Great spatial diversity exists in forest ecosystems in East Asia, thus it is necessary totake the difference among forest biomes into account in regional carbon cycle modelling. Thisstudy applied an Amax–N% relationship based model, the PnET-CN model, to eight flux sites tocomprehensively evaluating its performance and uncertainty. The biomes at these eight sites includedeciduous needle-leaved forest, deciduous broad-leaved forest, evergreen needle-leavedforest and evergreen broad-leaved forest. The climate ranges from cold temperate to tropical.The PnET-CN model was applied to these eight sites to model the monthly carbon flux variation.The overall PnET-CN model performance was comprehensively evaluated using three indicators:correlation coefficient (r), root mean square error (RMSE) and standard error (SD). Resultsshowed that: 1) at monthly scale, the PnET-CN model could model the gross ecosystemexchange (GEE) and the ecosystem respiration (RE) quite well (GEE: 0.85 ≤r≤ 0.98; RE:0.51 ≤|r|≤ 0.98) except in a tropical swamp forest (GEE:r= 0.16; RE:r=-0.21); 2) butthe applicability in different climate regimes was not the same; it had the best performance intemperate zone, then cold temperate zone, subtropical zone and last tropical zone; 3) the PnETCNmodel could model needle leaved forests better than broad-leaved forests; and 4) the PnETCNmodel underestimated GEE at low temperature and low radiation and vice versa; the samephenomena occurred to RE responding to temperature. Finally, this study analysed reasons forthe gaps between simulated and observed data and gave suggestions on improving the model:1) effects of soil moisture should be accounted for in estimating phenology and the process ofleaf senescence should be assigned different values depending on the climate zone; 2) the regulationof temperature and the optimal temperature for photosynthesis should be set differentlyin different ecosystems; 3) it is necessary to take the resilience and adaptation capacity of forestecosystems into account in response to disturbance such as drought and high temperature; 4)the PnET-CN model should improve its bucket model to simulate the seasonal dynamics of carbonfluxes in forest ecosystems with complex hydrological conditions. Our results and conclusionsare helpful for understanding the spatial heterogeneity in forest ecosystem carbon cycle in East Asian region and for filling gaps between the modelling and observation.
Based on the observation data from 109 meteorology stations during 1961-2010 andphenological data of single cropping rice from 16 agrometeorological stations during 1981-2010 well spread over the rice growing regions of Sichuan Province, the effective precipitationand water requirement of single cropping rice were calculated and water deficit and water deficientratio for the rice were analyzed in the study area. The results showed that the average waterdeficient ratio during 1961-2010 from booting to flowering was the highest, followed bythat from transplanting to booting, and that from flowering to maturity was the least. The effectiveprecipitation, water requirement and water deficit during the entire growth period of ricewere decreasing, but the water deficient ratio for the central and western rice-growing areasshowed an increasing trend. The effective precipitation decreased during the transplanting tobooting and flowering to maturity stages, but increased during the booting to flowering stage.The water requirement among the different growth stages showed a downward trend. The waterdeficit and water deficient ratio decreased during the booting to maturity stage, but increasedduring the transplanting to booting for the central and western rice-growing areas. The researchcan provide the basis for agricultural water use and reasonable irrigation in rice growing areasin Sichuan.
Peat bogs have seriously degraded due to global change and human disturbance andovergrazing of pastures in Gahai wetlands of Gansu Province. Using an approach of spatial sequenceinstead of temporal sequence, the investigations were conducted at four different degradationstages of peat bogs to find out the changing trends of soil properties and water conservationfunctions during the peat bogs degradation. The results showed: With the increase of peatbogs degradation gradient, 1) the average soil bulk density in 0-40 cm soil layers increased continuously,soil total porosity decreased gradually, and they both changed in different soil profiles.2)The value of soil chemical properties containing the soil organic matter, total nitrogen(TN), available potassium (AK) and hydrolysis nitrogen (HN) decreased gradually, ammoniumnitrogen (AN) increased gradually, the contents of total phosphorus and total potassium had nodefinite trend, whereas they were fluctuating changes along the soil profiles. 3) The highest contentsof soil natural moisture, minimum storage and capillary storage were found in the non-degradedpeat bogs, while the lowest were the middle-degraded. The results of variance analysisshowed that the soil bulk density, total porosity, organic matter, AN and water storage capacityhad significant differences among different degradation stages (P<0.05). The soil saturated storageand capillary storage were positively correlated with the soil organic material content (P<0.05), as well as influenced by plant coverage and depth of peat soil indirectly. These results indicatedthat the basically reasons for changes of soil properties and water conservation functionamong degradation process of Gahai peat bogs were the draw down of ground water and the decreasesof plant coverage, soil organic material and peat soil depth.
