西南喀斯特典型石漠化生态系统土壤养分生态化学计量特征及其影响因素

喀斯特石漠化生态系统土壤养分元素生态化学计量特征及其对环境变异的生态响应是喀斯特退化森林生态系统恢复重建必需明确的关键科学问题。为探明喀斯特石漠化土壤C、N、P、K养分元素生态化学计量特征,探讨其对环境因子的响应,对西南喀斯特3个典型石漠化调查点(贵州毕节鸭池、清镇红枫湖和关岭-贞丰花江) 90个样方土壤及环境因子调查取样,研究了其土壤有机碳(C)、全氮(N)、全磷(P)及全钾(K)的化学计量特征及其影响因素。结果表明:西南喀斯特典型石漠化生态系统土壤C、N、P、K平均含量分别为45.61、2.54、0.79 g/kg和3.33 g/kg,计量比C∶N、C∶P、C∶K、N∶P、N∶K、P∶K平均值分别为19.56、65.07、23.65、3.45、1.32和0.39。4个土壤养分元素中,K元素表现明显高于其他元素的波动性。土壤养分含量及化学计量比在不同调查点、石漠化等级及植被覆盖率环境均有显著差异。无石漠化环境土壤养分C、N、P含量显著大于潜在、轻度、中度和强度石漠化,而强度石漠化环境土壤养分K含量却显著高于其他等级石漠化。土壤养分含量之间及其与化学计量比之间多具有显著的非线性相关关系。降水、温度、岩石裸露率和土地覆被是西南喀斯特石漠化生态系统土壤养分及其化学计量比最主要的影响因素。研究结果对丰富土壤生态化学计量学科学理论和我国西南喀斯特石漠化退化植被科学恢复具有重要意义。

Stoichiometric characteristics of soil nutrient elements and its influencing factors in typical karst rocky desertification ecosystems, Southwest China

Understanding the ecological stoichiometry characteristics of soil nutrient elements and their ecological responses to environmental variation are fundamental for the restoration and reconstruction of degraded forest ecosystems in the karst rocky desertification area of Southwest China. In the present study, to investigate the stoichiometry and environmental influencing factors of soil C, N, P, and K nutrient elements of karst rocky desertification ecosystems, Yachi, Hongfenghu, and Huajiang, Southwest China, were selected as experimental sites. Ninety sample plots in the three experiment sites were set to study the stoichiometry and environmental influencing factors of soil C, N, P, and K nutrient elements. The results showed that the average contents of soil C, N, P, and K in the three experimental sites were 45.61, 2.54, 0.79, and 3.33 g/kg, respectively. The average values of C:N, C:P, C:K, N:P, N:K, and P:K were 19.56, 65.07, 23.65, 3.45, 1.32, and 0.39, respectively. Among the four soil nutrient elements studied, the variation of K was remarkably higher than that of the others. There were significant (P < 0.05) differences in the soil nutrient contents or stoichiometric ratios among the different experimental sites, rocky desertification degrees, or vegetation cover rates. Contents of soil C, N, and P of no rocky desertification were significantly more than those of potential, slight, and severe degrees of rocky desertification. In contrast, among the five degrees of rocky desertification, soil K content of severe rocky desertification was the highest. There were significant nonlinear correlations among soil nutrient contents, and significant nonlinear correlations between soil nutrient contents and their stoichiometric ratios. Precipitation, temperature, percentage of exposed rocks, and land cover were the main environmental influencing factors for the stoichiometric characteristics of soil nutrients in the karst rocky desertification ecosystem. Results of the present study have important implications for the theoretical improvement of soil ecological stoichiometry and scientific rehabilitation and reconstruction of degraded forest ecosystems of karst rocky desertification in Southwest China.