Potential of texture from SAR tomographic images for forest aboveground biomass estimation     

《International Journal of Applied Earth Observation and Geoinformation》2020

Synthetic Aperture Radar (SAR) texture has been demonstrated to have the potential to improve forest biomass estimation using backscatter. However, forests are 3D objects with a vertical structure. The strong penetration of SAR signals means that each pixel contains the contributions of all the scatterers inside the forest canopy, especially for the P-band. Consequently, the traditional texture derived from SAR images is affected by forest vertical heterogeneity, although the influence on texture-based biomass estimation has not yet been explicitly explored. To separate and explore the influence of forest vertical heterogeneity, we introduced the SAR tomography technique into the traditional texture analysis, aiming to explore whether TomoSAR could improve the performance of texture-based aboveground biomass (AGB) estimation and whether texture plus tomographic backscatter could further improve the TomoSAR-based AGB estimation. Based on the P-band TomoSAR dataset from TropiSAR 2009 at two different sites, the results show that ground backscatter variance dominated the texture features of the original SAR image and reduced the biomass estimation accuracy. The texture from upper vegetation layers presented a stronger correlation with forest biomass. Texture successfully improved tomographic backscatter-based biomass estimation, and the texture from upper vegetation layers made AGB models much more transferable between different sites. In addition, the correlation between texture indices varied greatly among different tomographic heights. The texture from the 10 to 30 m layers was able to provide more independent information than the other layers and the original images, which helped to improve the backscatter-based AGB estimation.  相似文献   

2016年夏季舟山近岸海域底栖生物调查与研究          下载免费PDF全文

蔡丽萍  金敬林  吴盈子 《海洋开发与管理》2018,35(9):82-87

底栖生物是海洋环境质量的重要指标。2016年夏季对舟山近岸海域37个站位的底栖生物进行调查，此次调查共鉴定出底栖生物45种，平均栖息密度为41 ind/m2，平均生物量为3.92 g/m2，底栖生物的栖息密度和生物量基本上由西向东逐渐升高。底栖生物的种类、密度、生物量、多样性指数与水深及水质中的盐度、pH、悬浮物、总磷、总氮呈弱或中等程度相关，与沉积物中重金属（铜、锌、铅、镉、铬、总汞）、砷、有机碳呈弱或中等程度的相关性，尤其与镉含量的相关性最为明显。由ABC曲线分析可知，该调查海域底栖生物受到一定程度的扰动。与2005年该海域调查结果比较表明，该海域底栖生物的多样性指数平均值较2005年略有降低，平均生物量较2005年降低，但平均密度较2005年升高。此次调查出现无底栖生物站位所占的比例较2005年上升。研究表明，2016年舟山海域海洋环境质量状况劣于2005年，应加强海洋环境监测与治理。  相似文献   

Development and implementation of a multiscale biomass model using hyperspectral vegetation indices for winter wheat in the North China Plain     

《International Journal of Applied Earth Observation and Geoinformation》2014

Crop monitoring during the growing season is important for regional management decisions and biomass prediction. The objectives of this study were to develop, improve and validate a scale independent biomass model. Field studies were conducted in Huimin County, Shandong Province of China, during the 2006–2007 growing season of winter wheat (Triticum aestivum L.). The field design had a multiscale set-up with four levels which differed in their management, such as nitrogen fertilizer inputs and cultivars, to create different biomass conditions: small experimental fields (L1), large experimental fields (L2), small farm fields (L3), and large farm fields (L4). L4, planted with different winter wheat varieties, was managed according to farmers’ practice while L1 through L3 represented controlled field experiments. Multitemporal spectral measurements were taken in the fields, and biomass was sampled for each spectral campaign. In addition, multitemporal Hyperion data were obtained in 2006 and 2007. L1 field data were used to develop biomass models based on the relation between the winter wheat spectra and biomass: several published vegetation indices, including NRI, REP, OSAVI, TCI, and NDVI, were investigated. A new hyperspectral vegetation index, which uses a four-band combination in the NIR and SWIR domains, named GnyLi, was developed. Following the multiscale concept, the data of higher levels (L2 through L4) were used stepwise to validate and improve the models of the lower levels, and to transfer the improved models to the next level. Lastly, the models were transferred and validated at the regional scale using Hyperion images of 2006 and 2007. The results showed that the GnyLi and NRI models, which were based on the NIR and SWIR domains, performed best with R² > 0.74. All the other indices explained less than 60% model variability. Using the Hyperion data for regionalization, GnyLi and NRI explained 81–89% of the biomass variability. These results highlighted that GnyLi and NRI can be used together with hyperspectral images for both plot and regional level biomass estimation. Nevertheless, additional studies and analyses are needed to test its replicability in other environmental conditions.  相似文献   

Carbon capture and storage, bio-energy with carbon capture and storage, and the escape from the fossil-fuel lock-in     

Philip J. Vergragt  Nils Markusson 《Global Environmental Change》2011,21(2):282-292

