太湖流域水供给服务供需时空演变分析

太湖流域是我国经济发展最快、人口最密集的地区之一。受土地利用和降水条件变化的影响,太湖流域水供给服务供需关系也发生着变化。通过分别设置1995～2015年太湖流域不同降水条件和土地利用变化情景,利用Invest模型定量评估水资源供给量,同时利用空间离散法定量评估水资源需求量,并进一步分析供需赤字和盈余区域的时空变化。结果表明:1995～2015年随着土地利用变化,尤其是建设用地的扩张(20年来涨幅达106%),水资源需求占供给量的比重由73%升至90%,需要依赖外来客水的县域面积占整个流域的比重由19%升至33%;2015年在不同降水条件下供需关系变化更为明显,降水量越少,供需赤字的县域越多,在干旱年份整个流域需求量占供给量的117%,供给量已不能满足需求量,且赤字县域的面积占整个流域的47%。两种情境下,太湖流域东北部水供给服务供需关系均比西南部紧张。作为影响太湖流域水资源供需变化的主要因素,土地利用和降水条件变化分别通过影响需求量和供给量改变供需关系。     

Forest dynamics in Mississippi, USA: a hybrid statistical and geospatial analysis

Understanding forest changes and its trajectory is important to develop policy options and future scenarios for climate analysis. This research is conducted to gain insights on secondary forests change using Mississippi, USA, as a case study. We investigate the spatial patterns and temporal dynamics of secondary forests at high resolution and examine the forces driving their changes. An extensive literature review is conducted to refine the conceptual framework of forest changes and identify the underlying key factors. Forest changes are quantified at high spatial (30-m) and temporal (biennial) resolutions, using time series remotely sensed data between 1984 and 2007. A number of geospatial and socioeconomic data were compiled to analyze the spatial variations of forest disturbances and their linkages to various socioeconomic, political, and biogeophysical factors. The results show that the secondary forests are highly dynamic and variable. Disturbances and regeneration occur continuously everywhere in a systematic and coordinated fashion. This pattern prevents an extensive disturbance and increases total forest cover. Market conditions (i.e., timber price) are the key predictor of the level and overall trend of forest disturbances. However, spatial patterns of forest dynamics cannot be explained by location-specific biophysical, socioeconomic, and policy factors identified in the literature. They can best be described by the ecological characteristics of the forests (i.e., the forest type and age distribution), which have a clear economic linkage. The research shows that regenerated forests frequently experience loss and gain of their extent, and their ecological characteristics change drastically on a short-term basis. These results point out challenges and opportunities in forest management and policy with regard to reforestation.     

厦门海岸带湿地变化的研究

通过“压力-状态-响应”分析模型，对厦门海岸带湿地变化的主要原因（压力）、成分退化和结构改变（状态）以及对厦门海岸带生态系统的主要影响（响应力）之间的作用机制进行了探讨。提出厦门海岸带湿地面临的主要压力来自海岸带围垦造地、近海滩涂养殖和九龙江河口输入；状态变化突出表现在浅海海域面积的减少。红树林的面积减少。近岸泥沙淤积。沉积物类型改变和沉积物污染；主要影响是造成厦门海域水质下降、近海底橙生物类型改变、航道泥沙淤积、水产养殖产量下降和珍稀海洋物种分布和数量改变。     

Significance of rodent population dynamics for the formation of long-term community structure

Changes occurring with time in the structure of communities are evaluated and strategies of community functioning are described using the example of murine rodents from three areas of Western Siberia that differ in landscapes and geographical conditions. Many rodent species are common to all communities included in analysis. The populations of these species have different ranks in the dominance structure of communities, depending on the natural climatic conditions of the landscape, and differently influence the composition of communities and time course of changes in their structure.     

Agricultural livelihood transition in the southern Yucatán region: diverging paths and their accompanying land changes

Land change science has demonstrated that rural livelihoods around the world both drive and reflect changing environmental regimes and political economic/structural transformations. This article explores the relationship between increasingly globalized rural livelihoods and in-place land change, assessing results from social surveys of smallholding households in the southern Yucatán region. We examine evidence for a transition in agricultural livelihood strategies as smallholders adjust to changing political economic and institutional conditions, and link these transitioning strategies to land use changes. Based on household surveys in 1997 and 2003, we comparatively assess both changes in the selection of livelihood strategies and in the land use and cover impacts of those strategies. Our results indicate that although impacts of given strategies have changed little over this period, there are increasing proportions of households pursuing two divergent adjustment paths—one of agricultural withdrawal and one of agricultural intensification and commercialization. We investigate what sociodemographic characteristics differentiate the groups of households following distinct livelihood strategies. Our findings point to the possibility of simultaneous and contradictory land change outcomes as smallholders adjust in different ways to their intensified incorporation into global economies.     

