立关于物种范围将如何随着气候变化而变化的机械预测。为了解决这些问题，作为LTER跨地点研究项目的一部分，将对两种分布广泛的苔原植物物种--苔藓Campion和阿尔卑斯比索特--进行人口统计学研究。这些物种将在两个栖息地和四个地理地点的16个种群中进行研究。这些地点横跨北美该物种的大部分纬度范围。这项研究旨在对每个物种的每个种群的随机矩阵模型进行参数化。虽然多地点人口统计学研究是不寻常的，但衡量和适当分析死亡率的时间随机性的研究就更少见了。除了对个体生命比率的均值和方差进行统计分析外，指数还将根据这些随机模型的输出进行大部分分析，包括随机增长率、随机弹性值和灭绝风险预测。此外，这项工作将利用LTER气候数据将生命比率的时空变异性与特定的环境因素联系起来。这些结果将被用来测试不同地理位置和栖息地的生活史变化的强度和模式，并确定如何利用有限的数据最好地预测人口变异性。最后，将对导致北部和南部山脉边界的人口因素进行具体测试。总体而言，这项研究将是第一个多地点、多年的人口统计分析，仔细包括时间随机性，并明确测试生活史模式如何以及以何种方式在物种范围内变化。

0087096MorrisEcologists increasingly understand the importance of spatial variability in natural systems, a recognition that led to the creation of the LTER network. However, we still know surprisingly little about spatial variation in the demography of individual species, creating an important gap in knowledge for both applied and basic ecology. The paucity of full demographic studies that span multiple populations across substantial geographic scales creates two general problems. First, population biologists are forced to extrapolate from the population dynamics and life history patterns found in single, well-studied populations to those occurring in distant parts of a species range. Such extrapolation is commonplace in conservation biology, comparative life history analysis, and climate change predictions, and is currently done with little understanding of how much spatial variation actually exists in the demography of individual species. Second is the question of what sets the range limits of species. While the physiological effects of climate are often well-known, the lack of broad-scale demographic studies makes it less clear how population dynamics vary near range limits, and thus the extent to which poor demographic performance versus other proposed factors, such as metapopulation dynamics, determine the distributional limits of species. As a result, we have little ground for building mechanistic predictions about how species ranges will shift as climate changes. To address these problems, a demographic study of two widespread tundra plant species, moss campion and alpine bisort, will be conducted as part of this LTER cross-site research project. These species will be studied in 16 populations across two habitats and four geographic sites. These sites span most of the latitudinal range of the species in North America. The study is designed to parameterize stochastic matrix models for each population of each species. While multi-site demographic studies are unusual, ones that measure and properly analyze temporal stochasticity in vital rates are even rarer. In addition to statistical analysis of the means and variance in individual vital rates, the PIs will base much of the analysis on outputs of these stochastic models, including stochastic growth rates, stochastic elasticity values and extinction risk predictions. Furthermore, the work will utilize LTER climate data to tie spatial and temporal variability in vital rates to specific environmental factors. The results will be used to test for the strength and pattern of life history variation across geographic sites and habitats, and to determine how best to make predictions about demographic variability with limited data. Finally, specific tests will be conducted for demographic factors leading to both northern and southern range boundaries. Overall, this study will be the first multi-site, multi-year demographic analysis to carefully include temporal stochasticity and to explicitly test how and in what ways life history patterns vary across species' ranges.