早期分解中油松与阔叶树种凋落叶混合分解效应及其相互影响

以油松（Pinus tabuliformis Carrière）和5种阔叶树的凋落叶为对象，使用分解袋法在室内进行为期6个月的针阔混合分解实验，研究产生的混合分解效应、针阔凋落叶对彼此分解速率的影响及其可能产生机理。结果显示：（1）油松分别与红桦（Betula albo-sinensis Burk.）、灰楸（Catalpa fargesii Bur.）、太白杨（Populus purdomii Rehd.）凋落叶混合对分解速率均产生加性效应，但其中油松凋落叶分解受到显著促进，而阔叶凋落叶分解受到显著抑制。油松与杜仲（Eucommia ulmoides Oliver）凋落叶混合时两者分解速率均显著降低，油松与槭树（Acer tsinglingense Fang et Hsieh）凋落叶混合时两者分解速率均显著提高；（2）总体而言，在蔗糖酶、羧甲基纤维素酶和多酚氧化酶参与凋落叶分解的主要时期，红桦、灰楸、太白杨分别与油松凋落叶混合分解使土壤中这3种酶的活性较油松单独分解时显著提高，而较阔叶凋落叶单独分解时显著降低；油松与杜仲混合分解使这3种酶活性较两者单独分解时显著降低，而油松与槭树混合分解则产生相反效果。本研究结果表明，从凋落叶混合分解对物质循环影响的角度考虑，红桦、灰楸、太白杨和槭树可以用于油松纯林的混交改造，但应注意混交对阔叶树种分解的抑制；杜仲与油松凋落叶混合分解将会妨碍彼此养分循环，不宜混交改造。

Mixed decomposition and interspecific effects during early decomposition of litter mixtures of Pinus tabuliformis Carrière and broadleaved species

In this study, the litter of Pinus tabuliformis Carrière and five broadleaved species was mixed and placed in litterbags for six-month early-stage mixed litter decomposition. The mixed decomposition effects and interspecific impacts of broadleaved and P. tabuliformis species on decomposition were determined. Results indicated that:(1) mixed decomposition of P. tabuliformis and Betula albo-sinensis Burk., Catalpa fargesii Bur., and Populus purdomii Rehd. showed additive effects; however, the decomposition of P. tabuliformis litter was significantly accelerated, whereas the decomposition of broadleaf litter was significantly inhibited. Mixing P. tabuliformis and Eucommia ulmoides Oliver litter inhibited the decomposition of both types of litter, whereas mixing P. tabuliformis and Acer tsinglingense Fang et Hsieh litter showed contrary results. (2) Generally, the activities of sucrase, carboxymethyl cellulase, and polyphenol oxidase in the decomposition medium of mixtures of P. tabuliformis with B. albo-sinensis,C. fargesii, or P. purdomii were significantly higher than those in the decomposition medium (soil) of P. tabuliformis, whereas they were significantly lower than those in the decomposition medium of broadleaf litter. The mixed decomposition of P. tabuliformis and E. ulmoides resulted in significantly lower activities of the above-mentioned enzymes in the decomposition medium of the mixture compared with the activities in both types of single-specific decomposition medium, whereas the mixed decomposition of P. tabuliformis and A. tsinglingense exhibited contrasting impact. Considering the effects of mixed litter decomposition on the material cycling of the ecosystem, B. albo-sinensis,C. fargesii,P. purdomii, and A. tsinglingense could be used for transformation of pure P. tabuliformis forests; however, the inhibitory effects of mixing on litter decomposition of these species should be taken into consideration. As mixed plantation hindered nutrient cycling, E. ulmoides should not be mix-planted with P. tabuliformis.