To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,lig...To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,light and moderate and severe drought treatments[(80±5),(65±5),(50±5),and(35±5)%of field water-holding capacity].Non-structural carbohydrates,carbon(C),nitrogen(N),and phosphorus(P)concentrations were measured in each plant component.The results show that:(1)With increasing drought,non-structural carbohydrates gradually increased in leaves,stems,and coarse roots,while gradually decreased in fine roots;(2)C concentrations of all were relatively stable under different stress levels.Phosphorous utilization of each component increased under light and moderate drought conditions,while N and P utilization efficiency of each plant component decreased under severe drought.Growth was mainly restricted by N,first decreasing and then increasing with increased drought;(3)There was a correlation between the levels of non-structural carbohydrates and C,N,and P in each component.Changes in N concentration affected the interconversion between soluble sugar and starch,which play a regulatory role in the fluctuation of the concentration of non-structural carbohydrates;and,(4)Plasticity analysis showed that P.yunnanensis seedlings responded to drought mainly by altering starch concentration,the ratio of soluble sugar to starch in leaves and stems,and further by alter-ing N and P utilization efficiencies.Overall,these results suggest that the physiological activities of all organs of P.yunnanensis seedlings are restricted under drought and that trade-offs exist between different physiological indicators and organs.Our findings are helpful in understanding non-structural carbohydrate and nutrient adaptation mechanisms under drought in P.yunnanensis seedlings.展开更多
Plant biomass, primary production and mineral cycling in the beech forest (Fagus sylvatica L.), Hestehave in Jutland, Denmark were studied over a 50-year period. The role of the forest as a carbon sink was also assess...Plant biomass, primary production and mineral cycling in the beech forest (Fagus sylvatica L.), Hestehave in Jutland, Denmark were studied over a 50-year period. The role of the forest as a carbon sink was also assessed. Aboveground tree biomass was 226 t·ha-1 in 1970 and after a 50-year 539 t·ha-1 in 2014, an unexpected increase with 313 t·ha-1. Annual production at those two points in time was 13.4 and 20.5 t·ha-1, respectively. It was apparent that the tree biomass was still acting as a sink for carbon, which was the dominant element in the aboveground parts. The concentration of other elements (N > K > Mg > P > S > Na > Mn > Zn > Fe > Cu) ranged from 495 to 0.4 kg·ha-1. Annual litterfall restored 3.2 t·ha-1 to the soil as organic matter or 1.6 t·ha-1 as carbon. Over the year 53% of the litterfall was decomposed. A pH decrease of 0.95 units in the soil was observed between 1968 and 1993. This was attributed to fallout from a neighbouring thermal heating station affecting sulfur deposition and increasing soil acidification. After 1993, when filters were fitted in the heating station, the pH decrease in the soil was smaller, only 0.09 pH-units up to 2011. The increased tree growth is an additional, likely explanation for the observed soil acidification. Deposition of the growth-limiting element nitrogen increased during later years and is now, most likely around 20 kg·ha-1 per annum, which may partly contribute to the increased production.展开更多
Due to the Tibetan Plateau’s unique high altitude and low temperature climate conditions,the region’s alpine steppe ecosystem is highly fragile and is suffering from severe degradation under the stress of increasing...Due to the Tibetan Plateau’s unique high altitude and low temperature climate conditions,the region’s alpine steppe ecosystem is highly fragile and is suffering from severe degradation under the stress of increasing population,overgrazing,and climate change.The soil stoichiometry,a crucial part of ecological stoichiometry,provides a fundamental approach for understanding ecosystem processes by examining the relative proportions and balance of the three elements.Understanding the impact of degradation on the soil stoichiometry is vital for conservation and management in the alpine steppe on the Tibetan Plateau.This study aims to examine the response of soil stoichiometry to degradation and explore the underlying biotic and abiotic mechanisms in the alpine steppe.We conducted a field survey in a sequent degraded alpine steppe with seven levels inNorthern Tibet.The plant species,aboveground biomass,and physical and chemical soil properties such as the moisture content,temperature,pH,compactness,total carbon(C),total nitrogen(N),and total phosphorus(P)were measured and recorded.The results showed that the contents of soil C/N,C/P,and N/P consistently decreased along intensifying degradation gradients.Using regression analysis and a structural equation model(SEM),we found that the C/N,C/P,and N/P ratios were positively affected by the soil compactness,soil moisture content and species richness of graminoids but negatively affected by soil pH and the proportion of aboveground biomass of forbs.The soil temperature had a negative effect on the C/N ratio but showed positive effect on the C/P and N/P ratios.The current study shows that degradation-induced changes in abiotic and biotic conditions such as soil warming and drying,which accelerated the soil organic carbon mineralization,as well as the increase in the proportion of forbs,whichwere difficult to decompose and input less organic carbon into soil,resulted in the decreases in soil C/N,C/P,and N/P contents to a great extent.Our results provide a sound basis for sustainable conservation and management of the alpine steppe.展开更多
