Spatio-temporal evolution and topographic gradient effect of land use and ecosystem service value in the Lhasa River Basin

The Lhasa River Basin forms an essential human settlement area in the southern part of the Qinghai-Tibet Plateau.This study employed ecosystem service value(ESV)evaluation model,terrain gradient grading,and Geodetector to analyze land use and ESV in the Lhasa River Basin from 1985 to 2020.The findings reveal that:(1)From 1985 to 2020,grassland was the dominant land use.There was a trend of grassland reduction and the expansion of other land types.(2)ESV has increased over the research period(with a total increase of 0.84%),with higher values in the southeast and lower values in the northwest.Grassland contributed the most to ESV,and climate regulation and hydrological regulation were the ecosystem services that contribute the most to ESV.(3)Natural factors like NDVI and altitude,as well as economic factors like population density and distance from roads,influenced the spatial differentiation of ESV,the explanatory power of NDVI reached up to 0.47.The interaction between factors had a greater impact than individual factors.These research results can provide theoretical support for national spatial planning and ecological environment protection in the Lhasa River Basin and other similar areas.

Elevational patterns of warming effects on plant community and topsoil properties: focus on subalpine meadows ecosystem

Climate warming profoundly affects plant biodiversity, community productivity, and soil properties in alpine and subalpine grassland ecosystems. However, these effects are poorly understood across elevational gradients in subalpine meadow ecosystems. To reveal the elevational patterns of warming effects on plant biodiversity, community structure, productivity, and soil properties, we conducted a warming experiment using open-top chambers from August 2019 to August 2022 at high(2764 m a. s. l.), medium(2631 m a. s. l.), and low(2544 m a. s. l.) elevational gradients on a subalpine meadow slope of Mount Wutai, Northern China. Our results showed that three years of warming significantly increased topsoil temperature but significantly decreased topsoil moisture at all elevations(P<0.05), and the percentage of increasing temperature and decreasing moisture both gradually raised with elevation lifting. Warming-induced decreasing proportions of soil organic carbon(SOC, by 19.24%), and total nitrogen(TN, by 24.56%) were the greatest at high elevational gradients. Experimental warming did not affect topsoil C: N, p H, NO_(3)^(-)-N, or NH_(4)^(+)-N at the three elevational gradients. Warming significantly increased species richness(P<0.01) and Shannon-Weiner index(P<0.05) at low elevational gradients but significantly decreased belowground biomass(P<0.05) at a depth of 0–10 cm at three elevational gradients. Warming caused significant increases in the aboveground biomass in the three elevational plots. Warming significantly increased the aboveground biomass of graminoids in medium(by 92.47%) and low(by 98.25%) elevational gradients, that of sedges in high(by 72.44%) and medium(by 57.16%) elevational plots, and that of forbs in high(by 75.88%), medium(by 34.38%), and low(by 74.95%) elevational plots. Species richness had significant linear correlations with SOC, TN, and C: N(P<0.05), but significant nonlinear responses to soil temperature and soil moisture in the warmed treatment(P<0.05). The warmed aboveground biomass had a significant nonlinear response to soil temperature and significant linear responses to soil moisture(P<0.05). This study provided evidence that altitude is a factor in sensitivity to climate warming, and these different parameters(e.g., plant species richness, Shannon-Weiner index, soil temperature, soil moisture, SOC, and TN) can be used to measure this sensitivity.

Spatiotemporal evolution of ecosystem service value and topographic gradient effect in the Da-Xiao Liangshan Mountains in Sichuan Province,China

The Da-Xiao Liangshan mountains are critical ecological function areas and essential ecological barriers in the upper reaches of the Yangtze River in China.This study selected a total of six periods of land use land cover(LULC)data from 1995 to 2020,to estimate the ecosystem service value(ESV)and analyzed its spatiotemporal evolution and topographic gradient divergence.The results showed that:(1)The ESV increased by 1.1 billion yuan,with an increase rate of 1.47%from 1995 to 2020.Two time periods,2005–2010 and 2015–2020,showed more significant increases than other periods.(2)The elevation and slope of mountainous areas determine the type of land use and further influence the spatial pattern of ESV.(3)Although woodland and grassland are the main land use types of the study area(more than 90%),the hydrological regulation function of the water area partially compensated for the impact of the encroachment of the built-up area on the ESV of grassland.(4)The spatial distribution of ESVs showed an inverted V-shaped characteristic as the topographic gradient increased,with the dominant position being the 5th topographic gradient zone.Finally,this study provided relevant recommendations for ecosystem protection and optimization.The findings of this study clarified the influence of topographical factors on the spatial differentiation of ESV and provided novel insights into ecosystem protection.

