Net Nitrogen Mineralization in Natural Ecosystems across the Conterminous US

Leeanna Y Chapman,Ge Sun,Steven G Mcnulty,Yang Zhang

doi:10.4236/ijg.2013.49125

Abstract

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, R 2 = 0.83), low elevation low temperature forests (R 2 =

Highlights

Nitrogen is the nutrient that most often limits plant growth in ecosystems [1,2,3]
Data were obtained from publications reporting both net nitrogen mineralization and total soil nitrogen data across the conterminous US (CONUS) for low elevation low temperature forests, low elevation high temperature forests, high elevation forests, and grasslands
High Elevation Forests In the high elevation forest category, the regression model for net nitrogen mineralization had a coefficient of determination (R2) of 0.80, adjusted coefficient of determination of 0.76, and standard error (S.E.) of 11.54 (Table 3)

Summary

Introduction

Nitrogen is the nutrient that most often limits plant growth in ecosystems [1,2,3]. Soil nitrogen limitations impact many components of an ecosystem, including limiting forest growth and yield and constraining carbon sequestration [4]. Too much nitrogen leaving soils can cause water pollution problems in watersheds [5,6]. Total soil nitrogen includes nitrogen in all organic and inorganic forms, but is not an indicator of plant available nitrogen. The conversion of organic nitrogen to ammonium, represents most of the nitrogen availability in unfertilized soils [8], and provides an index of plant available nitrogen [9]

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Methods

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Discussion

Conclusion