Homogenization Applied to Integrate Across Spatial and Temporal Scales in Forest/Insect Ecology

在一个当前感兴趣的生态问题中，所有的元素都存在于均质化的应用和测试中，以解决尺度问题，模拟气候和人类对暴发昆虫物种的影响。研究者和他的同事们开发了一个确定的山松甲虫（MPB, Dendroctonus ponderosae）扩散和松宿主大规模攻击的空间模型。在公顷空间尺度和日时间尺度上对模型进行了验证和描述。在这个项目中，他们利用MPB/宿主系统的均质化技术构建了一个森林尺度（100公顷/年）模型，反映了当前昆虫发育、扩散和对气候响应的小尺度时空模型的大尺度紧急后果。如此大规模的直接计算是令人望而却步的；类似的困难也存在于大多数涉及现实尺度的时空异质性和生命系统/扩散相互作用的生态模拟中。研究人员开发了均质化程序，使这种类型的生态模拟通常易于处理，并在MPB/宿主系统中实施和测试这些程序。均质化过程产生一个积分差分方程（IDE），在景观尺度上以一年的时钟“滴答”运行。在验证阶段，使用IDE模型对景观进行分类。统计分析错误分类与航空图像的比较，使模拟方法自我纠正。最后，情景研究用于检验假设的气候和管理轨迹对宿主/昆虫动力学的影响。这说明了同质化方法在生态学背景下的力量，并提供了必要的例子，使这些技术能够为生物学和环境研究人员所利用。均匀化方法是一种数学技术，可以从确定的小尺度模型中推导出大尺度特性。据我们所知，同质化的方法从未被应用于生态问题，而生态问题的规模问题是争论的焦点。一种可能的攻击角度是联合使用模型和仿真，然后用空间显式数据进行验证。由于时间和空间尺度的相互作用，全面描述空间异质性和气候变化的生态问题的直接计算方法是极其困难的。一方面，在任何生态尺度上都缺乏经过验证的确定性空间模型，另一方面，扩展空间观测的困难加剧了这一困难。在本项目中，研究者和他的同事将均质化技术应用于山松甲虫/洛奇波勒松生态系统，以解决尺度问题，模拟气候和人类对昆虫物种种群爆发的影响。

Powell0077663 In one ecological problem of current interest all theelements exist for application and testing of homogenization toresolve the scale issue and simulate climate and human impacts onoutbreak insect species. The investigator and his colleagues havedeveloped a deterministic spatial model of Mountain Pine Beetle(MPB, Dendroctonus ponderosae) dispersal and mass-attack of pinehosts. The model is validated and descriptive on spatial scalesof hectares and time scales of days. In this project they usetechniques of homogenization on the MPB/host system to constructa forest scale ( 100 hectare/years) model reflecting thelarge-scale emergent consequences of current small-scale spatialand temporal models of insect development, dispersal, andresponse to climate. Direct computation on such large scaleswould be prohibitive; similar difficulties face most ecologicalsimulations involving spatio-temporal heterogeneity at realisticscales and life-system/dispersal interactions. The investigatorsdevelop homogenization procedures that make this type ofecological simulation generally tractable, and implement and testthese procedures in the MPB/host system. The homogenizationprocedure generates an integro-difference equation (IDE),operating with year-long clock `ticks' on landscape scales. In avalidation phase, the IDE model is used to classify landscapes.Statistically analyzing misclassifications in comparison toaerial imagery makes the simulation methodology self-correcting.Finally, scenario studies are used to examine consequences ofhypothetical climate and management trajectories on host/insectdynamics. This illustrates the power of homogenizationapproaches in an ecological context, and provides needed examplesto make these techniques accessible to biological andenvironmental researchers. The method of homogenization is a mathematical techniquethat allows deduction of large-scale properties fromdeterministic small-scale models. To the best of our knowledgethe method of homogenization has never been applied to ecologicalproblems, where issues of scale are the focus of much debate. Onepossible angle of attack is joint use of models and simulation,followed by validation with spatially explicit data. Directcomputational approaches to ecological problems with fulldescription of spatial heterogeneity and climatic variation areextremely difficult due to interaction of scales in time andspace. The difficulty is exacerbated on the one hand by thepaucity of validated, deterministic spatial models at anyecological scale, and by the difficulty of extended spatialobservations on the other. In this project the investigators andhis colleagues apply the technique of homogenization to theMountain Pine Beetle/Lodgepole Pine ecosystem to resolve thescale issue and simulate climate and human impacts on populationoutbreaks of insect species.