Methane and Nitrous Oxide Emissions from Rice-Duck and Rice-Fish Complex Ecosystems and the Evaluation of Their Economic Significance

Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD and RF ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, we assessed the greenhouse effect of CH4 and N2O and their economic value. Results showed that the peaks of CH4 emission fluxes from RD and RF appeared at full tillering stage and at heading stage, and the average emission fluxes were significantly （P〈 0.05） lower than that from CK. N2O fluxes remained low when the field is flooded and high after draining the water. Compared with CK, the total amount of N2O emissions was significantly （P〈0.05） higher and slightly lower than those from RD and RF, respectively. In 2006 and 2007, the total greenhouse effect of CH4 and N20 from RD and RF were 4 728.3 and 4 611 kg CO2 ha^-1, 4 545 and 4 754.3 kg CO2 ha^-1, respectively. The costs of greenhouse effect were 970.89 and 946.81 RMB yuan ha^-1, and 933.25 and 976.23 RMB yuan ha^-1, respectively, which were significant lower than those from CK （5 997.6 and 5 391.5 RMB yuan ha^-1）. Except for the environment cost of CH4 and N2O, the economic benefits from RD and RF were 2 210.64 and 4 881.92 RMB yuan ha^-1; 3 798.37 and 5 310.64 RMB yuan ha^-1, respectively, higher than those from CK. Therefore, RD and RF complex ecological planting and breeding models can effectively decrease and control CH4 and N2O emissions, and they are two of the effective strategies to reduce greenhouse gases from rice paddy fields and contribute in alleviating global warming. Thus, their adoption is important to the environment together with their economy benefits.

Trend in seasonal amplitude of northern net ecosystem production:Simulated results from IAP DGVM in CAS-ESM2

北方陆地净生态系统生产力(NEP)具有明显的季节变化特征,这是大气CO_(2)季节变化的关键驱动.研究这些碳循环过程并理解潜在的驱动因素是气候研究的一个关键问题.本文利用第二代中国科学院地球系统模式(CAS-ESM2)中的全球植被动态模型(IAPDGVM),研究了1990-2014年北方NEP(40°-90°N)的季节振幅及其变化趋势.在初始化试验的基础上,本文开展了一个控制试验来评估模拟的北方NEP季节幅度的变化趋势,同时开展了三个敏感性试验来研究气候和大气CO_(2)的贡献.结果表明:1990-2014年,模拟的北方NEP季节振幅显著增加,趋势为9.69万吨碳/月/年,这主要是由于最大NEP增加所致.当分别排除CO_(2)施肥效应和气候效应时,上述增加趋势大大减弱.这些显著的减少表明大气CO_(2)和气候变化对北方NEP的季节性振幅有重要影响.尽管模式存在不确定性,但这些结果有利于进一步提升IAPDGVM对陆地碳循环的精确模拟,也为CAS-ESM研究碳-气候相互作用的应用提供了重要参考.

Land ecosystems classification and eco－economic evaluation in Wuding River Basin of Yulin Region

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The Environmental Effects of Tourism Architecture on Island Ecosystem in Cayo Guillermo, Cuba

The objective of this study is to determine the main adverse impacts that may be caused by tourism architecture upon island ecosystems consisting of small islands or islets and to propose an architectural and landscape design with a focus on the environmental sustainability of the same. A study of projects was undertaken in Cayo Guillermo, located to the north of Ciego de Avila in Cuba using methods of life-cycle assessment of buildings, matrix methods of the activities that caused severe environmental impact and statistical processing through multivariate analysis. Conclusions were reached on the need for designs that did not harm the ecosystems of islands with high ecological fragility. It has been determined that suitable construction intervention would decrease the negative impact and would allow the natural resources of these valuable ecosystems that are the basis for responsible sun and sand tourism to be preserved.

