Study On Litterfall Dynamics Of Pinus Koraiensis And Larix Gmelinii Plantations In Maoershan Area

Pinus koraiensis Sieb et Zucc. and Larix gmelinii (Rupr.) Rupr. are two important tree species in Northeast China. Both Pinus koraiensis and Larix gmelinii have high economic value, ecological value and social value. There were no detailed studies on litter and forestfloor ofPinus koraiensis and Larix gmelinii in this region. The research had been carried out intwo important forests of P. koraiensis and L. gmelinii, Laoshan station of Maoer mountainForest Park of Northeast Forestry University, Shangzhi, Heilongjiang province during May 2003 to April 2006. From aspects of amount, components, seasonal dynamics of litter, litter decomposition, the characteristic of nutrient element release during decomposition of litter and forest floor had been investigated. The results indicated:1. During the three years, the annual litterfall of P. koraiensis stand was 531.05 kg.hm^-2.yr^-1 and L. gmelinii stand was 361.51 kg·hm^-2·yr^-1, the former annual litterfall was 47% higher thanthe later one. Leaf litter was the most important component of litteifall, and it accounted for8.1% and 76.2% of total litterfall in P. koraiensis and L. gmelinii, respectively. The monthly variety of P. koraiensis and L. grnelinii showed one apexes, peaked in September and October annually.2. The Weightlessness ratio of leaf litter of P. koraiensis, P. koraiensis mixture, L. gmelinii and L. gmelinii mixture were 52.16%, 47.69%, 39.26% and 44.38% percent after two years, respectively. The Weightlessness ratio of leaf litter of the first year was also high: P. koraiensis, P. koraiensis mixture, L. gmelinii and L. gmelinii mixture were 26.66%, 23.49%, 33.24% and 27.82%. The time of 50% decomposition of leaf litter of P. koraiensis, P. koraiensis mixture, L. gmelinii and F.gmelinii mixture were 1.03a, 1.23a, 1.80a and 1.620a respectively, and the time of 95% decomposition were 4.46a, 4.87a, 7.76a and 7.02a, respectively.3. The quantities of microbes (bacteria, actinomyces and fungi) were similar during different period in two forests soil surface layer of the two forests. Bacteria were the dominant microbes from May to September, next was Actinomyces, Fungi were the least microbes.4. The maximum enzyme activities of catalase in P. koraiensis forests occurred in July. The enzyme activities of catalase in L. gmelinii forests increased with litterfall decomposing from May to September. The maximum enzyme activities of invertase and urease and proteinase in P. koraiensis and L. gmelinii forests occurred in May.5. C/N of the different litterfall layer in both stands was L＞F＞H. During the decomposing of leaf, C/N reduced gradually with the decomposition of litterfall in both of the mixed leaf sample and single needle sample in P. koraiensis and L. gmelinii stands. The decomposing rate depended on the leaf_fall charaters, especially their C/N. 6. The result showed that total content of 6 major nutrient elements after one year decreased 22.18% in P. koraiensis leaf litter, P. koraiensis mixture decreased 20.06%, L. gmelinii leaf litter decreased 14.61%, L. gmelinii mixture decreased 18.71%. As to the average concentration of the 6 major nutrient elements in four leaf litter, the order has not changed obversly after two years. Before decomposing, the 6 nutrient elements concentration from high to low was: N〉K〉P〉Ca〉Mg; after decomposing, the 6 nutrient elements concentration from high to low was:N〉P〉K〉Ca〉Mg.7. The storage amount of the un-decomposing and sub-decomposing layers were analyzed by investigating the remnant litter under the forest. The result showed that P. koraiensis forest total storage amount was 2156.7 kg·hm^-2. The total storage amount was 2189.2 kg.hm^-2 in L. grnelinii forest. To some extend, it reflects the facts that the litter has the ecological function of containing rainfall and balancing the water in ecosystem because the total water-holding amount and the average water-holding rate are so high that they reached 3.046 t·hm^-2 and130.5% in P. koraiensis forest, 2.746t·hm^-2 and 125.1% in L. grnelinii forest, respectively. The quantities of microbes (bacteria, actinomyces and fungi) and the activities of enzymes (such as proteinase, invertase, catalase, polyphenoloxidase and so on) in.the forest floor were different in different layer. The order of elements was in sequence of N > P > K > Ca > Mg in P. koraiensis and L. grnelinii forests.