Carbon, nitrogen and phosphorus net mineralization in organic horizons of temperate forests: stoichiometry and relations to organic matter quality

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• 作者：Christine Heuck ; Marie Spohn
• 关键词：Critical ratio ; Ecological stoichiometry ; Forest floor ; Nutrient cycling ; Respiration ; Threshold element ratio
• 刊名：Biogeochemistry
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：131
• 期：1-2
• 页码：229-242
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Biogeosciences; Ecosystems; Environmental Chemistry; Life Sciences, general;
• 出版者：Springer International Publishing
• ISSN：1573-515X
• 卷排序：131

文摘

The rates of mineralization processes influence C sequestration and soil fertility, but despite their importance for ecosystem functioning, C, N and P net mineralization rates are seldom investigated together. Hence, we studied the relationships between net mineralization rates and organic matter stoichiometry in an 8-week incubation experiment with Oi, Oe and Oa horizon material of six beech, one spruce and one pine site. We determined C, N and P net mineralization rates, organic C quality and C:N:P stoichiometry. Net N mineralization only occurred below molar organic matter C:N ratios of 40 (Oi) or 28 (Oa) and N:P ratios of 42 (Oi) or 60 (Oa), and increased with decreasing C:N and N:P ratios. Net P mineralization only occurred below C:P ratios of 1400 (Oi) and N:P ratios of 40 (Oi), and increased with decreasing C:P and N:P ratios. Net N and P mineralization were strongly positively correlated with each other (r = 0.64, p < 0.001), whereas correlations of both net N and net P mineralization with C mineralization were weak. The average C:N:P stoichiometry of net mineralization was 620:4:1 (beech, Oi), 15,350:5:1 (coniferous, Oi), 1520:8:1 (Oe) and 2160:36:1 (Oa). On average, ratios of C:N net mineralization were higher, and ratios of N:P net mineralization lower than organic matter C:N and N:P ratios. This difference contributed to the decrease of C:N ratios and increase of N:P ratios from the Oi to the Oa horizons. In conclusion, the study shows that C, N and P net mineralization rates were closely correlated with the organic matter stoichiometry and that these correlations were modified by the degree of decomposition of the organic matter.