Modelling for forest growing stock assessment using satellite data — A case study

The satellite digital vegetation index data has been correlated with the forest growing stock by fitting linear regression models. The goodness of fit was tested. The analysis showed that the vegetation index which is the ratio of reflectance of vegetation in near infrared band to red wave band of electromagnetic spectrum is highly correlated to forest growing stock and the same can be used to predict the volume in remote forest areas for quick assessment purpose. Implications for future forest inventory are discussed.     

海拉尔盆地基底晚古生代adakite的发现及其地质意义

海拉尔盆地的前中生代基底隶属中亚造山带东段的兴蒙造山带。 在盆地基底地层中发现了具有adakite成分特征的粗面安山岩、英安岩和闪长玢岩。 这些火成岩与晚古生代沉积地层交互或伴生, 共同构成晚中生代裂陷盆地的基底。 地球化学研究表明, 这些火成岩基本上属于高钾钙碱性和准铝质岩石系列, 具有高SiO₂和Al₂O₃含量, 高Sr、Sr/Y和La/Yb值, 富集轻稀土(LREE), 亏损重稀土(HREE)、Y和高场强元素(HFSE),Eu表现弱的负异常或轻微的正异常, 相容元素Mg、Cr和Ni含量低, 这些特征与增厚下地壳部分熔融成因的adakite非常相似, 而明显不同于典型的由俯冲洋壳熔融形成的adakite。 样品的(⁸⁷Sr/⁸⁶Sr)_i值基本一致,为0.7041, (¹⁴³Nd/¹⁴⁴Nd)_i值为0.51243~0.51247, ε_Nd (t)为正值(+3.7~+4.5), 显示其岩浆源区可能源于弱亏损地幔, 或亏损地幔受到地壳物质混染。 本文认为海拉尔地区晚古生代adakite型岩浆很可能是由当时新底侵的玄武质下地壳在角闪岩相向榴辉岩相过度或榴辉岩相条件下部分熔融形成。 这些adakite岩石的出现反映了兴蒙造山带晚古生代受到了古亚洲洋的俯冲消减引起的强烈的地幔玄武质岩浆底侵作用, 并由此导致地壳垂向上显著的增生加厚过程。     

A system-level modelling perspective of the KwaZulu-Natal Bight ecosystem,eastern South Africa

The KwaZulu-Natal Bight comprises the only sizeable shelf region on the eastern coast of South Africa, and is influenced by both the Agulhas Current on its seaward side and rivers and estuaries on its landward side. Established knowledge of the effect of the Agulhas Current includes the influence on nutrient concentrations in the bight of a semi-permanent upwelling cell at its northern border (St Lucia) and, to a much lesser extent, of a semi-permanent eddy feature at its southern extremity. Current modelling efforts, however, point to a very important role of land-derived nutrients, which supplement the productivity of food webs of the bight. This connectivity of the bight to its adjacent ecosystems has various implications. First, its productivity has traditionally been viewed via phytoplankton growth, whereas ecosystem modelling efforts point to a very high reliance on imported detritus (mainly land-derived) in order to sustain especially the rich benthic food web. The benthos in the bight dominates the food web, and is in marked contrast to the upwelling system of the west coast of South Africa (Atlantic Ocean) where water-column productivity dominates. Second, the importance of the connectivity of the Thukela Bank prawn-trawling ground to estuarine nursery areas, which has been modelled quantitatively, highlights the significance of this particular ecosystem connectivity for fisheries and also for the Thukela Bank food web. Heterogeneity across the bight is apparent for nutrient turnover rates (carbon, nitrogen, phosphorus), CNP content and stoichiometry, whereas nitrogen is a limiting nutrient across the entire bight. The food web near the Thukela River is richer in nutrient content and more active (higher turnover rates) compared to the northern and southern parts of the bight. This environmental heterogeneity was also apparent from the CNP content and stoichiometry of the various species and species groups in the bight. Requirements to take the hydrodynamic, biogeochemical and first ecosystem modelling efforts towards a meaningful predictive capability are discussed. The importance of adopting a system-level view of the bight and its connected systems for realistic exploration of global change scenarios is highlighted.     

Leigh Marine Laboratory contributions to marine conservation

Abstract

The Leigh Marine Laboratory (LML) has taken full advantage of its location on the shores of one of the world's first no-take marine reserves. The foresight of the founders of the laboratory has enabled the pursuit of ecological studies that have been amongst the first to demonstrate the effectiveness of reserves as a tool for conservation and restoration. The insights flowing from this work at Leigh are important, not only for targeted marine species, but also at the ecosystem level, and have proven to be highly relevant to broader resource management issues. Novel methodologies have been employed in the pursuit of these aims, helping to popularise their wider use. More recent work has focused on understanding the processes underlying the variability in response to marine conservation in marine reserves across the spectrum of coastal marine habitats in New Zealand. The LML has probably exceeded the expectations of its founders, who hoped the laboratory might generate information of interest in the fields of ‘resource management, food web dynamics and natural fluctuations distinct from man-induced changes’, and its contribution in the field of marine conservation has been significant both within New Zealand and internationally. This has been a 50-year journey that has gone from a focus on local effects of conservation to the broader context, from direct effects of protection to indirect effects, and from small-scale spatial conservation management to ecosystem-based management.     

