模拟牦牛和藏羊践踏对垂穗披碱草凋落物损失率和化学计量特征的影响

Effect of short-term simulated yak and Tibetan sheeptrampling on litters loss rate and decompositioncharacteristics of Elymus nutans

摘要:

为深入了解自然降雨条件下牦牛和藏羊践踏强度对青藏高原高寒草甸凋落物分解的分异影响,在天祝高寒草甸进行模拟牦牛和藏羊践踏调控试验,采用凋落物网袋法研究了牦牛和藏羊践踏强度对垂穗披碱草(Elymus nutans)凋落物损失率和化学计量特征(N、P、K 和C含量)的影响。结果表明:存放1、2、3、13、14和15个月的凋落物损失率在各践踏处理下均呈增加趋势。同等牦牛和藏羊强度下,已存放1~15个月的垂穗披碱草凋落物损失率,凋落物N,P和K含量在牦牛践踏处理下均大于藏羊处理。垂穗披碱草凋落物损失率,N 和P含量在藏羊轻度践踏处理下显著低于重度践踏,C和K 含量在藏羊轻度践踏处理显著高于重度践踏(P <0.05)。且在2015年度已存放1,2和3个月与在2016年度已存放13,14和15个月的凋落物C和K 含量均表现为释放模式,而凋落物N 和P表现为富集模式。综合分析,牦牛和藏羊的践踏促进了凋落物的分解,牦牛践踏下垂穗披碱草凋落物的分解快于藏羊处理。

Abstract:

In order to understand the differentiation effect of the yak and Tibetan sheep trampling intensityon the litter decomposition of alpine meadow on the Qinghai-Tibetan Plateau,the simulation experiment (simulatedyak and Tibetan sheep trampling) was carried out in the alpine meadow in Tianzhu by using the litter bagmethod to measure the litter loss rate and stoichiometry (N,P,K and C contents) of Elymus nutans.The resultsshowed that the loss rate of litter processed for 1,2,3,13,14 and 15 months under all trampling treatmentsshowed an increasing trend.Under the same trampling strength,the litter loss rate of Elymus nutansstored for 1~15 months caused by yak was higher than Tibetan sheep.And the contents of litter N,P and Kshowed a same trend.The of litter loss rate,contents of N and P under Tibetan sheep light trampling treatmentwere significantly lower than that of heavy trampling treatment.The contents of C and K in Tibetan sheep lighttrampling treatment were significantly higher than that of heavy trampling treatment (P <0.05).In addition,Cand K of litter stored for 1,2 and 3 months in 2015 and 13,14 and 15 months in 2016 showed a release mode,while N and P of litter showed enrichment mode.It could be concluded that the livestock trampling promotedthe litter decomposition,and the decomposition of the litter under the yak trampling was faster than that of Tibetansheep.