Quantifying greenhouse gas emissions from soils: Scientific basis and modeling approach

Abstract

Global climate change is one of the most important issues of contemporary environmental safety. A scientific consensus is forming that the emissions of greenhouse gases, including carbon dioxide, nitrous oxide and methane, from anthropogenic activities may play a key role in elevating the global temperatures. Quantifying soil greenhouse gas emissions is an essential task for understanding the atmospheric impacts of anthropogenic activities in terrestrial ecosystems. In most soils, production or consumption of the three major greenhouse gases is regulated by interactions among soil redox potential, carbon source and electron acceptors. Two classical formulas, the Nernst equation and the Michaelis–Menten equation, describe the microorganism-mediated redox reactions from aspects of thermodynamics and reaction kinetics, respectively. The two equations are functions of a series of environmental factors (e.g. temperature, moisture, pH, Eh) that are regulated by a few ecological drivers, such as climate, soil properties, vegetation and anthropogenic activity. Given the complexity of greenhouse gas production in soils, process-based models are required to interpret, integrate and predict the intricate relationships among the gas emissions, the environmental factors and the ecological drivers. This paper reviews the scientific basis underlying the modeling of greenhouse gas emissions from terrestrial soils. A case study is reported to demonstrate how a biogeochemical model can be used to predict the impacts of alternative management practices on greenhouse gas emissions from rice paddies.     

新疆绿洲区秸秆燃烧污染物释放量及固碳减排潜力

根据 2004-2013年新疆绿洲区主要作物产量,采用排放因子法对秸秆燃烧污染物排放量和碳释放量进行了估算,结果表明,2013年新疆地区作物秸秆燃烧排放的CO₂、CO、CH₄、NMVOC、OC、BC、SO₂、NO_x、NH₃和PM_2.5的量分别为9.0×10⁶ t、5.5×10⁵ t、1.6×10⁴ t、9.4×10⁴ t、1.9×10⁴ t、3.9×10³ t、2.4×10³ t、1.8×10⁴ t、7.8×10³ t和1.2×10⁵ t,碳排放总量为2.7×10⁶ t;在排放清单中,CO₂和CO是主要污染物,分别占污染物排放总量的91.6%和5.6%;棉花秸秆为排放贡献最大的污染源,占总排放量的43.3%,其次是小麦秸秆和玉米秸秆,分别占28.3%和21.9%.在此基础上,基于生物炭固碳技术,对该区域作物秸秆转化为生物炭的固碳量和碳封存潜力进行了估算,结果表明,若把被燃烧的三类秸秆(棉花、小麦和玉米)转化为生物炭,则每年可减少该区域54.9%的碳排放量;若将作物秸秆全部转化为生物炭,每年将有3.6×10⁶ t碳和1.3×10⁷ t CO₂被长期封存于生物炭中。可见,生物炭具有良好的固碳减排潜力,是一种可持续的碳封存技术。     

森林资源二类调查技术新旧规定的对比分析

对森林资源二类调查原“技术规定“和新“技术规定“进行了对比分析,提出了几点建设性意见.     

三类调查中手持GPS面积精度试验研究

采用后处理差分的方法,研究了手持GPS在三类调查中的面积精度。试验结果表明:在面积大于627.7m2以上时,利用后处理差分方法获得的数据面积精度可以达到95%,能够满足三类调查对面积精度的需要。     

在ISO9001标准模式下建立林业调查规划设计质量管理体系的探讨

基于质量管理的基本原则、方法和实践,对在ISO9001标准模式下建立林业调查规划设计质量管理体系进行探讨,从质量管理体系建立的必要性、基本要求、体系文件、实施要点等方面。阐述了林业调查规划设计质量管理体系建立的思路与方法。旨在提高林业调查规划设计管理水平和成果质量,满足开放式的市场竞争需要,更好地服务于现代林业建设事业。     

National inventories of down and dead woody material forest carbon stocks in the United States: Challenges and opportunities

Concerns over the effect of greenhouse gases and consequent international agreements and regional/national programs have spurred the need for comprehensive assessments of forest ecosystem carbon stocks. Down and dead woody (DDW) materials are a substantial component of forest carbon stocks; however, few surveys of DDW carbon stocks have been conducted at national-scales around the world. This study uses the DDW survey of the United States as a case study to examine the challenges of inventorying DDW at a national scale, reviews how dead wood carbon pools are currently estimated in the National Greenhouse Gas Inventory (NGHGI), and suggests opportunities for improving such inventories. The US currently estimates national DDW carbon stocks using models with standing live tree attributes as predictor variables, calibrated using preliminary DDW field estimates. In recent years, implementation of a national DDW inventory has resulted in inventory-based DDW estimates. National field-based DDW estimates follow the national patterns of DDW carbon dispersion seen in earlier model-based estimates. Although the current DDW inventory provides fairly repeatable measurements within a statistically defensible national sample design for producing national estimates of DDW carbon stocks, improving numerous aspects of the DDW survey would may improve the accuracy and precision of C estimates reported in the NGHGI.     

GPS手持机在森林资源连续清查中的应用探讨

对手持式GPS接收机在森林资源连续清查中应用方法如:地理坐标参数的获取、计算和设置;在样地初设及复查时的应用作了论述,认为应用其可减少工作量,提高定位精度和复位率,有利于质量管理.     

连续森林清查应用地理信息估计蓄积量的方法

提出了应用地理信息系统作为技术手段,以常规固定样地设置为抽样方式,以地形因子与蓄积量回归的估计方法来估计森林总体蓄积量的问题。讨论了可能性和可行性,给出和推导了总体无偏估计值和方差公式。     

A correction factor for,and its application to,visual censuses of littoral fish

Visual estimation techniques were used between October 1976 and May 1977 on the fish fauna of an enclosed mid-intertidal pool in the eastern Cape, South Africa, to test the usefulness and accuracy of this non-consumptive census method. In January, 1977, two pools were censused for fish, then poisoned using the ichthyocide ‘pronoxfish’ and all fish collected. Forty species in 21 families were obtained from the two stations. The accuracy of visual estimates varied with the species of fish. Secretive and cryptically coloured types, as well as species which Inhabit crevices, were underestimated, between 0 and 86% being counted. Other fish with protective colours but that occur more openly and do not react adversely to divers, as well as schooling species, were also underestimated, but up to 100% of the total were observed. Those which occur singly or in small groups in the water column were counted more accurately, with 57 to 100% of the actual number being seen. Correction factors were calculated from these data and applied to a census taken of one pool in May. Comparisons of corrected and actual numbers Indicate that these factors were relatively accurate for non-secretive species. The factors will, however, vary for each species, from observer to observer, depending on their personal experience, and from area to area.     

掌上森林资源调查仪(PDA)二类调查软件的开发应用及特点

阐述了对PDA二类调查软件的研究、实验与应用的过程,总结了调查软件的图像处理及显示、图层设计及调查数据存储、库文件接口程序、导航与定位、资源调查、调查数据统计等功能及特点,对软件作用与发展进行了论述.