【摘要】 第 1代人工杉木林皆伐后 ,3种不同的经营模式 ,即连载杉木纯林、杉木与固 N阔叶树混交林和杉木与非固 N阔叶树混交林 ,对林地土壤质量和土壤水化学的影响进行了比较。结果表明 ,在杉树与阔叶树混交经营模式下 ,土壤养分含量增加 ,物理性状改善 ,土壤生物活性提高 ,微生物商 (Cmic:Corg)上升 ,代谢商 (q CO2 )稍有下降 ,但杉木与固 N树种的混交对土壤质量的改善效果比杉木与非固 N树种混交好 ;相反 ,杉木连载只能导致林地土壤质量的逐渐恶化 ;土壤溶液中 ,主要来自于大气中的一些离子浓度 ,如 SO2 - 4,Cl- ,Na+和 Mg2 + ,在杉木纯林中显著高于混交林 ,而主要受系统内影响较大的一些离子 ,如 K+和NH+ 4,NO- 3,在经营模式间变异较小 ;H+ 和 Al3+ 浓度也是杉木纯林比混交林高。另外 ,研究结果还表明 ,总有机 C、CEC和微生物 C与其它土壤理化性质与生物学性质之间存在着较好的相关性 ,所以可以将总有机 C、CEC和微生物 C作为红黄壤地区亚热带人工林土壤质量的指示指标更多还原

【Abstract】 Chinese fir （Cunningharnia lanceolata）, a type of subtropical fast-growing conifer tree, widely distributed in South China, and its plantation area in China is more than 7×10⁶ hm², accounting for 24% of total area of planted forest in China. In recent decades, the system of successive plantation of Chinese fir is widely used in the southern china for an anticipated high economic return. However, recent studies have documented that the practice of this system led to dramatic decreases in soil fertility and forest environment as well as in productivity. Compared with the first plantation generation of Chinese-fir, soil organic C, N, P, K and forest productivity, respectively, decrease 12.0%, 18.8%, 16.7%, 10.2% and 12.5% for the second rotation, 18.5%, 31.2%, 27.5%, 25.4% and 45.5% for the third rotation. Therefore, in recent years, increasing concern about the sustainable productivity of Chinese fir plantation forest has emphasized the need to seek a way to control the forestland degradation effectively and maintain soil quality. Some forest ecologists and managers recognize the ecological role performed by broadleaf trees growing in mixtures with conifers, and a great deal of studies on mixtures effects have been conducted, particularly on mixture species of temperate and boreal forest, but these research results were not completely consistent each other. Maybe the mixtures effects depend in large part on specific site conditions, the interactions among species in mixtures and biological characteristics of species, etc.. Although some researchers also studied the effects of mixtures of Chinese fir and broadleaf tree species on soil fertility, forest environment and tree growth status, little information is available about systematic studies in mid-subtropical region on different forest management models such as mixtures of Chinese-fir and broadleaf trees （including N-fixing and non-N-fixing tree species）, effects on soil quality, in particular on soil microbiological and biological properties. Similarly, repots about effects of different forest management models on forest-floor solution chemistry are also very scarce. The experimental site was situated at Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, Hunan Province （N 26°40′～27°09′ latitude and E 109°26′～110°08′ longitude）. It locates at the transition zone from the Yunnan-Guizhou plateau to the low mountains and hills of southern bank of Yangtz River at an altitude of 300～1100 m above mean sea level and at the same time, it is also a member of the Chinese Ecosystem Research Network （CERN）, sponsored by the Chinese Academy of Sciences （CAS）. This region has a humid mid-subtropical monsoon climate with a mean annual precipitation of 1200～1400 mm, most of the rain falling between April and August, and a mean temperature of 16.5 ℃ with a mean minimum of 4.9 ℃ in January and a mean maximum of 26.6 ℃ in July. The soil of the experimental field is red-yellow soil. After a clear-cutting of the first generation Chinese-fir planted forest （Cunninghamia lanceolata） in autumn of 1989, three different forest management models, viz. mixture of Chinese-fir and N-fixing alder （Alnus cremastogyne） （MCA）, mixture of Chinese-fir and non-N-fixing Kalopanax septemlobus （MCK） and pure Chinese-fir stand （PCS）, were established in spring of 1990. The effects of these three planted forest stands on soil characteristics were evaluated by measuring physico-chemical, microbiological, biochemical parameters and soil solution chemistry. Both MCA and MCK exerted a favourable effect on soil fertility maintenance, the improvement being greater under MCA. The concentrations of the mainly atmospherically derived ions in sol solutions, including SO^2-₄, Cl^-, Na⁺ and Mg²⁺, were significantly higher under the conifer （PCS） than under the mixtures （MCA and MCK）. Whereas the concentrations of ions that mainly controlled by within system processes such as K⁺, NO^-₃ and NH⁺₄ varied small among the management models. The concentrations of H⁺ and更多还原