Ecosystems along the eastern margin of the Qinghai-Tibet Plateau(EQTP)are highly fragile and extremely sensitive to climate change and human disturbances.To quantitatively assess climate-induced ecosystem responses,th...Ecosystems along the eastern margin of the Qinghai-Tibet Plateau(EQTP)are highly fragile and extremely sensitive to climate change and human disturbances.To quantitatively assess climate-induced ecosystem responses,this study proposes a Climate-Induced Productivity Index(CIPI)based on the Super Slack-Based Measure(Super-SBM)model using remote sensing data from 2001 to 2020.The results reveal persistently low CIPI values(0.47-0.53)across major ecosystem types,indicating widespread vulnerability to climatic variability.Among these ecosystems,forests exhibit the highest CIPI(0.55),followed by shrublands(0.54),croplands(0.53),grasslands(0.51),and barelands(0.43).The Theil index analysis further demonstrates significant intra-group disparities,suggesting that extreme climatic events amplify CIPI heterogeneity.Moreover,the dominant environmental drivers differ among ecosystem types:the Palmer Drought Severity Index(PDSI)primarily constrains grassland productivity,solar radiation(SRAD)strongly influences shrub and cropland systems,whereas subsurface factors exert greater control in forested regions.This study provides a quantitative framework for evaluating climate-ecosystem interactions and offers a scientific basis for long-term ecological monitoring and security planning across the EQTP.展开更多
Net primary productivity （NPP） is the structure and function of the ecosystem. NPP can most important index that represents the be simulated by dynamic global vegetation models （DGVM）, which are designed to repres...Net primary productivity （NPP） is the structure and function of the ecosystem. NPP can most important index that represents the be simulated by dynamic global vegetation models （DGVM）, which are designed to represent vegetation dynamics relative to environ- mental change. This study simulated the NPP of China＇s ecosystems based on the DGVM Integrated Biosphere Simulator （IBIS） with data on climate, soil, and topography. The appli- cability of IBIS in the NPP simulation of China＇s terrestrial ecosystems was verified first. Comparison with other relevant studies indicates that the range and mean value of simula- tions are generally within the limits of observations; the overall pattern and total annual NPP are close to the simulations conducted with other models. The simulations are also close to the NPP estimations based on remote sensing. Validation proved that IBIS can be utilized in the large-scale simulation of NPP in China＇s natural ecosystem. We then simulated NPP with climate change data from 1961 to 2005, when warming was particularly striking. The following are the results of the simulation. （1） Total NPP varied from 3.61 GtC/yr to 4.24 GtC/yr in the past 45 years and exhibited minimal significant linear increase or decrease. （2） Regional differences in the increase or decrease in NPP were large but exhibited an insignificant overall linear trend. NPP declined in most parts of eastern and central China, especially in the Loess Plateau. （3） Similar to the fluctuation law of annual NPP, seasonal NPP also displayed an insignificant increase or decrease; the trend line was within the general level. （4） The re- gional differences in seasonal NPP changes were large. NPP declined in spring, summer, and autumn in the Loess Plateau but increased in most parts of the Tibetan Plateau.展开更多
The Three-River Headwater Region（TRHR）, known as the ＂Water Tower of China＂, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream r...The Three-River Headwater Region（TRHR）, known as the ＂Water Tower of China＂, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream regions in China and a number of Southeast Asian countries. The TRHR is a high-elevation, cold environment with a unique, but typical alpine vegetation system. Net primary productivity（NPP） is a key vegetation parameter and ecological indicator that can reflect both natural environmental changes and carbon budget levels. Given the unique geographical environment and strategic location of the TRHR, many scholars have estimated NPP of the TRHR by using different methods; however, these estimates vary greatly for a number of reasons. To date, there is no paper that has reviewed and assessed NPP estimation studies conducted in the TRHR. Therefore, in this paper, we（1） summarized the related methods and results of NPP estimation in the TRHR in a systematic review of previous research;（2） discussed the suitability of existing methods for estimating NPP in the TRHR and highlighted the most significant challenges; and（3） assessed the estimated NPP results. Finally, developmental directions of NPP estimation in the TRHR were prospected.展开更多
In this paper, the biomass productivity and nutrient cycling in an agroforestry system of coconut (Cocus nucifera) interplanted with pineapple (Ananas comosus) had been studied. The result showed that the biomass prod...In this paper, the biomass productivity and nutrient cycling in an agroforestry system of coconut (Cocus nucifera) interplanted with pineapple (Ananas comosus) had been studied. The result showed that the biomass productivity of this ecosystem was 47 460 kg...hm2...a?1, which was 4.3 times as much as that of pure coconut plantation. In the biological cycling of N, P. K elements, the total annual retention was 559.470 kg...hm?2, the annual return was 410.745 kg...hm?2, the annual uptake was 970.475 kg...hm?2, respectively. The average circulation rate in three nutrient elements (N, P, K) was 42.32%, which was 27.53% more than that in pure coconut stands. Coconut interplanted with pineapple was proved to be one of optimum cultural patterns, which had the higher biomass productivity, and better usage efficiency of environment resources in tropical areas.展开更多
This research classified vegetation types and evaluated net primary productivity （NPP） of southern China＇s grasslands based on the improved comprehensive and sequential classification system （CSCS）, and proposed ...This research classified vegetation types and evaluated net primary productivity （NPP） of southern China＇s grasslands based on the improved comprehensive and sequential classification system （CSCS）, and proposed 5 thermal grades and 6 humidity grades. Four classes of grasslands vegetation were recognized by improved CSCS, namely, tundra grassland class, typical grassland class, mixed grassland class and alpine grassland class. At the type level, 14 types of vegetations （9 grasslands and 5 forests） were classified. The NPP had a trend to decrease from east to west and south to north, and the annual mean NPP was estimated to be 656.3 g C m-2 yr-1. The NPP value of alpine grassland class was relatively high, generally more than 1200 g C m2 yr-1. The NPP value of mixed grassland class was in a range from 1 000 to 1200 g C m-2 yr-1. Tundra grassland class was located in southeastern Tibet with high elevation, and its NPP value was the lowest （〈600 g C m＇2yrl）. The typical grassland class distributed in most of the area, and its NPP value was generally from 600 to 1000 g C m-2 yr-1. The total NPP value in the study area was 68.46 Tg C. The NPP value of typical grassland class was the highest （48.44 Tg C）, and mixed grassland class was the second （16.54 Tg C）, followed by alpine grassland class （3.22 Tg C）, with tundra grassland class being the lowest （0.25 Tg C）. For all the grasslands types, the total NPP of forest meadow was the highest （34.81 Tg C）, followed by sparse forest brush （16.54 Tg C）, and montane meadow was the lowest （0.01 Tg C）.展开更多
