Biological invasions can alter soil properties within the range of their introduced,leading to impacts on ecosystem services,ecosystem functions,and biodiversity.To better understand the impacts of biological invasion...Biological invasions can alter soil properties within the range of their introduced,leading to impacts on ecosystem services,ecosystem functions,and biodiversity.To better understand the impacts of biological invasions on soil,we compared topsoil physiochemical properties at sites with invasive alien tree species(Prosopis juliflora),native tree species(Prosopis cineraria,Acacia tortilis,and Acacia ehrenbergiana),and mixed tree species in Hormozgan Province of Iran in May 2018.In this study,we collected 40 soil samples at a depth of 10 cm under single tree species,including P.juliflora,P.cineraria,A.tortilis,and A.ehrenbergiana,as well as under mixed tree species.The results showed that organic matter,moisture,potassium,calcium,nitrogen,and magnesium in topsoil at sites with A.tortilis and A.ehrenbergiana growing in combination with P.cineraria were higher than that at sites where P.juliflora was present(P<0.05).Sodium at sites with A.tortilis and A.ehrenbergiana growing in combination with P.cineraria and P.juliflora was lower as compared to that at sites with just A.tortilis and A.ehrenbergiana.Electrical conductivity was lower at sites with A.tortilis and A.ehrenbergiana growing in combination with P.cineraria,and it was higher at sites with mixed Acacia and P.juliflora trees.Based on the generally more positive effect of native Acacia and P.cineraria on topsoil physiochemical properties as compared to the P.julifora,afforestation with native tree species is preferable for soil restoration.In addition,due to the negative effects of P.julifora on soil properties,P.julifora spread should be better managed.展开更多
Spatial downscaling methods are widely used for the production of bioclimatic variables(e.g. temperature and precipitation) in studies related to species ecological niche and drainage basin management and planning. Th...Spatial downscaling methods are widely used for the production of bioclimatic variables(e.g. temperature and precipitation) in studies related to species ecological niche and drainage basin management and planning. This study applied three different statistical methods, i.e. the moving window regression(MWR), nonparametric multiplicative regression(NPMR), and generalized linear model(GLM), to downscale the annual mean temperature(Bio1) and annual precipitation(Bio12) in central Iran from coarse scale(1 km × 1 km) to fine scale(250 m ×250 m). Elevation, aspect, distance from sea and normalized difference vegetation index(NDVI) were used as covariates to create downscaled bioclimatic variables. Model assessment was performed by comparing model outcomes with observational data from weather stations. Coefficients of determination(R2), bias, and root-mean-square error(RMSE) were used to evaluate models and covariates. The elevation could effectively justify the changes in bioclimatic factors related to temperature and precipitation. Allthree models could downscale the mean annual temperature data with similar R2, RMSE, and bias values. The MWR had the best performance and highest accuracy in downscaling annual precipitation(R2=0.70; RMSE=123.44). In general, the two nonparametric models, i.e. MWR and NPMR, can be reliably used for the downscaling of bioclimatic variables which have wide applications in species distribution modeling.展开更多
Persian oak(Quercus brantii var.persica)is a dominant tree species of Zagros forests in a semi-arid area,western Iran.However,the capacity of biomass and carbon stocks of these forests is not well studied.We selected ...Persian oak(Quercus brantii var.persica)is a dominant tree species of Zagros forests in a semi-arid area,western Iran.However,the capacity of biomass and carbon stocks of these forests is not well studied.We selected three types of oak,i.e.,seed-originated oak,coppice oak and mixed(seed-originated and coppice)oak of Zagros forests in Dalab valley,Ilam Province,Iran to survey the capacity of biomass and carbon stocks in 2018.Thirty plots with an area of 1000 m2 were systematically and randomly assigned to each type of oak.Quantitative characteristics of trees,such as diameter at breast height(DBH),height,crown diameter and the number of sprouts in each plot were measured.Then,aboveground biomass(AGB),belowground biomass(BGB),aboveground carbon stock(AGCS)and belowground carbon stock(BGCS)of each tree in plots were calculated using allometric equations.The litterfall biomass(LFB)and litterfall carbon stock(LFCS)were measured in a quadrat with 1 m×1 m in each plot.One-way analysis of variance and Duncan's test were performed to detect the differences in biomass and carbon stocks among three types of oak.Results showed that AGB,BGB and BGCS were significantly different among three types of oak.The highest values of AGB,AGCS,BGB and BGCS in seed-originated oak were 76,043.25,14,725.55,36,737.79 and 7362.77 kg/hm2,respectively.Also,the highest values of LFB and LFCS in seed-originated oak were 3298.33 and 1520.48 kg/hm2,respectively,which were significantly higher than those of the other two types of oak.The results imply the significant role of seed-originated oak for the regeneration of Zagros forests.Further conservation strategy of seed-originated oak is an important step in the sustainable management of Zagros forests in Iran.展开更多
