鄂尔多斯高原油蒿灌丛群落生物量和净初级生产力研究(英文)

应用标准株收获法对鄂尔多斯高原油蒿灌丛群落生物量和净初级生产力进行了一个生长季(6月~10月)的研究。结果表明:(1)生长季内不同月份之间相同株型单株油蒿地上和地下生物量差异不显著(p>0.1),而地上当年生部分生物量差异显著(p<0.01);(2)油蒿群落中,地上和地下总生物量为699.76~1246.40gm-2,年地上部分NPP值为224.09 gm-2y-1;(3)单株油蒿生物量和 NPP 与灌丛体积具有较好的相关性,应用幂指数方程能够达到较好的拟合效果。     

长白山白桦林地土壤呼吸的季节变化

2004年5月至9月,研究了长白山白桦林土壤呼吸以及根系呼吸对土壤呼吸的贡献随土壤温度和土壤湿度的季节变化,研究结果表明：土壤总呼吸、断根土壤呼吸和根系呼吸在生长季内有相似的季节变化趋势,夏季潮湿而且温度较高,呼吸速率也较高,春季和秋季温度较低,呼吸速率也较低。2004年5月至9月,土壤总呼吸、断根土壤呼吸和根系呼吸的平均值分别为4.44,2.30和2.14μmol&#183;m^-2s^-1,三者与土壤温度均呈指数相关,与土壤湿度呈线性相关,三者的Q10值分别为2.82,2.59和3.16,这与其他学者的结果相似。根系呼吸是土壤呼吸的一个重要组成部分,2004年5月至9月,根系呼吸对土壤总呼吸的贡献在29.3～58.7%之间。根据Q10模型估算的土壤总呼吸、断根土壤呼吸和根系呼吸的全年平均值分别为1.96、1.08和0.87μmol&#183;m^-2s^-1,即741.73、408.71和329.24gC&#183;m^-2&#183;a^-1,全年根系对土壤总呼吸的贡献为44.4%。土壤呼吸和土壤温度之间的关系模型是了解和预测长白山白桦林生态系统潜在的随森林管理和气候变化而变化的有用工具。     

土壤呼吸的时空变化特征研究进展

土壤呼吸的研究早在20世纪之前就已经开始了,国外的研究比国内起步早,目前,有许多研究发现土壤呼吸具有很大的时空变化,为了更加准确了解与探讨土壤呼吸时空变化的规律,本文通过对国内外相关文献的查阅、整理、归纳、总结了其变化特征.时间变化主要有日变化、季变化和年际变化.空间变异主要包括群落水平、景观水平、区域尺度和生物区系尺...     

不同采伐强度柳杉人工林的夏季土壤呼吸日变化

利用CI-340光合仪的CID-301SR土壤呼吸室,对不同采伐强度(30%、50%、70%)柳杉人工林1a后夏季土壤CO2的日排放速率进行测定,结果表明,不同采伐强度和未采伐(ck)柳杉人工林夏季土壤呼吸速率的日变化均呈单峰曲线,与地温的日变化趋势相似,最大值均出现在12:00-14:00,最小值均出现在20:00-22:00;不同采伐强度柳杉人工林夏季土壤呼吸速率及其土壤呼吸速率的日变化幅度都随采伐强度的增大而增大,从大到小的排序为采伐强度70%[(5.39±0.51)～(6.78±0.33)μmol·m-2·s-1]、500%[(3.90±0.46)～(4.95±0.49)μmol·m-3·s-1]、30%[(3.32±0.32)～(4.23±0.37)μmol·m-2·s-1]、ck[(2.87±0.38)～(4.18±0.35)μmol·m-2·S-1];不同采伐强度的柳杉人工林夏季土壤呼吸日变化速率与不同土层温度呈明显的指数相关,但与土壤含水率不相关.     

不同桉树人工林土壤呼吸旱雨季变化特征

以雷州半岛气候背景条件下具有良好培育前景的5种桉树人工林(湿加松林为对照)为研究对象,测定并分析各个林分土壤呼吸速率在旱季和雨季的差异,以揭示其与土壤温、湿度的关系.结果表明:土壤呼吸速率在旱季表现为先减后增变化趋势,在雨季表现为先增后减或逐渐减小变化趋势,旱、雨季变化特征明显.6个林分旱、雨季土壤呼吸速率均值分别为1.63~3.32μmol·m-2·s-1和2.55~4.36μmol·m-2·s-1.旱季土壤温、湿度共同促进土壤呼吸作用,雨季土壤温度促进土壤呼吸,土壤湿度抑制土壤呼吸作用.     