Response of ecosystem service value to land use/cover change in the northern slope economic belt of the Tianshan Mountains, Xinjiang, China

Land use/cover change(LUCC)is becoming more and more frequent and extensive as a result of human activities,and is expected to have a major impact on human welfare by altering ecosystem service value(ESV).In this study,we utilized remote sensing images and statistical data to explore the spatial-temporal changes of land use/cover types and ESV in the northern slope economic belt of the Tianshan Mountains in Xinjiang Uygur Autonomous Region,China from 1975 to 2018.During the study period,LUCC in the study region varied significantly.Except grassland and unused land,all the other land use/cover types(cultivated land,forestland,waterbody,and construction land)increased in areas.From 1975 to 2018,the spatial-temporal variations in ESV were also pronounced.The total ESV decreased by 4.00×10^(8) CNY,which was primarily due to the reductions in the areas of grassland and unused land.Waterbody had a much higher ESV than the other land use/cover types.Ultimately,understanding the impact of LUCC on ESV and the interactions among ESV of different land use/cover types will help improve existing land use policies and provide scientific basis for developing new conservation strategies for ecologically fragile areas.

Functional diversity dominates positive species mixture effects on ecosystem multifunctionality in subtropical plantations

Mixed-species plantations generally exhibit higher ecosystem multifunctionality than monospecific plantations.However,it is unclear how tree species functional composition influences species mixture effects on ecosystem multifunctionality.We selected 171 monospecific and mixed-species plantations from nine regions across subtropical China,and quantified 13 key ecosystem functional properties to investigate how species mixture effects on ecosystem multifunctionality are modulated by functional diversity and identity.We found that ecosystem multifunctionality was significantly higher(p<0.05)in mixed tree plantations than in monospecific plantations except the mixed-conifer species plantations.Across all regions,ecosystem multifunctionality was significantly higher(p<0.05)in mixed conifer-broadleaf plantations than in monospecific plantations of the corresponding species,but not different between mixed and monospecific coniferous plantations.The magnitude of species mixture effects on ecosystem multifunctionality varied greatly with tree species compositions.Taking Cunninghamia lanceolata Lamb.as an example,the effects varied from a range of 2.0%–9.6%when mixed with a conifer species to 36%–87%when mixed with a broadleaf species.The functional diversity was the dominate driver shaping ecosystem multifunctionality,while functional identity,as expressed by community-weighted mean of specific leaf area,also had a positive effect on ecosystem multifunctionality through the increased below-ground nitrogen and phosphorus stocks regulated by specific leaf area of the mixing tree species.Our study highlights the important role of functional diversity in shaping ecosystem multifunctionality across region-wide environmental conditions.Mixed conifer-broadleaf tree plantations with distinct functional traits benefit the enhancement of ecosystem multifunctionality,and the magnitude of species mixture effects is modulated by the functional identity of tree species composition;those relationships deserve a special consideration in multifunctional management context of subtropical plantations.

Effects of diesel oil on the polychaete Annelida in model benthic ecosystem

An experiment about the effect of diesel oil pollution on the model benthic ecosystem was conducted inthe land-based tank at the 3rd Institute of Oceanography, State Oceanic Administration, in Xiamen, added with No.0 diesel oil at concentrations of 5, 25, 125, 625 mg/dm3 in water of series sub-tanks for 16 h. The changes in polychaete community were studied in the period of two weeks with results that though all concentrations did not basically altered the population structure and composition, the total biomass decreased significantly and individualstended to be smaller in size. The average weight of individual decreased with the increase of diesel pollutant stress.