Plant biomass, primary production and mineral cycling were studied in a mixed deciduous forest (Quercus robur L., Tilia cordata L. and Corylus avellana L.) in southern Sweden. Plant biomass amount above and below grou...Plant biomass, primary production and mineral cycling were studied in a mixed deciduous forest (Quercus robur L., Tilia cordata L. and Corylus avellana L.) in southern Sweden. Plant biomass amount above and below ground was 201 and 37 t·ha-1, respectively. Primary production above and below ground was an estimated 13.3 and 2.3 t·ha-1, respectively. Carbon was the dominant element in the forest ecosystem, comprising 133 t·ha-1. Other major elements were: N > Ca > K > Si > Mg > S > Mn > P > Fe and Na (range 1123 to 18 kg·ha-1), followed by some trace elements. Yearly litterfall restored 6.0 t·ha-1 organic matter or 2.3 t·ha-1 carbon. Approximately 45% decomposed and returned to the soil during the year. Monitoring of other elements revealed that the ecosystem received inputs through dry and wet deposition, in particular 34.4 kg·ha-1 S and 9.4 kg·ha-1 of N yearly as throughfall. Determination of yearly biomass increase showed that the oak forest ecosystem was still in an aggradation or accumulation phase.展开更多
Botanical, soil chemistry and soil microbiology variables were tested as predictors of in situ soil respiration rate in the various terrestrial habitats on sub-Antarctic Marion Island (47oS, 38oE). Inorganic P and tot...Botanical, soil chemistry and soil microbiology variables were tested as predictors of in situ soil respiration rate in the various terrestrial habitats on sub-Antarctic Marion Island (47oS, 38oE). Inorganic P and total N concentration were the best predictors amongst the chemistry variables and bacteria plate count the best of the microbiology variables. However, while these chemistry and microbiology variables could accurately predict soil respiration rate for particular habitats, they proved inadequate predictors across the whole range of habitats. The best suite of predictors comprised only botanical variables (relative covers of five plant guilds) and accounted for 94% of the total across-habitat variation in soil respiration rate. Mean field soil respiration rates (2.1 - 15.5 mmol CO2 m-2 h-1) for habitats not influenced by seabirds or seals are similar to rates in comparable Northern Hemisphere tundra habitats. Seabird and seal manuring enhances soil respiration rates to values (up to 27.6 mmol CO2 m-2 h-1) higher than found at any tundra site. Glucose, N, P or N plus P were added to three habitats with contrasting soil types;a fellfield with mineral, nutrient-poor soil, a mire with organic, nutrient-poor soil and a shore-zone herbfield heavily manured by penguins and with organic, nutrient-rich soil. Glucose addition stimulated soil respiration in the fellfield and mire (especially the former) but not in the coastal herbfield soil. N and P, alone or together, did not stimulate respiration at any of the habitats, but adding glucose to fellfield soils that had previously been fortified with P or NP caused a similar increase in respiration rate, which was greater than the increase when adding glucose to soils fortified only with N. This suggests that fellfield soil respiration is limited by P rather than N, and that there is no synergism between the two nutrients. For the mire and coastal herbfield, adding glucose to soils previously fortified with N, P or NP did not enhance rates more than adding glucose to soils that had received no nutrient pre-treatment.展开更多
Atmospheric nitrogen deposition is at a high level in some forests of South China. The effects of addition of exogenous N and P on soil organic carbon mineralization were studied to address: (1) if the atmospheric N d...Atmospheric nitrogen deposition is at a high level in some forests of South China. The effects of addition of exogenous N and P on soil organic carbon mineralization were studied to address: (1) if the atmospheric N deposition promotes soil C storage through decreasing mineralization; (2) if the soil available P is a limitation to organic carbon mineralization. Soils (0-10 cm) was sampled from monsoon evergreen broad-leaved forest (MEBF), coniferous and broad-leaved mixed forest (CBMF), and Pinus massoniana forest (PMF) in Dinghushan Biosphere Reserve (located in Guangdong Province, China). The soils were incubated at 25°C for 45 weeks, with addition of N (NH4NO3 solution) or P (KH2PO4 solution). CO2-C emission and the inorganic N (NH4+-N and NO3?