Ecosystem Service Tradeoffs And Synergies Of Different Vegetation Types In Daqing Mountain,Inner Mongolia

Inner Mongolia Dashan Mountain belongs to Yinshan Mountain range,which is the climate transitional zone from the semi-humid zone to semi-arid and arid zone in the middle temperate zone of northern China and is also the main secondary forest and plantation forest area in western Inner Mongolia.This area has remarkable ecosystem service functions,and is the main water conservation area and ecological protection area of Hohhot with high ecological environmental protection value.In recent years,research results on individual ecosystem services were abundant in this region,but there was a lack of exploration on the differences of ecosystem services,trade-offs and synergies between different vegetation types and different ages of plantation forests.Therefore,taking the widely distributed Betula platyphylla natural secondary forest（BH）,Larix principis-rupprechtii plantation forest（LYS）,Ostryopsis davidiana natural shrub forest（HZZ）and natural grassland（CD）as the research objects.We evaluated the differences ecosystem services including biodiversity,soil fertility,water conservation and carbon sequestration capacity of different vegetation types and different ages of Larix principis-rupprechtii plantation.The trade-offs and synergies relationships were studied by using the root mean square deviation method（RMSD）and discussed contribution and benefits of ecosystem services,While clarifying the status of ecosystem services in Daqingshan Mountain,the study aims to provide scientific basis for regional vegetation multi-functional management and sustainable development planning of ecosystem services.The results were as follows:（1）The biodiversity,water conservation and soil fertility of LYS were lowerthan BH,while the carbon sequestration capacity of LYS（339.61 t/hm~2）was significantly higher than BH（266.89 t/hm~2）.The carbon sequestration capacity of different vegetation types varies greatly,for specific performance:LYS>BH>HZZ>CD.（2）There were some differences in 4 service functions of 5 forest ages ofDaqingshan Mountains LYS.With the increase of stand age,except for soil total phosphorus,soil organic matter,total nitrogen,total potassium and carbon sequestration capacity all showed an overall trend of increase,while biodiversity showed an overall decreasing trend;water conservation decreased first and then increased with the increase of stand ages.In addition,the values of each ecosystem service function of the 45a（2）LYS with artificial tending were higher than that of the45a（1）LYS without artificial tending,indicating that certain tending methods could contribute to the improvement of ecosystem services.（3）The ecosystem services of 4 vegetation type were mainly trade-offs,BHshowed trade-offs except the synergistic relationship between biodiversity and soil fertility,and water conservation was always the one with higher relative benefits;LYS were all trade-off relations,and the trade-off degree was higher than BH,and carbon sequestration capacity was always the one with higher relative benefits,and the increase of carbon sequestration capacity was on the premise of depleting other ecosystem services.（4）Stand age was an important factor that caused the change of ecosystemservice trade-off.On the whole,the ecosystem service trade-off increased with the increase of stand ages.The 15a and 34a LYS ecosystem services were mainly trade-off,but the synergistic relationship between water conservation,biodiversity and carbon sequestration increased with the increase of the other.There were synergistic relationships among biodiversity,carbon sequestration capacity and water conservation of 22a LYS,while the rest were trade-off.The relative gains of biodiversity,water conservation and carbon sequestration at 15a,22a and 34a LYS were presupposed to be depletion of soil fertility.For the same 45a LYS,ecosystem services were highly trade-off,and the increase of carbon sequestration capacity will have adverse effects on other ecosystem services.The trade-off degree of ecosystem services in 45a（2）after artificial tending was basically lower than that in 45a（1）without artificial tending.（5）The contributions of different vegetation types to biodiversity,waterconservation,soil fertility and carbon sequestration were different.BH had the highest water conservation,followed by biodiversity;LYS had the highest carbon sequestration capacity,followed by water conservation.Soil fertility of HZZ and CD was superior to other ecosystem services.（6）From 15 to 45 age LYS,the value of ecosystem service change index was different,and the gain and loss states were different.Except for 34-45a（1）LYS,water conservation and carbon sequestration capacity were completely reduced,and 15-34a LYS,carbon sequestration capacity was completely gained,ecosystem services increased or decreased in other periods.Compared with 34-45a（1）,artificially nurtured45a（2）had significant ecosystem service gains.Therefore,the artificial tending process is very necessary for larch plantations.