| Ecological vulnerability assessment is a hot topic in today’s global change and sustainable development research.The unique above-ground and below-ground dual-structure and the prominent human-land conflict in karst areas have led to vulnerable habitats and weak self-regulation ability of forests.Although obvious results have been achieved through different modes of rocky desertification control,the problems of relatively homogeneous forest species,simple ecosystem structure and low function still exist,therefore,it is urgent to carry out the evaluation of forest ecological vulnerability of rocky desertification control and explore the strategy of resilience improvement,which is important for the practice of ecological protection and industrial revitalization in the region.In this paper,by synthesizing advanced research at home and abroad,based on the basic principles of geography,human-earth relationship theory,restoration ecology,plant physiology,combined with the theories of ecological adaptability,structure-determined function,vulnerability theory,ecosystem assessment theory and sustainable development,to address the scientific issues and technological needs of the internal characteristics,causes of vulnerability and resilience enhancement mechanisms of forest ecsystems in different rocky desertification control modes and resilience enhancement mechanisms,The study areas are Bijie Salaxi,Guanling-Zhenfeng Huajiang,and Shibing,a typical karst plateau valley in southern China,and two types of forest communities for rocky desertification control,namely closed forest and plantation,will be selected in the three study areas from 2019 to 2021 through literature and field survey.We will investigate the ecological vulnerability characteristics of karst forests in terms of forest community structure,function and habitat,and construct a vulnerability evaluation index system that is applicable to the framework of “ecological sensitivity-ecological resilience-ecological stress” under karst rockyy desertification control.The combination of hierarchical analysis and entropy method is used to assign weights to each index,classify forest vulnerability levels,and analyze the drivers of forest ecosystem vulnerability under karst rocky desertification control using the geographic probe model.The analysis focuses on clarifying the relationship between forest structure and function and habitat in different modes of rocky desertification control,revealing the causes of vulnerability,and proposing strategies to enhance resilience,which will provide a reference for ecological protection and forest industry development in karst rocky desertification areas.（1）The species composition,structure and functional characteristics of the forest ecosystem of rocky desertification control were analyzed,and the influencing factors were explored to elucidate the restoration capacity of forests in different modes of rocky desertification control: the ecological functions as a whole showed higher water connotation and carbon sequestration and oxygen release capacity in the closed forest and the planted forest,while the economic forest in the planted forest was higher in the soil conservation function.Soil total potassium and water content explained 47.8% and 17.2 of the variables,respectively,and the influence of soil on species diversity was greater than that of topography;the explanatory strength of community function was mainly total nitrogen and soil p H,which explained 58.0% and 15.5% of the variables,respectively.It indicates that the karst plateau mountains are more influenced by soils.The structure and function of the forest ecosystem are mainly influenced by topography and soil,and climate is mainly an indirect influence,with climate change leading to soil changes.The vulnerability assessment should be carried out with a synergistic structure-function-habitat layout,which is conducive to revealing the vulnerability mechanism of rocky desertification control forests in a comprehensive manner.（2）Considering the three dimensions of ecological sensitivity,resilience and stress in the study area,an index system for evaluating forest ecological vulnerability in different rocky desertification control modes was constructed: by formulating vulnerability evaluation criteria,constructing a forest ecological vulnerability evaluation model,and combining sample site survey and socio-economic survey data to build an index system.The index system includes target layer,criterion layer,element layer and indicator layer.The criterion layer is ecological sensitivity,ecological resilience and ecological stress;the element layer is a further refinement of the criterion layer,with meteorology,surface and topography in the ecological sensitivity element layer,species composition,structure and functional factors in the ecological resilience element layer,and population,social and economic development in the ecological stress element layer.The indicator layer has 18 indicators,including positive indicators,i.e.,the higher the value of the indicator,the higher the degree of ecological vulnerability,and vice versa,negative indicators.The combination of weighting of indicators using hierarchical analysis and entropy weighting method strengthens the objectivity and accuracy of evaluation results and provides an objective reference for the evaluation of forest ecological vulnerability of rocky desertification control.（3）The types of ecological vulnerability of forests in different modes of rocky desertification control were delineated,and the driving factors leading to their vulnerability were analyzed: the vulnerability of karst plateau mountain forests ranged from 0.40 to 0.67 points,with ecological forests（0.51）,economic forests（0.63-0.67）and secondary shrub forests（0.56-0.61）being moderately vulnerable;secondary tree forests were mildly vulnerable（0.40～ 0.44）;karst plateau valley forest vulnerability is between 0.44～0.67,economic forest（0.61～0.67）and secondary shrub forest（0.64～0.67）are moderately vulnerable secondary tree forest（0.44～0.49）and ecological forest（0.50）are lightly vulnerable.The vulnerability of karst plateau trough forest ranged from 0.41 to 0.69,with economic forest（0.53-0.69）and secondary shrub forest（0.61-0.67）being moderately vulnerable and secondary tree forest（0.41-0.47）and ecological forest（0.47）being mildly vulnerable.The driving factors with significant explanatory strength were carbon sequestration and oxygen release（0.858）> species diversity（0.750）> bare rocky rate（0.741）>water content（0.652）> depression（0.605）> mean diameter at breast height（0.599）,indicating that intra-system factors have the greatest explanatory power for forest ecological vulnerability,suggesting that plant structure homogeneity is the main factor affecting forest ecological vulnerability.From natural factors,topographic factors such as bare rock rate and elevation are more obvious and are the main natural factors;meteorological factors are relatively less influential;from human-driven aspects,population density,rural labor force and grazing intensity also have a greater impact on forest ecological vulnerability.The causes of forest ecological fragility need to be explored synergistically with internal and external factors of the system to achieve synergy between forest and human economy of rocky desertification control,which is conducive to the co-development of regional ecological and economic benefits.（4）In response to the causes of forest vulnerability formation in different rocky desertification control modes,strategies to improve forest ecological resilience are proposed: implementing forest classification control,implementing ecological environment monitoring and reducing ecological pressure are important ways to improve ecological resilience of forest industry in rocky desertification control.Specifically,for closed forestry,community configuration and ecological compensation can be used to enhance the system’s anti-disturbance ability and improve the system’s ecological resilience.For artificial afforestation,precise management strategies can be adopted,using pruning and shaping techniques and soil fertilization techniques to increase the soil nutrient conditions of economic forests,using undergrowth techniques to enhance the stability of the system,rational planning of cultivated land,optimizing the planting area and planting density of forest land,training of planting farmers to carry out professional techniques,correcting the crude management mode of planters,and giving full play to the ecological and economic benefits of economic forests.Habitat suitability analysis needs to be strengthened in the selection of management modes,and the restoration effectiveness of different management modes can be further improved by applying site-specific and situational measures. |
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