Human Activities In Region Research Articles

基于SNIC-CNN-SVM模型的京津风沙源二期工程区土地利用/土地覆盖遥感识别研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于SNIC-CNN-SVM模型的京津风沙源二期工程区土地利用/土地覆盖遥感识别研究 DOI: 10.5846/stxb202109262707 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国林业科学研究院院基金重点项目（CAFYBB2019ZB004）；国家高分重大科技专项（21-Y30B02-9001-19/22-3） Remote sensing recognition of land use/land cover in the Beijing-Tianjin sandstorm source region based on SNIC-CNN-SVM model Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:稀疏植被覆盖（草地、沙地、戈壁）演变能够直接表征区域生态环境和人类活动的动态影响变化。但由于大尺度稀疏植被区一般都具有地理跨度大，景观结构复杂多样，破碎化程度高，现有地表覆盖分类产品针对性不足等问题，使得该区域内林草沙的遥感提取难度较大，精度普遍偏低，直接制约生态效应评价模型的应用效果。因此，以典型大尺度稀疏植被区--京津风沙源治理二期工程区为研究区，研建了SNIC-CNN-SVM （SCS）模型，实现了大尺度稀疏植被区林草沙典型要素的信息自动提取和主要土地利用/土地覆盖类型识别。研究结果表明：1）引入惩罚性机制优化后的SNIC分割算法，有效提升了稀疏植被区与沙地区的边界区分度，有助于分类精度的提升；2）基于改进SNIC-CNN-SVM模型方案的研究区总体分类精度达89.41%，较优化前提高了11.17%，特别是乔、灌、草、沙地和戈壁的分类识别精度显著提升，表明该优化方案在以研究区为代表的稀疏植被区域分类中具有较好的应用效果和推广价值；3）分类结果显示，2020年工程区草地面积最大，占到了一半以上（51.52%），沙地占比11.96%，稀疏植被覆盖（草地、沙地、戈壁）区域占比68.68%，表明工程区处在林地-稀疏植被-沙地的过渡地带，生态环境保护压力与防沙治沙形势依然严峻；4）近20年来，乔灌草等植被增加面积约占工程区20.64%，主要由沙化土地转化，沙化土地减少面积约占工程区的4.58%，表明研究区植被状况不断改善，实施的各项生态工程作用显著，能够更有效地服务于多维度生态系统服务功能评价。该研究以期能够为京津风沙源二期工程区的生态系统演变规律研究及生态工程评价等工作提供重要科学支撑。 Abstract:The evolution of sparse vegetation cover (grassland, sandy land, Gobi) can directly characterize the dynamic changes of the regional ecological environment and human activities. However, large-scale sparse vegetation areas generally have large geographic spans, complex and diverse landscape structures, high fragmentation, and insufficient pertinence of existing land cover classification products. These problems make it difficult to extract the forest, grass, and sand in this area by remote sensing, and the accuracy is generally low, which directly restrict the application results of the ecological effect evaluation model. Therefore, this study took the typical large-scale sparse vegetation area, the Beijing-Tianjin sandstorm source region (BTSSR) as the study area, and the SNIC-CNN-SVM (SCS) model is proposed. The forest, grass, sand element information is automatically extracted and the land use/land cover types are identified in the study area. The results show that:1) the SNIC segmentation algorithm was optimized by the penalty mechanism and can effectively increase the boundary discrimination between the sparse vegetation area and the sandy area, which is helpful to improve the classification accuracy; 2) the overall classification accuracy of the optimized model reached 89.41%, which is 11.17% higher than that before optimization, especially the classification and recognition accuracy of trees, shrubs, grasses, sandy land and Gobi is significantly improved, indicating that the optimization model has good application effect and promotion value in the classification of sparse vegetation areas represented by the study area; 3) in 2020, the grassland area in the study area was the largest, accounting for more than half (51.52%), sandy land accounted for 11.96%, and sparse vegetation coverage (grassland, sandy land, Gobi) accounted for 68.68%, indicating that the project area is in the transition zone of woodland-sparse vegetation-sandy land, and the pressure on ecological environment protection and the situation of desertification prevention and control are still severe; 4) in the past 20 years, the increased area of vegetation such as arbor, shrub and grass accounted for about 20.64% of the project, which is mainly derived from desertified land. The reduced area of desertified land accounted for about 4.58% of the project area, indicating that the vegetation conditions in the study area are continuously improving, and the implemented ecological projects have a significant effect. The method in this paper can be more effectively used for multi-dimensional ecosystem service function evaluation. This study is expected to provide important scientific support for the research on the evolution law of the ecosystem and the evaluation of ecological engineering in the BTSSR. 参考文献 相似文献 引证文献

