Trade-offs/Synergies Of Forest Ecosystem Services And Function Optimization In The Karst Desertification Control

The report of the 20th National Congress of the Communist Party of China has proposed to"enhance the diversity,stability and sustainability of ecosystems,with emphasis on national essential ecological function areas,the ecological protection red line and nature reserves,and accelerate the implementation of major projects for the protection and conservation of important ecosystems".The Karst Rocky Desert region in southern China that is an important ecological function area has strong habitat heterogeneity and a fragile ecological environment.Improving the service capacity of forest ecosystems has been an effective way to enhance the stability of ecosystems and to maintain the effectiveness of desertification control.Based on the theories of physical geography,ecology,forest cultivation,coordinated human-land development,ecological niche and trade-off/synergy,the scientific issues and technological needs are addressed,such as vegetation degradation,forest ecosystem service,trade-offs/synergies relationship between services and functional optimization in karst areas.The research areas of Bijie Salaxi,Guanling-Zhenfeng Huajiang and Shibing Karst were selected in the Guizhou plateau mountains,which are representative of the general ecological and economic structure of southern karst.In 2020-2023,the study area was monitored and collected data on environmental elements such as altitude,topography and soil,species name,tree height and crown size.Correlation analysis and redundancy analysis were applied to study the basic frontier research on forest ecosystem service trade-offs/synergies and function optimization in desertification control.Aiming to clarify the current situation of forest ecosystem services in karst desertification areas,reveal the trade-offs/synergies of forest ecosystem services,and proposed functional optimization strategies based on the forest structure and trade-offs to synergies,so as to give theoretical support to the sustainable development of forest ecosystems in karst desertification control.（1）The characteristics of water-holding capacity,material production,soil conservation,species diversity,soil nutrient quality and carbon storage of desertification controlled forests and naturally restored forest ecosystems were revealed.The naturally restored forests in the karst plateau mountains had a higher capacity for water connotation(225.71t·hm^-2),species diversity（1.47）,carbon storage(145.04 t·hm^-2),soil conservation（1.98）,and material production(141.71 m³·hm^-2),which were significantly different from the desertification controlled forests,but their soil nutrient quality（0.14）is lower than that of the moderate（0.35）and intense（0.39）desertification controlled forests.The naturally restored karst plateau valley forest has a greater capacity for water-holding capacity,carbon storage(218.22 t·hm^-2)and material production(159.68 m³·hm^-2)than the desertification controlled forests,while the capacity for species diversity（2.31）and soil conservation（1.53）are lower than that of the lightly desertification controlled forests.The natural restoration of karst mountain canyon forests would be better.The water-holding capacity,species diversity,carbon storage and material production capacity of the forest ecosystem decreases with increasing stone desertification,while soil nutrient quality decreases with decreasing stone desertification.The ranking of soil conservation capacity was:moderate（1.77）>natural restoration（1.68）>intense（1.51）desertification controlled forests.The revelation of forest ecosystem service capacity of different desertification control modes would provide theoretical reference for forest ecosystem structure optimization.（2）The trade-offs/synergies between regulating and provisioning,regulating and supporting,and provisioning and supporting services in karst forest ecosystems are elucidated;the trade-offs/synergies between services under natural state,light,moderate and intense desertification ecological control are revealed.Soil conservation for forest ecosystem regulating services and material production for provisioning services are trade-offs.The carbon storage of regulating services is synergies with the water and material production of supply services,and the species diversity of supporting services,while trade-offs are made with the quality of soil nutrients of supporting services.The water-holding capacity,and material production of the provisioning services are synergies with the species diversity of the supporting services,while there are trade-offs with the quality of soil nutrients.Naturally restored forests:there are synergies relationships between species diversity and material production,water-holding capacity,the soil conservation and material production.The quality of soil nutrients has trade-offs with water-holding capacity and material production,and carbon storage with water-holding capacity and species diversity.Light desertification control:soil nutrient quality and soil conservation,carbon storage and material production,and water-holding capacity are positively correlated,while Soil conservation and material production,and water-holding capacity are negatively correlated.Moderate desertification control:the trend is positive between species diversity and material production and water-holding capacity.In contrast,there is a negative correlation between soil conservation and water-holding capacity,material production,species diversity,and soil nutrient quality.Intense desertification control:there are synergies between material production,water conservation and species diversity.Soil nutrient quality and soil conservation both have trade-offs with water availability,material production and species diversity.（3）Proposed functional optimization strategies for shifting forest structure and trade-offs to synergy:Based on the current situation of forest ecosystem services in karst desertification control,the tree species structure of forest stands was optimized in the study area by planting native species,etc.The density and depression of forest stands were regulated to bring into play the forest window effect,so that plants could obtain sufficient light conditions and growth space.Changing the way planted forests are managed,reducing excessive human interference and gradually adjusting and orienting the unreasonable spatial structure of existing forests to that of natural forests.Based on the trade-offs and synergies between forest ecosystem services,it is suggested that special economic forests,arbor,shrubs and grasses should be optimized and regulated to improve the structure and functions of the forest ecosystem and enhance its service capacity.This will help to transform the trade-off relationship between services into a synergies relationship,and provide a reference for the sustainable development of the forest industry in desertification control.