Mangrove forests are valuable resources in tropical and subtropical regions,which have been faced dieback due to various human activities including rapid expansion of shrimp farming,urban development,and pollution,as ...Mangrove forests are valuable resources in tropical and subtropical regions,which have been faced dieback due to various human activities including rapid expansion of shrimp farming,urban development,and pollution,as well as natural factors such as rising sea level,increasing air temperature,drought,and sharp decrease in rainfall.However,the mechanisms of dieback of mangrove forests are not well understood.Therefore,this research aimed to assess the vegetative,chemical,and physiological status of grey mangrove(Avicennia marina(Forsk.)Vierh.)forests at different intensities of dieback in the Hormozgan Province,Iran.A total of 40 plots categorized into four dieback intensities(severe,medium,low,and control)were randomly selected for monitoring,and various parameters related to vegetative,chemical,and physiological status of grey mangrove forests were examined.The results revealed that the control group had the highest tree density,seedling density,vitality levels,aerial root density,and aerial root height.Generally,as dieback severity increased,a decrease in demographic and vegetative parameters of trees and seedlings was observed in the dieback treatments.The amounts of heavy metals(lead,cadmium,and nickel)in the sediment,roots,and leaves of grey mangrove trees at different dieback levels indicated that lead levels were the highest in the sediment,roots,and leaves in the severe dieback treatment.At the same time,the control had the lowest values.Cadmium concentrations in the sediment followed the pattern of severe dieback>moderate dieback>low dieback>control with no significant differences in the roots and leaves.Nickel amounts in all three parts,i.e.,sediment,roots,and leaves showed the highest levels in the severe dieback treatment.Furthermore,metal level analysis in the organs of grey mangrove trees at different dieback levels revealed that lead and nickel were more abundant in the root organ compared with the leaves.In contrast,the leaf organ exhibited the highest cadmium levels.Dieback significantly impacted water electrical conductivity(EC),soil organic carbon(SOC),and chlorophyll a,b,and total chlorophyll contents,with the highest values observed in the severe dieback treatment.However,no significant differences were observed in acidity and carotenoid levels.In conclusion,sediment erosion and heavy metal accumulation were critical contributors to dieback of grey mangrove trees,affecting their physiological,vegetative,and plant production characteristics.As the ability of these plants to rehabilitate has diminished,effective management planning is imperative in dieback-affected areas.展开更多
Water availability and soil physicochemical properties are the most important factors for the establishment and growth of plant seedlings in arid and desert areas. Improving water use efficiency and soil properties ar...Water availability and soil physicochemical properties are the most important factors for the establishment and growth of plant seedlings in arid and desert areas. Improving water use efficiency and soil properties are two major factors for sustainable development in these regions. Therefore, this research aimed to study the effectiveness of biological hydrogel (b), PLANTBAC vegetation layer (PB), sand (sa) and barley straw (st) with inter-row system on some soil properties, including N, Cl, Zn, Fe, clay, silt and sand percentages, ρb?and water use efficiency under the cultivation of Nitraria schoberi. This experiment was tested in a split plot design with 3 replications and 10 observations in 2015 during 2 years at Semnan province’s Natural Resources Research Station. Data analysis was carried out in SAS software version 9.1.3. According to the results, the highest amount of Cl was obtained at non-micro catchment by straw and sand treatments, as well as at micro catchment by PB treatments. The highest amount of Zn was obtained at non-micro catchment by straw treatment (1.106). The results of mulch effect on Fe