Background: Global warming has brought many negative impacts on terrestrial ecosystems, which makes the vulnerability of ecosystems one of the hot issues in current ecological research. Here, we proposed an assessment...Background: Global warming has brought many negative impacts on terrestrial ecosystems, which makes the vulnerability of ecosystems one of the hot issues in current ecological research. Here, we proposed an assessment method based on the IPCC definition of vulnerability. The exposure to future climate was characterized using a moisture index(MI) that integrates the effects of temperature and precipitation. Vegetation stability, defined as the proportion of intact natural vegetation that remains unchanged under changing climate, was used together with vegetation productivity trend to represent the sensitivity and adaptability of ecosystems. Using this method, we evaluated the vulnerability of ecosystems in Southwestern China under two future representative concentration pathways(RCP 4.5 and RCP 8.5) with MC2 dynamic global vegetation model.Results:(1) Future(2017–2100) climate change will leave 7.4%(under RCP 4.5) and 57.4% of(under RCP 8.5) of areas under high or very high vulnerable climate exposure;(2) in terms of vegetation stability, nearly 45% of the study area will show high or very high vulnerability under both RCPs. Beside the impacts of human disturbance on natural vegetation coverage(vegetation intactness), climate change will cause obvious latitudinal movements in vegetation distribution, but the direction of movements under two RCPs were opposite due to the difference in water availability;(3) vegetation productivity in most areas will generally increase and remain a low vulnerability in the future;(4) an assessment based on the above three aspects together indicated that future climate change will generally have an adverse impact on all ecosystems in Southwestern China, with non-vulnerable areas account for only about 3% of the study area under both RCPs. However, compared with RCP 4.5, the areas with mid-and highvulnerability under RCP 8.5 scenario increased by 13% and 16%, respectively.Conclusion: Analyses of future climate exposure and projected vegetation distribution indicate widespread vulnerability of ecosystems in Southwestern China, while vegetation productivity in most areas will show an increasing trend to the end of twenty-first century. Based on new climate indicators and improved vulnerability assessment rules, our method provides an extra option for a more comprehensive evaluation of ecosystem vulnerability, and should be further tested at larger spatial scales in order to provide references for regional, or even global, ecosystem conservation works.展开更多
Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photos...Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photosynthetic vegetation （NPV）, bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity （NPP）. We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement （R2= 0.85, P〈0.001） between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to arid ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.展开更多
Changes in the sizes of precipitation events in the context of global climate change may have profound impacts on ecosystem productivity in arid and semiarid grasslands. However, we still have little knowledge about t...Changes in the sizes of precipitation events in the context of global climate change may have profound impacts on ecosystem productivity in arid and semiarid grasslands. However, we still have little knowledge about to what extent grassland productivity will respond to an individual precipitation event. In this study, we quantified the duration, the maximum, and the time-integrated amount of the response of daily gross primary productivity (GPP) to an individual precipitation event and their variations with different sizes of precipitation events in a typical temperate steppe in Inner Mongolia, China. Results showed that the duration of GPP-response (τ<sub>R</sub>) and the maximum absolute GPP-response (GPP<sub>max</sub>) increased linearly with the sizes of precipitation events (P<sub>es</sub>), driving a corresponding increase in time-integrated amount of the GPP-response (GPP<sub>total</sub>) because variations of GPPtotal were largely explained by τ<sub>R</sub> and GPP<sub>max</sub>. The relative contributions of these two parameters to GPP<sub>total</sub> were strongly P<sub>es</sub>-dependent. The GPP<sub>max</sub> contributed more to the variations of GPP<sub>total</sub> when P<sub>es</sub> was relatively small (<20 mm), whereas τ<sub>R</sub> was the main driver to the variations of GPP<sub>total</sub> when P<sub>es</sub> was relatively large. In addition, a threshold size of at least 5 mm of precipitation was required to induce a GPP-response for the temperate steppe in this study. Our work has important implications for the modeling community to obtain an advanced understanding of productivity-response of grassland ecosystems to altered precipitation regimes.展开更多
Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2...Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m （2500 stems·hm^-2） could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m^3·hm^-2 with mean annual increment （MAI） of 2.54×10^-2 m^3.treel.a^-1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m （1111 stems.hm^2） produced appreciably high timber volume of 315 m^3.hm^-2 and 165 m^3.hm^-2 with MAI of 1.77×10^-2 m^3.tree^-1·a^-1 and 0.92×10.2 m^3.tree^-1.a^-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m^3.hm^-2 with MAI of 1.47×10^-2 m^3.tree^-1.a^-1 followed by Samania saman （140 m^3.hm^-2）, Albizziaprocera （113 m^3·hm^-2） and Tectona grandis （79 m3.hm^-2） with MAI of 1.40, 1.13 and 0.78 × 10^-2 m^3 .tree^-1a^-1, respectively in 4 m × 4 m spacing （625 stems.hm^-2）. Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice （Oryza sativa - variety, AR-11）, groundnut （Arachis hypogaea - variety, JL-24） and sesamum （Sesamum indicum - variety, B-67） were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple （Ananas comosus - variety Queen）, turmeric （Curcuma longa -variety RCT -1） and cowpea （Vigna sinensis - variety Pusa Barsati） as forage crop were raised. The productivity of pineapple, turmeric and cowpea was comparatively high under Azadirachta indica. The productivity of horticultural and forage crops in association with trees such as G. arborea, A. procera, S. saman, T. grandis and M. champaca of high timber value could be harnessed as viable agroforestry systems. Changes in soil properties were also monitored. Amelioration of soil acidity, increase in soil organic carbon, and enhanced humification of soil humus, high nutrient availability, low soil erodibility and high surface soil （0-15 cm） moisture availability were noted in soils under MPTs.展开更多
Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richnes...Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richness and aboveground biomass,and simulated the competitive assemblages in a natural grassland ecosystem of China, aiming to test some assumptions and predictions about biodiversity–stability relationships. Our results show that aboveground productivity and temporal stability increased significantly with increasing species richness, and via a combination of overyielding, species asynchrony, and portfolio effects. Species interactions resulted in overyielding caused by trait-independent complementarity, and were not offset by a negative dominance effect and trait-dependent complementarity effect. Therefore, the mechanisms underlying the biodiversity effect shifted from the selection effect to the complementarity effect as diversity increased, and both effects were coexisted but the complementarity effect represent a mechanism that facilitates long term species coexistence in a natural grassland ecosystem of China.展开更多
