| Betula luminifera is a precious timber species in southern areas of China.It has economic benefits and ecological function of both soil and water conservation function.In this paper,the research regarded 11-and 16-year-old of B.luminifera plantation in Tian E Linduo Forest Farm of Guangxi as the object.The biomass,productivity,nutrient content,accumulation and annual net accumulation,and water holding capacity of different structures at different stand ages plantation were studied.The main results were as follows:(1)The tree biomass of 11-and 16-years-old B.luminifera plantation were 105.73t·hm–2 and 192.39 t·hm–2,respectively.Biomass of different organs in the proportion of forest trees divided into different age,The proportion of branches,leaves,bark and root biomass showed the opposite trend.The biomass of 11-and 16-years-old were 114.93 t·hm–2 and206.00 t·hm–2,the size of biomass of different structures was the tree layer > litter layer >shrub layer > herb layer.The tree layer productivities of 11-and 16-years-old stands were9.61 t·hm–2·a-1 and 12.02 t·hm–2·a-1,the proportion of net productive in different organs were the largest in stem and increase with the increase of the stand age;followed by root,branches and bark,leaves were the smallest.(2)The contents of 5 nutrient elements(N,P,K,Ca and Mg)in different organs of B.luminifera were different,the leaves were the highest,followed by the branches and bark,stem and root was the lowest.The contents of different nutrient elements in each organ were approximately N >Ca or K > P > Mg,The total nutrient accumulations at two different stand ages plantation were 1061.75 kg·hm-2 and 1641.60 kg·hm-2,respectively.The nutrient accumulation of tree layer was 882.83 kg·hm-2 and 1398.22 kg·hm-2,respectively,accounting for 83.15% and 85.17%,respectively;the vegetation layer was 39.79 kg·hm-2and 45.48kg·hm-2,accounting for 3.75% and 2.77%,the litter layer were 78.90 kg·hm-2 and 113.01kg·hm-2,accounting for 7.43% and 6.88%.The annual net accumulation of nutrient elements at two different stand ages plantation were 80.26 and 87.39 kg·hm-2·a-1,respectively.The net production of organic matter per ton needed 5 elements in plantations were 8.35 kg and 7.26 kg,the second was higher than that in the same stand age of Taiwania flousiana,Cunninghamia lanceolata and Masson pine,but lower than that of Betula alnoides and Manglietia glauca.(3)The total water-holding capacity of 11-and 16-years-old of B.luminifera plantation capacity were 3766.71 t·hm–2 and 3860.59 t·hm–2,were higher than the 16-year-old C.lanceolata plantation of 3680.24 t·hm–2.The canopy water holding capacity accounted for0.33% and 0.55%,the water holding capacity of shrub grass layer accounted for 0.09% and0.12%,the litter water holding capacity accounted for 0.33% and 0.57% of water holding capacity,soil layer accounted for 99.24% and 98.76%.The results of the study indicate that,the growth of T.flousiana trees had a strong adaptability in Northwest Guangxi.At the same time,it also has a high level of biological productivity.Therefore,B.luminifera plantation can improve soil structure,and has a good effect on improving the function of water conservation. |
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