Biogeochemical ocean-atmosphere transfers in the Arabian Sea

Transfers of some important biogenic atmospheric constituents, carbon dioxide (CO₂), methane (CH₄), molecular nitrogen (N₂), nitrous oxide (N₂O), nitrate , ammonia (NH₃), methylamines (MAs) and dimethylsulphide (DMS), across the air–sea interface are investigated using published data generated mostly during the Arabian Sea Process Study (1992–1997) of the Joint Global Ocean Flux Study (JGOFS). The most important contribution of the region to biogeochemical fluxes is through the production of N₂ and N₂O facilitated by an acute, mid-water deficiency of dissolved oxygen (O₂); emissions of these gases to the atmosphere from the Arabian Sea are globally significant. For the other constituents, especially CO₂, even though the surface concentrations and atmospheric fluxes exhibit extremely large variations both in space and time, arising from the unique physical forcing and associated biogeochemical environment, the overall significance in terms of their global fluxes is not much because of the relatively small area of the Arabian Sea. Distribution and air–sea exchanges of some of these constituents are likely to be greatly influenced by alterations of the subsurface O₂ field forced by human-induced eutrophication and/or modifications to the regional hydrography.     

Methane and nitrous oxide fluxes in the polluted Adyar River and estuary, SE India

We measured dissolved N(2)O, CH(4), O(2), NH(4)(+), NO(3)(-) and NO(2)(-) on 7 transects along the polluted Adyar River-estuary, SE India and estimated N(2)O and CH(4) emissions using a gas exchange relation and a floating chamber. High NO(2)(-) implied some nitrification of a large anthropogenic NH(4)(+) pool. In the lower catchment CH(4) was maximal (6.3+/-4.3 x 10(4)nM), exceeding the ebullition threshold, whereas strong undersaturation of N(2)O and O(2) implied intense denitrification. Emissions fluxes for the whole Adyar system approximately 2.5 x 10(8) g CH(4)yr(-1) and approximately 2.4 x 10(6)gN(2)O yr(-1) estimated with a gas exchange relation and approximately 2 x 10(9) g CH(4)yr(-1) derived with a floating chamber illustrate the importance of CH(4) ebullition. An equivalent CO(2) flux approximately 1-10 x 10(10)gy r(-1) derived using global warming potentials is equivalent to total Chennai motor vehicle CO(2) emissions in one month. Studies such as this may inform more effective waste management and future compliance with international emissions agreements.     

Carbon Dioxide and Methane Emissions from Mangrove-Associated Waters of the Andaman Islands,Bay of Bengal

We estimated CO₂ and CH₄ emissions from mangrove-associated waters of the Andaman Islands by sampling hourly over 24 h in two tidal mangrove creeks (Wright Myo; Kalighat) and during transects in contiguous shallow inshore waters, immediately following the northeast monsoons (dry season) and during the peak of the southwest monsoons (wet season) of 2005 and 2006. Tidal height correlated positively with dissolved O₂ and negatively with pCO₂, CH₄, total alkalinity (TAlk) and dissolved inorganic carbon (DIC), and pCO₂ and CH₄ were always highly supersaturated (330–1,627 % CO₂; 339–26,930 % CH₄). These data are consistent with a tidal pumping response to hydrostatic pressure change. There were no seasonal trends in dissolved CH₄ but pCO₂ was around twice as high during the 2005 wet season than at other times, in both the tidal surveys and the inshore transects. Fourfold higher turbidity during the wet season is consistent with elevated net benthic and/or water column heterotrophy via enhanced organic matter inputs from adjacent mangrove forest and/or the flushing of CO₂-enriched soil waters, which may explain these CO₂ data. TAlk/DIC relationships in the tidally pumped waters were most consistent with a diagenetic origin of CO₂ primarily via sulphate reduction, with additional inputs via aerobic respiration. A decrease with salinity for pCO₂, CH₄, TAlk and DIC during the inshore transects reflected offshore transport of tidally pumped waters. Estimated mean tidal creek emissions were ～23–173 mmol m^?2 day^?1 CO₂ and ～0.11–0.47 mmol m^?2 day^?1 CH₄. The CO₂ emissions are typical of mangrove-associated waters globally, while the CH₄ emissions fall at the low end of the published range. Scaling to the creek open water area (2,700 km²) gave total annual creek water emissions ～3.6–9.2?×?10¹⁰ mol CO₂ and 3.7–34?×?10⁷ mol CH₄. We estimated emissions from contiguous inshore waters at ～1.5?×?10¹¹ mol CO₂?year^?1 and 2.6?×?10⁸ mol CH₄?year^?1, giving total emissions of ～1.9?×?10¹¹ mol CO₂?year^?1 and ～3.0?×?10⁸ mol CH₄?year^?1 from a total area of mangrove-influenced water of ～3?×?10⁴ km². Evaluating such emissions in a range of mangrove environments is important to resolving the greenhouse gas balance of mangrove ecosystems globally. Future such studies should be integral to wider quantitative process studies of the mangrove carbon balance.     