The state and fate of lake ice thickness in the Northern Hemisphere

Lake ice thickness (LIT) is important for regional hydroclimate systems, lake ecosystems, and human activities on the ice, and is thought to be highly susceptible to global warming. However, the spatiotemporal variability in LIT is largely unknown due to the difficulty in deriving in situ measurements and the lack of an effective remote sensing platform. Despite intensive development and applications of lake ice models driven by general circulation model output, evaluation of the global LIT is mostly based on assumed “ideal” lakes in each grid cell of the climate forcing data. A method for calculating the actual global LIT is therefore urgently needed. Here we use satellite altimetry to retrieve ice thickness for 16 large lakes in the Northern Hemisphere (Lake Baikal, Great Slave Lake, and others) with an accuracy of ∼0.2 m for almost three decades. We then develop a 1-D lake ice model driven primarily by remotely sensed data and cross-validated with the altimetric LIT to provide a robust means of estimating LIT for lakes larger than 50 km2 across the Northern Hemisphere. Mean LIT (annual maximum ice thickness) for 1313 simulated lakes and reservoirs covering ∼840,000 km2 for 2003–2018 is 0.63 ± 0.02 m, corresponding to ∼485 Gt of water. LIT changes are projected for 2071–2099 under RCPs 2.6, 6.0, and 8.5, showing that the mean LIT could decrease by ∼0.35 m under the worst concentration pathway and the associated lower ice road availability could have a significant impact on socio-economic activities.

Climate vs. Human Impact: Quantitative and Qualitative Assessment of Streamflow Variation

This paper presents a novel framework comprising analytical, hydrological, and remote sensing techniques to separate the impacts of climate variation and regional human activities on streamflow changes in the Karkheh River basin (KRB) of western Iran. To investigate the type of streamflow changes, the recently developed DBEST algorithm was used to provide a better view of the underlying reasons. The Budyko method and the HBV model were used to investigate the decreasing streamflow, and DBEST detected a non-abrupt change in the streamflow trend, indicating the impacts of human activity in the region. Remote sensing analysis confirmed this finding by distinguishing land-use change in the region. The algorithm found an abrupt change in precipitation, reflecting the impacts of climate variation on streamflow. The final assessment showed that the observed streamflow reduction is associated with both climate variation and human influence. The combination of increased irrigated area (from 9 to 19% of the total basin area), reduction of forests (from 11 to 3%), and decreasing annual precipitation has substantially reduced the streamflow rate in the basin. The developed framework can be implemented in other regions to thoroughly investigate human vs. climate impacts on the hydrological cycle, particularly where data availability is a challenge.

Comprehensive analysis of water carrying capacity based on wireless sensor network and image texture of feature extraction

This article takes the complex uncertainty in the carrying process of water resources system as the research object. Firstly, the water resources carrying capacity system is divided into three sub-systems: bearing support capacity, bearing pressure and bearing regulation capacity. System analysis methods based on wireless sensor network and image texture of feature extraction for correlation analysis, gray correlation analysis, and multi-dimensional conditional cloud algorithm are introduced into the field of water resources carrying capacity evaluation research. Moreover, combine it with the subtraction set opposition, the effect partial bias connection number, and the risk matrix. Finally, three types of models for water resource carrying capacity evaluation and trend analysis were constructed. The evaluation results of water resources carrying capacity are consistent with the actual process, and the overall development trend is gradually improving. The application results of the evaluation model of water resource carrying capacity are established. The calculation results of the image texture feature of extraction model are similar to the overall change trend of the model before the improvement. The trend of change is more obvious. It can not only describe the water resource carrying level as a whole, but also characterize the reliability of the calculation results and the bearing risk caused by the uncertainty of the water resource carrying system. The water resources carrying capacity evaluation and trend analysis of calculation results are reasonable and feasible. The research results can provide a reasonable and effective decision-making basis for the systematic analysis of the bearing boundary issues between regional complex water resources systems and human water activities, and then propose adaptive risk prevention and control strategies for water resources carrying capacity.