Impacts of future land use/land cover on wildfire occurrence in the Madrid region (Spain)

This paper assesses the relative importance of socioeconomic factors linked to fire occurrence through the simulation of future land use/land cover (LULC) change scenarios in the Madrid region (Spain). This region is a clear example of the socioeconomic changes that have been occurring over recent decades in the European Mediterranean as well as their impact on LULC and fire occurrence. Using the LULC changes observed between 1990 and 2006 as a reference, future scenarios were run up to 2025 with the conversion of land use and its effects model. Simultaneously, the relationship between LULC arrangement (interfaces) and historical fire occurrence was calculated using logistic regression analysis and used to quantify changes in future fire occurrence due to projected changes in LULC interfaces. The results revealed that it is possible to explain the probability of fire occurrence using only variables obtained from LULC maps, although the explanatory power of the model is low. In this context, border areas between some LULC types are of particular interest (i.e., urban/forest, grassland/forest and agricultural/forest interfaces). Results indicated that expected LULC changes in Euro-Mediterranean regions, particularly given the foreseeable increase in the wildland–urban interface, will substantially increase fire occurrence (up to 155 %). This underlines the importance of future LULC scenarios when planning fire prevention measures.     

Plant induced changes in concentrations of caesium, strontium and uranium in soil solution with reference to major ions and dissolved organic matter

For a better understanding of the soil-to-plant transfer of radionuclides, their behavior in the soil solution should be elucidated, especially at the interface between plant roots and soil particles, where conditions differ greatly from the bulk soil because of plant activity. This study determined the concentration of stable Cs and Sr, and U in the soil solution, under plant growing conditions. The leafy vegetable komatsuna (Brassica rapa L.) was cultivated for 26 days in pots, where the rhizosphere soil was separated from the non-rhizosphere soil by a nylon net screen. The concentrations of Cs and Sr in the rhizosphere soil solution decreased with time, and were controlled by K+NH(4)(+) and Ca, respectively. On the other hand, the concentration of U in the rhizosphere soil solution increased with time, and was related to the changes of DOC; however, this relationship was different between the rhizosphere and non-rhizosphere soil.     

Group effect on individual locomotor activity of common toad (<Emphasis Type="Italic">Bufo bufo</Emphasis> L.) and brown frog (<Emphasis Type="Italic">Rana temporaria</Emphasis> L.) tadpoles

Different components of group effect on the locomotor activity of single common toad and brown frog tadpoles have been studied by estimating the length of their trajectories, the speed of movement, the number of crossings of experimental field zones, and the number and duration of stops. The results show that toad tadpoles are more active than frog tadpoles. Conspecific metabolites added to the water do not change the pattern of their locomotor activity. Under conditions of visual contact with other tadpoles, locomotor activity of a toad tadpole decreases, whereas that of a frog tadpole increases. Thus, tadpoles of the two amphibian species show species-specific behavioral responses to changes in experimental conditions.     

Variability of biochemical parameters and radiation resistance of the seed progeny of <Emphasis Type="Italic">Descurainia sophia</Emphasis> and <Emphasis Type="Italic">Lepidium apetalum</Emphasis> under exposure to various factors

The physiological and biochemical characteristics of seedlings of Descurainia sophia (Fisch.) and Lepidium apetalum Wild. have been used as examples to demonstrate that long-term exposure of plant populations to environmental stress factors causes adaptive changes in antioxidant and genomic systems that may considerably affect the radioresistance of seed progeny. The resistance to additional acute irradiation of seed progeny of wild plants adapted to different environmental conditions has been found to be determined not only by the combination of antioxidant and DNA-repair protection systems and the vulnerability of the functioning genome, but also by their variability. The data on the relationship of the radioresistance of wild plant populations with physiological and biochemical characteristics and their variability may be used for expert environmental assessment of the state of the biota and prediction of its viability under exposure to abiotic environmental factors.     

An empirical model for primary sedimentation of sewage

Theoretical mathematical models of primary sedimentation and column settling tests have failed until now to predict the behaviour of sedimentation tanks under actual operating conditions due to the difficulties in simulating the effect of the density currents and the complex phenomenon of flocculation. Therefore, empirical models can be helpful in the design of sedimentation tanks. Using performance data from three different pilot-scale sedimentation tanks, empirical mathematical models were developed in this paper relating suspended solids (SS) removal efficiency to surface overflow rate, influent SS concentration, and sewage temperature. The model coefficients were derived from the combined analysis of three well correlated sets of data, thus giving a good indication for their possible general applicability. The analysis of experimental data also gave a relationship between SS and chemical oxygen demand (COD) removal efficiencies.     