showed that four mulch treatments did not have significant difference with the control. Also, the highest amount of total N content was observed at micro catchment by hydrogel treatment. There was not any significant difference among environment and clay, silt and sand treatments and about plant establishment and, all four mulch treatments had significantly higher moisture content and establishment than the control. The results of mulch effect on water use efficiency showed that there was a significant difference between all four mulch treatments (P 0.01) and the control. The highest water use efficiency occurred in sand treatment (0.243), and the lowest was under straw mulches (0.154). Thus, considering the effects of different types of mulch on soil properties and considering the price of each, the availability and area conditions, they can be used to establish plants in desert areas, and therefore, restore these areas.展开更多
Mangrove forests in southern Iran are of high ecological and economic importance.These forests are being threatened because of uncontrolled harvesting to provide fodder for livestock.The objective of this study is to ...Mangrove forests in southern Iran are of high ecological and economic importance.These forests are being threatened because of uncontrolled harvesting to provide fodder for livestock.The objective of this study is to provide recommendations for appropriate harvesting intensities by quantifying the effect of different harvesting intensities on vegetative and vigor characteristics of mangrove trees.This study was conducted using a randomized complete block design comprising four treatments(10.00%,20.00%,and 30.00% trimming,along with a control)replicated three times.Vegetative characteristics were measured before and after trimming(five-year period)and analyzed using generalized linear model statistical analysis.The growths of the average diameter of canopy,canopy area,canopy volume,canopy height,tree height,and collar diameter in the control treatment were all significantly higher than those in the trimming treatments.In addition,there was a decreasing trend in leaf fresh and dry mass,leaf area index,total area of canopy leaves,and health status of tree in the trimming treatments.For example,the percentage change in fresh and dry leaf mass in the control treatment was positive(29.87% and 38.31%,respectively),whereas the trimming treatments of 10.00%,20.00% and 30.00% had negative effects(-7.01% and -4.79%,-11.32% and -14.30%,and -15.84% and -17.29%,respectively).In addition,the changes in leaf area index in the control(4.95%)and 30.00% trimming(-24.57%)treatments were the highest and lowest,respectively.The percentage change in soil organic matter in the control,10.00%,20.00%,and 30.00% treatments were 22.94%,-9.90%,-16.91%,and -18.68%,respectively.The study demonstrated that gray mangrove trees were highly sensitive to canopy trimming,with even minimal trimming intensities negatively affecting vegetative growth and soil organic matter.Therefore,it is recommended that cutting and trimming of mangrove trees should be prevented even at low intensity to preserve mangrove ecosystem health and resilience against environmental stressors.展开更多
文摘Biological invasions can alter soil properties within the range of their introduced,leading to impacts on ecosystem services,ecosystem functions,and biodiversity.To better understand the impacts of biological invasions on soil,we compared topsoil physiochemical properties at sites with invasive alien tree species(Prosopis juliflora),native tree species(Prosopis cineraria,Acacia tortilis,and Acacia ehrenbergiana),and mixed tree species in Hormozgan Province of Iran in May 2018.In this study,we collected 40 soil samples at a depth of 10 cm under single tree species,including P.juliflora,P.cineraria,A.tortilis,and A.ehrenbergiana,as well as under mixed tree species.The results showed that organic matter,moisture,potassium,calcium,nitrogen,and magnesium in topsoil at sites with A.tortilis and A.ehrenbergiana growing in combination with P.cineraria were higher than that at sites where P.juliflora was present(P<0.05).Sodium at sites with A.tortilis and A.ehrenbergiana growing in combination with P.cineraria and P.juliflora was lower as compared to that at sites with just A.tortilis and A.ehrenbergiana.Electrical conductivity was lower at sites with A.tortilis and A.ehrenbergiana growing in combination with P.cineraria,and it was higher at sites with mixed Acacia and P.juliflora trees.Based on the generally more positive effect of native Acacia and P.cineraria on topsoil physiochemical properties as compared to the P.julifora,afforestation with native tree species is preferable for soil restoration.In addition,due to the negative effects of P.julifora on soil properties,P.julifora spread should be better managed.