Sedimentary Pediastrum record of middle–late Holocene temperature change and its impacts on early human culture in the desert-oasis area of northwestern China

Although the pattern of Holocene temperature variations in central Asia is complex, it is clear that temperature played a fundamental role in influencing humidity conditions and regional human activity. We reconstructed temperature changes using Pediastrum species data, verified by clumped isotopes (Δ47), in the carbonates of sediment cores recovered from Bosten Lake in Xinjiang Province, northwestern China. Combined with archaeological data, the results indicate an unusually warm climatic interval that peaked at ∼4.7–4.3 kyr and promoted human occupation of the Altai Mountains. The climate cooled during 4.2–4.1 kyr and 3.6–3.5 kyr, as indicated by the decrease or absence of Pediastrum simplex. These cold events may have triggered the southward human migration out of the Altai region, resulting in the widespread distribution of archaeological sites at lower latitudes, in the Tienshan Mountains, and in the desert-oasis areas of the Tarim Basin in southern Xinjiang. Our data support the notion that a series of cultural transitions across the monsoonal Loess Plateau and Tibetan Plateau of China may have been linked to temperature changes during the middle to late Holocene.

Keys to discern the Phoenician, Punic and Roman mining in a typical coastal environment through the multivariate study of trace element distribution

Trace element concentrations in the Cartagena Bay coastal record reveal a contribution of natural processes. However, the influence of anthropogenic factors predominates in the last three millennia, particularly aerosol deposition linked to mining and industrial activities in the area. The coastal record of Cartagena can be considered a preserved environment, suitable to search for regional human activity fingerprinting, specifically that related to the deposition of heavy metals such as Pb and Cu. A multivariate statistical analysis was carried out to clarify the geochemical behaviour of trace and major elements. Our study design represents a novel approach to assign natural contributions, such as eolian and riverine input, to coastal deposits, and organic matter preservation under anoxic environments. Therefore, synergies obtained by the simultaneous study of multivariate statistics and enrichment factors allow robust conclusions about palaeoenvironmental evolution and human activities. Anthropogenic influence suggested that Pb mining and metallurgy began during the Chalcolithic period, with considerable inputs of Pb and Cu to atmospheric pollution during Phoenician, Punic and Roman times.

Pollen-based mapping of Holocene vegetation on the Qinghai-Tibetan Plateau in response to climate change

Improved studies of past vegetation change are required to better understand the variation of alpine ecosystems on the Qinghai-Tibetan Plateau (QTP) in response to future climate change. Spatial and temporal variations of past vegetation can be traced by fossil pollen data mapping. In this paper, we synthesized 57 continuous pollen records on the QTP covering the past 15 kyr to depict large-scale vegetation change and its response to climate variations. In order to minimize potential chronological biases, age-depth models were revised using a state-of-the-art and consistent method for all the records. The spatial and temporal variation of major pollen taxa were examined based on interpolated pollen maps at 1000-year intervals. The arboreal pollen (AP, mainly of Pinus, Betula and Abies/Picea) content expressed significant climate signals over a broad spatial and temporal gradient. During the late glacial period, high proportions of AP widely occurred in regions that are presently unforested owing to the sparse local vegetation coverage. For the Holocene period, AP showed relatively high contributions in records from the southeastern margin of the QTP, with a decreasing gradient in abundance towards the northwest. The transportation of AP to unforested regions corresponds closely to the intensity of monsoon wind, which can be used to track the Holocene evolution of the summer monsoon. The dominant shrub and herbaceous taxa (including Artemisia, Chenopodiaceae, Cyperaceae, Poaceae and Ephedra) generally represent developments of local vegetation responding to climate variations. In addition, the persistent increase in Poaceae pollen during the mid to late Holocene correlates possibly to regional human activities. The inferred spatial and temporal patterns of major pollen types on the QTP provide significant knowledge about long-term vegetation change and its potential response to climate variations.

