Hydric Soils of the Prairie Pothole Region

我的研究计划的主要长期目标是将土壤功能与土地利用和气候变化联系起来。这使我们能够了解土地管理决策如何影响区域土壤生物地球化学过程，并最终影响生态系统的可持续性。具体的长期问题包括：碳氮循环等关键土壤功能与土地利用变化有何关系？基于地貌的采样能加深我们对营养动态的理解吗？这些关系能为地方、区域或国家规模的土地管理提供信息吗？加拿大大草原和美国大平原北部的大草原坑坑区(Prairie Pothole Region，PPR)面积超过70,000平方公里。它的特点是数百万个湿地被春季的积雪融化填满，但在夏季的几个月里干涸；每年春天持续的饱和形成了独特的湿地土壤，我们将其称为“氢化土壤”。PPR湿地和氢化土壤提供许多生态系统服务，包括水和养分的保持和循环、洪水消减、水过滤、地下水补给、碳固存、野生动物栖息地和生物多样性。每年的干湿循环被认为在许多此类服务中发挥着重要作用，但大多数PPR湿地已被排水用于农业生产和郊区开发，而没有完全了解排水对土壤养分动态的长期影响。传统上，PPR的含水土壤已经跨越了学科界限：对土壤科学家来说太湿了，对湿地科学家来说太干了。在短期内，我的研究计划旨在确定PPR中湿地管理历史的土壤指标，并研究土地利用变化对湿润土壤碳、氮动态的影响。水文发生变化后，含氢土壤作为含氢土壤的作用还会持续多久？我们能否根据湿地的生态系统功能对其进行分类，从而确定对保护或恢复最重要的湿地？通过增进我们对农业生态系统内的氢化土壤的了解，拟议的项目将改善PPR湿地的综合管理，最大限度地增加生态系统服务，同时最大限度地减少生产性土地的损失。

The primary long-term objective of my research program is to link soil function to land use and climate change. This allows us to understand how land management decisions influence regional soil biogeochemical processes and ultimately ecosystem sustainability. Specific long-term questions include: How are key soil functions such as carbon and nitrogen cycling related to land use change? Can landform-based sampling refine our understanding of nutrient dynamics? Can these relationships inform land management at the local, regional, or national scales? The Prairie Pothole Region (PPR) encompasses over 700,000 square kilometres of the Canadian Prairies and northern Great Plains of the U.S. It is characterized by millions of wetlands that are filled by spring snowmelt but dry down during the summer months; the prolonged saturation each spring gives rise to unique wetland soils we refer to as "hydric soils". PPR wetlands and hydric soils provide a number of ecosystem services, including water and nutrient retention and cycling, flood attenuation, water filtration, groundwater recharge, carbon sequestration, wildlife habitat and biodiversity. Annual wet-dry cycles are thought to play an important role in many of these services, but a majority of PPR wetlands have been drained for agriculture production and suburban developments, without complete understanding of the long-term implication of drainage for soil nutrient dynamics. Traditionally, hydric soils of the PPR have fallen through disciplinary boundaries: too wet for soil scientists and too dry for wetland scientists. In the short term, my research program aims to identify soil indicators of wetland management history in the PPR and examine how carbon and nitrogen dynamics of hydric soils are affected by land use change. How long do hydric soils continue to behave as hydric soils following a change to their hydrology? Can we classify wetlands by their ecosystem function and therefore identify those most essential for preservation or restoration? By improving our understanding of hydric soils within agro-ecosystems, the proposed project will improve integrated management of PPR wetlands, maximizing ecosystem services while minimizing loss of productive land.