农地流转背景下地块规模对农户种粮投入影响分析

近年来粮食安全受到国家和社会的广泛关注,农地投入作为粮食生产的重要要素,是保障粮食稳定产出的前提。学者就农地规模对农户种粮投入的影响已进行了较多研究,但受农地流转的影响,土地要素更具多样化,土地规模与农户种粮投入的关系发生变化。随着农地流转在我国的快速发展,探析农地流转影响下土地规模对农户种粮投入影响的变化成为一个亟待研究的问题,对保障国家粮食安全具有重要意义。考虑到地块的异质性,本文基于山东、河南、安徽三个粮食主产省622户农户1 284个地块的粮食生产数据从村庄和农户两个层次控制了生产要素市场价格、地块要素等非主观因素,进行多层模型回归分析。结果表明,农地流转特征及地块特征对农户粮食生产单位面积投入有显著影响。地块规模和转入地占比对农地投入影响为负,转入地占比越大,地权稳定性越低,农户投入积极性受到挫伤越明显,在转入地上的投入减少。随着转入土地面积的增加,农户从事粮食生产的机会成本增大,使其有更强的动力增加种粮投入,地块规模的负向影响程度降低。基于分析结果,本文得出以下3点结论:(1)规模化经营有利于降低单位面积种粮成本;(2)农地流转发生时,地块规模对种粮投入的影响发生改变,成片规模化经营将成为我国粮食生产的必然趋势;(3)提高土地综合条件可以降低投入成本,并提高农户投入积极性。要保障国家粮食安全,需从降低种粮成本、提高农户收益着手,建议鼓励农村土地流转,推动粮食规模化生产,同时也要注重增加财政拨款,建设高标准粮田,强化高标准粮田的农业基础设施建设,完善田间配套工程。     

基于时序NDVI的湖北省植被覆盖动态变化监测分析

基于1998～2011年7、8月份SPOT VEGETATION NDVI数据,求取两月份NDVI平均值,构建14 a间的NDVI时序文件,通过对NDVI时序文件进行信息提取、分析,反映湖北省植被生长情况,从而监测、研究湖北省植被生长高峰期植被覆盖动态变化及趋势。具体为：利用植被覆盖分区法,将研究区分为弱植被覆盖区、稀疏植被覆盖区、低植被覆盖区、中植被覆盖区、高植被覆盖区和密集植被覆盖区等区域,监测各区域14 a间植被覆盖动态变化,结果表明,研究区整体上植被覆盖变化不大;利用Mann Kendall趋势分析法,对研究区植被覆盖变化趋势进行研究,结果表明绝大部分呈现无明显变化趋势,1655%的区域表现增加趋势,033%的区域表现减少趋势。通过以上分析结论可知,植被覆盖分区法和Mann Kendall趋势分析法的分析结果基本一致,表明两种方法能从植被覆盖状况和变化趋势角度动态反映植被的变化情况     

秭归县植被结构演变及土壤侵蚀评价

为详细了解水库建设期秭归县植被结构演变及土壤侵蚀风险情况,使用TM和SPOT等中高分辨率遥感数据获取的秭归县1992、2007年1〖DK〗∶50 000土地利用分类、植被覆盖度、土壤侵蚀风险及1999～2007年SPOT VEGETATION NDVI等。利用景观格局方法研究植被景观格局演变,分析植被结构与土壤侵蚀风险变化特点。结果表明：1992～2007年,植被景观格局更加破碎,斑块离散程度变大,多样性提高,乔、灌等仍是优势类型,受不同人类政策的影响,不同类型植被类型景观特征响应表现出差异性。植被覆盖度得到改善,其中秭归中南部植被水平密度结构得到明显改善,对降低土壤侵蚀风险起到了积极作用。水库周边地区作为人类活动扰动的集中区,水土保持任务依然艰巨。通过遥感和GIS手段分析区域土地景观格局演变及其生态环境效应,分析变化背后的驱动机制和限制因素,甄别人类活动影响力,为研究三峡人地关系和谐发展提供借鉴和参考     

Influence of Hydrologic Conditions of the Lower Ob Floodplain on Reproduction in Coregonids

The influence of the water level in the period of the open river channel and the duration of lower floodplain inundation on the feeding conditions, abundance, and population state of coregonids in the Lower Ob was investigated. The long-term dynamics of catches of some coregonid species was analyzed and compared with changes in the hydrologic conditions in the floodplain. The relationship between basic hydrologic conditions in the Lower Ob (water level in the period of the open channel, the duration of the lower floodplain inundation), the coregonid population sizes, the state of spawners, and the size of catches is demonstrated.     