Human impacts on the cladoceran community of Jili Lake, arid NW China, over the past century

Deterioration of aquatic ecosystems, as a consequence of human-induced disturbances, is a critical global concern. To fully understand the responses of aquatic systems to anthropogenic impacts, it is crucial to assess long-term changes in lakes. The water quality of Jili Lake, a large water body in northwest China, has deteriorated recently, owing to the growing impacts of regional warming and human activities. Thus, Jili Lake was a prime candidate for evaluation of historical multi-stressor impacts. Meteorological data, historical documents, and assemblages of cladoceran microfossils in the sediments of Jili Lake were employed to investigate changes in the cladoceran community over the past century, and to evaluate the response of that aquatic community to human activities. From the 1920s to the 1950s, species richness of the cladoceran community was high, which reflected conditions of relatively low human impact. From the 1960s to 1970s, a sharp decrease in Bosmina longirostris, a planktonic cladoceran species, suggested a decrease in water level as a result of dam construction and intensified water exploitation. Since the 1980s, the water level in the lake has been restored, but increased fish farming and construction of a water storage facility caused salinisation and eutrophication of Jili Lake. Accordingly, the cladoceran community displayed distinct signs of a regime shift, with a gradual transition to dominance of B. longirostris and a sharp decrease in littoral species (e.g. Leydigia leydigi, L. acanthocercoides, Alona quadrangularis, Alona affinis). Our results suggest that human-induced disturbances were the main factor that drove changes in the cladoceran community since about the mid-20th century.

Mammal conservation in Amazonia’s protected areas: A case study of Peru’s Ichigkat Muja - Cordillera del Cóndor National Park

The protected areas of the Amazon Basin provide a core refuge for many threatened forest mammals species, but their effectiveness in wildlife conservation is poorly documented. To better understand the impact of protected areas on mammal conservation in the Amazon Basin, this study evaluates the diversity, abundance, and conservation status of medium and large forest mammals in a borderland sector of Peru’s Ichigkat Muja - Cordillera del Cóndor National Park. Over two field seasons, a total of 26 medium and large forest-dwelling mammal species belonging to 19 families were recorded using camera traps and field surveys. In comparison with regional reference sites, 63% of the mammal species recorded in the regional reference sites were documented in the study area. The drivers of species diversity and abundance within the study area were assessed using park guard reports, published literature, and regression analysis, and the intactness of the local mammal fauna was evaluated using regional comparison sites. A combination of factors explain the diversity and abundance of the mammal fauna recorded in the protected study area, including regional geography and human activities. Given the location of the protected area in Peru and its adjacency to the border of Ecuador, long-term conservation of the park’s mammals depends on binational efforts that invest in collaborative institutions and local communities. This case study provides an example of how borderland protected areas can present challenging wildlife conservation scenarios that require binational collaboration. The current condition and at-risk status of mammal fauna in the protected study area also underlines the importance of consistent field-based monitoring to inform management and evaluate protected area effectiveness.

