杉木林改造前后的土壤肥力对比分析及综合评价

Comprehensive Evaluation and Variation of Soil Fertility before and after Reconstruction with Broadleaved Trees in Cunninghamia lanceolata Plantations

基于福寿林场3个龄组杉木（Cunninghamia lanceolata）生态公益林9块固定样地的实测数据,选用土壤有机质、全氮、全磷、碱解氮、有效磷、速效钾、土壤容重和pH值8个指标对杉木林改造前后的土壤肥力进行了对比分析,并基于乘除法原理提出了土壤肥力综合评价指数和评价等级。结果表明：与改造前相比,改造后3个龄组杉木生态公益林0~20 cm表层土壤的有机质、全氮、全磷、碱解氮、有效磷、速效钾的含量都有不同程度的提高,且杉木幼、中林提高程度更明显,改造后的杉木幼、中龄林的土壤容重略有下降,pH值略有增加,但杉木近熟林的土壤容重和pH值基本保持没变。说明补植了阔叶树种栾树（Koelreuteria bipinnata）和马褂木（Liriodendron tulipifera）的杉木幼龄林和补植了阔叶树种栾树、马褂木和深山含笑（Michelia maudiae）的杉木中龄林土壤质量的改善程度明显优于在林下补植了红豆杉（Taxus chinensis）的杉木近熟林,通过树种结构调整改造后的3个龄组杉木林土壤肥力综合评价指数值也有不同程度的提高,土壤肥力质量从差变为较差。相比传统的土壤肥力综合评价指标,本文提出的土壤肥力综合评价指数不需要计算指标权重,计算量小,而且可以根据不同的土壤系统,对模型参数的个数适当增减,适用性较强。

Based on the measured data of nine permanent sample plots in Cunninghamia lanceolata ecological forest of three age groups in Fushou Forest Farm, soil fertility before and after the reconstruction in Cunninghamia lanceolata plantation was compared with 8 indices of soil organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus, available potassium, soil bulk density and pH value. And the comprehensive evaluation index and levels of soil fertility were put forward based on multiplication and division principle. The results showed that compared with the previous reconstruction, soil organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus, available potassium, soil bulk density and pH value at 0 ~ 20 cm soil depth in Cunninghamia lanceolata ecological forest of three age groups were obviously improved after reconstruction. Moreover, the increase was more obvious in young and half-mature Cunninghamia lanceolata plantation. Soil bulk density declined slightly and pH value increased slightly in young and half-mature Cunninghamia lanceolata plantation, but they remained unchanged in the near mature forest of Cunninghamia lanceolata. This illustrated that the improvement degree in soil quality was significantly better in young and half-mature Cunninghamia lanceolata plantation than in near-mature Cunninghamia lanceolata plantation. The evaluation index value of soil fertility was also improved to various extent, and the quality of soil fertility was changed from poor to less poor in three age groups of Cunninghamia lanceolata forest after adjusting the tree species structure. Compared to the traditional comprehensive evaluation index of soil fertility, this index proposed in this paper did not need to calculate the index weight, with the characteristics of less calculation and strong applicability, which leads to appropriately increase or decrease the number of model parameters according to the different soil systems.