Growing demand for local products in the northeastern U.S. may incentivize forest conversion to pasture, degrading critical soil hydrologic properties such as surface infiltration (K h ) and subsurface saturated hydraulic conductivity (K sat ). Silvopasture, combining tree cover and grazing, may mitigate these impacts by maintaining the positive effects of trees on soil hydraulic properties. We tested this hypothesis using an experimental field manipulation to compare effects of forest conversion to open pasture versus silvopasture on K h and K sat at the Organic Dairy Research Farm (ODRF) and North Branch Farm (NBF). Measurements of surface K h and K sat at two soil depths (15 cm and 30 cm) were taken 1 and 4 years after treatment establishment at ODRF and NBF, respectively. Data were analyzed using a mixed effects modeling framework. Results show 15 cm K sat was significantly lower in pasture compared to forest across both sites. However, in contrast to our hypothesis, soil hydraulic properties in silvopasture did not differ from other treatments at either site. Notwithstanding, silvopasture 15 cm K sat at ODRF (9.4 cm h −1 ) was statistically similar to both the forest (22.6 cm h −1 ) and pasture (3.4 cm h −1 ) and exhibited a weak positive correlation with proximity to trees (R 2 = 0.219, P = 0.042). In conclusion, our study did not find strong evidence that recently established silvopastures mitigate negative hydrologic impacts of forest conversion. Future research should focus on a broader range of northeastern sites and include greater replication over longer time scales to better elucidate opportunities for silvopasture.

中文翻译：

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森林转变为林场和露天牧场：对土壤水力特性的影响

美国东北部对当地产品不断增长的需求可能会促使森林转变为牧场，从而降低关键的土壤水文特性，如地表入渗 (K h ) 和地下饱和导水率 (K sat )。Silvopasture 结合树木覆盖和放牧，可以通过保持树木对土壤水力特性的积极影响来减轻这些影响。我们使用实验性田间操作测试了这一假设，以比较有机乳制品研究农场 (ODRF) 和北分支农场 (NBF) 的森林转化为开放牧场与森林牧场对 K h 和 K sat 的影响。在 ODRF 和 NBF 处理建立后 1 年和 4 年，分别测量了两个土壤深度（15 厘米和 30 厘米）的表面 K h 和 K sat。使用混合效应建模框架分析数据。结果显示，与两个地点的森林相比，牧场中的 15 cm K sat 显着降低。然而，与我们的假设相反，森林牧场的土壤水力特性与任一地点的其他处理没有区别。尽管如此，在 ODRF (9.4 cm h -1 ) 的 silvopasture 15 cm K 在统计上与森林 (22.6 cm h -1 ) 和牧场 (3.4 cm h -1 ) 相似，并且与树木的接近程度呈弱正相关( R 2 = 0.219，P = 0.042）。总之，我们的研究没有发现强有力的证据表明最近建立的林场可以减轻森林转变对水文的负面影响。未来的研究应侧重于更广泛的东北地区，并包括在更长的时间范围内进行更大的复制，以更好地阐明森林放牧的机会。