喀斯特山地不同密度林鸡复合系统对表层土壤和林下植被的影响研究

Effects of forest chicken complex system with different densities on topsoil and understory vegetation in karst mountains

林鸡复合经营作为创新农作模式之一,具有生态经济效益好的优点,但养殖户生态环境保护意识不强,缺乏科学理念指导,片面追求最大经济效益,使得林下养殖对脆弱的喀斯特山地生态环境造成较大不利影响。因此,本研究通过设置密度梯度试验,分析600只/hm^(2)(T1)、1200只/hm^(2)(T2)、2400只/hm^(2)(T3)3类养鸡密度对林下表层土壤质量及植被的影响,综合考虑生态经济价值,以确定喀斯特山地林下生态养鸡合理养殖密度。经4个月的养殖试验表明:1)T1、T2处理土壤饱和导水率变大,最大持水量上升,但土壤容重与孔隙度变化不明显;T3处理土壤饱和导水率下降、孔隙度降低,土壤出现较为明显的板结现象。2)各处理全氮(TN)、土壤有机碳(SOC)养分含量较养殖前均出现不同程度的增加,呈先升后降趋势,在T2处理时养分含量最高,分别提升了69.0%和89.3%;全磷(TP)、全钾(TK)养分含量总体呈上升趋势,随养殖密度增大而增加,在T3处理时,养分含量分别提升了29.3%和36.8%。3)各处理草本植被生物量平均减少程度均超过95%。养殖结束自然恢复4个月后,T1、T2和T3处理草本植被生物量较养殖前恢复比分别为41.2%、3.5%、1.5%。4)T1、T2和T3各处理养鸡收益分别为7.2、14.4和28.8万元/(hm^(2)·a)。综合以上结果认为,喀斯特山地林鸡复合系统的合理密度应控制在600只/hm^(2),同时划分禁牧区与轮牧区,能够提升土壤质量和保护植被多样性,兼顾生态效益和经济效益,实现山地农业的可持续绿色发展。

As one of the innovative agricultural modes of Compound Management of Forest and Poultry,forests ecological chicken brood has high ecological and economic benefits.However,in pursuit of maximum economic benefits,farmers often ignore ecological environmental protection,resulting in a negative impact on karst region with fragile ecological environment.Therefore,this study analyzed the effects of 600 chickens/hm^(2)(T1),1200 chickens/hm^(2)(T2)and 2400 chickens/hm^(2)(T3)on the surface soil and vegetation under the forest,and comprehensively considered the ecological and economic value to determine the reasonable poultry-raising density of under-forest economy in karst mountain area.After four months of poultry-raising experiment,the results showed that:1)Under T1 and T2 poultryraising conditions,saturated hydraulic conductivity and maximum moisture capacity of the soil increased,but the change of soil bulk density and porosity is not obvious.Under T3 condition,the saturated hydraulic conductivity and porosity of soil decreased,and the soil appeared obvious hardening phenomenon.2)The contents of soil total nitrogen and soil organic carbon in all conditions increased compared with those before poultry-raising,with the largest increment at T2 condition,increased by 69.0%and 89.3%respectively.The contents of total phosphorus and total potassium in soil increased with the poultry-raising density,which increased by 29.3%and 36.8%respectively under T3.3)The biomass of herbaceous vegetation decreased by more than 95%under all conditions.Four months after stopping poultry-raising,the biomass of herbaceous vegetation in T1,T2 and T3 conditions recovered to 41.2%,3.5%and 1.5%of that before poultry-raising,respectively.4)The chicken raising income of T1,T2 and T3 conditions were 72000,144000 and 288000 RMB per hectare per year respectively.Based on the above results,the density of forests ecological chicken brood in karst mountainous area should be controlled within 600 chickens/hm^(2),and the forbidden grazing area and rotational grazing area should be divided,which can improve soil quality and protect vegetation diversity,take into account economic and ecological benefits,and achieve sustainable green development of mountain agriculture.