漓江流域森林景观格局时空变化特征及驱动因素

Spatio-temporal Characteristics and Driving Factors of Forest Landscape Pattern in Lijiang River Basin

关键词:  森林景观  景观格局  驱动机制  漓江流域

Key words:  forest landscape  landscape pattern  driving mechanism  Lijiang River Basin

摘要:

森林景观是自然景观中的主要成分。漓江流域森林景观是典型喀斯特景观资源的重要组成部分，为进一步了解漓江流域森林景观分布及变化规律，本研究通过定性与定量分析相结合的方式，采用1985年、2000年和2020年3期全球30 m精细地表覆盖数据(GLC_FCS30)，通过ArcGIS空间分析、数据统计及景观指数计算，探究漓江流域1985-2020年森林景观格局的时空变化特征及森林景观的异质性水平，从自然环境地形因子(海拔、坡度、坡向)和人文活动(人口、经济、政策)等驱动因素探寻森林景观变化的驱动机制，对漓江流域森林景观的保育和可持续利用提供决策建议及科研依据。研究表明，1985-2020年，漓江流域森林景观面积由417 928.86 hm²缩减至382 268.44 hm²,森林景观减少主要受森林砍伐、建设用地扩张和果树种植的侵占影响，前期森林景观缩减的程度和范围大于后期；由于森林保育政策和流域治理措施等保护工作的开展，漓江流域森林景观在缩减的同时也在不同程度地恢复，集中体现在漓江风景名胜区的绿化建设和漓江上游的水源林保育，森林景观不同时期发生彼此消长的地区林木采伐与更新种植较为频繁。35年间，漓江流域森林景观格局呈现先破碎化和异质性水平先明显增大、后缓慢减小的趋势，针叶林、常绿阔叶林面积减少，落叶阔叶林和灌木林面积增加，不同森林景观类型的面积比例趋向均衡。喀斯特地区由于土层相对浅薄，相对非喀斯特地区灌木林占比大，落叶阔叶林占比小，长期以来森林与水体的用地转换相对非喀斯特地区更小。漓江流域森林景观面积变化主要发生在海拔较低(200-600 m)、坡度较缓(10°-30°)和偏东南坡向的地区，随着与居民点距离的增大，森林景观面积变化呈现先增加后减少的趋势，在1 000-1 400 m距离达到最大值，森林景观变化的面积与道路距离呈反比。本研究针对漓江流域森林景观格局的变化特征及驱动因素提出适于当地的森林景观保育策略，为漓江流域及同类地区的生态环境修复和林业可持续发展提供理论支撑。

Abstract:

Forest landscape is the main component of natural landscape.The forest landscape in the Lijiang River Basin is an important part of typical karst landscape resources.In order to further understand the distribution and change rules of the forest landscape in the Lijiang River Basin,this study combines qualitative and quantitative analysis methods,and uses the three phases of global 30 m fine land cover data (GLC_FCS30) in 1985,2000 and 2020.Through ArcGIS spatial analysis,data statistics and landscape index calculation,the spatial and temporal variation characteristics of forest landscape pattern and the heterogeneity level of forest landscape in the Lijiang River Basin from 1985 to 2020 were explored.The driving mechanism of forest landscape change was explored from the driving factors of natural environment terrain factors (altitude,slope,aspect) and human activities (population,economy,policy),which provided decision-making suggestions and scientific research basis for the conservation and sustainable utilization of forest landscape in the Lijiang River Basin.The results showed that from 1985 to 2020,the area of forest landscape in the Lijiang River Basin decreased from 417 928.86 hm² to 382 268.44 hm².The reduction of forest landscape was mainly affected by deforestation,expansion of construction land and occupation of fruit tree planting.The degree and scope of forest landscape reduction in the early stage were greater than those in the later stage.Restricted by forest conservation policies and watershed management measures,the forest landscape in the Lijiang River Basin is also being restored to varying degrees while shrinking.It is mainly reflected in the greening construction of the Lijiang River scenic spots and the conservation of water source forests in the upper reaches of the Lijiang River.Forest harvesting and renewal planting are more frequent in areas where forest landscapes have changed with each other in different periods.During the past 35 years,the forest landscape pattern in the Lijiang River Basin showed a trend of fragmentation and heterogeneity increasing at first,and then slowly decreasing.The area of coniferous forest and evergreen broad-leaved forest decreased,while the area of deciduous broad-leaved forest and shrub forest increased.The area proportion of different forest landscape types tended to be balanced.Due to the relatively shallow soil layer in the karst area,the shrub forest accounted for a large proportion and the deciduous broad-leaved forest accounted for a small proportion in the non-karst area.For a long time,the land conversion between forest and water body was smaller than that in the non-karst area.The changes of forest landscape area in the Lijiang River Basin mainly occurred in areas with low altitude (200-600 m),gentle slope (10°-30°) and southeast slope.With the increase of distance from residential areas,the change of forest landscape area showed a trend of increasing first and then decreasing,reaching the maximum at a distance of 1 000-1 400 m.The area of forest landscape change was inversely proportional to the road distance.According to the change characteristics and driving factors of forest landscape pattern in the Lijiang River Basin,the forest landscape conservation strategy suitable for the local area is put forward,which provides theoretical support for ecological environment restoration and sustainable development of forestry in the Lijiang River Basin and similar areas.