岩溶地区景观格局演变及其生态安全的时空分异——以贵州省东北部槽谷为例

景观生态安全能反映区域生态保护与经济发展之间的关系,有助于了解生态环境压力和缓解人地关系矛盾具有重要意义。基于2005、2010、2014和2017年LandSat影像为数据源,借助ArcGIS和景观格局指数法构建景观生态安全指数,对槽谷区景观格局演变及其对生态安全的时空分异规律研究,从而提出环境友好型的土地利用组合模式。结果表明：（1）2005—2017年,槽谷区景观内部整体呈现破碎化,景观斑块数量增多,景观格局由单一规则化、简单化向复杂混合型转变,多样性增加且空间异质性增强。随着时间变化,岩溶槽谷区景观生态安全整体呈现上升趋势,西、东部槽谷景观生态安全指数（Ecological Security Index,ESI）由槽坝向山坡两侧逐渐增加,而中部槽谷则由山坡向槽坝增加。（2）在200 m尺度下,西部槽谷ESI的全局正相关性最显著,其Moran''s I值呈先增加后减小的趋势,而中部和东部槽谷则相反。岩溶槽谷区ESI的空间集聚形式主要表现为高高和低低值集聚区,空间集聚程度较高,而高低和低高集聚区分布较少且变化不明显。（3）景观集聚分布格局受低地形起伏和坡度较缓区域影响较高且呈现倒"U"型共性趋势,而海拔则相反。（4）岩溶槽谷区景观格局以扩充"林地-灌木林地-草地"的土地利用组合模式能增加景观生态安全。（5）景观格局及其生态安全的时空分异是受当地自然环境、社会经济和政策导向共同作用的结果,通过分析多重因素对槽谷区景观格局及其生态安全演变趋势的驱动机制可为地区科学决策提供科学参考。

Spatio-temporal differentiation of landscape pattern evolution and its ecological security in karst areas: a case study of trough valley in northeast Guizhou Province

Landscape ecological security can reflect the relationship between regional ecological protection and economic development. It is of great significance to understand the pressure on the ecological environment and alleviate the contradiction between human and land. Based on the remote sensing image of 2005, 2010, 2014 and 2017 as the data source combined with field survey to verify the images, we used the ArcGIS and landscape pattern index method to construct landscape ecological security index to analyze the evolution of landscape pattern and the spatio-temporal differentiation laws of ecological security in the trough valley area. Therefore, an environment-friendly land use combination model is proposed. The results were as follows:(1) from 2005 to 2017, the overall landscape pattern of trough valley area presented fragmentation, the number of landscape patches increased, the landscape pattern changed from single regularization and simplification to complex and mixed type, the diversity increased and the spatial heterogeneity enhanced. With the variation of time, the overall landscape ecological security in karst trough valley showed an upward trend,the Ecological Security Index (ESI) of the western and eastern trough valleys increased from the trough basin to the two sides of the hillside, while the middle trough valley increased from the hillside to the trough basin. (2) At a research scale of 200 m,the global positive correlation of ESI in the western trough valleys is the most significant, and its Moran''s I value showed a trend of first increased and then decreased,but the middle and eastern troughs were the opposite.The spatial agglomeration pattern of ESI in karst trough valley area was mainly manifested as high-high and low-low value agglomeration areas, and the spatial agglomeration degree was higher, while the distribution of high-low and low-high agglomeration areas was less and its change was not obvious.(3) The landscape agglomeration distribution pattern is influenced by low topographic relief and low slope that presents similar trend of inverted "U" shape, while the elevation is opposite. (4) The landscape pattern of karst trough valley area can increase the landscape ecological security by expanding the land use combination pattern of "woodland-shrub woodland-grassland". (5) The spatio-temporal differentiation of landscape pattern and its ecological security is the result of the joint action of the local natural environment, social economy and policies. We can provide scientific reference for regional scientific decision-making by analyzing the driving mechanism of multiple factors on landscape pattern and ecological security evolution trend of trough valley area.