The classification and grading of seawater could provide scientific basis for valuating,levying, and planning for sea use. Taking 0.01° × 0.01° as the evaluation unit, this study assessedthe sea area for mariculture use in Jiangsu Province. The integrated index method wasused to do the evaluation, based on the five sub-index groups, namely, the physical environmentalconditions, physical and chemical properties of seawater, marine nutrient content, abundanceof biological resources and geographic conditions. The limiting factors, such as pollutantcontent in seawater and policy, were also employed to assess the mariculture use. The weightsfor the index were determined by principal components analysis when these indexes are highlycorrelated with each other. Otherwise, the weights for the index were determined by expert assessmentmethod. The evaluation results were classified into seven grades at equal value range.If the limiting factors were not considered in the evaluation process, the area at low grades (1-3) accounted for 30.72%, and the high grades (4-7) accounted for 69.28%. If the pollution conditionswere considered, about 4638 km2 seawater could not be used for mariculture. The areaat low grades accounted for 27.79%, the high grades accounted for 56.71%, and the substandardgrades accounted for 15.50%. If we only evaluated the mariculture area based on marinefunction zoning (5655 km2), then 68.70% was located in the area of high grades, while about24.88% was located in the area of substandard grades.
The technique of stable isotope has been widely applied to study the moisturesource, supplement relationships among different water bodies and water balance in water cycle.Based on the δ18O and δD of event-based precipitation and river water, the meteorologicaldata in the summer during 2012 on Qinghai Lake Basin, we analyzed the spatial and temporalvariation characteristics of stable isotopes (oxygen and deuterium) in event-based precipitationand river water. The results indicated that the compositions of stable isotopes in precipitationpresented two distinct variation phases, low isotopic values were showed before the mid August,but after that the isotopic values became higher, this may be related with the recycled localmoisture and summer monsoon; the slope (8.69) and intercept (17.5) of LMWL (local meteoricwater line) were evidently larger than GMWL in the Qinghai Lake Basin, this showed thatthe summer precipitation was partly influenced by the moist maritime air masses carried bysummer monsoon; there was a negative correlation between stable isotopes in precipitation andprecipitation amount and temperature, which indicated that a significant precipitation amounteffect existed in summer precipitation but no temperature effect; the variation of stable isotopesin river water had a lower fluctuation range than that of precipitation, this was induced by themixture and adjustment of precipitation, groundwater and glacier melt water; the compositionsof stable isotopes in precipitation became larger replenished by the recycled moisture from Qinghai Lake in summer via Rayleigh fractionation model. Therefore, these would provide the scientificbasis for the study of precipitation, groundwater and surface water in hydrologic cycle in Qinghai Lake Basin, and are of great significance for understanding the trans forming relationships among different water bodies, utilization and management of water resources in future.