Carbon capture and storage (CCS) is increasingly depicted as an important element of the carbon dioxide mitigation portfolio. However, critics have warned that CCS might lead to “reinforced fossil fuel lock-in”, by perpetuating a fossil fuel based energy provision system. Due to large-scale investments in CCS infrastructure, the fossil fuel based ‘regime’ would be perpetuated to at least the end of this century.In this paper we investigate if and how CCS could help to avoid reinforcing fossil fuel lock-in. First we develop a set of criteria to estimate the degree of technological lock-in. We apply these criteria to assess the lock-in reinforcement effect of adding CCS to the fossil fuel socio-technical regime (FFR).In principle, carbon dioxide could be captured from any carbon dioxide point source. In the practice of present technological innovations, business strategies, and policy developments, CCS is most often coupled to coal power plants. However, there are many point sources of carbon dioxide that are not directly related to coal or even fossil fuels. For instance, many forms of bio-energy or biomass-based processes generate significant streams of carbon dioxide emissions. Capturing this carbon dioxide which was originally sequestered in biomass could lead to negative carbon dioxide emissions.We use the functional approach of technical innovations systems (TIS) to estimate in more detail the strengths of the “niches” CCS and Bio-Energy with CCS (BECCS). We also assess the orientation of the CCS niche towards the FFR and the risk of crowding out BECCS. Next we develop pathways for developing fossil energy carbon capture and storage, BECCS, and combinations of them, using transition pathways concepts. The outcome is that a large-scale BECCS development could be feasible under certain conditions, thus largely avoiding the risk of reinforced fossil fuel lock-in.  相似文献   

胶州湾浮游纤毛虫丰度和生物量的周年变化   总被引：3，自引：1，他引：2  

于莹  张武昌  赵楠  孙晓霞  张翠霞  丰美萍  肖天 《海洋与湖沼》2011,42(5):690-701

于2007年1—12月在胶州湾搭载＂创新号＂考察船完成了12个航次的浮游纤毛虫丰度和生物量调查。结果表明,胶州湾纤毛虫丰度的范围为41—31077ind/L,生物量范围为0.06—99.37μgC/L。表层纤毛虫平均丰度于6月达到全年最高值（6065ind/L）,12月为最低值（843ind/L）;平均生物量8月达全年...  相似文献   

Volumetric mapping of tubeworm colonies in Kagoshima Bay through autonomous robotic surveys     

Toshihiro Maki  Ayaka KumeTamaki Ura 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(7):757-767

We developed and tested a comprehensive method for measuring the three-dimensional distribution of tubeworm colonies using an autonomous underwater vehicle (AUV). We derived volumetric measurements such as the volume, area, average height, and number of tubes for colonies of Lamellibrachia satsuma, the world's shallowest-dwelling vestimentiferan tubeworm discovered at a depth of 82 m, at the Haorimushi site in Kagoshima Bay, Japan, by processing geometric and visual data obtained through low-altitude surveys using the AUV Tri-Dog 1. According to the results, the tubeworm colonies cover an area of 151.9 m², accounting for 5.8% of the observed area (2600 m²). The total number of tubes was estimated to be 99,500. Morphological parameters such as area, volume, and average height were estimated for each colony. On the basis of average height, colonies could be clearly separated into two groups, short (0.1-0.3 m) and tall (0.6-0.7 m), independent of the area.  相似文献   

The influence of flood frequency, geomorphic setting and grazing on plant communities and plant biomass on a large dryland floodplain     

M.A. Reid  R. OgdenM.C. Thoms 《Journal of Arid Environments》2011,75(9):815-826

Plant communities on semi-arid floodplains are ecologically important and support a diverse local and regional fauna and often pastoral economies. Water resource development may affect these communities and economies by decreasing water supply; determining the nature of these relationships is not straightforward because of the complex nature of plant responses to wetting and possible interactions with other drivers. We investigate the effects of reduced wetting on vegetation by examining spatial patterns in plant communities and above-ground herbaceous plant biomass across a flood frequency gradient, geomorphic settings and grazing exclosures. Community and biomass changes were also examined over time in relation to wetting events. The results demonstrate the importance of wetting on plant communities across timescales. At longer timescales, flood frequency influences community composition; at shorter timescales, wetting increase plant biomass and has a secondary influence on community composition. Plant biomass is also influenced in the short-term by grazing, but there is little influence of grazing on community composition. Soil nutrients do not vary systematically across the floodplain and have little influence on species distributions. We conclude that reduced water availability due to water resource development will result in reduced productivity in the short-term and community composition changes in the long-term.  相似文献   

Holocene climate–fire–vegetation interactions at a subalpine watershed in southeastern British Columbia,Canada     