Temporal and spatial differences of lake ecosystem regime shift in China

人类活动的加强导致湖泊生态系统发生“突变”，造成生物多样性下降、藻类暴发、水质恶化等等环境和生态问题.中国许多湖泊已经发生“突变”或面临着突变风险.获悉湖泊生态系统发生突变的时空差异对于区域湖泊的保护，预防湖泊突变的发生以及制定合适的修复策略至关重要.本研究收集了中国55个不同区域湖泊的古湖沼学数据，探讨了湖泊突变的区域特点.研究确定了湖泊生态系统发生突变时间和区域差异，并揭示了空间差异的原因.结果表明，中国湖泊生态系统突变时间的区域分异特征为：长江中下游湖泊最早出现突变；东部和东北湖区湖泊突变时间明显早于西南、内蒙古和新疆湖泊；各湖区内，城郊湖泊突变时间早于乡村湖泊.人类活动强度是造成湖泊突变时空差异的主要驱动力.研究认为，区域人类活动强度影响了湖泊生态系统的演化进程，造成了中国湖泊生态系统突变的区域差异.本研究从生态系统突变的角度，利用古湖沼学综述了中国湖泊生态系统在人类活动下的演化进程，更深刻地认识了中国湖泊现状，为湖泊保护提供了有力的科学依据.;Increased human activity has caused a regime shift in lake ecosystem, which causes environmental and ecological problems such as biodiversity decline, algae blooms and deterioration of water quality. Many Chinese lakes have undergone regime shift or are facing the risk of abrupt change. It is essential to know the temporal and spatial differences of regime shift for the protecting lake ecosystem, preventing regime shift and formulating appropriate restoration strategies. This study collected paleolimnology data of 55 lakes in different regions of China and discussed the regional characteristics of lake mutations. The study determined the temporal and spatial differences of regime shift in lake ecosystem and revealed the reasons for the spatial differences. Our study found that the regime shift time of Chinese lakes has the characteristics of regional differentiation: regime shift time of lakes in the middle and lower reaches of the Yangtze River is much earlier than that of the whole country. Regime shift happens earlier in the east and northeast lake areas than in the southwest, Inner Mongolia and Xinjiang lakes. In various lake region, regime shift happens earlier in the suburban lakes than in rural lakes. The intensity of human activities is the main driving force for the temporal and spatial differences of regime shift. Lakes with slower warming but stronger human activities are more likely to undergo regime shift. Our result suggests that the intensity of regional human activities has affected the evolution progress of lake ecosystems and caused regional differences of the regime shift in Chinese lakes. From the perspective of abrupt change in ecosystem, this study uses paleolimnology data to summarize the evolution of Chinese lake ecosystems under human activities, achieves a deeper understanding of the current situation of Chinese lakes, and provides a strong scientific basis for lake protection.

Climate-human-landscape interaction in the eastern foothills of Mt. Kilimanjaro (equatorial East Africa) during the last two millennia

The Mt. Kilimanjaro region is known for its long history of intensive agriculture, but the temporal extent of human activity and its impact on the regional ecosystem are not well known. In this study, climate-human-landscape interactions during the past ~2200 years were examined using climate and vegetation proxies extracted from the continuous and high-resolution sediment record of Lake Chala. Ancient-to-modern regional human activity is documented against a backdrop of long-term vegetation dynamics in the low-elevation savanna woodland southeast of Mt. Kilimanjaro and riparian forest within Chala crater. During prolonged dry periods (~1170–1300 CE), succulent dry crater forest expanded relative to the moist lakeshore forest. The savanna landscape surrounding Chala crater was relatively stable through time, except that savanna grasses were stimulated by higher precipitation, consistent with the fuel-limited fire regime evidenced in the charcoal record. Expansion of subalpine ericaceous vegetation and a general decline in Afromontane forest taxa on Mt. Kilimanjaro after 550 CE may reflect a lowering of its upper forest line. The earliest robust signature of human influence on regional vegetation involves an increase in ruderal (weedy) plant taxa around 1100 CE, possibly associated with the development of Chagga homegardens and associated agroforestry in the submontane forest zone. A first hint of cereal agriculture (likely sorghum) is observed around 1550 CE, followed by a more robust signature from 1780 CE onwards which likely reflects the start of lowland irrigation agriculture. From 1780 CE we also find the first undisputed appearance of maize, introduced to East Africa about a century earlier.

11000-Year Record of Trace Metals in Sediments off the Southern Shandong Peninsula in the South Yellow Sea

Geochemical background values are the normal concentration of trace metals in the natural environment and sediment cores have been proved to be excellent samples to get these values. The trace metal (Cu, Pb, Zn, Cr, Cd, As, Hg, Ni, Li, and Co) concentration profiles along a sediment core are investigated to get the background values and to assess the depositional processes and contamination levels off the southern Shandong Peninsula, China. All the metals, except As and Hg, had similar concentration profiles with the highest average values during the period of 6 − 3 kyr. The high concentrations of As and Hg occurred before 6ka and during the period of 3 − 0 kyr. The difference in metal concentrations before and after 6 kyr was mainly attributed to the source of core sediments, which are derived from proximal sediment on the Shandong Peninsula before 6 kyr and the mixture of proximal sediment and Yellow River sediment after 6 kyr. The effects of particle size and human activity were mainly contributed to the metal concentrations since 6 kyr. The average concentrations of trace elements in sediments between 6 and 3 kyr were selected as background values. The principal component factor analysis indicate that the metals were from the natural sources throughout the observed depositional period, with the exception of As and Hg, which may had anthropogenic sources for the sediments from the bottom 2 m of the core. Their geoaccumulation indices indicate that the sediments were not contaminated for Cu, Zn, Cr, Cd, Pb, Ni, Li and Co, whereas they were contaminated recently for As and Hg due to the regional civilization and human activities.

