桂西北西南桦人工林生长规律和生物生产力

The growth regularity and biomass productivity of Betula alnoides plantation in Northwest Guangxi

以广西天峨县林朵林场12年生西南桦人工林为研究对象,研究其生长过程和生物生产力特征。结果表明:西南桦在桂西北具有较强的生长适应性,12年生平均胸径(去皮)、平均树高和平均蓄积量分别达到15.6 cm,16.8 m,170.10 m3/hm2;西南桦树高和胸径生长均以前5 a最快,随后随林龄的增长而下降;材积生长在8年生时达到峰值,之后开始下降但仍然保持较高的年生长量。12年生西南桦人工林林分生物量为130.86 t/hm2,其中乔木层、灌木层、草本层和凋落物层生物量依次为122.38,2.35,1.87和4.26 t/hm2,分别占93.52%,1.80%,1.43%和3.26%。林分乔木层年净生产力为10.20 t/(hm2·a),不同器官净生产力大小次序为树干、树叶、树枝、树根、树皮。

In order to understand the growth regularity and biomass productivity of the Betula alnoides plantation,the 12-year-old B.alnoides plantation was studied in Linduo Forest Farm of Tian＇ e County in Northwest Guangxi,China.The results showed that the growth of B.alnoides trees presented a strong adaptability in Northwest Guangxi.Its average diameter at breast height （DBH）,height and volume of stand were up to 15.6 cm,16.8 m and 170.10 m3/hm2 respectively.Both the tree height and the DBH were grow fastest in the initial 5 years.The growth of DBH and height represented declining trend after the age of 5 years.The annual volume growth would achieve the peak at 8 years.After 8 years,it＇ s annual volume growth still maintained a higher growth tendency.The biomass of stands of 12-year-old B.alnoides plantation was 130.86 t/hm2,in which the biomass were 122.38,2.35,4.26 and 1.87 t/hm2 for the arbor layer,shrub layer,herb layer and litter layer,accounting for 93.52％,1.80％,3.26％ and 1.43％ respectively.The annual net productivity of arbor layer was 10.20 t/（hm2 ·a）.The net productivity of different organs were in order of trunk ＞ leaves ＞ branch ＞ root ＞bark.