安徽女山麻粒岩包体：矿物学特征、下地壳地温曲线及其成因意义

女山玄武岩中麻粒岩包体的主要矿物组合为 Opx+Cpx+Pl,均呈条带状构造 ,具有细粒粒状变晶结构或不等粒结构。女山麻粒岩包体的斜方辉石及单斜辉石的化学成分都非常相似于华北太古代麻粒岩地体 ,而明显区别于汉诺坝麻粒岩包体。通过对世界上含石榴石麻粒岩的检验 ,表明 Wells(1977) :二辉石温度计与 Mc Carthy & Pati～no Douce(1998)的 Cpx+Pl+Qz压力计的温压计组合是计算麻粒岩平衡温压的可行方法 ,并得到了女山麻粒岩包体平衡温度分布于 80 9～ 899℃之间 ,主要集中于 85 0± 2 0 C,平衡压力为 0 .6 0～ 0 .95 GPa。由麻粒岩包体的平衡温压所建立起的女山地区下地壳地温曲线与 Xuet a1.(1998)建立的上地幔地温曲线上延部分非常吻合。根据地温线推得的“岩石学”Moho面深度为 31km土 ,与“地震”Moho面深度相一致 ,表明女山地区不具有明显的壳幔过渡带。女山地区缺乏强烈的底侵作用以及麻粒岩包体的特征矿物化学成分暗示了女山麻粒岩包体可能来源于华北克拉通结晶基底     

A Lagrangian biogeochemical study of an eddy in the Northeast Atlantic

We report the results of an experiment in the Northeast Atlantic in which sulphur hexafluoride (SF₆) was released within an eddy and the behaviour of trace gases, nutrients and productivity followed within a Lagrangian framework over a period of 24 days. Measurements were also made in the air above the eddy in order to estimate air-sea exchange rates for some components. The physical, biological and biogeochemical properties of the eddy resemble those of other eddies studied in this area, suggesting that the results we report may be applicable beyond the specific eddy studied. During a period of low wind speed at the start of the experiment, we are able to quantitatively describe and balance the nutrient and carbon budgets for the eddy. We also report concentrations of various trace gases in the region which are similar to those observed in other studies and we estimate exchange rates for several trace gases. We show that the importance of gas exchange over other loss terms varies with time and also varies for the different gases. We show that the various trace gases considered (CO₂, dimethyl sulphide (DMS), N₂O, CH₄, non-methane-hydrocarbons, methyl bromide, methyl iodide and volatile selenium species) are all influenced by physical and biological processes, but the overall distribution and temporal variability of individual gases are different to one another. A storm disrupted the stratification in the eddy during the experiment, resulting in enhanced nutrient supply to surface waters, enhanced gas exchange rates and a change in plankton community, which we quantify, although overall productivity was little changed. Emphasis is placed on the regularity of storms in the temperate ocean and the importance of these stochastic processes in such systems.     

Simulating estuarine nitrous oxide production by means of a dynamic model

We describe a dynamic model developed from a commercially available modeling package (ECoS-III) to simulate estuarine dissolved inorganic nitrogen (DIN) dynamics, and consequent N(2)O production and atmospheric flux on the timescale of tidal cycles. Simulated model state variables were NH(4)(+), NO(3)(-) and N(2)O concentrations, and salinity. Model outputs were evaluated through comparison with summer field data for the Tyne estuary, UK. The model adequately reproduced the observed axial profiles of NH(4)(+), NO(3)(-) and N(2)O concentrations. Nitrification was shown to be the dominant N(2)O source and estimates of the ratios nitrification to DIN load and N(2)O emission to DIN load are considerably lower than the corresponding values adopted in global scale models of estuarine N(2)O emissions based on DIN transformations. Hence our results are consistent with the requirement imposed by atmospheric N(2)O growth rate constraints that the amount of atmospheric N(2)O arising from agriculturally related sources, including estuarine transformations of N, be revised downward.