Reconstruction and Spatial Analysis of Historical Forest Structure and Disturbance Across Ponderosa Pine Landscapes

一些森林在地理学上的一系列理论问题仍然没有解决，这与历史上的自然干扰有关。 这些扰动是否罕见、规模大且严重，表明景观处于不平衡状态，具有变化的、不完整的空间结构？ 干扰频繁和低的严重程度，保持持久的，空间均匀的古老的森林？ 或者这些干扰的严重程度是可变的，在不同的景观中有不同的模式？ 答案具有广泛的影响，因为法律，政策，行业和公共用途都受到影响。 对于一些主要的森林类型，如美国西部的黄松林，这些问题仍然没有答案，因为在欧美土地广泛使用之前，关于森林结构和干扰的数据有限。 一般土地办公室（GLO）的调查，这是进行土地最初调查的欧美定居点，有系统的数据在美国各地的调查，主要是在19世纪后期在西部完成，记录数据的“见证树”在调查的角落，包括树种，直径，轴承，距离角落。 GLO调查还记录了严重的干扰，如树冠火灾和吹泄。 本研究项目将使用校准和改进的方法来分析GLO数据，以解决关于黄松景观的四个一般性问题：（1）森林结构在空间上如何均匀或可变（例如，树木密度，树木直径分布）在大型景观？ (2)关键因素是什么（例如，火灾）的高度严重干扰，以及这些景观的速率和模式？ (3)高强度干扰的空间结构和作用是否因区域而异？ (4)森林结构和严重干扰是否有联系，如果有，联系的模式是什么？ 研究人员将使用GLO数据来重建美国西部三个大型黄松景观的森林结构和干扰，并分析重建结果，以解决四个一般性问题和九个与之相关的具体假设。西部一些主要森林（如黄松林）的变化模式和规模在被广泛的土地利用改变之前知之甚少。 只有一些小的，分散的重建，历史轶事，和早期的照片是为这些重要的西部森林。 该项目将通过使用早期的调查记录来重建19世纪末美国黄松森林在三个大的，有代表性的土地面积的属性，扩大对这些森林的理解。 该项目将提供关于火灾和其他干扰的数据以及重建森林变化的地图。 这些数据应有助于各机构和利益集团制定政策，并有助于管理和恢复。 这些地图和信息对管理和恢复也很有价值，因为将提供关于树木密度、大小和其他森林特征的具体数据。

A set of theoretical question in biogeography that remains unresolved regarding some forests relates to historical natural disturbances. Were these disturbances infrequent, large, and of high severity, suggesting landscapes that were in disequilibrium, having a shifting, patchy spatial structure? Were the disturbances frequent and of low severity, maintaining an enduring, spatially uniform old-growth forest? Or were these disturbances variable in severity with a mixture of patterns across landscapes? The answers have broad implications, as laws, policy, industries, and public uses are affected. The questions remain unanswered for some major forest types, such as ponderosa pine forests in the western United States, because data are limited about forest structure and disturbance before widespread EuroAmerican land uses. The General Land Office (GLO) survey, which was conducted when lands were initially surveyed for EuroAmerican settlement, has systematic data across the U.S. The surveys, largely done in the late-1800s in the West, recorded data on "witness trees" at surveyed corners, including tree species, diameter, bearing, and distance from the corner. The GLO survey also recorded high-severity disturbances, such as crown fires and blowdowns. This research project will use calibrated and refined methods for analyzing the GLO data to address four general questions about ponderosa pine landscapes: (1) How spatially uniform or variable was forest structure (e.g., tree density, tree diameter distributions) across large landscapes? (2) What were the key agents (e.g., fire) of high-severity disturbance, and the rates and patterns of these across landscapes? (3) Did the spatial structure and the role of high-severity disturbance vary among regions? (4) Were forest structure and high-severity disturbance linked, and, if so, what was the pattern of linkage? The investigators will use the GLO data to reconstruct forest structure and disturbances across three large ponderosa pine landscapes in the western U.S. and analyze the reconstructions to address the four general questions and nine specific hypotheses related to them.The pattern and scale of variation in some major western forests, such as ponderosa pine forests, are poorly known before alteration by widespread land uses. Only a few small, scattered reconstructions, historical anecdotes, and early photographs are available for these important western forests. This project will expand understanding of these forests by using early survey records to reconstruct the attributes of late-1800s ponderosa pine forests across three large, representative land areas. The project will provide data about fires and other disturbances and maps of reconstructed forest variation. These data should aid policy formulation by agencies and interest groups and be useful in management and restoration. The maps and information will also be valuable in management and restoration, as specific data will be provided on tree densities, sizes, and other forest characteristics.