川中丘陵区柏木林下养鸡的生态经济效益分析

    Ecological and Economic Benefits of Chicken Rearing in Cypress Forest in Hilly Areas of Central Sichuan

    • 摘要: 选择川中丘陵区郁闭度为0.5~0.7、林龄为25 a、林地平均坡度为15°的柏木(Cypressus funebris)纯林林分,设置600、900、1 200和1 500只•hm-2 4种养殖密度处理,每种养殖密度设3个重复,并设置1个林下不养鸡的对照样地,进行林下生态养鸡试验,1 a后对养殖前后的生态和经济效益进行对比分析。结果表明,林下养殖能促进林木的生长和林地土壤肥力的提高。4种养殖密度样地柏木胸径和高度年增长量分别比对照提高30.80%和33.73%;0~20 cm土壤有机质、全N、全P和全K含量比养殖前分别增加5.95%、14.88%、10.75%和5.34%。林下养鸡对林下植被有一定影响。养殖后灌木盖度降低6.67~26.50百分点,种数减少2~6种;草本盖度降低9.20~27.17百分点,种类减少3~8种;枯落物盖度减少9.30~20.90百分点。4种养殖密度样地0~20cm土壤容重比养殖前增加11.38%~17.99%,>20~40 cm土层增加8.40%~15.75%;土壤总孔隙度平均减少3.20百分点。养殖密度分别为600、900、1 200和1 500只•hm-2的样地土壤径流深分别比对照提高33.59%、52.97%、109.06%和144.60%,产沙量分别比对照提高45.59%、67.27%、123.65%和146.96%,但土壤流失量均明显低于SL 190—2007《土壤侵蚀分类分级标准》规定的容许土壤流失量(500 t•km-2•a-1)。以养殖密度为600只•hm-2来计算,投入产出比为1: 2.76,净收益为6.88万元•hm-2。综合分析认为,养殖密度以900只•hm-2为最适宜,既可获得可观的经济收益,又能控制水土流失量。

       

      Abstract: Pure cypress stands, 0.5-0.7 in canopy density, 25 a of age, and 15 degree in average slope, were chosen for experiment of chicken rearing in hilly areas of Central Sichuan. The experiment was designed to have five treatments in chicken density, i.e. 600 (Treatment I), 900 (Treatment II), 1200 (Treatment III) and 1500 (Treatment IV)hm-2 and control (Treatment V, no chicken), and each, except for Treatment V, had three replicates. After one year of experiment, comparison was made in ecological and economic benefits between the treatments and the control. Results show that chicken rearing in the stands promotes tree growth and improves soil fertility. The treatments were 30.80% and 33.73% higher than the control in growth rate of the trees in diameter at breast height (DBH) and height, and 5.95%, 14.88%, 10.75% and 5.34% higher, respectively, in soil organic matter, TN, TP and TK in the 0 -20 cm soil layer. However, chicken rearing did have some negative effects on understory of the forests, like reducing shrub coverage by 6.67 - 26.50 percentage point, shrub species by 2 - 6; herbage coverage by 9.20 - 27.17percentage point, herbal species by 3 - 8, and litter coverage by 9.30 - 20.90percentage point. Besides, chicken rearing increased soil bulk density by 11.38% -17.99% in the 0 - 20cm soil layer and by 8.40%-15.75% in the >20 -40cm soil layer, and reduced total soil porosity by 3.20 percentage point. Runoff of Treatment, I, II, III and IV, increased by 33.59%, 52.97%, 109.06%, and 144.60% and sediment yield by 45.59%, 67.27%, 123.65%, and 146.96%, respectively. However, soil losses in the treatments were still much lower than the permissible limit (500 t•km-2•a-1) specified in the National Standard for Classification and Grading of Soil Erosions (SL 190-2007). Calculation on the basis of 600 cheickens per hm2 in rearing density shows that the input-output ratio was 1:2.76, and the net income reached 68 800 yuan•hm2. The comprehensive analysis reveals that chicken rearing at a density of 900 chinckens per hm2 is the most appropriate and can be expected to generate considerable economic benefits and reduce water and soil losses.

       

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