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首页> 外文期刊>International Journal of Geosciences >Net Nitrogen Mineralization in Natural Ecosystems across the Conterminous US
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Net Nitrogen Mineralization in Natural Ecosystems across the Conterminous US

机译：整个美国自然生态系统中的净氮矿化

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Nitrogen is the primary nutrient limiting ecosystem productivity over most of the US. Although soil nitrogen content is important, knowledge about its spatial extent at the continental scale is limited. The objective of this study was to estimate net nitrogen mineralization for the conterminous US (CONUS) using an empirical modeling approach by scaling up site level measurements. Net nitrogen mineralization and total soil nitrogen data across the CONUS were obtained from three different ecosystems: low elevation forests, high elevation forests, and grasslands. Equations to predict net nitrogen mineralization were developed through stepwise linear regression using total Kjeldahl nitrogen, air temperature, precipitation, and nitrogen deposition as predictor variables for four categories: low elevation high temperature forests (coefficient of determination, R2 = 0.83), low elevation low temperature forests (R2 = 0.74), high elevation forests (R2 = 0.80), and grasslands (R2 = 0.88). A map of net nitrogen mineralization was developed in GIS using these equations and national-scale databases for the CONUS. The result shows that net nitrogen mineralization varies widely across the US. Grasslands were predicted to have the lowest net nitrogen mineralization, while low elevation forests in the east had the highest. Mean values were 14.3 kg·ha-1·yr-1 for grasslands, 22.6 kg·ha-1·yr-1 for high elevation forests, 58 kg·ha-1·yr-1 for low elevation low temperature forests, and 82.9 kg·ha-1·yr-1 for low elevation high temperature forests. This continental scale estimation of net nitrogen mineralization provides a means of comparing net nitrogen mineralization across regions, and the databases developed from this study are useful for accounting for nitrogen limitations in large scale ecosystem modeling.
机译：在美国大部分地区，氮是限制生态系统生产力的主要养分。尽管土壤中的氮含量很重要，但在大陆范围内关于其空间范围的知识却有限。这项研究的目的是通过经验模型方法通过扩大站点水平测量来估算美国本土的净氮矿化量。整个CONUS的净氮矿化和土壤总氮数据来自三种不同的生态系统：低海拔森林，高海拔森林和草地。通过逐步线性回归，使用凯氏定氮总量，空气温度，降水量和氮沉降量作为四类预测变量的预测线性变量，建立了方程式：低海拔高温森林（测定系数，R2 = 0.83），低海拔低高温森林（R2 = 0.74），高海拔森林（R2 = 0.80）和草地（R2 = 0.88）。使用这些方程式和CONUS的国家级数据库，在GIS中绘制了净氮矿化图。结果表明，全美国的净氮矿化程度差异很大。据预测，草原的净氮矿化程度最低，而东部的低海拔森林则最高。草原的平均值为14.3 kg·ha-1·yr-1，高海拔森林的平均值为22.6 kg·ha-1·yr-1，低海拔的低温森林为58 kg·ha-1·yr-1，82.9 kg·ha-1·yr-1用于低海拔高温森林。大陆上净氮矿化的规模估算提供了一种比较各地区净氮矿化的方法，并且从本研究中开发的数据库可用于说明大规模生态系统建模中的氮限制。

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