Collaborative Research: Using Demographic Techniques to Test for the Signatures of Environmental Change

在评估当前或未来气候变化的真实的环境重要性方面的一个主要困难是缺乏过去的充分监测数据。特别是，用于推断气候变化后果的大多数方法都依赖于过去的数据来确定正常或基线条件。在这里提出的工作中，开发了一种技术来规避这个问题，而是依赖于当前人口规模或年龄结构与当前人口统计学预测的人口结构之间的比较，以在缺乏过去数据的情况下测试当地或全球环境变化的生态影响的证据。在拟议的工作中，人口学和人口结构的无茎蝇子草，环北方高山垫植物，将被量化。这项工作将在阿拉斯加中南部进行。在过去的三十年里，这个地区的气温迅速上升。 在阿拉斯加的兰格尔山脉的实地考察点，将收集两种类型的数据：1）个体植物生长、繁殖和存活的人口统计学指标; 2）几个不同种群中植物的大小频率。通过比较观察到的大小频率的随机计算机模型预测的数据，使用当前的人口统计率，具体的假设如何Silene人口可能已经改变，由于环境的改变将进行测试（例如，较早的融雪和较高的夏季温度导致减少幼苗招聘，但增加成年人的增长率？）。为了证实我们的模型所确定的过去气候变化最可能的人口反应，还将进行额外的实验来修改季节长度和温度，以直接评估气候变化对人口表现的影响。这些实验将符合国际苔原实验（ITEX，北极和高山全球变化研究人员国际联合会）的标准协议，从而使实验结果能够与环北方气候变化影响评估联系起来。通过提供一种方法来回顾环境变化对人口的影响，拟议的工作将扩大可用于检测过去变化的生物影响的方法工具箱，并为确定目前气候变化的影响是否会在未来加速提供基线。

Morris/Doak 9806818 A major difficulty in assessing the real environmental importance of ongoing or future climate change is the lack of adequate monitoring data from the past. In particular, most methods used to infer the consequences of climate change rely upon past data to determine normal or baseline conditions. In the work proposed here, a technique is developed that circumvents this problem, relying instead on a comparison between current population size or age structures and those predicted by current demography to test for evidence of the ecological effects of local or global environmental change, in the absence of past data.. In the proposed work, the demography and population structure of Silene acaulis, a circumboreal alpine cushion plant, will be quantified. The work will be conducted in southcentral Alaska,. an area that has undergone rapid increases in temperature over the last three decades. At the field sites in Alaska's Wrangell Mountains, two types of data will be collected: 1) demographic measures of the growth, reproduction, and survival of individual plants; and 2) the size frequencies of plants in several distinct populations. By comparing the observed size frequencies to those predicted by stochastic computer models using the data on current demographic rates, specific hypotheses about how Silene demography may have changed due to environmental alteration will be tested (for examples, has earlier snowmelt and higher summer temperatures led to decreased seedling recruitment but an increase in the growth rates of adults?). In order to corroborate the most likely population responses to past climate changes identified by our models, additional experiments will be also be conducted to modify season length and temperature in order to directly assess the effects of climatic changes on demographic performance. These experiments will conform to the standard protocols of the International Tundra Experiment (ITEX, an international consortium of arctic and alpine global change researchers), thus allowing the results to be linked to a circumboreal assessment of climate change effects. By providing a method to look retrospectively at the population-level effects of environmental change, the work proposed will both expand the toolbox of methodologies available for detecting biotic effects of past changes and provide a baseline for determining whether effects of ongoing climate changes will accelerate in the future.