LTREB: Long-term ecosystem responses to directional changes in precipitation amount and variability in an arid grassland

LTREB：干旱草原降水量和变异性方向变化的长期生态系统响应

基本信息

批准号：
1754106
负责人：
Osvaldo Sala
金额：
$ 52万
依托单位：
Arizona State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1754106&HistoricalAwards=false
关键词：
LTREB Long term ecosystem responses

项目摘要

In the American Southwest, rainfall patterns are changing, and are likely to continue to change in the coming decades. Major droughts and floods will occur more often and will be more intense. These changes are likely to have a large impact on grasslands and the ecosystem services they provide. Scientists have studied grassland ecosystems and the plant species that live in them for many years. Predicting the future of grasslands as the environment changes remains a challenge, however, because it is very difficult to understand causes of patterns using observations alone. Controlled experiments can uncover what causes changes in grasslands with enough confidence to predict their future as they begin to experience conditions never seen before. It is also difficult to predict long-term changes using only short-term experiments. This project will expand on decade-long field experiments in which rainfall amount and variability were manipulated to learn how grassland ecosystems are likely to change. Results from these experiments will yield new understanding that will provide guidance to managers of drylands in the Southwest United States, and around the world. This project will also train a new generation of scientists, many of whom are members of underrepresented minority groups.This project is guided by two hypotheses about endogenous and exogenous phenomena that interact with each other to generate dryland responses to changes in amount and variability of precipitation. (1) Endogenous biogeochemical and demographic phenomena mediate abrupt or continuous changes in populations, communities and ecosystem processes. (2) Exogenous phenomena, such as El Niño events that occur with low frequency, interact with endogenous mechanisms to affect system resilience, leading to changes in population dynamics and ecosystem processes. This project will capture the impacts of infrequent exogenous phenomena and the cumulative effects of endogenous factors on populations of desert species, communities and ecosystems. The project will build upon two extant experiments located in a Desert Grassland in New Mexico: (a) manipulation of rainfall amount (80% reduced precipitation, ambient, 80% increased) crossed with changes in nitrogen availability, and (b) manipulation of rainfall variability (control, enhanced variability by 50% and 80%). Long-term manipulations of precipitation amount are accomplished using rainout shelters coupled with irrigation systems. Different levels of nitrogen availability are achieved via fertilization. Manipulations of precipitation variability are conducted by flipping drought and irrigation treatments from year to year in the same plots. Response variables include above and belowground net primary production, species composition, net nitrogen mineralization and leaf nitrogen isotopic ratios. This research has the potential to transform understanding of long-term ecosystem responses to changes in patterns of precipitation, which is critical to assessment of how ecosystem services are likely to change over the coming decades.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在美国西南部，降雨模式正在发生变化，并且在未来几十年中可能会继续改变。重大干旱和地板会更频繁地发生，并且会更加激烈。这些变化可能会对草原及其提供的生态系统服务产生重大影响。科学家研究了草原生态系统和居住在其中多年的植物物种。然而，随着环境变化而预测草原的未来仍然是一个挑战，因为仅使用观测值就很难理解模式的原因。受控的实验可以发现什么导致草原变化，以足够的信心来预测他们的未来，因为他们开始体验从未见过的条件。也很难仅使用短期实验来预测长期变化。该项目将在长达十年的现场实验中进行扩展，在该实验中，操纵降雨量和可变性以了解草地生态系统可能如何改变。这些实验的结果将产生新的了解，这将为美国西南部和世界各地的旱地经理提供指导。该项目还将培训新一代的科学家，其中许多人是代表性不足的少数群体的成员。该项目的指导下，这两个关于内源性和外源现象的假设相互相互作用，以产生旱地对降水量和变异性变化的反应。（1）内源性生物地球化学和人口统计学现象媒体的突然或人群，社区和生态系统过程的持续变化。（2）外源现象，例如以低频率发生的厄尔尼诺事件，与内源性机制相互作用以影响系统的弹性，从而导致人口动态和生态系统过程的变化。该项目将捕获不经常的外源现象的影响以及内源性因素对沙漠，社区和生态系统种群的累积影响。该项目将建立在新墨西哥州沙漠草原的两个现存实验上：（a）操纵降雨量（80％减少降水量，环境，80％，增加80％）随氮的可用性变化而跨越，以及（b）操纵降雨量的可变性（对照，对照，增强变异性增强了50％和80％）。长期操纵降水量是使用与灌溉系统相结合的Rainout避难所来完成的。通过施肥可实现不同水平的氮利用率。氮变异性的操纵是通过在同一地块中每年翻转干旱和灌溉处理来进行的。响应变量包括上述和地下净初级生产，物种组成，净氮矿化和叶氮同位素比。这项研究有可能改变对长期生态系统对降水模式变化的反应的理解，这对于评估未来几十年中生态系统服务可能会发生变化至关重要。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和更广泛影响的评估来审查审查标准的评估，被视为珍贵的支持。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Changes in belowground biodiversity during ecosystem development

DOI：
10.1073/pnas.1818400116
发表时间：
2019-04-02
期刊：
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
影响因子：
11.1
作者：
Delgado-Baquerizo, Manuel;Bardgett, Richard D.;Fierer, Noah
通讯作者：
Fierer, Noah

Global change effects on plant communities are magnified by time and the number of global change factors imposed

DOI：
10.1073/pnas.1819027116
发表时间：
2019-09-03
期刊：
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
影响因子：
11.1
作者：
Komatsu, Kimberly J.;Avolio, Meghan L.;Zhang, Yunhai
通讯作者：
Zhang, Yunhai

Effect of interannual precipitation variability on dryland productivity: A global synthesis