-N) of the soils were determined during the incubation. The results showed that CO2-C emission decreased with the N addition. The addition of P led to a short-term sharp increase in CO2 emission after P application, and the responses of CO2-C evolution to P addition in the later period of incubation related to forest types. Strong P inhibition to CO2 emission occurred in both PMF and CBMF soils in the later incubation. The two-pool kinetic model was fitted well to the data for C turnover in this experiment. The model analysis demonstrated that the addition of N and P changed the distribution of soil organic C between the labile and recalcitrant pool, as well as their mineralization rates. In our experiment, soil pH can not completely explain the negative effect of N addition on CO2-C emission. The changes of soil inorganic N during incubation seemed to support the hypothesis that the polymerization of added nitrogen with soil organic compound by abiotic reactions during incubation made the added nitrogen retard the soil organic carbon mineralization. We conclude that atmospheric N deposition contributes to soil C accretion in the three subtropical forest ecosystems, however, the shortage of soil available P in CBMF and PMF may also retard soil organic C mineralization.展开更多
Biogas slurry is a traditional high-quality organic liquid fertilizer. Three terrestrial plants with high economic value, fu </span><span style="font-family:Verdana;">gui</span> <span st...Biogas slurry is a traditional high-quality organic liquid fertilizer. Three terrestrial plants with high economic value, fu </span><span style="font-family:Verdana;">gui</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;">, yang </span><span style="font-family:Verdana;">xin</span> <span style="font-family:Verdana;">cai</span> <span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> strawberry, were selected for hydroponic cultivation using an optimal dilution of biogas slurry. The results of the experiments showed that strawberries could bloom and bear fruit and fu </span><span style="font-family:Verdana;">gui</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> and yang </span><span style="font-family:Verdana;">xin</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> grew well. However, in comparison with the control groups planted in soil, all three crops were subject to a certain degree of environmental stress, as shown by changes in growth, biomass indicators, physiological indicators </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> morphological indicators. The leaves and stems of yang </span><span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> and fu </span><span style="font-family:Verdana;">gui</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> were tested for several types of heavy metals, and all met the requirements for human consumption. It is feasible to cultivate these three plants with biogas slurry. The results of this study can help guide hydroponic production practices and have practical significance and reference value.展开更多
基金This study was supported by the National Natural Science Foundation of China(31960306).
文摘To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,light and moderate and severe drought treatments[(80±5),(65±5),(50±5),and(35±5)%of field water-holding capacity].Non-structural carbohydrates,carbon(C),nitrogen(N),and phosphorus(P)concentrations were measured in each plant component.The results show that:(1)With increasing drought,non-structural carbohydrates gradually increased in leaves,stems,and coarse roots,while gradually decreased in fine roots;(2)C concentrations of all were relatively stable under different stress levels.Phosphorous utilization of each component increased under light and moderate drought conditions,while N and P utilization efficiency of each plant component decreased under severe drought.Growth was mainly restricted by N,first decreasing and then increasing with increased drought;(3)There was a correlation between the levels of non-structural carbohydrates and C,N,and P in each component.Changes in N concentration affected the interconversion between soluble sugar and starch,which play a regulatory role in the fluctuation of the concentration of non-structural carbohydrates;and,(4)Plasticity analysis showed that P.yunnanensis seedlings responded to drought mainly by altering starch concentration,the ratio of soluble sugar to starch in leaves and stems,and further by alter-ing N and P utilization efficiencies.Overall,these results suggest that the physiological activities of all organs of P.yunnanensis seedlings are restricted under drought and that trade-offs exist between different physiological indicators and organs.Our findings are helpful in understanding non-structural carbohydrate and nutrient adaptation mechanisms under drought in P.yunnanensis seedlings.