干旱地区土地利用结构变化与生态服务价值的关系研究——以酒泉市为例

利用酒泉市1997-2006年土地利用变更调查数据和相关统计资料,计算土地利用结构异质性指数和生态服务价值,分析土地利用结构与生态服务价值的变化及其相互关系.结果表明:1997-2006年酒泉市耕地、林地、园地面积在增加,其中耕地增加最多,增加了9 803.15hm2,牧草地、水域和未利用地面积不断减小,其中牧草地减少最多,减少了207 470.56 hm2;酒泉市土地利用结构多样性指数和均匀度增加而优势度降低,土地利用趋于多样化和均匀化;各类土地的生态服务价值都有不同程度的增加,土地利用生态服务价值总体呈增加趋势;土地利用生态服务价值与土地利用结构线性相关,通过增加牧草地、水域和耕地等生态用地面积,提高土地利用集约度,调整土地利用结构促进土地利用的多样化、均匀化,可以增加生态系统稳定性和提高生态系统服务功能的经济价值.     

Food Chains and Their Dynamics in Ecosystems of Shallow Lakes with Different Water Salinities

The dynamics of food chains upon changes in water salinity has been analyzed using the example of six poly- and hyperhaline lakes in the Crimea. The results show that ecosystems of saline lakes are sensitive to the impact of external factors. Changes in weather conditions often lead to fluctuations of water salinity, which may cause a changeover in the hydrobiological regime of the lake. In lakes with high water salinity, the shortening of food chain takes place, and the cascade effect is observed in their dynamics.     

Structural-temporal organization of a rodent community in the Teletskaya Taiga,Altai Mountains

The structural-temporal organization of a murine rodent community in the taiga has been studied near Lake Teletskoe, Mountain Altai. The results show that the long-term dynamics of indices characterizing community diversity depend mainly on changes in the structure of dominance rather than on the population dynamics of species. The distribution of species in the factor space corresponds to their preference for certain biotopes, from dry to relatively moist. An analysis of relationships within the rodent community has revealed the synchronous dynamics of species abundance and antiphase pattern of changes in the structural indices of dominant species.     

Application of remote sensing techniques toward the role of traditional water bodies with respect to vegetation conditions

Sri Lanka being an agrarian country, the role of water is important for agricultural production. In Sri Lanka, various tank cascade systems, earthen dams and distribution canals have been accepted as few of the most complex ancient traditional water systems of the world. Rainfall, surface water, groundwater and runoff are linked with each other, they have close interactions to land cover classes such as forests and agriculture. The monitoring of vegetation conditions can show subsurface manifestations of groundwater. In this study, an effort to understand the role of traditional water reservoirs and groundwater recharge was made using remote sensing techniques. We have analyzed various vegetation indices such as Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI-2), Soil-Adjusted Vegetation Index (SAVI), tasselled cap transformation analysis (TCA brightness, greenness and wetness) and their relations with the existence of soil, vegetation and water. Result shows that EVI, SAVI, and TCA-based Greenness Index indicates good relationship with the vegetation conditions as compared to other indices. Therefore, these indices could play a crucial role in depicting the interaction between soil, vegetation, and water. However, multi-temporal observations can provide significant results about these interactions more accurately.     

Holocene dynamics of vegetation and ecological conditions in the southern Yamal Peninsula according to the results of comprehensive analysis of a relict peat bog deposit

A comprehensive analysis of samples from a frozen peat deposit in the upper reaches of the Khadytayakha River by palynological, carpological, entomological, and radiocarbon methods has been performed to reconstruct changes in the regional and local vegetation and climatic conditions during the Holocene. The results show that this peat deposit was formed from 8000 to 5000 years BP. During that period, the climate in the southern Yamal Peninsula was considerably warmer, and the present-day subarctic shrub tundra zone was occupied by plant communities of spruce, birch, and larch forests.     

The holocene dynamics of vegetation and environmental conditions on the eastern slope of the Northern Urals

Consideration is given to changes in the vegetation and climatic conditions on the eastern slope of the Northern Urals in the second half of the Holocene as reconstructed on the basis of integrated palynological, botanical, paleocarpological, and radiocarbon analysis of material from a peat bog section in the floodplain of the Loz’va River. The results show that the northern taiga zone of the study region in the period between approximately 5000 and 700 years BP was occupied by forests of southern taiga facies, as the climate was significantly warmer than it is today.