Increasing human activities during the past 2,100 years in southwest China inferred from a fossil pollen record

Besides natural climate variations, human activities can also cause significant changes in regional vegetation composition, especially during the late Holocene period. Southwest China has experienced a long history of human activities in terms of deforestation and agricultural development. Here we present a continuous fossil pollen record covering the past 2,100 years from Beihai Wetland in western Yunnan Province, for a better understanding of regional vegetation history and potential human activities. The pollen results indicate that the forest components show decreasing trends, including Alnus dominated deciduous broadleaved forest and evergreen broadleaved forest represented by evergreen Quercus. On the other hand, herbs such as Poaceae and Artemisia expanded along with the decline of forest, especially during the period after ad 1120. The results of ordination analysis further confirm such a pattern in which the first PCA component (PC1, capturing 42.2% of total variance) represents an increasing trend, which is subsequently interpreted as an index of human activities. Our findings show broadly identical patterns to previously published sedimentary records from Yunnan as well as historical documents. The human activities increased following the expansion in regional population, in the form of deforestation and regional agricultural development. They may also have caused the expansion of herbs, especially Poaceae, which replaced forest. Therefore, as indicated by the fossil pollen record from the Beihai Wetland, human activities in southwest China increased gradually during the past 2,100 years and more rapidly after ad 1120. Results of sediment influx and grain size analyses showed generally consistent patterns with the signs of summer monsoons captured by stable oxygen isotope records from stalagmites, indicating limited influence from human activities within the wetland system compared to the regional landscape.

MONITORING TEMPORAL AND SPATIAL CHANGES OF LAND USE AND LAND COVER BASED ON REMOTE SENSING IN THE HILLY REGION OF CENTRAL SICHUAN BETWEEN 1989 AND 2009

Abstract. In recent years, under the background of government policy and the development of social economy, land use in hilly region of central Sichuan has changed drastically. Especially the Changzhi soil erosion control project that has been carried out since 1989 and the policy of converting from farm land to forest which has been carried out after flooding disaster in 1998, have seriously affected the land use in hilly region of central Sichuan between 1989 and 2009. In order to detect these changes and acquire the land use information, this study was conducted in Lizixi basin which is the typical area in hilly region of central Sichuan. Supervised classification was applied to the processing procedure of TM, SPOT data in 1989, 1999 and Rapideye data in 2009. The results were further improved by visual interpretation. The overall classification accuracy reaches 88.33% and the kappa is 0.8350. The elevation was classified into five grades to detect the land use distribution in different elevation gradients in 2009. Post-classification comparisons of the classified images indicated that the major change consists that the cultivated land is decreasing and forest is increasing. The force factor of these changes may be the policy of converting from farmland to forest. Because of the labor shortage, 53.29% of the decreased cultivated land has changed to abandoned arable land which is covered by lush grass and mainly distribute on the halfway up to the hill. The urban area has enlarged 7 times due to the large number of migrants from rural to urban. Overall these changes reflect the regional policies and human activities are the major and important force factors of changes in the hilly region of central Sichuan during last two decades.

Evolution of Ecological Security in the Tableland Region of the Chinese Loess Plateau Using a Remote-Sensing-Based Index

Maintaining optimal ecological security is a serious issue in the Chinese Loess Plateau (CLP). Remote sensing ecological indexes (RSEI) of three main tableland regions of the CLP were calculated based on spectral information provided by remote sensing imaging satellites between 2000 and 2018. We were able to use RSEI values to systematically evaluate the temporal and spatial variation in the regional ecological environment and determine the influential factors that mainly associated with these changes. The results showed that between 2000 and 2018, the ecological environment improved, remained stable, and deteriorated, respectively, in the Gansu, Shaanxi, and Shanxi tablelands. Regions with poor or fair RSEIs were concentrated around the main river basins, while regions with moderate RSEIs were associated with poor ecological conditions and poor areas. The significant spatiotemporal variation in RSEI indicates that the ecological system in this region is relatively fragile. We also observed that natural factors such as the temperature, potential evapotranspiration, and precipitation had the greatest influence on the overall ecological quality. The rapid increase in the regional population and human activity played an important role in the variation in the regional RSEI. This research will provide important information on controlling regional soil erosion and ecological restoration in the CLP.