Drought, as a recurring extreme climate event, affects the structure, function, and process of terrestrial ecosystems. Despite the increasing occurrence and intensity of the drought in the past decade in Southwestern ...Drought, as a recurring extreme climate event, affects the structure, function, and process of terrestrial ecosystems. Despite the increasing occurrence and intensity of the drought in the past decade in Southwestern China, the impacts of continuous drought events on vegetation in this region remain unclear. During 2001–2012, Southwestern China experienced the severe drought events from 2009 to 2011. Our aim is to characterize drought conditions in the Southwestern China and explore the impacts on the vegetation condition and terrestrial ecosystem productivity. The Standardized Precipitation Index(SPI) was used to characterize drought area and intensity and a light-use efficiency model was used to explore the effect of drought on the terrestrial ecosystem productivity with Moderate Resolution Imaging Spectrometer(MODIS) data. The SPI captured the major drought events in Southwestern China during the study period, indicated that the 12-year period of this study included both ‘normal' precipitation years and two severe drought events in 2009–2010 and 2011. Results showed that vegetation greenness(Normalized Difference Vegetation Index, NDVI and Enhanced Vegetation Index, EVI) both declined in 2009/2010 drought, but the 2011 drought resulted in less declines of vegetation greenness and productivity due to shorten drought duration and rising temperature. Meanwhile, it was about 5 months lapse between drought events and maximum declines in vegetation greenness for 2009/2010 drought events. In addition, forest, grassland and cropland revealed significant different ecosystem responses to drought. It indicated that grassland showed an early sensitivity to drought, while cropland was the most sensitive to water deficit and forest was more resilient to drought. This study suggests that it is necessary to detect the difference responses of ecosystem to drought in a regional area with satellite data and ecosystem model.展开更多
A Nutrient -Phytoplankton -Zooplankton（NPZD） type of ecological model is developed to reflect the biochemical process, and further coupled to a primitive equation ocean model, an irradiation model as well as a river...A Nutrient -Phytoplankton -Zooplankton（NPZD） type of ecological model is developed to reflect the biochemical process, and further coupled to a primitive equation ocean model, an irradiation model as well as a river discharge model to reproduce ecosystem dynamics in the Bohai Sea. Modeled primary production shows reasonable consistency with observations quantitatively and qualitatively; in addition, f-ratio is examined in detail in the first time, which is also within the range reported in other studies and reveals some meaningful insight into the relative contributions of ammonium and nitrate to the growth of phytoplankton in the Bohai Sea.展开更多
Fire is a global phenomenon and a major source of aerosols from the terrestrial biosphere to the atmosphere.Most previous studies quantified the effect of fire aerosols on climate and atmospheric circulation,or on the...Fire is a global phenomenon and a major source of aerosols from the terrestrial biosphere to the atmosphere.Most previous studies quantified the effect of fire aerosols on climate and atmospheric circulation,or on the regional and site-scale terrestrial ecosystem productivity.So far,only one work has quantified their global impacts on terrestrial ecosystem productivity based on offline simulations,which,however,did not consider the impacts of aerosol–cloud interactions and aerosol–climate feedbacks.This study quantitatively assesses the influence of fire aerosols on the global annual gross primary productivity(GPP)of terrestrial ecosystems using simulations with the fully coupled global Earth system model CESM1.2.Results show that fire aerosols generally decrease GPP in vegetated areas,with a global total of−1.6 Pg C yr^−1,mainly because fire aerosols cool and dry the land surface and weaken the direct photosynthetically active radiation(PAR).The exception to this is the Amazon region,which is mainly due to a fire-aerosol-induced wetter land surface and increased diffuse PAR.This study emphasizes the importance of the influence of fire aerosols on climate in quantifying global-scale fire aerosols’impacts on terrestrial ecosystem productivity.展开更多
We examined patterns of plant species richness on an elevation gradient and evaluated the effects of cli- matic variables including mean annual temperature and precipitation, area, the mid-domain effect and productivi...We examined patterns of plant species richness on an elevation gradient and evaluated the effects of cli- matic variables including mean annual temperature and precipitation, area, the mid-domain effect and productivity on species richness along two transects on Mt. Seorak, South Korea. A total of 235 plant species of 72 families and 161 genera were recorded from 130 plots along the two transects. Two different patterns, monotonic decline and a unimodal shape, were observed for woody plants with the change in elevation along the two transects, whereas multimodal patterns were observed for all plant species considered together and for herbaceous plants. Area and productivity showed significant relationships with total plant richness. Climatic variables were better predictors than other variables for variation by elevation in woody plant richness, whereas productivity was a more important variable for herbaceous plant richness. Although area was an important variable for predicting species richness pat- terns, the effects differed by transect and plant group. No empirical evidence was linked to the mid-domain effect.Different elevational patterns may characterize different groups in the same taxon and there might be fundamental differences in the mechanisms underlying these richness patterns.展开更多
The main characteristics of energy environment, energy products, primary productivity and basic process ofenergy flow for three-hardwood forest(Juglans mandshurica, Fraxinus mandshurica, and Phellodendron amurense) we...The main characteristics of energy environment, energy products, primary productivity and basic process ofenergy flow for three-hardwood forest(Juglans mandshurica, Fraxinus mandshurica, and Phellodendron amurense) werestudied. The research was mainly hased on the thcory and method of community energetics, dealing with fixed position,quantitative test and expcrimental analysis. The time-space dynamics of sun-radiation in three-hardwood forest were measured and the energy compartment model was set up. his rescarch work provided a scientitic basis for the exploitation, utilization and management of three-hardtwood forest.展开更多