Socio-Economic Drivers of Degradation and Their Implication on Conservation of River Lumi Riparian Ecosystem in Kenya

Riparian forests ecosystems play significant role in biodiversity conservation and provision of ecosystem goods and services which support local livelihoods. However, riparian ecosystems are threatened by degradation attributed to anthropogenic activities. Understanding the interaction between anthropogenic activities and socio-economic factors, and their associated impact on riparian degradation is essential for designing appropriate management strategies for these ecosystems. This study assessed the socio-economic factors that drive degradation and their implication on conservation of River Lumi riparian ecosystem. Semi-structured questionnaires, Focus Group Discussion (FGDs) and key informant interviews were used to collect the data. The findings indicate that crop farming and livestock production were the main sources of livelihood practiced by 84% and 70% of the households respectively. Consequently, agricultural intensification resulting from increased demand for agricultural commodities (33%), over-grazing coupled with influx of livestock from private ranches and neighbouring pastoralist Maasai community (20%), and deforestation fuelled by population increase (17%) were the main drivers of degradation in River Lumi riparian ecosystem. The findings indicate that about 91% of the adjacent communities are dependent on River Lumi for their sustenance and their livelihoods will be affected by continued degradation of the riparian ecosystem;thus there is need for development of appropriate management strategies including sustainable livelihood systems to conserve River Lumi riparian ecosystem.

Economic Effects

The past two years have witnessed great fluctuations ininternational oil prices,and diplomatic efforts,both above andunder the table,by major powers around this issue.The currenttension in the war-threatened Iraq has added more uncertainties to thefuture world oil situation.Will the world oil supply and demand change?What impact would this exert on big powers’ oil strategy choices,geopolitics as well as world economy?What should China do in such asituation?To find the answers to these questions,at the invitation of theeditor of the Contemporary International Relations,seven experts fromChina Institute of Contemporary International Relations gathered to have adiscussion in early February this year.Naturally,they have differentviews over many issues.Still,we hope our readers would find theirdiscussion interesting.Following is the list of participants.

Effects of a mixture of Cu, Cd, Hg and Zn on marine plankton: Marine Ecosystem Enclosure Experiment

Five experiment ecosystems (MEEE) were employed in April, 1985 to test the effects of a mixture of Cu, Cd, Hg, Pb and Zn on a subtropical planktonic ecosystem in Xiamen Bay, Xiamen, China. The results indicated that the ppb-level of the mixture could suppress the planktonic production. Zooplankton in Xiamen were very sensitive to the metal contamination, especially the larvaceans.

The effects of sediment from an industrial outfall area on a marine planktonic ecosystem

-Sediment from Xiamen industrial area was added to marine ecosystem enclosures to test the effects on the planktonic communities in Xiamen Bay, China, in April, 1985. Sediments were added at two concentrations, 11.2 and 112 ppm dry wt. respectively. The species of phytoplankton did not change as compared with the control, but the number of diatoms markedly decreased in the sediment treated enclosures. A suppression of photosynthesis was presumed to be due to light attenuation by the added sediment. Microflagellates, zooplankton and bacteria were resistant to sediment increase in water column.

Change of ecosystem service value in Menglian county with large-area economic gardens

From the point of spatio-temporal changes of ecological system type,function and value,in Menglian county,land using/cover data was based on three Landsat TM images(respectively obtained in2000,2005,2010 and 2015) which were interpreted as basic information sources by using RS and GIS technology and then revising ecosystem service value per unit area in Menglian county.This paper has researched on the changes of ecosystem service value of economic garden for large area planting as well as evaluated ecosystem service value scientifically in Menglian county combined with the sensitivity analysis.The Results showed that:(1) In Menglian county,from 2000 to 2015,land use pattern manifested as the transformation from large areas of cultivated land,forest land and shrub to the economic landscape,the economic landscape is increased by 24458.31 hm^2,however,farm land,wood land and shrub are reduced by 24865.74 hm2 in total;(2) Changes of ecosystem service value is closely related to economic landscape development in Menglian county.The situation of ecosystem service value shows the changing trend from improvement to severity in 2000-2015.ESV is increased by 96.39 million yuan from 2000 to2005,whose annual growth rate is about 0.56%·a^(-1).But in the year of 2005 to 2015,ESV is reduced by120.23 million yuan and annual reduced rate is about 0.34%·a^(-1);(3) In Menglian county,the main ecological system is the woodland ecological system,the primary ecosystem service functions are biodiversity protection,gas regulation,soil formation and retention,climate regulation and water supply,the ecological benefit were decreased in 2000-2015;(4) From the aspect of space distribution,ecosystem service value in Menglian county is relatively high in the central area and relatively not high in the western and eastern area.ESV(yuan·hm`(-2)) was changed obvious,Gongxin town trended to decline,other towns increased first the then reduced.The temporal and spatial variation of ecosystem service value in Menglian county is affected by natural and human factors.The key to the development of economic landscape is rational land use according to the practical situation,which can create economic value and also keep its ecological value.

