热带季节雨林碳通量年变化特征及影响因子初探

为深入分析西双版纳热带季节雨林碳通量年变化特征及其与各种因子的关系,通过西双版纳主要自然生态系统(热带季节雨林)2003～2004年林冠一大气间和近地层的碳通量以及不同覆盖状况下的地表碳通量(土壤呼吸)的长期观测,并结合植物光合作用、叶面积指数、凋落物和凋落物分解速率以及温度、辐射等常规气象的测定,对热带季节雨林碳通量的年变化特征及其影响因子进行了综合的分析与研究．结果表明:热带季节雨林的碳通量表现出和其它热带雨林不同的特征,在干季(11～4月)的林冠．大气间碳通量为负值,森林生态系统呈现碳汇效应;而在雨季(5～10月)表现出较弱的碳源效应;森林生态系统碳通量具有明显的日变化特征,在白天呈现碳汇效应,而夜间为碳源效应,并且干季昼间碳通量较大;雨季较小;夜间则呈现相反趋势．林冠植物在昼间具有较强的光合作用,对昼间林冠-大气间碳通量有较大的贡献;林冠和植物林内低矮植物的光合速率均与林冠-大气间碳通量有显著的相关关系,而林内低矮植物的光合速率与林内近地层碳通量仅在干热季存在显著的相关关系．林内不同覆盖状态的地表碳通量具有明显的季节变化;林冠-大气间碳通量与地表碳通量同样具有较好的相关性,地表碳通量是导致热带季节雨林生态系统碳通量呈现特殊分布的主要因子;另外,林冠-大气间碳通量与凋落物量、凋落物分解速率、降水量、土壤含水率和土壤温度均表现出较好的相关性．初步的统计表明,西双版纳热带季节雨林林冠-大气间碳通量在不同季节呈现不同的汇/源效应,在总体上表现为一个较弱的碳汇

Dynamic characteristics of soil respiration of Savanna ecosystem in dry hot valley of Yuanjiang

[Objective] Soil respiration plays an important role in regulating CO_2 concentration in the atmosphere.Soil respiration in the Savanna ecosystem is one of the main sources of global greenhouse gas emissions,but its emission characteristics and main influencing factors are not clear.[Method] Taking the Savanna ecosystem in dry hot valley of Yuanjiang inYunnan Province as an example,the soil respiration was measured from June 2014 to June 2015 by static chamber method,and the dynamic characteristics and its influencing factors in the Savanna ecosystem in Yuanjiang were studied.[Result] Soil temperature,soil moisture and soil respiration had obvious seasonal variations,and as expected,they were significantly(P<0.01)higher in rainy season than in dry season.The relationship between soil respiration and soil temperature and soil moisture are exponential and parabola.The temperature Q_(10) at 5 and 10 cm of soil was 1.73 and 1.98 respectively,which was less than the global average of 2.0.Therefore,using 10 cm soil temperature could better simulate soil respiration.Fitting analysis of soil temperature,water content and soil respiration showed that the soil respiration of Savanna ecosystem in Yuanjiang was mainly restricted by water condition.The annual emission of soil respiration in the ecosystem was 4.20 t·hm~(-2)·a~(-1),including 2.71 t·hm~(-2) in rainy season,accounting for 64.5% of the total annual carbon emission,and 1.49 t·hm~(-2) in dry season,accounting for 35.5% of the total annual carbon emission.The average value of soil respiration in global Savanna ecosystem is 8.16 t·hm~(-2)·a~(-1).[Conclusion] Compared with the global Savanna ecosystem,the total amount of soil respiration in Yuanjiang was in a lower position,which could be attributed to the lower rainfall in the Savanna ecosystem in Yuanjiang.There exists a significant positive correlation between rainfall and soil respiration in the Savanna region(R~2=0.61,P<0.001)

