International Research Fellowship Program: Water Use Strategies and Leaf Function in Mature and Regenerating Tropical Dry Forests in Mexico

国际研究奖学金计划：墨西哥成熟和再生热带干燥森林的用水策略和叶子功能

• 批准号: 0754502
• 负责人: Radika Bhaskar
• 金额: $ 14.53万
• 依托单位: Bhaskar Radika
• 依托单位国家: 美国
• 项目类别: Fellowship
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-10-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0754502&HistoricalAwards=false
• 关键词: International; Research; Fellowship; Program; Water

0754502BhaskarThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Radika Bhaskar to work with Dr. Patricia Balvanera at UNAM in Mexico, and with Dr. Todd Dawson at the University of California, Berkeley in the US.Due to their vulnerability and bio-complexity, tropical dry forests (TDFs) present a compelling system to assess functional diversity in the dry tropics and the effect of anthropogenic land use on ecosystem function. In TDFs, precipitation is strongly seasonal; within undisturbed stands, this temporal variability is associated with a highly diverse woody plant community with a wide spectrum of water use strategies accompanied by large variation in leaf phenology. This study addresses how land transformation and land-use history affect the loss and recovery of functional diversity, specifically related to plant water use and cycling. The objectives are two-fold: 1. To assess how land-use history influences community-level patterns of water use, and 2. To examine whether hydraulic trait variation is associated with leaf phenology and carbon gain. The research is conducted in and around the Biosphere Reserve in Chamela, Mexico, which contains well preserved TDF stands of high floristic diversity, as well as established research plots in abandoned agricultural fields representing regenerating forests at different ages since disturbance. In the first part of the study, traits related to water acquisition and use are measured from dominant species of mature stands and along a chronosequence of regenerating plots of 3 different ages. In the second study two aspects of functional diversity are examined in greater detail: hydraulic and leaf trait variation. This data is used to assess whether water use traits differ among leaf phenological groups, and how they correlate with photosynthesis. The hypothesis is that, rather than falling into distinct groups based on phenological functional types, interspecific variation in hydraulic traits will correlate with maximum seasonal water stress. The proposed research will increase basic understanding of the coupling between hydraulic properties and leaf function, specifically leaf phenology and carbon gain. Instead of focusing on differences between phenological groups, this study will examine how species are arrayed along an axis of maximum seasonal water stress, and ask whether leaf traits co-vary. The little research that has been conducted in Chamela on the consequences of past land-use on abiotic resources has focused primarily on the changes to nutrient availability: its losses through soil erosion and through fire. This project focuses on another critical resource: water. These results will contribute to a general understanding of the functioning of tropical dry forest in terms of water storage and cycling and the effects of past-management on these key processes. Few studies have examined shifts in hydraulic traits in TDFs in relation to succession, and this project aims to fill this important science gap.

0754502Bhaskar国际研究奖学金计划使美国科学家和工程师能够在国外进行九到二十四个月的研究。 该项目的奖项为联合研究以及使用国外独特或互补的设施、专业知识和实验条件提供了机会。该奖项将支持 Radika Bhaskar 博士与墨西哥国立自治大学的 Patricia Balvanera 博士以及美国加州大学伯克利分校的 Todd Dawson 博士合作为期 24 个月的研究奖学金。由于其脆弱性和生物复杂性，热带 干旱森林（TDF）提供了一个引人注目的系统，可以评估干旱热带地区的功能多样性以及人为土地利用对生态系统功能的影响。 在 TDF 中，降水具有很强的季节性；在未受干扰的林分内，这种时间变化与高度多样化的木本植物群落有关，该群落具有广泛的用水策略，伴随着叶子物候的巨大变化。 这项研究探讨了土地转型和土地利用历史如何影响功能多样性的丧失和恢复，特别是与植物水分利用和循环相关的功能多样性。 目标有两个：1. 评估土地利用历史如何影响社区层面的用水模式；2. 检查水力性状变异是否与叶片物候和碳增益相关。 这项研究是在墨西哥查梅拉生物圈保护区及其周边地区进行的，该保护区包含保存完好的植物多样性高的 TDF 林，以及在废弃农田中建立的研究地块，代表了干扰后不同年龄的再生森林。 在该研究的第一部分中，与水获取和利用相关的性状是从成熟林分的优势物种以及 3 个不同年龄的再生地块的时间序列中测量的。 在第二项研究中，更详细地研究了功能多样性的两个方面：水力和叶片性状变异。 该数据用于评估叶片物候组之间的水分利用特征是否不同，以及它们与光合作用的相关性。 假设是，水力性状的种间变异将与最大季节性水分胁迫相关，而不是根据物候功能类型分为不同的组。 拟议的研究将增加对水力特性和叶片功能之间耦合的基本了解，特别是叶片物候和碳增益。 这项研究不是关注物候群之间的差异，而是研究物种如何沿着最大季节性水分胁迫轴排列，并询问叶子性状是否共同变化。 在查梅拉进行的关于过去土地利用对非生物资源的影响的研究主要集中在养分供应的变化：土壤侵蚀和火灾造成的损失。 该项目重点关注另一种重要资源：水。 这些结果将有助于总体了解热带干燥森林在水储存和循环方面的功能以及过去管理对这些关键过程的影响。 很少有研究探讨与演替相关的 TDF 水力特性的变化，该项目旨在填补这一重要的科学空白。