干扰对牦牛坪景观格局及草地生态系统服务的影响

玉龙雪山高山草甸位于横断山区生物多样性保护关键地区,也是滇西北重要的生态旅游资源,提供了多种重要的生态系统服务,然而当下面临着放牧旅游复合干扰等多重压力。为明晰放牧和旅游干扰对玉龙雪山高山草甸景观格局及草地生态系统服务的影响,通过野外调查和遥感影像解译数据,区分出旅游、放牧和干扰交互区3个干扰类型区,并将草甸划分出重度、中度、轻度和未退化等4个级别。分别从调节、供给、文化服务等3个方面6个指标评估研究区生态系统服务,从景观数量组成(PLAND和PD指数)与景观空间结构(SHAPE和CONNECT指数)角度评估研究区的景观格局,运用冗余分析(RDA)探讨干扰影响下的景观格局对草地生态系统服务的影响。结果表明:(1)旅游干扰集中区域的未退化和轻度退化草甸斑块面积占比(PLAND)比其他干扰区低15%,中度和重度退化草甸面积占比则明显增加;放牧干扰集中区轻度退化草甸的斑块密度指数(PD)比其他干扰区域高2-7倍,斑块破碎化明显;(2)在干扰交互区和放牧干扰集中区,都出现了斑块形状指数(SHAPE)和斑块连接度指数(CONNECT)随着草甸退化程度增加而增加的现象,中度退化草甸斑块更破碎且连接度增加,进一步扩大分布范围的趋势明显;(3)景观组成特征对研究区生态系统服务作用明显,PD指数是研究区最重要的景观指标,PD越高景观越破碎,生态系统服务供给越差。旅游干扰集中区的生态系统服务更多受景观空间结构特征的影响,放牧干扰集中区的生态系统服务则主要受景观组成特征的影响。不同干扰区域景观组成与结构的差异对草地生态系统服务的供给的影响,可作为景区草地资源保护与景观规划管理的参考。

Effects of Disturbance on Landscape Pattern and Meadow Ecosystem Services,in the Yak Park of Mt. Jade Dragon,Yunnan

As a key area of biodiversity conservation in Mts.Hengduan,as well as a valuable eco-tourism resource of Northwest Yunnan province,Mt.Jade Dragon provides a variety of important ecosystem services(ES).However,at present,it is facing multiple pressures,such as disturbance from grazing and tourism.In order to clarify the impacts of grazing and tourism disturbances on alpine meadow in Mt.Jade Dragon,in particular on the landscape pattern and ES provision,based on the field investigation and remote sensing image,three types of disturbance region were distinguished:Tourism zone(TZ),Grazing zone(GZ)and Tourism&Grazing disturbance interaction zone(TGZ),and the meadow in the study area was divided into four degradation levels:non-degraded(ND),lightly degraded(LD),middle degraded(MD)and highly degraded(HD).While,six indicators from three aspects(regulation,provision and cultural)were calculated to evaluate the ecosystem services(ES)of the alpine meadow ecosystem,and four landscape metrics(PLAND,PD,SHAPE,CONNECT)were used to assess landscape structure,namely the landscape composition or the landscape configuration.Then a RDA was computed to investigate the relationship between the provision of multiple ES and landscape structure.The results showed that:(1)The PLAND of ND and LD in TZ was 15%lower than other region due to tourism disturbance,while the PD indicated the patch fragmentation of LD increased significantly,which was 2-7 times higher than others due to grazing disturbance.(2)Both SHAPE and CONNECT index increased with meadow degradation increasing in TGZ and GZ,which indicated that the MD meadow with fragmented patches and well connected,likely to expand their distribution.And(3)landscape composition plays an important role in ecosystem services provision in the study area.PD was the most important landscape index,and the higher the PD index,the more fragmented the landscape,the worse the supply of ecosystem services.The ES in TZ were more affected by landscape structure(SHAPE and CONNECT),while the ES in GZ were mainly affected by landscape composition(PLAND and PD).The finding on the influence of the difference of landscape composition and structure in different disturbed areas on the supply of grassland ESs,could be provided for the management of the meadow resource protection and landscape planning in the park.