DISSERTATION RESEARCH: Origins of alternate ecosystem states - effects of drought on postfire tree regeneration and shifting dominance of western conifers

论文研究：替代生态系统状态的起源 - 干旱对火灾后树木再生的影响和西部针叶树优势的转变

• 批准号: 1600716
• 负责人: Monica Turner
• 金额: $ 1.99万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1600716&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Origins; alternate; ecosystem

This doctoral dissertation research seeks to understand how drought following wildfires affects the establishment of two widespread Rocky Mountain tree species, lodgepole pine and Douglas-fir. In Yellowstone National Park, warming, drying conditions are leading to increased frequency of severe wildfires that kill existing trees and trigger regrowth of the forest. These trends are expected to continue. Many tree species in Yellowstone are well adapted to fire. Yet, early and abundant seedling establishment after fire is critical for forests to recover. Tree seedlings are particularly sensitive to drought, and evidence suggests that sufficiently dry postfire conditions could cause the widespread death of tree-seedlings, with consequences that may last decades. This research will determine how seedlings from two tree species respond to drought conditions expected in the mid-21st century and will identify the mechanisms that influence seedling response to dry conditions. The results of this study will advance understanding of how forests in the western United States will respond to environmental change over the coming decades and provide useful information for western land managers who are grappling with increased wildfires. In addition to providing important scientific knowledge, the study will provide opportunities for undergraduate students to experience research in the field of forest ecology. Researchers will also engage local residents of the Greater Yellowstone area by presenting an exhibit of science art in local shops that features photographs of the research. A handout will accompany the exhibit that presents the study findings to residents, such as how changing forests may influence recreational opportunities.This research will address the questions: How will 21st century drought alter postfire regeneration of a widespread western conifer? Will future climate conditions favor an alternate dominant tree species of non-forest cover? A greenhouse experiment will be conducted, where a combination of projected growing season daily temperature and soil-moisture conditions will be simulated to determine how expected drought will influence rates of postfire tree-seedling establishment in different soil types. The experiment will be conducted in a unique facility at the University of Wisconsin-Madison in which environmental conditions can be controlled at sub-daily resolutions, and the work will complement an ongoing field-based experiment in Yellowstone. Results will be integrated into process-based models to explore consequences of drought and increased fire activity at landscape and regional scales.

这项博士学位论文研究旨在了解野火后的干旱如何影响建立两种广泛的岩石山树种，即洛奇波尔松树和道格拉斯 - 费尔。在黄石国家公园，变暖，干燥条件导致杀死现有树木并触发森林再生的严重野火的频率增加。这些趋势有望继续。黄石中的许多树种都非常适合着火。然而，火灾后的早期和丰富的幼苗建立对于森林恢复至关重要。树幼苗对干旱特别敏感，有证据表明，足够干燥的后火后条件可能会导致树木种子的广泛死亡，并可能持续数十年。这项研究将确定来自两个树种的幼苗如何应对21世纪中叶预期的干旱状况，并确定影响幼苗对干燥条件的反应的机制。这项研究的结果将促进了解美国西部的森林如何在未来几十年中对环境变化做出反应，并为正在与野火增加的西方土地管理者提供有用的信息。除了提供重要的科学知识外，该研究还将为本科生提供在森林生态学领域进行研究的机会。研究人员还将在大黄石地区的当地居民参与，通过在当地商店中展示科学艺术展览，其中包括研究的照片。展览将伴随着向居民展示研究结果的讲义，例如变化的森林如何影响娱乐机会。这项研究将解决以下问题：21世纪的干旱将如何改变广泛的西方针叶树的后火后再生？未来的气候条件会有利于非森林覆盖的另一种主要树种吗？ 将进行一项温室实验，其中将模拟预计生长季节的每日温度和土壤植物条件的结合，以确定预期的干旱将如何影响不同土壤类型的后火养树种子率。该实验将在威斯康星大学麦迪逊分校的独特设施中进行，在该设施中，可以在下天的解决方案中控制环境条件，并且该工作将补充一项基于现场的实验在黄石公园。结果将集成到基于过程的模型中，以探索干旱的后果，并在景观和区域尺度上增加火灾活动。