洞庭湖滩地开沟抬垄造杨树林效益分析

对季节性淹水的洞庭湖滩地进行开沟抬垄造杨树林试验。结果表明：滩地开沟抬垄造林降低了杨树林地的相对淹水时间和高度，提高了杨树造林保存率，促进树高和单株材积的生长，提高单位面积蓄积，提高径阶≥12cm的林木的比例和林分木材的价值；开沟抬垄造林能显著提高杨树林分生物量和生产力，开沟抬垄营造的7年生杨树单株生物量、保存林分生物量、林分平均净生产量分别为32.32kg／hm^2、32.34t／hm^和4.62t／（hm^2·年），分别是未开沟抬垄的1.43、3.16和3.2倍；滩地开沟抬垄与未开沟抬垄营造的杨树林各器官生物量大小均遵循干〉根〉皮〉枝〉叶的规律；开沟抬垄造杨树林增加的木材效益比开沟抬垄工程总投入多，经济效益较好，第1个轮伐期年均利润为166.3元／（hm^2·年），投入产出比是0.95。

Benefits analysis of poplar forest made in beach of ditching lift ridge on Dongting Lake

The poplar plantation test was conducted on seasonally flooded Dongting Lake shoal through beach ditching lift ridge. The results showed that, afforestation with beach ditching lift ridge reduced the relative flooded time and height of poplar forest land, in- creased the save rate of poplar afforestation, promoted the growth of tree height and individual volume, increased the per unit area accumulation, and increased the proportion and the value of timber of which the diameter was larger than 12 cm. The biomass and productivity of poplar stands were improved significantly by afforestation with ditching lift ridge, and the biomass per plant, preservation stand biomass and the stand average net production of 7-year-old poplar were 32.32 kg/hm2 , 32.34 t/hm2 and 4.62 t/ （ hm^2·year） respectively, which were 1.43 times, 3.16 times and 3.2 times as much as that of non-ditching lift ridge. The organ biomass of poplar afforestation with ditching lift ridge and non-ditching lift ridge followed the law of stem 〉 root 〉 bark 〉 branches 〉 leaves. The multi-out-put of poplar timber due to open ditch lift ridge was more than the total investment of ditching lift ridge, the economic benefit was good, the average annual profit was 166. 3 yuan/ （ hm2·year） in the first rotation period and the input-output ratio was 0.95.