| Larixprincipis-rupprechtii Mayr. is an afforestation tree specie which has the most widely distributed area in Yanshan mountain,and which has high ecological protection benefits. It plays an integral role in maintaining ecological security of the Beijing-TianjinHebei region. Leaf litter in forests is an important part of forest ecosystem, and it is one of the main function layers of forest ecosystem,and which has important function on promoting the material circulation, nutrient balance, keeping the water and soil, water conservation as well as forest natural regeneration and so on. Many scholars at home and abroad have deeply studied storage of the litter, Water-holding characteristics,Nutrient cycling, mechanism which impact surface runoff and soil erosion of different forest types in different regions.Because different tree species have different biological characteristics and stand structures, there is a certain difference on effect of water conservation of different forest types, so it is necessary to research litter water-holding characteristics of main tree species, main forest types, key development period in different climate zones, so as to give full play to the function of water conservation of forest.Natural regeneration ability of Larixprincipis-rupprechtii Mayr. forest is weak and poor, that is the true portraiture of Larixprincipis-rupprechtii Mayr plantation in Yanshan mountain. Investigate its reason, light in forest is not suitable for regeneration. Rearch about impacts of Leaching solution and secretions on regeneration is lack.To solve the above problems, this study takes litters of Larix principisrupprechtii(main afforestation tree species in Yanshan mountain)(16a, 23 a, 34 a and 42a), Betula platyphylla(main mixed species), Populus davidiana of 30 a as research object, reveals water holding characteristics of different developmental stages and different components. At the same time, litter extracts was used to act on the seeds and seedlings of Larix principis-rupprechtii,aimed at testing autointoxication as well as influences of litter on seeds and seedlings of Larix principis-rupprechtii,so as to test whether the reasonable mixed mode is an effective way to improve problems of regeneration or not. The results show that:(1) Litter reserves of Larix principis-rupprechtii plantation(16a, 23 a, 34 a, 42a), Betula platyphylla secondary forest(26a) and Populus davidiana secondary forest(30a) are respectively 35.75 t /hm2, 45.50 t /hm2, 60.00 t /hm2, 65.94 t /hm2, 25.40 t /hm2, 19.39t/hm2.(2) The litter water-holding rate of different ages of stand present a trend of 16a>23a> 34 a > 42 a, litter water-holding rate of Larix principis-rupprechtii + Betula platyphylla(1:3) is maximum among these several mixed forms, and water-holding rate of litters present exponential increase along with soak time increases.(3) Water absorption rate of litter in Larix principis-rupprechtii plantation of different ages present a trend of 16a>23a>34a>42a. The litter water-holding rate of Larix principis-rupprechtii + Betula platyphylla(1:3) is maximum among the 6 mixed forms. There is a power function relationship between litter water-holding rate and soaking time, water absorption rate reduces along with soaking time.(4) Litter extracts of the 4 ages of Larix principis-rupprechtii stands have similar effects on germination rate, germination index, radicle length, germ length, seedling height, root length of different diameter grades,surface area of different diameter grades,root volume of different diameter grades.The effect is not significant in low concentration(0.001 g/ml), even has promoting effect. Inhibition increases as the concentration increases, inhibition effect on germination of seeds and growth of seedlings reaches the maximum value when the concentration is 0.1 g/ml(5) Inhibition effect of litter extracts(4 different ages of Larix principis-rupprechtii stands) on seeds and seedlings generally characterized by 42 a > 34 a > 23 a > 16 a, no matter in which concentration.(6) Mixed leaf litter extracts of Larix principis-rupprechtii and Betula platyphylla have similar effects on germination rate, germination index, radicle length, germ length, seedling height, root length of different diameter grades,surface area of different diameter grades,root volume of different diameter grades.It has promoting effect at low concentration, and the promoting effect enhances as the concentration increases,it turns to inhibition effect when concentration increases to 0.05g/ml, and inhibition effect enhances as the concentration increases, the inhibition effect reaches to maximum value when concentration increases to 0.1 g/ml. Mixed leaf litter extracts of Larix principis-rupprechtii and Populus davidiana with different concentrations have inhibition effect on Seed germination and seedling growth of Larix principis-rupprechtii,inhibition effect enhances as the concentration increases. litter extracts of Larix principis-rupprechtii have obvious autointoxication on Seed germination and seedling growth of Larix principis-rupprechtii, and inhibition effect significantly enhances as the concentration increases.(7) no matter in which concentration, the growth of seed and seedling which have been under the treatment of 7 different litter extracts generally characterized by Larix principis-rupprechtii+Betula platyphylla(1:3) > Larix principis-rupprechtii+ Betula platyphylla(1:1) > Larix principis-rupprechtii+ Betula platyphylla(3:1) >Larix principis-rupprechtii+ Populus davidiana(3:1) > Larix principis-rupprechtii+ Populus davidiana(1:1) > Larix principis-rupprechtii+ Populus davidiana(1:3) >Larix principis-rupprechtii. |
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