刈割对滇西北退化高寒草甸植物化学计量特征的影响OA北大核心CSTPCD

This study aimed to investigate the effects of environmental disturbances on the stoichiometry characteristics of plants in degraded alpine meadows.To achieve this,a mowing experiment was conducted on an alpine meadow with three degradation levels[light degradation(LD),moderate degradation(MD),and severe degradation(SD)]in Shangri-La from 2018 to 2020.Subsequently,differences in plant carbon(C)content,nitrogen(N)content,phosphorous(P)content,C∶N∶P ratio,and N-P power function relationship among different mowing durations(0,1,2 a,respectively)were analysed.The results were as follows:(1)Except for the P content of Cyperaceae,plant C,N and P contents of the entire plant community,Gramineae and forbs did not vary among degradation levels(P＞0.05)during the mowing experiment.Plant C,N and P contents tended increase and then decrease with increasing mowing years,i.e.,these indices were the highest after 1 a of mowing(P＜0.05).(2)At the plant community and functional group levels,there was no significant difference in plant C∶N ratio and C∶P ratio among degradation levels(P＞0.05).From LD to SD,the N∶P ratio of the plant community,Cyperaceae and forbs tended to decrease slightly first and then increased(P＜0.05),while the N∶P ratio of Gramineae did not change significantly(P＞0.05).(3)The N∶P ratio and C∶P ratio showed a parabolic trend,while the C∶N ratio showed an inverse trend with the increasing of mowing duration.Before mowing(i.e.,mowing 0 a),the C∶P ratio and N∶P ratio of Cyperaceae were higher than those of forbs(P＜0.05)but did not vary from those of the plant community and Gramineae(P＞0.05).After mowing(i.e.,mowing 1 a or 2 a),the C∶P ratio and N∶P ratio of Cyperaceae were higher than those of the whole plant community,Gramineae,and forbs(P＜0.05).At each mowing duration,the C∶N ratio of plants did not vary among plant communities and functional groups(P＞0.05).(4)Mowing caused a stronger N-P power function relationship and a stable power exponent both at the plant community and functional group levels.And the N-P power exponent of Cyperaceae was less than 0.1,while those of the plant community,Gramineae and forbs remained stable at 0.19-0.22.In conclusion,this study found that plant stoichiometry remained stable across degradation levels but changed significantly with the prolongation of the mowing duration,which implies that different degraded alpine meadows in Northwest Yunnan may share common response mechanisms to mowing disturbance.