Degradation processes affect a vast area of arid and semi-arid lands around the world and damage the environment and people′s health. Degradation processes are driven by human productive activities that cause direct ...Degradation processes affect a vast area of arid and semi-arid lands around the world and damage the environment and people′s health. Degradation processes are driven by human productive activities that cause direct and indirect effects on natural resources, such as species extinction at regional scale, reduction and elimination of vegetation cover, soil erosion, etc. In this context, ecological rehabilitation is an important tool to recover key aspects of the degraded ecosystem. Rehabilitation trials rely on the use of native plant species with characteristics that allow them to obtain high survival and growth rates. The aim of this work was to assess the survival and growth of native woody species in degraded areas of northeastern Patagonia and relate them to plant functional traits and environmental variables. We observed high early and late survival rates, and growth rates in Prosopis flexuosa DC. var. depressa F.A. Roig and Schinus johnstonii F.A. Barkley, and low values in Condalia microphylla Cav. and Geoffroea decorticans(Gillies ex Hook. & Arn.) Burkart. Early survival rates were positively associated with specific leaf area(SLA) and precipitation, but negatively associated with wood density, the maximum mean temperature of the warmest month and the minimum mean temperature of the coldest month. Late survival rates were positively associated with SLA and soil organic matter, but negatively associated with plant height and precipitation. The temperature had a positive effect on late survival rates once the plants overcame the critical period of the first summer after they were transplanted to the field. Prosopis flexuosa and S. johnstonii were the most successful species in our study. This could be due to their functional traits that allow these species to acclimatize to the local environment. Further research should focus on C. microphylla and G. decorticans to determine how they relate to productive conditions, acclimation to environmental stress, auto-ecology and potential use in ecological rehabilitation trials.展开更多
The responses of field-grown Fagus engleriana Seem.seedlings to light and soil nutrient availability were investigated.Two-year-old seedlings were grown for two growing seasons under six treatment conditions,including...The responses of field-grown Fagus engleriana Seem.seedlings to light and soil nutrient availability were investigated.Two-year-old seedlings were grown for two growing seasons under six treatment conditions,including three light levels(L1:1%-2%of full sunlight;L2:18%of full sunlight;L3:100%of full sunlight),with and without fertilizer addition(F1 and F0)for each light level.The results showed that light and nutrients had significant effect on seedling growth as measured in terms of shoot height,stem basal diameter and biomass;the mean increments of shoot height over two growing seasons were significantly less in L1 than in L2 and L3(P<0.001),and in L3 than in L2(P<0.01),but the increments during the first growing season were not significantly different among the treatments;the increments of stem basal diameter and biomass components were significantly less in L1 than in L2 and L3(P<0.001);the increments of stem basal diameter and whole plant biomass were not statistically different between L2 and L3;adding fertilizer did not affect the seedling growth under closed forest canopy,but had effect in the environments with more sunlight.The results suggest that(1)two-year-old F.engleriana seedlings couldsurvive the conditions of closed forest canopy,but their growth might be severely inhibited;(2)the seedlings could grow as well as or even better in small forest gaps than in open sites;and(3)fertile soil might enhance seedling growth in forest gaps and open sites,but not under closed forest canopy.展开更多
基金funded by the National University of Río Negro, Argentina (PI40c658, PI40c654)。
文摘Degradation processes affect a vast area of arid and semi-arid lands around the world and damage the environment and people′s health. Degradation processes are driven by human productive activities that cause direct and indirect effects on natural resources, such as species extinction at regional scale, reduction and elimination of vegetation cover, soil erosion, etc. In this context, ecological rehabilitation is an important tool to recover key aspects of the degraded ecosystem. Rehabilitation trials rely on the use of native plant species with characteristics that allow them to obtain high survival and growth rates. The aim of this work was to assess the survival and growth of native woody species in degraded areas of northeastern Patagonia and relate them to plant functional traits and environmental variables. We observed high early and late survival rates, and growth rates in Prosopis flexuosa DC. var. depressa F.A. Roig and Schinus johnstonii F.A. Barkley, and low values in Condalia microphylla Cav. and Geoffroea decorticans(Gillies ex Hook. & Arn.) Burkart. Early survival rates were positively associated with specific leaf area(SLA) and precipitation, but negatively associated with wood density, the maximum mean temperature of the warmest month and the minimum mean temperature of the coldest month. Late survival rates were positively associated with SLA and soil organic matter, but negatively associated with plant height and precipitation. The temperature had a positive effect on late survival rates once the plants overcame the critical period of the first summer after they were transplanted to the field. Prosopis flexuosa and S. johnstonii were the most successful species in our study. This could be due to their functional traits that allow these species to acclimatize to the local environment. Further research should focus on C. microphylla and G. decorticans to determine how they relate to productive conditions, acclimation to environmental stress, auto-ecology and potential use in ecological rehabilitation trials.
文摘The responses of field-grown Fagus engleriana Seem.seedlings to light and soil nutrient availability were investigated.Two-year-old seedlings were grown for two growing seasons under six treatment conditions,including three light levels(L1:1%-2%of full sunlight;L2:18%of full sunlight;L3:100%of full sunlight),with and without fertilizer addition(F1 and F0)for each light level.The results showed that light and nutrients had significant effect on seedling growth as measured in terms of shoot height,stem basal diameter and biomass;the mean increments of shoot height over two growing seasons were significantly less in L1 than in L2 and L3(P<0.001),and in L3 than in L2(P<0.01),but the increments during the first growing season were not significantly different among the treatments;the increments of stem basal diameter and biomass components were significantly less in L1 than in L2 and L3(P<0.001);the increments of stem basal diameter and whole plant biomass were not statistically different between L2 and L3;adding fertilizer did not affect the seedling growth under closed forest canopy,but had effect in the environments with more sunlight.The results suggest that(1)two-year-old F.engleriana seedlings couldsurvive the conditions of closed forest canopy,but their growth might be severely inhibited;(2)the seedlings could grow as well as or even better in small forest gaps than in open sites;and(3)fertile soil might enhance seedling growth in forest gaps and open sites,but not under closed forest canopy.
