Semi-arid shrublands of southern California, including chaparral and coastal sage, are found in widely varying elevation and microclimatic regimes and are subjected to disturbance such as fire and atmospheric N deposition that have the capacity to alter soil and litter C and N storage. Here we present a case study where soil and litter C and N were measured over 19 months in post-fire chaparral and mature coastal sage stands to assess whether differences in soil and litter C and N between these diverse shrublands could be attributed to differences in elevation, stand age, rainfall, and/or estimated N deposition exposure. Our results indicate that atmospheric N deposition exposure, either alone or in conjunction with other environmental variables (elevation, rainfall, and/or stand age), was the most frequent predictor of the spatial pattern in the soil and litter N and C variables observed. These results are consistent with those reported for high-elevation coniferous forests arrayed along an N deposition gradient in southern California, suggesting that N deposition may affect the soil N and C storage of semiarid shrublands and woodlands in a qualitatively similar manner.

中文翻译：

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南加州半干旱灌丛土壤和凋落物中的碳和氮储存

南加州的半干旱灌木林，包括灌木丛和沿海鼠尾草，海拔高度和小气候条件差异很大，并受到火灾和大气氮沉降等干扰，这些干扰有能力改变土壤和枯枝落叶碳和氮的储存。在这里，我们提出了一个案例研究，其中在火灾后丛林和成熟的沿海鼠尾草林中测量了 19 个月的土壤和枯枝落叶 C 和 N，以评估这些不同灌木林之间土壤和枯枝落叶 C 和 N 的差异是否可归因于海拔差异、林龄、降雨量和/或估计的 N 沉积暴露量。我们的结果表明，大气 N 沉积暴露，无论是单独的还是与其他环境变量（海拔、降雨量和/或林龄）相结合，是观察到的土壤和凋落物 N 和 C 变量中空间格局的最常见预测因子。这些结果与加利福尼亚南部沿 N 沉积梯度排列的高海拔针叶林所报道的结果一致，表明 N 沉积可能以质量相似的方式影响半干旱灌木地和林地的土壤 N 和 C 储存。