Colin J. Courtney Mustaphi  Michael F.J. Pisaric 《Quaternary Research》2014

Vegetation assemblages and associated disturbance regimes are spatially heterogeneous in mountain ecosystems throughout the world due to the complex terrain and strong environmental gradients. Given this complexity, numerous sites describing postglacial vegetation and fire histories are needed to adequately understand forest development and ecosystem responses to varying climate and disturbance regimes. To gain insight into long-term historical climate–fire–vegetation interactions in southeastern British Columbia, Canada, sedimentological and paleoecological analyses were performed on a sediment core recovered from a small subalpine lake. The pollen assemblages, stomata, and macroremains indicate that from 9500 to 7500 cal yr BP, Pinus-dominated forests occurred within the catchment and Alnus was also present. Climate was an important control of fire and fire frequency was highest at this time, peaking at 8 fires 1000 yr^− 1, yet charcoal accumulation rates were low, indicative of low terrestrial biomass abundance. From 7500 to 4600 cal yr BP, Pinus decreased as Picea, Abies and Larix increased and fire frequencies decreased to 3–6 fires 1000 yr^− 1. Since 7500 cal yr BP the fire regime varied at a millennial scale, driven by forest biomass abundance and fuel accumulation changes. Local scale (bottom-up) controls of fire increased in relative importance since at least 6000 cal yr BP.  相似文献   

中国燃煤电厂碳捕集与生物质掺烧碳捕集改造的经济性     

袁家海  王耀  张为荣  张健 《气候变化研究进展》2022,18(6):764-776

碳捕集与封存（CCS）技术作为解决全球气候变化问题的重要手段之一,能够有效减少CO₂排放。中国作为碳排放大国,当前电力的主要来源仍是煤电,碳捕集（CC）改造在燃煤电厂中有很大的应用潜力。经济性对CC改造的部署至关重要。为此,本文计算了中国各省典型电厂CC改造前后的平准化度电成本,比较了不同省份的CO₂捕集成本与CO₂避免成本,分析了不同掺烧率下生物质掺烧结合碳捕集(bioenergy with carbon capture,BECC)改造的经济性。研究发现,CC改造会导致不同地区的燃煤电厂度电成本增加57.51%~93.38%。煤价较低的华北和西北地区（青海除外）CC改造经济性较好,BECC改造则更适合华中地区。建议在推进燃煤电厂CC和BECC改造时要充分考虑区域资源特点,完善碳市场建设,形成合理碳价以促进CC和BECC部署。  相似文献   

Evaluation of environmental fate and sinks of PCDD/Fs during specific extreme weather events in Taiwan     

《Journal of Asian Earth Sciences》2013

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are persistent organic pollutants (POPs) that are formed and released unintentionally from anthropogenic sources. The high persistence of PCDD/Fs results in the concentrations of these contaminants in environment decreasing only very slowly. Two transport pathways, air and water, carry PCDD/Fs into all regions of the world. Recently, more frequent extreme weather events, such as storms and floods, have been projected to occur as a result of global warming. Extreme weather events have a documented impact on the remobilization and subsequent bioavailability of POPs. In this study, three specific episodes, namely winter monsoon, southeast biomass burning and tropical cyclone (typhoon) events, which influence the environmental fate and transport of PCDD/Fs in Taiwan, were evaluated based on a climate change scenario. During the winter (northeast) monsoon period, the temperature and relative humidity observed in northern Taiwan decreases sharply. During this time, the quantity of PCDD/Fs adsorbed onto suspended particles, as observed at background sites, was found to increase from 300 ± 127 to 630 ± 115 pg I-TEQ g-TSP⁻¹, which is even higher than that measured in Taipei City (438 ± 80 pg I-TEQ g-TSP⁻¹). Hence, the winter monsoon not only brings cold air but also transports air pollutants and dust over long distances from mainland China to Taiwan. During the 2010 Southeast Asia biomass burning events (2010/3/22–3/28), the level of atmospheric PCDD/Fs were measured in central Taiwan (Mt. Lulin) and in the source region of northern Thailand (Chiang Mai); this revealed that the variations in atmospheric PCDD/F concentrations at these two sites followed a similar pattern. On 25 March 2010, the atmospheric PCDD/F concentration increased dramatically from 1.43 to 6.09 fg I-TEQ m⁻³ at Mt. Lulin and from 7.64 to 12.1 fg I-TEQ m⁻³ in northern Thailand. However, the atmospheric PCDD/F concentration decreased dramatically 1 day after the biomass burning event. Based on the measurements from a dated sediment core collected at a reservoir in northern Taiwan, the sharp increases in input fluxes of PCDD/Fs and mineral-derived elements levels in 1990 (20 ng I-TEQ m⁻² year⁻¹), 2001 (17 ng I-TEQ m⁻² year⁻¹), 2004 (16 ng I-TEQ m⁻² year⁻¹) and 2005 (15 ng I-TEQ m⁻² year⁻¹) seem to be a result of a deep turbid layer formed upstream due to landslides and/or mud flows during the typhoon season. This finding demonstrates the effect of typhoon events on the long-term remobilization of PCDD/Fs as well as supporting the hypothesis that such events would have the potential to remobilize pollutants that have been deposited previously.  相似文献