The study analyzes the technical efficiency of vegetable farmers in root and tuber-based farming systems within selected sites of the humid tropics of Cameroon. Multistage sampling was used to collect primary data fro...The study analyzes the technical efficiency of vegetable farmers in root and tuber-based farming systems within selected sites of the humid tropics of Cameroon. Multistage sampling was used to collect primary data from a cross-section of vegetable farmers drawn from eight selected sites in Santa sub division, Northwest region of Cameroon. Stochastic frontier analysis was used to estimate the technical efficiency of vegetable farmer and to examine its determinants. The results showed that farmyard manure was the most productive factor input, followed by farm equipment and labor. The mean technical efficiency level was 67%, revealing production shortfalls and indicating possibilities of significantly increasing production with the current input Jevels. Female, as well as more educated farmers were found to be significantly more efficient than their counterparts. The results also showed that farmers become less technical efficient as farm sizes become larger. Our study findings suggest that smallholder farmers＇ access to manure, farm implements, and increased women participation in vegetable farming, will produce huge payoffs in vegetable production efficiency in Cameroon.展开更多
The pan-Arctic is confronted with air pollution transported from lower latitudes.Observations have shown that aerosols help increase plant photosynthesis through the diffuse radiation fertilization effects(DRFEs).Whil...The pan-Arctic is confronted with air pollution transported from lower latitudes.Observations have shown that aerosols help increase plant photosynthesis through the diffuse radiation fertilization effects(DRFEs).While such DRFEs have been explored at low to middle latitudes,the aerosol impacts on pan-Arctic ecosystems and the contributions by anthropogenic and natural emission sources remain less quantified.Here,we perform regional simulations at 0.2o×0.2ousing a well-validated vegetation model(Yale Interactive terrestrial Biosphere,YIBs)in combination with multi-source of observations to quantify the impacts of aerosol DRFEs on the net primary productivity(NPP)in the pan-Arctic during 2001-19.Results show that aerosol DRFEs increase pan-Arctic NPP by 2.19 Pg C(12.8%)yr^(-1)under clear-sky conditions,in which natural and anthropogenic sources contribute to 8.9% and 3.9%,respectively.Under all-sky conditions,such DRFEs are largely dampened by cloud to only 0.26 Pg C(1.24%)yr^(-1),with contributions of 0.65% by natural and 0.59% by anthropogenic species.Natural aerosols cause a positive NPP trend of 0.022% yr^(-1)following the increased fire activities in the pan-Arctic.In contrast,anthropogenic aerosols induce a negative trend of-0.01% yr^(-1)due to reduced emissions from the middle latitudes.Such trends in aerosol DRFEs show a turning point in the year of 2007 with more positive NPP trends by natural aerosols but negative NPP trends by anthropogenic aerosols thereafter.Though affected by modeling uncertainties,this study suggests a likely increasing impact of aerosols on terrestrial ecosystems in the pan-Arctic under global warming.展开更多
The net primary productivity of vegetation reflects the total amount of carbon fixed by plants through photosynthesis each year. The study of vegetation net primary productivity is one of the core contents of global c...The net primary productivity of vegetation reflects the total amount of carbon fixed by plants through photosynthesis each year. The study of vegetation net primary productivity is one of the core contents of global change and terrestrial ecosystems. This article reviews the current research status of net primary productivity of terrestrial vegetation, and comprehensively analyzes the advantages and disadvantages of three types of productivity estimation models, climate relative models, biogeochemical models, and light energy utilization models. The light energy utilization models have become the mainstream method for estimating vegetation net primary productivity because they can directly use remote sensing data. However, there are still many deficiencies in the estimation of vegetation net primary productivity, which need to be further improved and tested.展开更多
A model of a potentially effective type energy-resource-saving of optimization of agro-technologies, based on the principle subordination of synergetics, was established. There was developed computer system energy-res...A model of a potentially effective type energy-resource-saving of optimization of agro-technologies, based on the principle subordination of synergetics, was established. There was developed computer system energy-resource-saving optimization of agricultural technologies. The main feature of crop production is provided by the plants which themselves are self-organizing organisms. This allows us to adopt the principle of subordination of synergetics as the basis of the model. The value of free energy at the input into plants, estimated by the process of photosynthesis, is equal to the value of “radiation exergy for plant growth”. Assessment of the use of radiation energy is carried out based on the energy-converting characteristics of plants, which were obtained in climate chambers under controlled conditions. We used the model based on the principle of subordination of synergetics to develop common quantitative mutually agreed definitions of the main agroecological variables: Agroclimatic and Meliorative potentials of lands, their fertility, and potential (maximum) productivity of plants under different environment conditions.展开更多
The productivity of traditional agrisilviculture system(agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004?2...The productivity of traditional agrisilviculture system(agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004?2006.A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system.The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system.The results show that the annual productivity of all tree species was 3 775 kg·ha-1·a-1 in northern aspect(site-N) and 3 101 kg·ha-1·a-1 in southern aspect(site-S).G.optiva had the highest productivity in both site-N and site-S among the tree species, followed by M.azedarach, Quercus leucotrichophora and C.australis.The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area.The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system.The sole agricultural crop productivity(without trees) in northern aspect was also higher than that in southern aspect.An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect.The overall productivity in traditional agrisilviculture system(crop + tree) was 24%(in northern aspect) and 21%(in southern aspect) higher than that in sole cropping system.展开更多
基金National Key R&D Program of China,No.2022YFF1302401National Natural Science Foundation of China,No.42271007。
文摘Ecosystems along the eastern margin of the Qinghai-Tibet Plateau(EQTP)are highly fragile and extremely sensitive to climate change and human disturbances.To quantitatively assess climate-induced ecosystem responses,this study proposes a Climate-Induced Productivity Index(CIPI)based on the Super Slack-Based Measure(Super-SBM)model using remote sensing data from 2001 to 2020.The results reveal persistently low CIPI values(0.47-0.53)across major ecosystem types,indicating widespread vulnerability to climatic variability.Among these ecosystems,forests exhibit the highest CIPI(0.55),followed by shrublands(0.54),croplands(0.53),grasslands(0.51),and barelands(0.43).The Theil index analysis further demonstrates significant intra-group disparities,suggesting that extreme climatic events amplify CIPI heterogeneity.Moreover,the dominant environmental drivers differ among ecosystem types:the Palmer Drought Severity Index(PDSI)primarily constrains grassland productivity,solar radiation(SRAD)strongly influences shrub and cropland systems,whereas subsurface factors exert greater control in forested regions.This study provides a quantitative framework for evaluating climate-ecosystem interactions and offers a scientific basis for long-term ecological monitoring and security planning across the EQTP.