元江干热河谷稀树灌草丛生态系统土壤呼吸动态特征

【目的】土壤呼吸对大气中二氧化碳浓度有重要的调节作用。萨王纳生态系统土壤呼吸是全球温室气体主要排放源之一,但是其排放特征与主要影响因子尚不清楚。【方法】以元江干热河谷(萨王纳)稀树灌草丛生态系统为对象,利用静态箱法,从2014年6月到2015年6月对元江土壤呼吸进行测量,研究了元江干热河谷稀树灌草丛生态系统土壤呼吸动态特征及其影响因子。【结果】元江干热河谷稀树灌草丛生态系统土壤温度、水分和呼吸速率具有明显的季节变化,雨季高于干季。土壤呼吸速率与土壤温度和土壤湿度分别呈指数和抛物线关系,土壤5和10cm处温度Q_(10)分别为1.73和1.98,小于全球均值2.0,采用10cm土壤温度能更好地模拟土壤呼吸。通过土壤温度、湿度与土壤呼吸双因子拟合分析得出元江萨王纳生态系统的土壤呼吸主要受到水分条件的制约;生态系统土壤呼吸年排放量为4.20t·hm~(–2)·a~(–1),其中雨季2.71t·hm~(–2),占全年碳排放总量的64.5%,干季的二氧化碳排放量为1.49t·hm~(–2),占全年碳排放总量的35.5%。全球萨王纳生态系统土壤呼吸均值为8.16t·hm~(–2)·a~(–1)。【结论】元江土壤呼吸总量在全球萨王纳生态系统中处于较低位置,主要是因为元江萨王纳生态系统降水量较全球萨王纳低,而降水量与萨王纳地区土壤呼吸呈极显著正相关关系(R~2=0.61,P<0.001)

1995～2011年CERN土壤环境元素含量数据集

土壤环境是地球环境的重要组成部分。目前土壤环境问题的关注重点在于土壤污染。我国土壤污染以无机污染为主。中国生态系统研究网络(Chinese Ecosystem Research Network,CERN)自1988年组建以来,在中国主要农田、森林、草原、荒漠、湿地生态系统中,按统一的规范,对与土壤环境状况有关的铁、锰、铜、锌、硼、钼、镉、铬、铅、镍、汞、砷、硒元素进行了长期定位监测。通过对CERN典型生态样地表层土壤环境元素监测数据进行加工处理,获得1995～2011年中国陆地生态系统土壤环境元素含量数据集。本数据集中13种土壤环境元素指标测定的相对误差平均为6.55%,重复测定的相对偏差为7.70%。同时附有完整的背景信息,保证了数据在空间和时间上的一致性。本数据集可以为全国和区域土壤环境质量评估、土壤污染风险评价以及环境土壤学研究等工作提供数据基础

燃煤烟气脱硫镁渣对沙冬青种子萌发及幼苗生长的影响/Effects of Desulphurization Magnesium Slag from Flue Gas on Seed Germination and Seedling Growth of Ammopiptanthus mongolicus[J]

采用室内光照培养法（光温自动控制的光照培养箱）,研究沙质土壤中施加燃煤烟气脱硫镁渣（以下简称脱硫镁渣）对沙冬青（Ammopiptanthus mongolicus）种子萌发及幼苗生长的影响。结果表明：脱硫镁渣对种子萌发、幼苗出土和幼苗根系生长有显著的抑制作用;施用脱硫镁渣对幼苗的单株鲜/干重、总生物量及茎生长有显著的促进作用。与对照相比,在种子萌发到幼苗建成的整个过程中,当脱硫镁渣施用量在5～15 g/kg时,种子萌发率和幼苗出土率显著降低,幼苗生物量显著提高;脱硫镁渣施用量小于5 g/kg时,对于种子萌发和幼苗生长均无显著影响;施用量大于15 g/kg,单株干重、鲜重、生物量和幼苗茎生长均极显著增加,种子萌发率和幼苗出苗率极显著降低