文摘Plant biomass, primary production and mineral cycling in the beech forest (Fagus sylvatica L.), Hestehave in Jutland, Denmark were studied over a 50-year period. The role of the forest as a carbon sink was also assessed. Aboveground tree biomass was 226 t·ha-1 in 1970 and after a 50-year 539 t·ha-1 in 2014, an unexpected increase with 313 t·ha-1. Annual production at those two points in time was 13.4 and 20.5 t·ha-1, respectively. It was apparent that the tree biomass was still acting as a sink for carbon, which was the dominant element in the aboveground parts. The concentration of other elements (N > K > Mg > P > S > Na > Mn > Zn > Fe > Cu) ranged from 495 to 0.4 kg·ha-1. Annual litterfall restored 3.2 t·ha-1 to the soil as organic matter or 1.6 t·ha-1 as carbon. Over the year 53% of the litterfall was decomposed. A pH decrease of 0.95 units in the soil was observed between 1968 and 1993. This was attributed to fallout from a neighbouring thermal heating station affecting sulfur deposition and increasing soil acidification. After 1993, when filters were fitted in the heating station, the pH decrease in the soil was smaller, only 0.09 pH-units up to 2011. The increased tree growth is an additional, likely explanation for the observed soil acidification. Deposition of the growth-limiting element nitrogen increased during later years and is now, most likely around 20 kg·ha-1 per annum, which may partly contribute to the increased production.
基金supported by the State Key Research Development Program of China (Grant 2016YFC0502002)Youth Innovation Research Team Project (LENOM2016Q0003)
文摘Due to the Tibetan Plateau’s unique high altitude and low temperature climate conditions,the region’s alpine steppe ecosystem is highly fragile and is suffering from severe degradation under the stress of increasing population,overgrazing,and climate change.The soil stoichiometry,a crucial part of ecological stoichiometry,provides a fundamental approach for understanding ecosystem processes by examining the relative proportions and balance of the three elements.Understanding the impact of degradation on the soil stoichiometry is vital for conservation and management in the alpine steppe on the Tibetan Plateau.This study aims to examine the response of soil stoichiometry to degradation and explore the underlying biotic and abiotic mechanisms in the alpine steppe.We conducted a field survey in a sequent degraded alpine steppe with seven levels inNorthern Tibet.The plant species,aboveground biomass,and physical and chemical soil properties such as the moisture content,temperature,pH,compactness,total carbon(C),total nitrogen(N),and total phosphorus(P)were measured and recorded.The results showed that the contents of soil C/N,C/P,and N/P consistently decreased along intensifying degradation gradients.Using regression analysis and a structural equation model(SEM),we found that the C/N,C/P,and N/P ratios were positively affected by the soil compactness,soil moisture content and species richness of graminoids but negatively affected by soil pH and the proportion of aboveground biomass of forbs.The soil temperature had a negative effect on the C/N ratio but showed positive effect on the C/P and N/P ratios.The current study shows that degradation-induced changes in abiotic and biotic conditions such as soil warming and drying,which accelerated the soil organic carbon mineralization,as well as the increase in the proportion of forbs,whichwere difficult to decompose and input less organic carbon into soil,resulted in the decreases in soil C/N,C/P,and N/P contents to a great extent.Our results provide a sound basis for sustainable conservation and management of the alpine steppe.
文摘Plant biomass, primary production and mineral cycling were studied in a mixed deciduous forest (Quercus robur L., Tilia cordata L. and Corylus avellana L.) in southern Sweden. Plant biomass amount above and below ground was 201 and 37 t·ha-1, respectively. Primary production above and below ground was an estimated 13.3 and 2.3 t·ha-1, respectively. Carbon was the dominant element in the forest ecosystem, comprising 133 t·ha-1. Other major elements were: N > Ca > K > Si > Mg > S > Mn > P > Fe and Na (range 1123 to 18 kg·ha-1), followed by some trace elements. Yearly litterfall restored 6.0 t·ha-1 organic matter or 2.3 t·ha-1 carbon. Approximately 45% decomposed and returned to the soil during the year. Monitoring of other elements revealed that the ecosystem received inputs through dry and wet deposition, in particular 34.4 kg·ha-1 S and 9.4 kg·ha-1 of N yearly as throughfall. Determination of yearly biomass increase showed that the oak forest ecosystem was still in an aggradation or accumulation phase.