基金"Strategic Priority Research Program of China"of the Chinese Academy of Sciences,No.XDA05090307National Key Technology R&D Program of the 12th Five-Year Plan,No.2012BAC19B10Open Project of Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration,No.SHUES2012A04
文摘Net primary productivity （NPP） is the structure and function of the ecosystem. NPP can most important index that represents the be simulated by dynamic global vegetation models （DGVM）, which are designed to represent vegetation dynamics relative to environ- mental change. This study simulated the NPP of China＇s ecosystems based on the DGVM Integrated Biosphere Simulator （IBIS） with data on climate, soil, and topography. The appli- cability of IBIS in the NPP simulation of China＇s terrestrial ecosystems was verified first. Comparison with other relevant studies indicates that the range and mean value of simula- tions are generally within the limits of observations; the overall pattern and total annual NPP are close to the simulations conducted with other models. The simulations are also close to the NPP estimations based on remote sensing. Validation proved that IBIS can be utilized in the large-scale simulation of NPP in China＇s natural ecosystem. We then simulated NPP with climate change data from 1961 to 2005, when warming was particularly striking. The following are the results of the simulation. （1） Total NPP varied from 3.61 GtC/yr to 4.24 GtC/yr in the past 45 years and exhibited minimal significant linear increase or decrease. （2） Regional differences in the increase or decrease in NPP were large but exhibited an insignificant overall linear trend. NPP declined in most parts of eastern and central China, especially in the Loess Plateau. （3） Similar to the fluctuation law of annual NPP, seasonal NPP also displayed an insignificant increase or decrease; the trend line was within the general level. （4） The re- gional differences in seasonal NPP changes were large. NPP declined in spring, summer, and autumn in the Loess Plateau but increased in most parts of the Tibetan Plateau.
基金National Key Research and Development Program of China,No.2016YFC0500205National Basic Research Program of China(973 Program),No.2015CB954103,No.2015CB954101
文摘The Three-River Headwater Region（TRHR）, known as the ＂Water Tower of China＂, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream regions in China and a number of Southeast Asian countries. The TRHR is a high-elevation, cold environment with a unique, but typical alpine vegetation system. Net primary productivity（NPP） is a key vegetation parameter and ecological indicator that can reflect both natural environmental changes and carbon budget levels. Given the unique geographical environment and strategic location of the TRHR, many scholars have estimated NPP of the TRHR by using different methods; however, these estimates vary greatly for a number of reasons. To date, there is no paper that has reviewed and assessed NPP estimation studies conducted in the TRHR. Therefore, in this paper, we（1） summarized the related methods and results of NPP estimation in the TRHR in a systematic review of previous research;（2） discussed the suitability of existing methods for estimating NPP in the TRHR and highlighted the most significant challenges; and（3） assessed the estimated NPP results. Finally, developmental directions of NPP estimation in the TRHR were prospected.
文摘In this paper, the biomass productivity and nutrient cycling in an agroforestry system of coconut (Cocus nucifera) interplanted with pineapple (Ananas comosus) had been studied. The result showed that the biomass productivity of this ecosystem was 47 460 kg...hm2...a?1, which was 4.3 times as much as that of pure coconut plantation. In the biological cycling of N, P. K elements, the total annual retention was 559.470 kg...hm?2, the annual return was 410.745 kg...hm?2, the annual uptake was 970.475 kg...hm?2, respectively. The average circulation rate in three nutrient elements (N, P, K) was 42.32%, which was 27.53% more than that in pure coconut stands. Coconut interplanted with pineapple was proved to be one of optimum cultural patterns, which had the higher biomass productivity, and better usage efficiency of environment resources in tropical areas.
基金the National Basic Research Program of China(2010CB950702)the National High-Technology Reaearch and Development Program of China(2007AA10Z231)the Asia-Pacific Network for Global Change Research Project(ARCP201106CMY-Li)
文摘This research classified vegetation types and evaluated net primary productivity （NPP） of southern China＇s grasslands based on the improved comprehensive and sequential classification system （CSCS）, and proposed 5 thermal grades and 6 humidity grades. Four classes of grasslands vegetation were recognized by improved CSCS, namely, tundra grassland class, typical grassland class, mixed grassland class and alpine grassland class. At the type level, 14 types of vegetations （9 grasslands and 5 forests） were classified. The NPP had a trend to decrease from east to west and south to north, and the annual mean NPP was estimated to be 656.3 g C m-2 yr-1. The NPP value of alpine grassland class was relatively high, generally more than 1200 g C m2 yr-1. The NPP value of mixed grassland class was in a range from 1 000 to 1200 g C m-2 yr-1. Tundra grassland class was located in southeastern Tibet with high elevation, and its NPP value was the lowest （〈600 g C m＇2yrl）. The typical grassland class distributed in most of the area, and its NPP value was generally from 600 to 1000 g C m-2 yr-1. The total NPP value in the study area was 68.46 Tg C. The NPP value of typical grassland class was the highest （48.44 Tg C）, and mixed grassland class was the second （16.54 Tg C）, followed by alpine grassland class （3.22 Tg C）, with tundra grassland class being the lowest （0.25 Tg C）. For all the grasslands types, the total NPP of forest meadow was the highest （34.81 Tg C）, followed by sparse forest brush （16.54 Tg C）, and montane meadow was the lowest （0.01 Tg C）.