文摘Spatial downscaling methods are widely used for the production of bioclimatic variables(e.g. temperature and precipitation) in studies related to species ecological niche and drainage basin management and planning. This study applied three different statistical methods, i.e. the moving window regression(MWR), nonparametric multiplicative regression(NPMR), and generalized linear model(GLM), to downscale the annual mean temperature(Bio1) and annual precipitation(Bio12) in central Iran from coarse scale(1 km × 1 km) to fine scale(250 m ×250 m). Elevation, aspect, distance from sea and normalized difference vegetation index(NDVI) were used as covariates to create downscaled bioclimatic variables. Model assessment was performed by comparing model outcomes with observational data from weather stations. Coefficients of determination(R2), bias, and root-mean-square error(RMSE) were used to evaluate models and covariates. The elevation could effectively justify the changes in bioclimatic factors related to temperature and precipitation. Allthree models could downscale the mean annual temperature data with similar R2, RMSE, and bias values. The MWR had the best performance and highest accuracy in downscaling annual precipitation(R2=0.70; RMSE=123.44). In general, the two nonparametric models, i.e. MWR and NPMR, can be reliably used for the downscaling of bioclimatic variables which have wide applications in species distribution modeling.
文摘Persian oak(Quercus brantii var.persica)is a dominant tree species of Zagros forests in a semi-arid area,western Iran.However,the capacity of biomass and carbon stocks of these forests is not well studied.We selected three types of oak,i.e.,seed-originated oak,coppice oak and mixed(seed-originated and coppice)oak of Zagros forests in Dalab valley,Ilam Province,Iran to survey the capacity of biomass and carbon stocks in 2018.Thirty plots with an area of 1000 m2 were systematically and randomly assigned to each type of oak.Quantitative characteristics of trees,such as diameter at breast height(DBH),height,crown diameter and the number of sprouts in each plot were measured.Then,aboveground biomass(AGB),belowground biomass(BGB),aboveground carbon stock(AGCS)and belowground carbon stock(BGCS)of each tree in plots were calculated using allometric equations.The litterfall biomass(LFB)and litterfall carbon stock(LFCS)were measured in a quadrat with 1 m×1 m in each plot.One-way analysis of variance and Duncan's test were performed to detect the differences in biomass and carbon stocks among three types of oak.Results showed that AGB,BGB and BGCS were significantly different among three types of oak.The highest values of AGB,AGCS,BGB and BGCS in seed-originated oak were 76,043.25,14,725.55,36,737.79 and 7362.77 kg/hm2,respectively.Also,the highest values of LFB and LFCS in seed-originated oak were 3298.33 and 1520.48 kg/hm2,respectively,which were significantly higher than those of the other two types of oak.The results imply the significant role of seed-originated oak for the regeneration of Zagros forests.Further conservation strategy of seed-originated oak is an important step in the sustainable management of Zagros forests in Iran.
文摘Mangrove forests are valuable resources in tropical and subtropical regions,which have been faced dieback due to various human activities including rapid expansion of shrimp farming,urban development,and pollution,as well as natural factors such as rising sea level,increasing air temperature,drought,and sharp decrease in rainfall.However,the mechanisms of dieback of mangrove forests are not well understood.Therefore,this research aimed to assess the vegetative,chemical,and physiological status of grey mangrove(Avicennia marina(Forsk.)Vierh.)forests at different intensities of dieback in the Hormozgan Province,Iran.A total of 40 plots categorized into four dieback intensities(severe,medium,low,and control)were randomly selected for monitoring,and various parameters related to vegetative,chemical,and physiological status of grey mangrove forests were examined.The results revealed that the control group had the highest tree density,seedling density,vitality levels,aerial root density,and aerial root height.Generally,as dieback severity increased,a decrease in demographic and vegetative parameters of trees and seedlings was observed in the dieback treatments.The amounts of heavy metals(lead,cadmium,and nickel)in the sediment,roots,and leaves of grey mangrove trees at different dieback levels indicated that lead levels were the highest in the sediment,roots,and leaves in the severe dieback treatment.At the same time,the control had the lowest values.Cadmium concentrations in the sediment followed the pattern of severe dieback>moderate dieback>low dieback>control with no significant differences in the roots and leaves.Nickel amounts in all three parts,i.e.,sediment,roots,and leaves showed the highest levels in the severe dieback treatment.Furthermore,metal level analysis in the organs of grey mangrove trees at different dieback levels revealed that lead and nickel were more abundant in the root organ compared with the leaves.In contrast,the leaf organ exhibited the highest cadmium levels.Dieback significantly impacted water electrical conductivity(EC),soil organic carbon(SOC),and chlorophyll a,b,and total chlorophyll contents,with the highest values observed in the severe dieback treatment.However,no significant differences were observed in acidity and carotenoid levels.In conclusion,sediment erosion and heavy metal accumulation were critical contributors to dieback of grey mangrove trees,affecting their physiological,vegetative,and plant production characteristics.As the ability of these plants to rehabilitate has diminished,effective management planning is imperative in dieback-affected areas.
