Study On The Dynamic Of Litterfall And Leaf Decomposition Of Aleurites Montana Plantation

As metabolites by forests and important nutrients to forest soils, forest litter plays a significant role in linking vegetation to soil in forest ecosystem nutrient cycling. The study of forest litter mainly focuses on litterfall and litter decomposition since these two aspects are always considered as complex and critical factors influencing vegetation structure and ecosystem function. In this paper, the Aleurites Montana plantation in Fuzhou Minhou Tongkou National Forestry Centre was studied for one year in dynamic of litterfall and litter nutrients and weight loss rate, nutrients dynamic and nutrients release in the process of foliage decomposition, together with the sampling analysis of water holding capacity of the litter and activity of soil enzymes. The results were shown in the following parts:1. The annual litter dynamic of Aleurites Montana plantation simply showed the increasing tendency. The litterfall of Aleurites Montana plantation from Feb. to Apr. was comparatively few with the total sum of 124.7g, occupying only 2.15% of the annual total litterfall. The summit of litterfall appeared in autumn and winter from Oct. to Dec. with the total sum of 4395g, occupying 75.68% of the annual total litterfall.2. The amounts of litter nutrients were in the sequence of organic C>N>Ca>K>Mg>P>Mn>Na>Zn. The dynamic of organic carbon amount showed the bimodal pattern with the peak values appearing in Mar. (432.52g/kg) and Jun. (414.06g/kg). The amounts of nitrogen and potassium mainly showed the unimodal pattern with the peak values respectively appearing in Jun. (19.34g/kg) and Apr. (7.96g/kg). The peak value of phosphorus amount and the lowest level of calcium amount both appeared from May to July. The amount of magnesium showed the increasing pattern after Apr. and reached the peak value of 1.7835g/kg in Oct. The amounts of manganese, natrium and zincum were comparatively few, less than 1g/kg. No apparent rule was shown in the amounts dynamic of these three nutrients and the peak values of manganese, natrium and zincum appeared respectively in Nov. (0.7052g/kg), Jun. (0.3638g/kg) and Oct. (0.0654g/kg).3. In water holding capacity, the water holding amount increased rapidly within 8 hours, increased slowly from 8 to 12 hours and maintained steadily from 12 to 16 hours. The tendency of water holding rate generally consisted with that of the water holding amount. The maximum water holding amounts of Aleurites Montana litter in the sample plots from No.1 to No. 5 were respectively 1.89, 2.03, 1.77, 2.02 and 1.96 times of the amounts of litterfall in each sample plot.4. The litter remnant rates were in the sequence of pattern E>A>D>C>B. Pattern A was designed as 100% Aleurites Montana foliage, pattern B as 100% P. pubescences foliage, pattern C as 50% Aleurites Montana foliage and 50% P. pubescences foliage, pattern D as 75% Aleurites Montana foliage and 25% P. pubescences foliage and pattern E as 80% Aleurites Montana foliage and 20% P. pubescences foliage. Pattern B with 100% P. pubescences foliage decomposed the fastest with the remnant rate of only 10.97%, followed by the remnant rate of 14.38% in pattern C with 50% Aleurites Montana foliage and 50% P. pubescences foliage. The remnant rate remained 22.53% when the ratio of Aleurites Montana foliage to P. pubescences foliage was 3:1 in pattern D and pattern E exhibited the slowest decomposition rate with 80% Aleurites Montana foliage and 20% P. pubescences foliage. The five patterns varied in monthly weight loss rate: patterns A and B exhibited the tendency of slow-fast-slow, pattern C showed unapparent trend and patterns D and E exhibited the increasing trend in decomposition. 5. After one year, the organic carbon contents of the five patterns were in the sequence of C>D>A>E>B, the nitrogen contents were D>A>E>B>C and the phosphorus contents were C>B>A>D>E. The calcium amount dynamic of the patterns mainly exhibited unimodal mode except for the fluctuant trend of pattern A and the peak values appeared at the beginning of decomposition from Mar. to Jun. , the lowest levels at the end of decomposition from Nov. to Jan. The peak values of potassium contents all appeared at the beginning of decomposition , followed by heavy release of potassium and enrichment-release mode thereafter. The magnesium contents of the patterns mainly exhibited decreasing tendency except for the bimodal mode of pattern B and the amounts of magnesium decreased sharply after one-year decomposition. The dynamic of natrium amounts generally presented obvious unimodal trend with varied months of peak values. The manganese amounts showed unapparent tendency with complex fluctuant changes. The amounts of zincum remained between 0.04-0.08g/kg at the beginning of decomposition and the peak value appeared in July, followed by the modes of release or enrichment in different patterns.6. The sucrase concentrations in the natural soil layers without litter were obviously lower than those with 100% Aleurites Montana litter but higher than those with 100% P. pubescences litter. The sucrase concentrations were activated in the soil layers of 5-10cm in varied mixture of Aleurites Montana and P. pubescences litter. The amplitude variation of catalase was unremarkable, between 0.11-0.65mg/ (g·20min). The catalase activity was relatively high in enzyme release and accumulation in the soil layers of 5-10cm of the five patterns but relatively low in the soil layers of 10-20cm.