| Along with the large-scale “Grain for Green” in the Loess Plateau.Based on plant functional traits,research on vegetation restoration and ecosystem multifunctionality can provide a theoretical basis for ecological restoration practices.Previous studies have mostly compared the single ecosystem functions with different restoration methods or vegetation types,and the research on ecosystems multifunctionality needs to be strengthened urgently.It is great significance for the ecosystem restoration to quantitatively discuss the mechanism of the effects of plant functional traits on ecosystem multifunctionality in vegetation restoration.We conducted an ecosystem multifunctionality study in Longtan watershed of Dingxi,Gansu Province,China.Based on survey data from 38 plots,which included 2 restoration methods(natural restoration and artificial restoration)in contrast to native grassland and 6 vegetation types(Stipa bungeana grassland,Leymus secalinus grassland,Medicago sativa grassland,Caragana korshinskii shrub,Pinus tabuliformis forests and Armeniaca sibirica forests).We selected 20 functional indexes related to soil fertility,water conservation type,nutrient transformation and cycling,above ground primary production,plant growth strategies and plant nutrient uptake to quantify ecosystem multifunctionality by averaging approach and single threshold approach(20%,40%,60% and 80%).This paper mainly studies the differences in single ecosystem functions and ecosystem multifunctionality under different restoration methods,and further explores more effective artificial restoration methods through vegetation types.Based on the weighted mean value and functional diversity of functional traits,and the mass-ratiohypothesis and niche complementarity hypothesis of plant traits on ecosystem multifunctionality were investigated.(1)By studying the single ecosystem functions under different restoration methods,the results showed that.Except for organic matter,soil total phosphorus,available phosphorus,capillary porosity.The soil single ecosystem function had significant differences among different restoration methods and vegetation types(P<0.05).In general,the function related to soil fertility such as total soil carbon,total nitrogen,available nitrogen and soil N: P ratio,and artificial restoration are significantly higher than natural restoration(P<0.05).In the artificially restored vegetation,the soil fertility of M.sativa grassland and C.korshinskii shrub is relatively higher than that of P.tabuliformis forests and A.sibirica forests.In terms of water conservation and nutrient transformation and cycling,and natural restoration vegetation was significantly higher than artificial restoration vegetation(P<0.05).Except for plant total phosphorus and specific leaf area,and the plant single ecosystem function had significant differences among different restoration methods and vegetation types(P<0.05).In terms of above ground primary production and plant nutrient uptake,and the above ground biomass,plant total carbon and plant total nitrogen of artificial restoration vegetation were significantly higher than natural restoration vegetation(P<0.05).In the artificially restoration vegetation,the plant total nitrogen of M.sativa grassland,the plant total carbon and above ground biomass of P.tabuliformis forests,leaf area index of A.sibirica forests are relatively higher than other vegetation types,and they are the main contributors to ecosystem functions in artificial restoration vegetation.The function related to plant growth strategies,such as plant C: N ratio and plant N: P ratio.The results show that there is no significant difference between natural restoration vegetation and artificial retoration vegetation.The N: P ratio of M.sativa grassland,the C: N ratio of P.tabuliformis forests and A.sibirica forests is are relatively higher than other vegetation types,and it was significantly different from L.secalinus grassland(P<0.05).(2)The results of research on the ecosystem multifunctionality under different restoration methods show that.Except for the soil multifunctionality of the 20% threshold,and the soil multifunctionality of the other thresholds approach and the averaging approach have significant differences between different restoration methods and vegetation types(P<0.05).There is no significant difference between the soil multifunctionality of natural restoration vegetation and artificial restoration vegetation,but both have significant difference with native grassland(P<0.05).In the comparison of vegetation types,it was found that the soil multifunctionality of C.korshinskii shrub was higher than that of other vegetation types,and it was significantly different from L.secalinus grassland(P<0.05).Except for the plant multifunctionality of 20% threshold.The plant multifunctionality of the other thresholds approach and the averaging approach have significant differences between different restoration methods and vegetation types(P<0.05).The plant multifunctionality of artificial restoration vegetation was significantly higher than that of natural restoration vegetation(P<0.05),and they have significant difference from native grassland(P<0.05).In the comparison of vegetation types,it was found that the plant multifunctionality of C.korshinskii shrub,P.tabuliformis forests and A.sibirica forests was significantly higher than that of other vegetation types,and it was significant difference from L.secalinus grassland(P<0.05).Except for the ecosystem multifunctionality of the 20% and 80% thresholds approach,and the ecosystem multifunctionality of the other thresholds approach and averaging approach have significant differences among different restoration methods and vegetation types(P<0.05).The ecosystem multifunctionality of artificial restoration vegetation is significantly higher than that of natural restoration vegetation(P<0.05).In the comparison of vegetation types,it was found that the ecosystem multifunctionality of C.korshinskii shrub and M.sativa grassland is significantly higher than other vegetation types(P <0.05),and was significant different from L.secalinus grassland(P<0.05).(3)Based on plant functional traits to explore the impact mechanism of ecosystem multifunctional.The results showed that the community weighted mean is negatively correlated with ecosystem multifunctionality(P<0.01),and the functional diversity has significant promoting ecosystem multifunctionality(P<0.05).When the averaging approach,20%threshold approach and 40% threshold approach are used to quantify the ecosystem multifunctionality,plant functional traits can better explain the ecosystem multifunctionality.When the 60% threshold approach and 80% threshold approach are used,the interpretation of plant functionality traits is low(<5%).The ecosystem multifunctionality is mainly affected by the " mass-ratio hypothesis ",and secondly by the " niche complementarity hypothesis ",and they also have complex collinearity.In summary,ecosystem multifunctionality of artificial restoration vegetation was significantly higher than that of natural restoration vegetation.But the water conservation of the artificial restoration vegetation was lower than that of the natural restoration vegetation,which was not conducive to the sustainable development of the ecosystem.It is considered that in the practice of vegetation restoration,vegetation restoration strategy should be formulated according to the different restoration objectives and the functional characteristics of each vegetation type.It provides new ideas for vegetation construction and sustainable ecosystem management in the region. |
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