Impact of seagrass establishment, industrialization and coastal infrastructure on seagrass biogeochemical sinks

The study of a Posidonia sinuosa sedimentary archive has delivered a millenary record of environmental change in Cockburn Sound (Western Australia). Ecosystem change is a major environmental problem challenging sustainable coastal development worldwide, and this study shows baseline trends and shifts in ecological processes in coastal ecosystems under environmental stress. The concentrations and fluxes of biogeochemical elements over the last 3,500 years indicate that important changes in ecosystem dynamics occurred over the last 1,000 years, in particular after ~1900's, probably related to establishment of seagrass meadows in the area and to local and regional human activities (industry and coastal development), respectively. The establishment of seagrasses ~1,000 years ago in the area of study is supported by the appearance of Posidonia fibres from ~40 cm soil depth until the core top, higher δ13C values indicating a larger contribution of seagrass-matter to the soil organic carbon pool, and increased concentration of fine sediments driven by the effect of seagrass canopy in enhancing sedimentation. The comparison of organic carbon, nutrients and metal concentrations and fluxes between pre- and post-establishment of seagrasses shows that seagrass establishment resulted in up to 9-fold increase in the soil biogeochemical sink. In ~1900's, shifts in the concentrations of metals, carbonates, organic carbon, sediment grain size, and δ13C and δ15N values of the organic matter were detected, demonstrating an alteration in seagrass ecosystem functioning following the onset of European settlement. Anthropogenic activities, and in particular the construction of a causeway in 1970's, enhanced seagrass soil organic carbon and metal accumulation rates by 36- and 39-fold, respectively, showing that human-made structures can enhance the biogeochemical sink capacity of seagrasses. Here we reconstruct the impact of human activities on seagrass ecosystem dynamics and blue carbon, which can inform local management of Cockburn Sound and seagrass conservation for climate change mitigation and adaptation.

Regional Ecological Risk Assessment of Wetlands in the Sanjiang Plain with Respect to Human Disturbance

Characterization of the intensity of regional human disturbances on wetlands is an important scientific issue. In this study, the pole-axis system (involving multi-level central places and roads) was recognized as a proxy of direct risk to wetlands stemming from human activities at the regional or watershed scale. In this respect, the pole-axis system and central place theory were adopted to analyze the spatial agglomeration characteristics of regional human activities. Soil erosion and non-point source (NPS) pollution, indicating the indirect effect of human activities on wetlands, were also considered. Based on these human disturbance proxies, which are considered regional risk sources to wetlands, incorporated with another two indicators of regional environment, i.e., vulnerability and ecological capital indexes, the regional ecological risk assessment (RERA) framework of wetlands was finally established. Using this wetland RERA framework, the spatial heterogeneity of risk grades within the Naoli River Basin, a typical concentrated wetland region in the Sanjiang Plain, was analyzed. The results showed that (1) high- and very high-risk source intensity areas displayed a ring-shape distribution pattern, which reflected the influence of the regional pole-axis system; (2) owing to their high ecological capital value per unit area and vulnerability level, the wetlands had the highest risk grade, as did central places (i.e., those areas where county seats and administration bureaus of farms were located). In terms of proportion, the low-, medium-, high-, and very high-risk areas accounted for 72.0%, 16.8%, 10.1%, and 1.1% of the study area, respectively. The identification and classification of risk sources to wetlands that are related to human activity at the watershed scale could provide clear perspectives in order to reduce severe risk sources to these areas, especially those Ramsor Convention-appointed sites of international importance. Moreover, the assessment framework used in this paper will provide a helpful reference for related research in the future. Finally, the new management guidelines proposed in this paper will be beneficial for lowering the ecological risk level of wetlands at the watershed or regional scale for the Sanjiang Plain or other wetland-concentrated regions.