文摘Water availability and soil physicochemical properties are the most important factors for the establishment and growth of plant seedlings in arid and desert areas. Improving water use efficiency and soil properties are two major factors for sustainable development in these regions. Therefore, this research aimed to study the effectiveness of biological hydrogel (b), PLANTBAC vegetation layer (PB), sand (sa) and barley straw (st) with inter-row system on some soil properties, including N, Cl, Zn, Fe, clay, silt and sand percentages, ρb?and water use efficiency under the cultivation of Nitraria schoberi. This experiment was tested in a split plot design with 3 replications and 10 observations in 2015 during 2 years at Semnan province’s Natural Resources Research Station. Data analysis was carried out in SAS software version 9.1.3. According to the results, the highest amount of Cl was obtained at non-micro catchment by straw and sand treatments, as well as at micro catchment by PB treatments. The highest amount of Zn was obtained at non-micro catchment by straw treatment (1.106). The results of mulch effect on Fe showed that four mulch treatments did not have significant difference with the control. Also, the highest amount of total N content was observed at micro catchment by hydrogel treatment. There was not any significant difference among environment and clay, silt and sand treatments and about plant establishment and, all four mulch treatments had significantly higher moisture content and establishment than the control. The results of mulch effect on water use efficiency showed that there was a significant difference between all four mulch treatments (P 0.01) and the control. The highest water use efficiency occurred in sand treatment (0.243), and the lowest was under straw mulches (0.154). Thus, considering the effects of different types of mulch on soil properties and considering the price of each, the availability and area conditions, they can be used to establish plants in desert areas, and therefore, restore these areas.
文摘Mangrove forests in southern Iran are of high ecological and economic importance.These forests are being threatened because of uncontrolled harvesting to provide fodder for livestock.The objective of this study is to provide recommendations for appropriate harvesting intensities by quantifying the effect of different harvesting intensities on vegetative and vigor characteristics of mangrove trees.This study was conducted using a randomized complete block design comprising four treatments(10.00%,20.00%,and 30.00% trimming,along with a control)replicated three times.Vegetative characteristics were measured before and after trimming(five-year period)and analyzed using generalized linear model statistical analysis.The growths of the average diameter of canopy,canopy area,canopy volume,canopy height,tree height,and collar diameter in the control treatment were all significantly higher than those in the trimming treatments.In addition,there was a decreasing trend in leaf fresh and dry mass,leaf area index,total area of canopy leaves,and health status of tree in the trimming treatments.For example,the percentage change in fresh and dry leaf mass in the control treatment was positive(29.87% and 38.31%,respectively),whereas the trimming treatments of 10.00%,20.00% and 30.00% had negative effects(-7.01% and -4.79%,-11.32% and -14.30%,and -15.84% and -17.29%,respectively).In addition,the changes in leaf area index in the control(4.95%)and 30.00% trimming(-24.57%)treatments were the highest and lowest,respectively.The percentage change in soil organic matter in the control,10.00%,20.00%,and 30.00% treatments were 22.94%,-9.90%,-16.91%,and -18.68%,respectively.The study demonstrated that gray mangrove trees were highly sensitive to canopy trimming,with even minimal trimming intensities negatively affecting vegetative growth and soil organic matter.Therefore,it is recommended that cutting and trimming of mangrove trees should be prevented even at low intensity to preserve mangrove ecosystem health and resilience against environmental stressors.
