Understanding and mitigating the impacts of altered temperature and precipitation regimes on the function and biodiversity of rangeland communities

加拿大有2200万公顷的土地专门用于牧场和牧草生产。这块土地支持着400万对母牛/牛犊，过度放牧导致该地区只有不到50%的地区被列为“良好”状态。改善牧场条件提供了直接的经济效益，由于原生牧场储存的碳比牧场更多，这也将导致碳储量的增加。健康的牧场储存相当于每公顷森林的碳，由于这种碳主要在地下，因此在火灾中释放的风险较低。不幸的是，我们对驱动牧场动态的地下过程了解有限。对于气候变化将如何影响这些系统的可持续性，普遍缺乏信息。了解牧场气候与放牧的相互作用有可能(1)增加碳储存，(2)增强生物多样性和生态系统功能，(3)提供经济回报。为了减轻气候变化对加拿大牧场生物多样性和可持续生产的潜在影响，至关重要的是从机制上了解温度、降水、土壤化学、微生物和无脊椎动物多样性和活动、初级生产和放牧之间的联系。*我们将在阿尔伯塔省、萨斯喀彻温省、在每个地点，我们将建立三个生长季经历落叶、变暖和降水处理的地块。我们将测量初级生产力和牧场健康，特别强调地下动态。我们将使用微型根茎，以提高初级生产力和碳流估计的准确性。我们还将测量微生物和无脊椎动物群落、凋落物分解以及碳和氮循环的变化，并探索这些过程之间的联系。根据这些数据，我们将为农业社区的这一部分确定一套关于如何改变放牧制度以减轻气候变化的各种影响的管理建议。

Canada contains 22,000,000 ha of land dedicated to range and forage production.  This land supports 4M cow/calf pairs and overgrazing has resulted in less than 50% of this area listed as in "good" condition.  Improving rangeland condition provides direct economic benefits and since native range stores more C than pasture, this will also lead to increase C storage.  A healthy rangeland stores equivalent C per ha as forest, and since this C is primarily belowground, it is at a lower risk of release during fires.  Unfortunately, we have a limited understanding of the belowground processes that drive rangeland dynamics, and a general lack of information on how climate change will impact the sustainability of these systems.  Understanding the climate-grazing interactions in rangelands has the potential to (1) increase C storage, (2) enhance biodiversity and ecosystem functioning, and (3) provide economic returns.        To mitigate the potential impacts of climate change on the biodiversity and sustainable production of Canada's rangelands, it is essential to gain a mechanistic understanding of the links between temperature, precipitation, soil chemistry, microbial and invertebrate diversity and activity, primary production, and grazing.  We will conduct experiments in the Parkland regions of Alberta, Saskatchewan, and Manitoba.  At each location, we will establish plots subjected to combinations of defoliation, warming, and precipitation treatments for three growing seasons.  We will measure primary productivity and range health, with a particular emphasis on belowground dynamics.  We will use mini-rhizotrongs to allow for enhanced accuracy in estimations of primary productivity and carbon flow. We will also measure changes in microbial and invertebrate communities, litter decomposition, and C and N cycling and explore linkages among these processes.  From these data, we will identify a set of management recommendations for this sector of the agricultural community on how to alter grazing regimes to mitigate the varied impacts of climate change.