文摘Botanical, soil chemistry and soil microbiology variables were tested as predictors of in situ soil respiration rate in the various terrestrial habitats on sub-Antarctic Marion Island (47oS, 38oE). Inorganic P and total N concentration were the best predictors amongst the chemistry variables and bacteria plate count the best of the microbiology variables. However, while these chemistry and microbiology variables could accurately predict soil respiration rate for particular habitats, they proved inadequate predictors across the whole range of habitats. The best suite of predictors comprised only botanical variables (relative covers of five plant guilds) and accounted for 94% of the total across-habitat variation in soil respiration rate. Mean field soil respiration rates (2.1 - 15.5 mmol CO2 m-2 h-1) for habitats not influenced by seabirds or seals are similar to rates in comparable Northern Hemisphere tundra habitats. Seabird and seal manuring enhances soil respiration rates to values (up to 27.6 mmol CO2 m-2 h-1) higher than found at any tundra site. Glucose, N, P or N plus P were added to three habitats with contrasting soil types;a fellfield with mineral, nutrient-poor soil, a mire with organic, nutrient-poor soil and a shore-zone herbfield heavily manured by penguins and with organic, nutrient-rich soil. Glucose addition stimulated soil respiration in the fellfield and mire (especially the former) but not in the coastal herbfield soil. N and P, alone or together, did not stimulate respiration at any of the habitats, but adding glucose to fellfield soils that had previously been fortified with P or NP caused a similar increase in respiration rate, which was greater than the increase when adding glucose to soils fortified only with N. This suggests that fellfield soil respiration is limited by P rather than N, and that there is no synergism between the two nutrients. For the mire and coastal herbfield, adding glucose to soils previously fortified with N, P or NP did not enhance rates more than adding glucose to soils that had received no nutrient pre-treatment.
基金the National Natural Science Foundation of China (No. 30725006, 40730102)the Chinese Ecological Research Net
文摘Atmospheric nitrogen deposition is at a high level in some forests of South China. The effects of addition of exogenous N and P on soil organic carbon mineralization were studied to address: (1) if the atmospheric N deposition promotes soil C storage through decreasing mineralization; (2) if the soil available P is a limitation to organic carbon mineralization. Soils (0-10 cm) was sampled from monsoon evergreen broad-leaved forest (MEBF), coniferous and broad-leaved mixed forest (CBMF), and Pinus massoniana forest (PMF) in Dinghushan Biosphere Reserve (located in Guangdong Province, China). The soils were incubated at 25°C for 45 weeks, with addition of N (NH4NO3 solution) or P (KH2PO4 solution). CO2-C emission and the inorganic N (NH4+-N and NO3?-N) of the soils were determined during the incubation. The results showed that CO2-C emission decreased with the N addition. The addition of P led to a short-term sharp increase in CO2 emission after P application, and the responses of CO2-C evolution to P addition in the later period of incubation related to forest types. Strong P inhibition to CO2 emission occurred in both PMF and CBMF soils in the later incubation. The two-pool kinetic model was fitted well to the data for C turnover in this experiment. The model analysis demonstrated that the addition of N and P changed the distribution of soil organic C between the labile and recalcitrant pool, as well as their mineralization rates. In our experiment, soil pH can not completely explain the negative effect of N addition on CO2-C emission. The changes of soil inorganic N during incubation seemed to support the hypothesis that the polymerization of added nitrogen with soil organic compound by abiotic reactions during incubation made the added nitrogen retard the soil organic carbon mineralization. We conclude that atmospheric N deposition contributes to soil C accretion in the three subtropical forest ecosystems, however, the shortage of soil available P in CBMF and PMF may also retard soil organic C mineralization.
文摘Biogas slurry is a traditional high-quality organic liquid fertilizer. Three terrestrial plants with high economic value, fu </span><span style="font-family:Verdana;">gui</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;">, yang </span><span style="font-family:Verdana;">xin</span> <span style="font-family:Verdana;">cai</span> <span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> strawberry, were selected for hydroponic cultivation using an optimal dilution of biogas slurry. The results of the experiments showed that strawberries could bloom and bear fruit and fu </span><span style="font-family:Verdana;">gui</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> and yang </span><span style="font-family:Verdana;">xin</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> grew well. However, in comparison with the control groups planted in soil, all three crops were subject to a certain degree of environmental stress, as shown by changes in growth, biomass indicators, physiological indicators </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> morphological indicators. The leaves and stems of yang </span><span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> and fu </span><span style="font-family:Verdana;">gui</span> <span style="font-family:Verdana;">cai</span><span style="font-family:Verdana;"> were tested for several types of heavy metals, and all met the requirements for human consumption. It is feasible to cultivate these three plants with biogas slurry. The results of this study can help guide hydroponic production practices and have practical significance and reference value.
