Holocene Fire-Climate-Vegetation Linkages in the Western Mid-latitude Forests of North and South America

该奖项将帮助研究人员了解北美和南美西部中纬度森林中气候、植被和火灾动态的相互作用。这两个地区在目前的气候、植被、火灾状况和环境历史方面提供了重要的比较。这两个地区的植被类型不同，但气候历史大体相似。不同的气候历史源于对全新世大尺度气候强迫机制（即夏季日照变化）的不同响应。本研究将发挥每个地区的异同，提供一套在单一地区无法实现的自然实验。这一点很重要，因为气候、火灾和植被是南北美洲西部森林生态系统密切相关的组成部分。这些组成部分之间联系的强度和性质因感兴趣的时间尺度而异。在年内的时间尺度上，天气条件通过影响给定季节内的燃料湿度和点火源来决定火灾事件的可能性。在年际到年代际的时间尺度上，气候变率很重要，因为干湿期的顺序间接地促进了火灾的发生。年际和年代际尺度上的植被变化也通过决定燃料的性质和分布来影响火灾活动。火灾事件反过来塑造了森林演替，并创造了为随后的干扰事件奠定基础的景观模式。在百年至千年的时间尺度上，气候控制着火灾频率、规模和严重程度以及植被组成和物种分布的长期变化。植被特征在长时间尺度上也通过决定燃料生物量的性质对火情产生正反馈。这项研究将在北美西部和巴塔哥尼亚建立一个高分辨率的火灾历史网络，与现有的植被历史网络相媲美，辨别促进或抑制火灾的气候控制等级，并检查现代气候数据，以确定影响研究地区火灾制度的大规模气候异常。这种开发火灾历史数据库并分析当前和过去与火灾相关的气候异常的方法，将使研究人员能够在多个尺度上理解气候-火灾-植被的联系。研究人员将通过共享数据库（包括国家地球物理数据中心）和出版物与更大的科学界分享他们的数据。此外，这些研究人员将与南美的同事建立强有力的合作，使北美和南美的研究人员之间能够进行技术转让。这将在一定程度上通过支持外国科学家前往美国分享数据和分析技术来实现。

This award will help researchers understand the interplay of climate, vegetation, and fire dynamics in the mid-latitude forests of western North and South America. The two regions offer important comparisons in terms of their present climate, vegetation, and fire regime and their environmental history. Both regions feature different vegetation types but broadly similar climate histories. The varying climate histories arise from distinct responses to large-scale climate forcing mechanisms in the Holocene (i.e., variations in summer insolation). This research will play each region's similarities and differences against each other to provide a set of natural experiments not possible in a single region. This is important because climate, fire, and vegetation are closely related components of forest ecosystems in western North and South America. The strength and nature of the linkages among these components vary depending on the time scale of interest. On intra-annual time scales, weather conditions determine the likelihood of fire events by influencing fuel moisture and ignition sources within a given season. On inter-annual to decadal time scales, climate variability is important because the sequence of wet and dry periods indirectly promotes fire occurrence. Vegetation changes on inter-annual and decadal scales also affect fire activity by determining the character and distribution of fuels. Fire events, in turn, shape forest succession and create landscape patterns that set the stage for subsequent disturbance events. On centennial-to-millennial time scales, climate governs the long-term variations in fire frequency, size, and severity as well as vegetation composition and species distributions. Vegetation characteristics on long time scales also exert a positive feedback to fire regimes by determining the nature of the fuel biomass.This research will develop a high-resolution fire-history network in western North America and Patagonia comparable to existing vegetation-history networks, discern the hierarchy of climate controls that either promote or suppress fire, and examine modern climate data to determine the large-scale climate anomalies that influence fire regimes in the study areas. This approach of developing a fire-history database and analyzing climate anomalies associated with fire at present and in the past, will allow the researchers to understand climate-fire-vegetation linkages on multiple scales.The researchers will share their data with the larger scientific community through shared databases (including the National Geophysical Data Center) and publications. In addition, the researchers will forge strong collaboration with South American colleagues to enable technology transfer between North and South American researchers. This will be accomplished, in part, through the support of foreign scientist's travel to the United States to share data and analytical techniques.