| Planting non-wood forests in karst rocky desertification areas is an effective way to control the ecological environment and take into account economic and social benefits.Exploring the decline mechanism of characteristic non-wood forests,and proposing and demonstrating key technologies to improve the forest productivity are of great significance to the restoration of the productivity and the non-wood forestry development in rocky desertification areas.Based on the basic principles of natural geographical environment evolution,human-land relationship and plant nutrition,combined with the relevant theories of non-wood forests'ecological adaptability,soil nutrient supply,system coupling and sustainable development,the study selected the typical and representative potential-mild desertification area of karst plateau mountain and the moderate-severe desertification area of the karst plateau gorge.Through the methods of literature tracking,statistical investigation,experiment,and quantitative and qualitative analysis,the non-wood forest survey was conducted from 2016 to 2017,and four species including Rosa roxburghii Tratt,Juglns regiaa,Zanthoxylum bungeanum and EriobotryajaPonica?Thunb.?Lindl were selected as research objects to explore soil physical and chemical properties,soil quality status and stand photosynthetic physiological characteristics of the forest land.Measures were taken to improve the forest growth environment and increase its productivity.Main conclusions are as follows.1.The physical and chemical properties of soil were important factors affecting the decline of characteristic non-wood forests in karst rocky desertification areas.From the weight of comprehensive evaluation results:soil total phosphorus,available potassium,and pH in the potential-mild rocky desertification area of Salaxi were the limiting factors for the decline of Rosa roxburghii Tratt,and soil bulk density,total nitrogen,and total potassium Juglns regiaa.Soil total phosphorus and available potassium in the moderate-severe rocky desertification area of Huajiang were the limiting factors for the decline of Zanthoxylum bungeanum,and soil total potassium EriobotryajaPonica?Thunb.?Lindl.2.The aboveground biomass of the characteristic non-wood forests in the karst rocky desertification area could reflect the soil nutrient content,and the biomass and soil nutrients interacted with each other showing good synergistic effect.Leaf functional trait was one of the important indicators affecting the decline of photosynthesis of characteristic non-wood forests in karst rocky desertification areas.The level of net photosynthetic rate depended largely on changes in leaf functional traits.In particular,the leaf area and specific leaf area had direct effects on the net photosynthetic rate and leaf dry matter accumulation of the decline characteristic non-wood forests in Salaxi and Huajiang.In addition,photosynthesis was also affected by environmental factors.3.Focusing on the main problem of the decline of characteristic non-wood forests in karst rocky desertification areas,the following technical measures were taken in this paper:in potential-mild Salaxi rocky desertification area,main techniques for Juglns regiaa and Zanthoxylum bungeanum were grass planting and intercropping,supplemented by soil fertilization,dense forest cutting,and pruning and shaping.In the moderate-severe Huajiang rocky desertification area,the key technology was pruning and shaping,supplemented by intercropping,grass cultivation,and soil fertilization.4.It can be concluded from technology demonstration results that the photosynthesis of characteristic non-wood forests in karst rocky desertification area had been significantly enhanced,and the productivity and economic benefits had been significantly improved,forming a three-dimensional and multi-level compound management model suitable for the development of karst rocky desertification area.The photosynthetic rates of Rosa roxburghii Tratt and Juglns regiaa in Salaxi Township demonstration area increased from 3.83 and 4.88?mol·m-2·s-1 to 7.13 and 8.11?mol·m-2·s-1,respectively.Meanwhile,the photosynthetic rates of Zanthoxylum bungeanum and Eriobotryajaponica?Thunb.?Lindl)increased from 7.11?8.97?mol·m-2·s-1 to 0.85?15.65?mol·m-2·s-1,with an increase on yield per plant by 49.93%and 27.38%,respectively. |
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