Emissions of CH4 and N2O in swamps especially at high latitudes are significant toevaluate greenhouse gases emissions at the northern latitudes. During the growing season of2011, using a static opaque chamber-GC technique, we researched CH4 and N2O emission fluxesin two typical island-forested swamps (Betula platyphylla-Carex schmidtii swamp and Larixgmelinii-Carex schmidtii swamp) in Da Hinggan Mountains of China, analyzed the seasonal characteristics of CH4 and N2O fluxes, and investigated the influences from temperature and watermaster factors to the emission fluxes. The results showed that: CH4 was in weak absorption during growing season in both B. platyphylla-C. schmidtii swamp and Larix gmelinii-Carex schmidtiiswamp except that CH4 fluxes had emission peaks in spring; while N2O emissionpeaks appeared in early summer and spring in two swamps. The average emission fluxes were -60.61,-93.21 μg·m-2·h-1 and 82.92, 45.06 μg· m-2·h-1 respectively. CH4 and N2O emissionfluxes during growing season in L. gmelinii-C. schmidtii swamp were in negative correlationwith 10-40 cm and 15-40 cm soil temperatures respectively; while CH4 and N2O emissionfluxes during growing season in B. platyphylla-C. schmidtii swamp were only in negative correlationwith 40 cm soil temperature. Neither two types of swamp and soil water ratio had approachedstrong correlations. CH4 and N2O emission fluxes during growing seasonwere-2.21,-2.74 kg·hm-2 and 2.74, 0.93 kg·hm-2 respectively in B. platyphylla-C. schmidtii swamp and L. gmelinii-C. schmidtii swamp, which became the sinks of CH4 weak absorptionand the sources of N2O weak emission.
Since entering the new century, China's industrial carbon emission is still increasingwith fluctuation. In order to investigate China's industrial carbon emission reduction performanceand change rule of its affecting factors, through building China's industrial carbon emissionsdatabase and the use of Laspeyres index decomposition technique, this paper dynamically decomposes the influencing factors of CO2 emission of China's 36 industrial sectors in 2001-2010. The results show that: 1) although China's total volume of industrial CO2 emissions is increasing,the rate of growth and intensity are decreasing. Carbon dioxide emissions increased to7.16×109 t in 2010 from 2.89×109 t in 2001, but the growth rate of carbon dioxide emissions decreasedto 5.77% in 2009 from 18.86% in 2003, the carbon intensity decreased to 181.2 thousandtons per hundred million yuan in 2010 from 291.4 thousand tons per hundred million yuanin 2001. 2) Growing scale of industrial economies is the dominant factor of increasing industrial CO2 emissions; while technological progress and structural adjustment effectively inhibitsthe increase of CO2. The contribution of economic scale effect to the increasing of CO2 emissionsreached an average annual rate of 191.81% in the decade, but due to the effect of technologicalprogress and structural adjustment, the function of total effect value only reached an annualrate of 109.15% in 10 years. 3) Compared with technological progress effect, structural adjustmenteffect makes greater contribution to the reduction of CO2 emissions. The cumulativepromotion carbon reduction of structural adjustment effect is 2.07×109 t, and the amount oftechnological progress effect is 1.14×109 t. This paper proposes that long-term emission reduction policies should be formulated to ensure the continuous function of technical progress, andthe other pragmatic choice is to fully tap the potential effect of structural adjustment on CO2emissions reduction.
Since land use patterns in coastal zones are of ten characterized by complexity and diversity,it is difficult to acquire accurate land-use information from remote sensing image usingtraditional methods. Thus, this paper, taking the Rushan coastal zone, located in the east of Shandong Peninsula as a case, tries to fill this gap and develop a new method based on objectoriented classification to extract more accurate coastal zone land-use information. We collect Landsat TM image as the basic information sources for further data processing and analysis.Based on the method of object-oriented classification, this paper makes use of the characteristicsof different objects, such as spectrum, shape, texture and spatial relationships, and extractsl and-use information in the study area through multiresolution segmentation, Membership Functionand Standard Nearest Neighbor, and then evaluates classification accuracy. The results include:1) Twelve kinds of land-use information are classified in the Rushan coastal zone byboth Membership Function and Standard Nearest Neighbor methods. The salt and aquaculturewater, the woodland and orchard are well identified, and the elongated linear features wereclearly extracted. 2) Through comparing the extraction results using maximum likelihood method,the object-oriented classification accuracy was 82.50%, Kappa was 0.8091, 11.44% and 0.1055 higher than that using the maximum likelihood method. The results showed that the object-oriented classification method is an effective technical method for extraction of land-use informationquickly and accurately in coastal zones, because it can improve the classification precision of high resolution remote sensing image through attenuating effectively the effects onthe classification accuracy due to "same object with different spectrums" and "different objectswith same spectrums", and "salt-pepper".