基金supported by the National Key Research and Development Program of China (No. 2016YFC0502104,No. 2017YFC0503901)the National Natural Science Foundation of China (No. 31870430)。
文摘Background: Global warming has brought many negative impacts on terrestrial ecosystems, which makes the vulnerability of ecosystems one of the hot issues in current ecological research. Here, we proposed an assessment method based on the IPCC definition of vulnerability. The exposure to future climate was characterized using a moisture index(MI) that integrates the effects of temperature and precipitation. Vegetation stability, defined as the proportion of intact natural vegetation that remains unchanged under changing climate, was used together with vegetation productivity trend to represent the sensitivity and adaptability of ecosystems. Using this method, we evaluated the vulnerability of ecosystems in Southwestern China under two future representative concentration pathways(RCP 4.5 and RCP 8.5) with MC2 dynamic global vegetation model.Results:(1) Future(2017–2100) climate change will leave 7.4%(under RCP 4.5) and 57.4% of(under RCP 8.5) of areas under high or very high vulnerable climate exposure;(2) in terms of vegetation stability, nearly 45% of the study area will show high or very high vulnerability under both RCPs. Beside the impacts of human disturbance on natural vegetation coverage(vegetation intactness), climate change will cause obvious latitudinal movements in vegetation distribution, but the direction of movements under two RCPs were opposite due to the difference in water availability;(3) vegetation productivity in most areas will generally increase and remain a low vulnerability in the future;(4) an assessment based on the above three aspects together indicated that future climate change will generally have an adverse impact on all ecosystems in Southwestern China, with non-vulnerable areas account for only about 3% of the study area under both RCPs. However, compared with RCP 4.5, the areas with mid-and highvulnerability under RCP 8.5 scenario increased by 13% and 16%, respectively.Conclusion: Analyses of future climate exposure and projected vegetation distribution indicate widespread vulnerability of ecosystems in Southwestern China, while vegetation productivity in most areas will show an increasing trend to the end of twenty-first century. Based on new climate indicators and improved vulnerability assessment rules, our method provides an extra option for a more comprehensive evaluation of ecosystem vulnerability, and should be further tested at larger spatial scales in order to provide references for regional, or even global, ecosystem conservation works.
基金National Project for Basic Research, No.2002CB412507 National key project of fundamental research, No.G1999043500 National Natural Science Foundation of China, No.90202002
文摘Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photosynthetic vegetation （NPV）, bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity （NPP）. We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement （R2= 0.85, P〈0.001） between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to arid ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.
基金jointly supported by the National Natural Science Foundation of China(31400425,31570437,41301043,31420103917)the National Key Project of Scientific and Technical Supporting Program(2013BAC03B03)+1 种基金the Funding for Talented Young Scientists of IGSNRR(2013RC203)the Social Foundation of Beijing Academy of Social Sciences(154005)
文摘Changes in the sizes of precipitation events in the context of global climate change may have profound impacts on ecosystem productivity in arid and semiarid grasslands. However, we still have little knowledge about to what extent grassland productivity will respond to an individual precipitation event. In this study, we quantified the duration, the maximum, and the time-integrated amount of the response of daily gross primary productivity (GPP) to an individual precipitation event and their variations with different sizes of precipitation events in a typical temperate steppe in Inner Mongolia, China. Results showed that the duration of GPP-response (τ<sub>R</sub>) and the maximum absolute GPP-response (GPP<sub>max</sub>) increased linearly with the sizes of precipitation events (P<sub>es</sub>), driving a corresponding increase in time-integrated amount of the GPP-response (GPP<sub>total</sub>) because variations of GPPtotal were largely explained by τ<sub>R</sub> and GPP<sub>max</sub>. The relative contributions of these two parameters to GPP<sub>total</sub> were strongly P<sub>es</sub>-dependent. The GPP<sub>max</sub> contributed more to the variations of GPP<sub>total</sub> when P<sub>es</sub> was relatively small (<20 mm), whereas τ<sub>R</sub> was the main driver to the variations of GPP<sub>total</sub> when P<sub>es</sub> was relatively large. In addition, a threshold size of at least 5 mm of precipitation was required to induce a GPP-response for the temperate steppe in this study. Our work has important implications for the modeling community to obtain an advanced understanding of productivity-response of grassland ecosystems to altered precipitation regimes.
文摘Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m （2500 stems·hm^-2） could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m^3·hm^-2 with mean annual increment （MAI） of 2.54×10^-2 m^3.treel.a^-1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m （1111 stems.hm^2） produced appreciably high timber volume of 315 m^3.hm^-2 and 165 m^3.hm^-2 with MAI of 1.77×10^-2 m^3.tree^-1·a^-1 and 0.92×10.2 m^3.tree^-1.a^-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m^3.hm^-2 with MAI of 1.47×10^-2 m^3.tree^-1.a^-1 followed by Samania saman （140 m^3.hm^-2）, Albizziaprocera （113 m^3·hm^-2） and Tectona grandis （79 m3.hm^-2） with MAI of 1.40, 1.13 and 0.78 × 10^-2 m^3 .tree^-1a^-1, respectively in 4 m × 4 m spacing （625 stems.hm^-2）. Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice （Oryza sativa - variety, AR-11）, groundnut （Arachis hypogaea - variety, JL-24） and sesamum （Sesamum indicum - variety, B-67） were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple （Ananas comosus - variety Queen）, turmeric （Curcuma longa -variety RCT -1） and cowpea （Vigna sinensis - variety Pusa Barsati） as forage crop were raised. The productivity of pineapple, turmeric and cowpea was comparatively high under Azadirachta indica. The productivity of horticultural and forage crops in association with trees such as G. arborea, A. procera, S. saman, T. grandis and M. champaca of high timber value could be harnessed as viable agroforestry systems. Changes in soil properties were also monitored. Amelioration of soil acidity, increase in soil organic carbon, and enhanced humification of soil humus, high nutrient availability, low soil erodibility and high surface soil （0-15 cm） moisture availability were noted in soils under MPTs.
