Trade-offs between biodiversity and soil carbon storage in grasslands due to cattle grazing

草地提供生态系统货物和服务，包括：碳储存、牲畜饲料和生物多样性。大多数草地的主要用途是放牧，虽然草地是随着放牧（即野牛）而进化的，但它可以改变植物群落，最终影响多种EGS。但很少同时审查提供多种环境商品和服务的问题。因此，该计划将研究放牧对EGS之间的关系和权衡的影响，重点是放牧驱动的植物转移在介导这些影响中的作用。我们问1）在多个尺度上的多个EGS之间的关系是什么牲畜的影响，和2）植物物种在响应放牧和影响EGS的反应中的作用是什么。个别EGS放牧的反应进行了研究，但EGS之间的权衡模式少。通常认为植物生产力和土壤碳是相关的。然而，这些变量之间的关系很弱，并且对于某些植物物种，多样性，生产力和碳之间的关系并不遵循这些模式。我们将在小尺度上测量这些模式，将植物物种组成与本地化EGS和大尺度（牧场管理）相关联，以研究景观异质性改变所产生的影响。一个基于性状的方法将被用来研究植物的功能作用，在驱动效应的EGS。植物是EGS的主要提供者，个别物种可能是不同EGS的更好提供者或对放牧的反应不同。为了了解放牧对EGS的影响，我们将测量与生态系统功能直接相关的植物性状（例如树叶的分解率）和响应性状，例如对放牧的敏感性。这些特征将与草地群落组成和生态系统功能以及牲畜的偏好有关。我们将遵循这种方法与功能性的“敲除”实验，旨在研究放牧和全球变化过程对EGS的影响。该计划将开始解决放牧如何通过植物群落的变化改变多种EGS。随着社会对草原的认识提高，以及通过放牧管理实施增加土壤碳储存的政策，这类研究至关重要，这可能会对生物多样性产生意想不到的后果。其次，它将提供一个机械的理解，如何个别植物物种，通过他们的特点，既响应放牧，并导致在草原土壤碳储量的变化。我们目前有一个不完整的，有时是相反的一套模式，放牧可能会或可能不会有利于草原生态系统，最终这些影响是由放牧动物选择不同的植物物种，导致其相对丰度的变化，但为什么一个特定的物种转变改变EGS并不总是清楚。

Grasslands provide ecosystem goods and services (EGS), including: carbon storage, forage for livestock and biodiversity. The primary use of most grasslands is livestock grazing, and while grasslands evolved with grazing (i.e. bison), it can alter plant communities and ultimately affect multiple EGS. But rarely has the provision of multiple EGS been examined simultaneously. Thus, this program will examine the effects of grazing on the relationships and trade-offs among EGS with a focus on the role of grazing driven plant shifts in mediating these effects. We ask 1) what is the relationship among multiple EGS at multiple scales as affected by livestock, and 2) what are the roles of plant species in responding to grazing and affecting responses in EGS. The responses of individual EGS to grazing have been studied, however the pattern of trade-offs among EGS less so. It is often assumed that plant productivity and soil carbon are correlated. However, there are weak and highly noisy relationships between these variables and for some plant species the relationship between diversity, productivity and carbon do not follow these patterns. We will measure these patterns at small scale to relate plant species composition to localized EGS and large scale (pasture management) to examine affects resulting from altered landscape heterogeneity. A trait-based approach will be used to examine the functional role of plants in driving effects on EGS. Plants are key providers of EGS, and individual species may be better providers of different EGS or respond differently to grazing. To understand the effects of grazing on EGS we will measure plant traits that are directly related to ecosystem function (e.g. decomposition rate of leaves) and response traits, such as sensitivity to grazing. These traits will be linked to grassland community composition and ecosystem function, as well as preference by livestock. We will follow this approach with functional "knock-out" experiments designed to examine the impacts of grazing and global change process on EGS. This program will begin resolving how grazing alters multiple EGS through plant community changes. Such research is critical as societal awareness of grasslands increases, and policy to increase soil carbon storage is implemented through grazing management, which may have unintended consequences for biodiversity. Second, it will provide a mechanistic understanding of how individual plant species, through their traits, both respond to grazing and lead to changes in soil carbon storage in grasslands. We currently have an incomplete and sometimes opposing set of patterns in which grazing may or may not be beneficial for grassland ecosystems and ultimately these effects are driven by the selection of different plant species by grazing animals that leads to changes in their relative abundance, but why a particular species shift alters EGS is not always clear.