Stability of the permafrost peatlands carbon pool under climate change and wildfires during the last 150 years in the northern Great Khingan Mountains, China

Peatlands store one-third of the total global soil carbon (C.) despite covering only 3–4% of the global land surface. Most peatlands are distributed in mid-high latitude regions and are even in permafrost regions, are sensitive to climate change and are disturbed by wildfire. Although several studies have focused on the impact of historical climate change and regional human activities on the C. accumulation process in these peatlands, the impact of these factors on the stability of the C. pool remains poorly understood. Here, based on the 210Pb age-depth model, we investigated the historical variations of C. stability during the last 150 years for five typical peatlands in the northern Great Khingan Mountains (Northeast China), an area located in a permafrost region that is sensitive to climate change and to wildfires, which have clearly increased due to regional human activities. The results showed that low C. accumulation rates (CARs) and weakly C. stability in studied peatlands before 1900. While, the increasing anthropogenic wildfire frequency and the residual products (e.g. pyrogenic carbon) increased the CARs and C. stability in peatlands from 1900 to 1980. The mean July temperature is the most important climate factor for peatlands C. stability. After 1980, due to the low wildfire frequencies influenced by human policies, increasing temperatures and decreasing precipitation not only increased the CARs but also markedly increased the C. stability of the peatlands C. pool in the northern Great Khingan Mountains, especially after 2000.

MONITORING THE SPATIO-TEMPORAL TRAJECTORY OF URBAN AREA HOTSPOTS IN WUHAN, CHINA USING TIME-SERIES NIGHTTIME LIGHT IMAGES

Abstract. Urban area hotspots can be considered as an ideal representation of spatial heterogeneity of human activities within a city, which is susceptible to regional urban expansion pattern pattern. However, in previous studies most researchers focused on extracting urban extent, leaving the interior variation of nighttime radiance intensity poorly explored. With the help of multi-source data sets such as DMSP/OLS (NTL), LST and NDVI, we proposed an applicable framework to identify and monitor the spatiotemporal trajectory of polycentric urban area hotspots. Firstly, the original NTL dataset were calibrated to reduce inconsistency and discontinuity. And we integrated NTL, LST as well as NDVI and established an urban index TVANUI capturing the approximate urban extents. Secondly, multi-resolution segmentation algorithm, neighborhood statistics analysis and a local-optimized threshold method were employed to get more precise urban extent with an overall accuracy above 85% and a Kappa above 0.70. Thirdly, the urban extents were utilized as masks to get corresponding radiance intensity from calibrated NTL. Finally, we established the Gaussian volume model for each cluster and the resulting parameters were used to quantitatively depict hotspot features (i.e., intensity, morphology and centroid dynamics). All the identified urban hotspot showed our framework could successfully capture polycentric urban hotspots, whose fitting coefficients were over 0.7. The spatiotemporal trajectory of hotspot powerfully revealed the impact of the regional urban growth pattern and planning strategies on human activities in the city of Wuhan. This study provides important insights for further studies on the relationship between the regional urbanization and human activities.

OMV Petrom starts up PolyFuel unit at Petrobrazi refinery in Romania

Detection and attribution of streamflow changes would be a standing point towards optimizing the management of basin-scale water resources. The Three Gorges Reservoir (TGR), the largest hydropower project worldwide, has recently experienced obvious inflow reduction, which has restricted its capability to achieve the designed electricity generation. This study considered the design period of TGR (1961–1990) as the baseline period for evaluating inflow variations during the subsequent impact period (1991–2015). Annual inflow reduced by 6%, and seasonal inflow significantly decreased by 16% in autumn, which is the main season for filling reservoir. A new stepwise procedure with the help of a water-use model, a lumped hydrological model, and a generic reservoir operation model is presented to unravel the causes of inflow reduction. Results revealed that the drier climate predominantly caused inflow decreases. Human activities have notably enhanced in recent decades, however, they have not posed significant threats to inflow deficiency. Climate variability, water consumption, and upstream reservoir operation contributed by 78%, 15%, and 7% to decrease annual inflow while they contributed by 63%, 4%, and 33% to reduce autumn inflow, respectively. The proposed procedure can quantitatively disentangle major human impacts including water consumption and reservoir regulation. Such information enriches policy makers' knowledge for framing delicacy management of regional human activities in response to changing streamflow pattern.