基金supported by the National Basic Research Program of China (No. 2013CB429903)the National Natural Science Foundation of China (Nos. 41471024 41771038)
文摘Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richness and aboveground biomass,and simulated the competitive assemblages in a natural grassland ecosystem of China, aiming to test some assumptions and predictions about biodiversity–stability relationships. Our results show that aboveground productivity and temporal stability increased significantly with increasing species richness, and via a combination of overyielding, species asynchrony, and portfolio effects. Species interactions resulted in overyielding caused by trait-independent complementarity, and were not offset by a negative dominance effect and trait-dependent complementarity effect. Therefore, the mechanisms underlying the biodiversity effect shifted from the selection effect to the complementarity effect as diversity increased, and both effects were coexisted but the complementarity effect represent a mechanism that facilitates long term species coexistence in a natural grassland ecosystem of China.
基金Under the auspices of National Key Research and Development Program of China(No.2016YFB0501501,2017YFB0504000)National Natural Science Foundation of China(No.41401110,31400393)
文摘Drought, as a recurring extreme climate event, affects the structure, function, and process of terrestrial ecosystems. Despite the increasing occurrence and intensity of the drought in the past decade in Southwestern China, the impacts of continuous drought events on vegetation in this region remain unclear. During 2001–2012, Southwestern China experienced the severe drought events from 2009 to 2011. Our aim is to characterize drought conditions in the Southwestern China and explore the impacts on the vegetation condition and terrestrial ecosystem productivity. The Standardized Precipitation Index(SPI) was used to characterize drought area and intensity and a light-use efficiency model was used to explore the effect of drought on the terrestrial ecosystem productivity with Moderate Resolution Imaging Spectrometer(MODIS) data. The SPI captured the major drought events in Southwestern China during the study period, indicated that the 12-year period of this study included both ‘normal' precipitation years and two severe drought events in 2009–2010 and 2011. Results showed that vegetation greenness(Normalized Difference Vegetation Index, NDVI and Enhanced Vegetation Index, EVI) both declined in 2009/2010 drought, but the 2011 drought resulted in less declines of vegetation greenness and productivity due to shorten drought duration and rising temperature. Meanwhile, it was about 5 months lapse between drought events and maximum declines in vegetation greenness for 2009/2010 drought events. In addition, forest, grassland and cropland revealed significant different ecosystem responses to drought. It indicated that grassland showed an early sensitivity to drought, while cropland was the most sensitive to water deficit and forest was more resilient to drought. This study suggests that it is necessary to detect the difference responses of ecosystem to drought in a regional area with satellite data and ecosystem model.
基金by the National Natural 0ur studies were supported Science Foundation of China under contract No.50339040the National Basic Research Program of China under contract No.2005CB422301.
文摘A Nutrient -Phytoplankton -Zooplankton（NPZD） type of ecological model is developed to reflect the biochemical process, and further coupled to a primitive equation ocean model, an irradiation model as well as a river discharge model to reproduce ecosystem dynamics in the Bohai Sea. Modeled primary production shows reasonable consistency with observations quantitatively and qualitatively; in addition, f-ratio is examined in detail in the first time, which is also within the range reported in other studies and reveals some meaningful insight into the relative contributions of ammonium and nitrate to the growth of phytoplankton in the Bohai Sea.
基金This study was co-supported by the National Key R&D Program of China[grant number 2017YFA0604302]the National Natural Science Foundation of China[grant numbers 41475099 and 41875137]the Chinese Academy of Sciences Key Research Program of Frontier Sciences[grant number QYZDY-SSW-DQC002].
文摘Fire is a global phenomenon and a major source of aerosols from the terrestrial biosphere to the atmosphere.Most previous studies quantified the effect of fire aerosols on climate and atmospheric circulation,or on the regional and site-scale terrestrial ecosystem productivity.So far,only one work has quantified their global impacts on terrestrial ecosystem productivity based on offline simulations,which,however,did not consider the impacts of aerosol–cloud interactions and aerosol–climate feedbacks.This study quantitatively assesses the influence of fire aerosols on the global annual gross primary productivity(GPP)of terrestrial ecosystems using simulations with the fully coupled global Earth system model CESM1.2.Results show that fire aerosols generally decrease GPP in vegetated areas,with a global total of−1.6 Pg C yr^−1,mainly because fire aerosols cool and dry the land surface and weaken the direct photosynthetically active radiation(PAR).The exception to this is the Amazon region,which is mainly due to a fire-aerosol-induced wetter land surface and increased diffuse PAR.This study emphasizes the importance of the influence of fire aerosols on climate in quantifying global-scale fire aerosols’impacts on terrestrial ecosystem productivity.
基金a part of the ‘Korea Big Tree Project’ funded by the Korea Green Promotion Agency,Korea Forest Service
文摘We examined patterns of plant species richness on an elevation gradient and evaluated the effects of cli- matic variables including mean annual temperature and precipitation, area, the mid-domain effect and productivity on species richness along two transects on Mt. Seorak, South Korea. A total of 235 plant species of 72 families and 161 genera were recorded from 130 plots along the two transects. Two different patterns, monotonic decline and a unimodal shape, were observed for woody plants with the change in elevation along the two transects, whereas multimodal patterns were observed for all plant species considered together and for herbaceous plants. Area and productivity showed significant relationships with total plant richness. Climatic variables were better predictors than other variables for variation by elevation in woody plant richness, whereas productivity was a more important variable for herbaceous plant richness. Although area was an important variable for predicting species richness pat- terns, the effects differed by transect and plant group. No empirical evidence was linked to the mid-domain effect.Different elevational patterns may characterize different groups in the same taxon and there might be fundamental differences in the mechanisms underlying these richness patterns.
