Oles Kristin M, Weixelman Dave A, Lile David F, Tate Kenneth W, Snell Laura K, Roche Leslie M
Department of Plant Sciences, University of California, One Shields Avenue, Davis, California, 95616, USA.
USDA Forest Service Pacific Southwest Region, Nevada City, CA, 95959, USA.
Environ Manage. 2017 Sep;60(3):383-395. doi: 10.1007/s00267-017-0897-1. Epub 2017 Jun 2.
Riparian meadows occupy a small proportion of the public lands in the western United States but they provide numerous ecosystem services, including the production of high-quality forage for livestock grazing. Modern conservation management strategies (e.g., reductions in livestock stocking rates and adoption of new riparian grazing standards) have been implemented to better balance riparian conservation and livestock production objectives on publicly managed lands. We examined potential relationships between long-term changes in plant community, livestock grazing pressure and environmental conditions at two spatial scales in meadows grazed under conservation management strategies. Changes in plant community were not associated with either livestock stocking rate or precipitation at the grazing allotment (i.e., administrative) scale. Alternatively, both grazing pressure and precipitation had significant, albeit modest, associations with changes in plant community at the meadow (i.e., ecological site) scale. These results suggest that reductions in stocking rate have improved the balance between riparian conservation and livestock production goals. However, associations between elevation, site wetness, precipitation, and changes in plant community suggest that changing climate conditions (e.g., reduced snowpack and changes in timing of snowmelt) could trigger shifts in plant communities, potentially impacting both conservation and agricultural services (e.g., livestock and forage production). Therefore, adaptive, site-specific management strategies are required to meet grazing pressure limits and safeguard ecosystem services within individual meadows, especially under more variable climate conditions.
河岸草甸在美国西部公共土地中所占比例较小,但它们提供了众多生态系统服务,包括为牲畜放牧生产优质草料。现代保护管理策略(例如,降低牲畜存栏率和采用新的河岸放牧标准)已经实施,以便在公共管理土地上更好地平衡河岸保护和牲畜生产目标。我们在采用保护管理策略放牧的草甸中,在两个空间尺度上研究了植物群落的长期变化、牲畜放牧压力和环境条件之间的潜在关系。在放牧分配(即行政)尺度上,植物群落的变化与牲畜存栏率或降水量均无关联。相反,在草甸(即生态地点)尺度上,放牧压力和降水量与植物群落的变化均有显著关联,尽管关联程度不大。这些结果表明,降低存栏率改善了河岸保护和牲畜生产目标之间的平衡。然而,海拔、场地湿度、降水量与植物群落变化之间的关联表明,不断变化的气候条件(例如,积雪减少和融雪时间变化)可能引发植物群落的转变,这可能会对保护和农业服务(例如,牲畜和草料生产)产生影响。因此,需要采取适应性的、因地制宜的管理策略,以满足放牧压力限制并在各个草甸内保障生态系统服务,尤其是在气候变化更大的条件下。