Economic Effects of China’s Import Expansion Strategy

Since 2018,China has enacted a string of policy initiatives to increase imports.To quantify this import expansion strategy’s economic effects,we created a large numerical general equilibrium model and quantitatively simulated the economic effects of the reductions of tariff and non-tariff barriers on China and other economies.Our simulation results show that overall,China’s import expansion strategy benefited both itself and others and contributed to employment,welfare,and trade growth in China and the rest of the world.In relative terms,however,China’s import expansion strategy benefited other countries more than it did itself and contributed more to the growth of the world economy.Additionally,the import expansion strategy may effectively promote China’s trade balance,and the trade equilibrium effect driven by the reduction of non-tariff barriers is more significant than that of tariff barriers.Furthermore,regarding the self-benefiting effects of import expansion,the effects of nontariff measures are significantly greater than those of tariff measures,and this result has policy implications for China’s import expansion strategy going forward.

The effects of nutrients and heavy metals on the plankton in marine enclosed ecosystem

Applying marine enclosed ecosystem extensively to study the nutrient variation and its relation to biochemical process by marine ecologists and biogeologists in North America, Europe, Japan and Australia has been lasting for many years. Santschi (1982) reviewed the geochemical recirculation of nutrients systematically. Kremling et al. (1978) described the changes in nutrient in marine enclosed e-

Economic Effect of Rural Labor Transfer in China

With the continuous development of China’s economy and the acceleration of urbanization,more and more rural labor force is gradually transferred to cities and non-agricultural industries.Although the transfer of rural labor force can increase farmers’income,improve farmers’quality of life,and accelerate the process of urbanization and agricultural modernization in China,the unreasonable transfer of rural labor force has also brought some problems to China’s agricultural development.This paper mainly through the method of combining theoretical derivation and empirical analysis,using the data from 2010 to 2015 to analyze,study the influence of rural labor transfer on agricultural production,explore the relationship between rural labor transfer and agricultural development and provide relevant policy suggestions.

Effects of Mountain Rivers Cascade Hydropower Stations on Water Ecosystems

China is rich in hydropower resources,and mountain rivers have abundant water resources and huge development potential,which have a profound impact on the pattern of water resources allocation in China.As the main way of water resources and hydropower development,the construction of cascade hydropower stations,while meeting the requirements of water resources utilization for social development,has also brought adverse effects on river ecosystems.Therefore,the impact of the construction of cascade hydropower stations on mountainous river ecosystems,where the minimum ecological flow of rivers must be ensured and reviewed.In addition,this paper proposed the deficiencies and outlooks for cascade hydropower stations based on previous research results.

Effects of Elevated Solar UV-B Radiation from Ozone Depletion on Terrestrial Ecosystems

In the last three decades much researchhas been carried out to investigate the biologicaleffects of a thinning stratospheric ozone layeraccompanied by an enhanced level of solarultraviolet-B radiation at the Earth’s surface.Enhanced UV-B radiation affects ecosystems in manyways directly and indirectly. The responses can bebiochemical, physiological, morphological oranatomical, and the direction of the response can varybetween different species, communities andecosystems. In this paper we firstly introduce generalconcepts, and methods for measuring the ecologicaleffects of UV-B radiation. Secondly, we provide anoverview interpretation of the effects of enhancedUV-B on terrestrial ecosystems from recent studies.These studies include effects of UV-B on growth andreproduction, composition of communities,competitive balance, decomposition of litter, andinteractions with other factors etc. Finally, werecommend future research directions to identify theeffects of elevated UV-B radiation on ecosystems inChina.