Household adaptation responses of land use to environmental stresses have becomethe focus of climate change and sustainability science. This paper reviews the determinants ofhouseholds'adaptive capacity, the barriers for adaptation responses, and the assessment on ecologicaland environmental consequences of household adaptation to environmental stressors ofland utilization. The approaches of household adapting environment are presented, involvingcomposite index method, participatory rural assessment, statistic and econometric model, andadaptive co-management model. Some problems are proposed for further study in need of transformative adaptation: 1) Theoretically, building the theoretical framework of adaptation to supply theoretical support for empirical research; 2) more attention be paid to the assessment ofecological and environmental consequences of household adaptation practices and policies forimproving adaptive capacity, which providing scientific basis for sustainable adaptation; 3) toexplore the mechanism of household adaptation process of land use across multiple actors; and4) to construct adaptive co-management model of household to environmental stresses involve dmultiple actors on the basis of systematic ideas, multidisciplinary and interdisciplinary knowledge,and present methodologies for realizing the combination of qualitative and quantitative research.
Energy resources are dynamic sources of development of human society and economy.In reality, spatial distribution of energy resources is often uneven, and spatial dislocation ofenergy production and consumption is a more common phenomenon. So, the flow process ofenergy resources, including spatial displacement process and material utilization process, is themain mode of exploitation and utilization of energy resources, which is also an important directionin the study of resources flow. Currently, the study of energy resources flow mainly concernsof primary energy resources, such as coal and oil, which is of significant representativeness,typicality and important practical application value in the study of resources flow. Theyare widely used in macroeconomic analysis, energy policy and strategy development, transportationplanning, logistics and trading plan, analysis of energy efficiency, environmental valueaccounting, energy saving and emission reduction and other areas of policy formulation and decision-making.
The article combed and summarized research efforts of energy resources flow, and elaboratedthe content, focal points and characteristics of energy resources flow study from all relateddisciplines'research perspectives. It indicated that geonomics, geography of communication,logistics, industrial economics and industrial ecology were most closely related subjects tothe study of energy resources flow.
Next, this article elaborated the main contents of energy resources flow study from fouroutlines including the characteristics, mechanisms, effect, optimization and regulation. Accordingto the above-mentioned, the study of energy resources flow from various subjects mademuch enrichment and development on the theoretical study of resources flow. Therefore, this articleindicated that the directionality of resources flow and elements deconstruction of spatialstructure of resources flow should be a useful addition to the resources flow theory.
In discussion on energy resources flow research framework, Cheng Shengkui made ananalysis on resources flow into two main flow forms, one of which put resources flow resolveto horizontal flow, and another vertical flow. Horizontal flow occurred when resources made adisplacement in different geographic space. And vertical flow occurred when resourcesachieved of form, features and value's transformation in the process from original state resourcesto wastes. That was not only an accurate analysis on resources flow connotation, but also providinga basic research framework for thereafter resources flow empirical research. This articlesupposed that existing study framework of energy resources flow was consistent to the frameworkof vertical and horizontal analysis of resources flow. Their vertical and horizontal researchconducted independently and formed two very different research styles. At the sametime, the article pointed out that this research framework lacked of effective contact mechanismswhich could link up vertical and horizontal analysis. On the basis of the earlier studies,this paper finally put forward some gradual goals and outlook contents of the future energy resourcesflow research.
CGE model and its applications in water resources are briefly introduced in this article.The approaches to integrate water resources in CGE model and problems and outlooks forthe CGE model application in water resources are discussed. Four approaches to integrate waterresources in CGE model are widely used, including constraints, elements, intermediate inputsand comprehensive treatment. With the improvement of data and modeling techniques,more and more detailed, complicated and practical models have been developed. Although theapplication of CGE model in water resources is still subject to modeling defects and the understandingof the water resources issues and its treatment, with the theoretical development anddata collection, CGE model applications in water resources will gradually develop toward standardization,modularization, as well as being more sophisticated and practical.
