| Litter decomposition is the main form of nutrient return in ecosystem, which was an important process to maintain the forest soil nutrient cycling and forest productivity. With the rapid development of industry, acid rain poseed a serious damage and impact to the Earth’s forest ecosystems. Cunninghamia lanceolata was an important fast-growing timber species in the south of China, which played an important role in China histroical forestry production. Cunninghamia lanceolata plationation’s soil fertility was decreased due to the difficulty of litter decomposition and the continuously planting problem. Soil fertility could be healthily improved by adjusting the forest structure and exerting the role of biodiversity in some degree. The research of the litter decomposition of different proprotrions of Cunninghamia lanceolata and Michelia macclurel in Cunninghamia lanceolata plantation (4,5,32 a) were conducted to explore the dynamics characteristics of the litter decomposition and soil enzyme activities on litter-soil interface under the acid rain background in Cunninghamia lanceolata plantation to provide basic data and scientific basis for the rational reconstruction of ecosystem and sustainable management for Cunninghamia lanceolata plantation by analysising the rate of litter decomposition, substrate quality, the soil enzyme activity (protease, cellulase, invertase, acid phosphatase, polyphenol oxidase) on litter-soil surface and the statistical analysis between the dry weight of litter remaining rate and substrate quality, soil enzyme activity among on litter substrate quality, forest environment,the correlation analysis among the various soil enzyme activities in acid rain region. The main conclusions followed:1-The monthly average rainfall was 30.70 to 477.90 mm, of which the average pH was 4.25-5.22; the average incidence of monthly acid rain was 68.2%-100% in Shaowu Forest.2.In the same age and process, the dry weight of the remaining rate of litter decreased slowly at the beginning of decomposition,which the decomposition rate of decline accelerating. In the same age and time, the dry weight of the remaining rate of litter had different performance alonged with litter decomposition,the decreasement of the dry weight of the remaining rate of litter decomposition the mixure of Cunninghamia lanceolata-Michelia macclurel was faster. In the same time and process, the dry weight of the remaining rate of litter had different variation range,32 a maximum, followed by 15 a, the most gentle was 4 a Cunninghamia lanceolata plantation.3.The litter substrate quality (total nitrogen, total carbon, C/N) had similar changes decomposition stage during the process of litter decomposition:in the same age and proportion, the total nitrogen content of litter of the litter mixure of Cunninghamia lanceolata-Michelia macclurel showed the trend "substantial increase-decrease-a slight increase-decrease-stabilized"; the total carbon content was manifested with decomposition of "wavy" decreasing trend, which had greatly reduced decomposition stage; while the C/N ratio showed trend "decrease-increase-decrease-stabilized". In the same age and time, the total nitrogen content of different proportions of Cunninghamia lanceolata-Michelia macclurel performanced B>E>D>C>A, the total carbon content and the C/N ratio showed A>C>D>E>B.In the same time and process, the substrate quality of litter decomposition of Cunninghamia lanceolata plantation with ages had big fluctions, the total nitrogen of litter behaved higer in 32 Cunninghamia lanceolata plantation, the total carbon content and C/N ratio showed 4 a>32 a>15 a.4.The five kinds of soil enzyme activities on litter-soil surface showed different performance during the whole process of litter decomposition of different proportions of Cunninghamia lanceolata-Michelia macclurel. The main followed:In the same age and proportion, the soil cellulase activity showed the trend "increasing-decreasing" over the process of litter decomposition; the soil invertase activity pre-exploded higher activity, lower activity mid decomposition, decomposition late activity improved slightly; the soil polyphenol oxidase activity showed the trend decreased at the beginning, increeased in latter; the soil acid phosphatase showed the decreased trend at the beginning, increased in the middle phase, decreased phase in latter; the soil protease activity showed an increased trend before mid decomposition, decreased trend followed, but there was a slight recovery process.In the same time and age, the soil enzyme activities of cellulose, sucrose of the different mixure of Cunninghamia lanceolata-Michelia macclurel had higer showed soil enzyme activities in different phase, the generally trend whose soil enzyme activities behaved higer with the higher proportions of Michelia macclurel, the soil activity of polyphenol had litter difference during the whole proress of litter decomposition, the activity of soil acid phosphatase and protease showed a big difference at the beginning of litter decomposition, litter difference between the different proportions of Cunninghamia lanceolata-Michelia macclurel with litter decomposition.There was closely relation with the phase in litter decomposition.In the same time and proportion, the soil cellulase activity manifested 4 a or 32 a> 15 a, the soil cellulase activity of 15 behaved lowed. The soil invertase activity was generally performanced 32 a>4 a>15 a. The soil polyphenol oxidase activity exhibited mature forest (32 a)>middle Age (15 a)> young forest (4 a). The soil acid phosphatase activity generally exhibited greater than 15 a or 4 a>32 a, and little difference between 15 a and 4 a; the protease activity showed the increasing trend with ages.5.Through correlation analysised, the dry weight of the remaining rate of litter was significantly related to or very significantly related to the total carbon content of the litter. The soil protease activity was highly significant negative correlation with the soil polyphenol oxidase; the soil sucrase and cellulase was a significant positive correlation, while with the soil acid phosphatase was significantly negatively correlated; the soil activity between cellulase and polyphenol oxidase activity was significantly negatively correlated. |
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