文摘The main characteristics of energy environment, energy products, primary productivity and basic process ofenergy flow for three-hardwood forest(Juglans mandshurica, Fraxinus mandshurica, and Phellodendron amurense) werestudied. The research was mainly hased on the thcory and method of community energetics, dealing with fixed position,quantitative test and expcrimental analysis. The time-space dynamics of sun-radiation in three-hardwood forest were measured and the energy compartment model was set up. his rescarch work provided a scientitic basis for the exploitation, utilization and management of three-hardtwood forest.
基金Humidtropics(through the World Vegetable Center for leading this study)supported this research through their contributions to the Consultative Group on International Agricultural Research(CGIAR)fund
文摘The study analyzes the technical efficiency of vegetable farmers in root and tuber-based farming systems within selected sites of the humid tropics of Cameroon. Multistage sampling was used to collect primary data from a cross-section of vegetable farmers drawn from eight selected sites in Santa sub division, Northwest region of Cameroon. Stochastic frontier analysis was used to estimate the technical efficiency of vegetable farmer and to examine its determinants. The results showed that farmyard manure was the most productive factor input, followed by farm equipment and labor. The mean technical efficiency level was 67%, revealing production shortfalls and indicating possibilities of significantly increasing production with the current input Jevels. Female, as well as more educated farmers were found to be significantly more efficient than their counterparts. The results also showed that farmers become less technical efficient as farm sizes become larger. Our study findings suggest that smallholder farmers＇ access to manure, farm implements, and increased women participation in vegetable farming, will produce huge payoffs in vegetable production efficiency in Cameroon.
基金jointly supported by the National Key Research and Development Program of China(Grant No.2022YFE0106500)Jiangsu Science Fund for Distinguished Young Scholars(Grant No.BK20200040)。
文摘The pan-Arctic is confronted with air pollution transported from lower latitudes.Observations have shown that aerosols help increase plant photosynthesis through the diffuse radiation fertilization effects(DRFEs).While such DRFEs have been explored at low to middle latitudes,the aerosol impacts on pan-Arctic ecosystems and the contributions by anthropogenic and natural emission sources remain less quantified.Here,we perform regional simulations at 0.2o×0.2ousing a well-validated vegetation model(Yale Interactive terrestrial Biosphere,YIBs)in combination with multi-source of observations to quantify the impacts of aerosol DRFEs on the net primary productivity(NPP)in the pan-Arctic during 2001-19.Results show that aerosol DRFEs increase pan-Arctic NPP by 2.19 Pg C(12.8%)yr^(-1)under clear-sky conditions,in which natural and anthropogenic sources contribute to 8.9% and 3.9%,respectively.Under all-sky conditions,such DRFEs are largely dampened by cloud to only 0.26 Pg C(1.24%)yr^(-1),with contributions of 0.65% by natural and 0.59% by anthropogenic species.Natural aerosols cause a positive NPP trend of 0.022% yr^(-1)following the increased fire activities in the pan-Arctic.In contrast,anthropogenic aerosols induce a negative trend of-0.01% yr^(-1)due to reduced emissions from the middle latitudes.Such trends in aerosol DRFEs show a turning point in the year of 2007 with more positive NPP trends by natural aerosols but negative NPP trends by anthropogenic aerosols thereafter.Though affected by modeling uncertainties,this study suggests a likely increasing impact of aerosols on terrestrial ecosystems in the pan-Arctic under global warming.
文摘The net primary productivity of vegetation reflects the total amount of carbon fixed by plants through photosynthesis each year. The study of vegetation net primary productivity is one of the core contents of global change and terrestrial ecosystems. This article reviews the current research status of net primary productivity of terrestrial vegetation, and comprehensively analyzes the advantages and disadvantages of three types of productivity estimation models, climate relative models, biogeochemical models, and light energy utilization models. The light energy utilization models have become the mainstream method for estimating vegetation net primary productivity because they can directly use remote sensing data. However, there are still many deficiencies in the estimation of vegetation net primary productivity, which need to be further improved and tested.
文摘A model of a potentially effective type energy-resource-saving of optimization of agro-technologies, based on the principle subordination of synergetics, was established. There was developed computer system energy-resource-saving optimization of agricultural technologies. The main feature of crop production is provided by the plants which themselves are self-organizing organisms. This allows us to adopt the principle of subordination of synergetics as the basis of the model. The value of free energy at the input into plants, estimated by the process of photosynthesis, is equal to the value of “radiation exergy for plant growth”. Assessment of the use of radiation energy is carried out based on the energy-converting characteristics of plants, which were obtained in climate chambers under controlled conditions. We used the model based on the principle of subordination of synergetics to develop common quantitative mutually agreed definitions of the main agroecological variables: Agroclimatic and Meliorative potentials of lands, their fertility, and potential (maximum) productivity of plants under different environment conditions.
文摘The productivity of traditional agrisilviculture system(agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004?2006.A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system.The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system.The results show that the annual productivity of all tree species was 3 775 kg·ha-1·a-1 in northern aspect(site-N) and 3 101 kg·ha-1·a-1 in southern aspect(site-S).G.optiva had the highest productivity in both site-N and site-S among the tree species, followed by M.azedarach, Quercus leucotrichophora and C.australis.The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area.The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system.The sole agricultural crop productivity(without trees) in northern aspect was also higher than that in southern aspect.An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect.The overall productivity in traditional agrisilviculture system(crop + tree) was 24%(in northern aspect) and 21%(in southern aspect) higher than that in sole cropping system.