森林生态系统土壤呼吸空间异质性研究进展

土壤呼吸作用是陆地生态系统碳循环的重要组成部分。了解森林土壤呼吸的空间异质性是估算整个陆地生态系统碳源、汇的基础。文中概述了森林生态系统土壤呼吸空间异质性的研究进展及其影响因子,以及研究土壤呼吸空间异质性的主要方法,指出当前森林生态系统土壤呼吸空间异质性研究中存在的问题及未来该领域的研究重点。     

杉木人工林土壤呼吸日变化及其影响因素分析

通过野外定点监测,对杉木抚育林、杉木撂荒林和林外草地的土壤呼吸日变化及其影响因素进行了研究.结果表明:不同土地利用条件下杉木人工林土壤呼吸速率的日变化均呈单峰曲线,抚育林和撂荒林最高值出现在16:00,林外草地最高值出现在12:00,土壤呼吸速率的最低值均出现在04:00;林外草地各时刻的土壤呼吸速率均比抚育林和撂荒林高;土壤呼吸递减速率在20:00~00:00间抚育林比撂荒林慢,在00:00~04:00抚育林比撂荒林快;土壤温度与土壤呼吸速率的相关性均达到了显著水平(p<0.05),土壤含水率与土壤呼吸速率的相关性不显著(p>0.05);以土壤5 cm处温度为依据得到的温度系数(Q10值)大小排序为林外草地>撂荒林>抚育林.     

祁连山东段高寒灌丛地被物与土壤的水文特征

The surface cover and soil hydrological characteristics of three alpine shrubs in eastern Qilian Mountains were studied in the report. The experimental alpine shrubs are Potentilla fruticosa shrub,Sali...     

华北平原人工杨树林的土壤呼吸特征

对华北徒骇河流域河岸林与非河岸林两种生境下杨树林的土壤呼吸速率进行监测分析,结果表明:两种生境条件下,杨树人工林土壤呼吸速率在8∶00—20∶00的变化趋势呈单峰曲线,具有明显白天高夜间低的规律,在12∶00—16∶00期间达到峰值。河岸林呼吸速率明显高于非河岸林。两种生境下,土壤呼吸与大气湿度呈负相关的关系,两者之间的相关系数分别为-0.4713、-0.8329,而土壤呼吸与大气温度的变化趋势大致相似,都是单峰趋势,两者之间的相关系数分别为0.8066、0.7257。回归分析表明,春季人工杨树林的土壤呼吸主要受大气温度的影响。     

中国南方喀斯特石漠化地区3种经济林土壤呼吸日动态特征

喀斯特石漠化作为一个脆弱生态系统,对全球气候变化和碳循环具有重要影响。为阐明中国南方喀斯特石漠化生态治理工程背景下土壤呼吸作用的时空动态变化特征及其影响因素,选取贵州省贞丰县北盘江镇查耳岩村的核桃林Julans regia、花椒林Zanthoxylum bungeamum和关岭县花江镇峡谷村的枇杷林Eriobotrya japonica3种特色经济林作为研究对象,采用英国ADC Bioscientific公司生产的Lcpro+便携式土壤呼吸仪对土壤呼吸进行了监测。结果表明:1)土壤温度能预测土壤呼吸速率变异83%～89%的信息,是影响土壤碳排放量变异的主要因素;2)3种经济林中土壤呼吸的温度敏感性(Q10)有所差异,Q10为4.34～6.40;3)喀斯特石漠化地区冬季土壤的月平均碳排放量达到了63.46 g·m-2;4)土壤呼吸速率的偏离程度变化较大,在-56%～83%之间;5)花椒林在09:00、15:00、21:00,核桃林0:00、11:00,枇杷林在12:00土壤的呼吸速率与日平均值偏离程度较小(<10%),为最佳观测时间;6)各土壤特征因子中,全钾是影响土壤呼吸速率变异的主要因素。     

Diurnal and seasonal dynamics of soil respiration in desert shrubland of Artemisia Ordosica on Ordos Plateau of Inner Mongolia, China

The diurnal and seasonal dynamics of soil respiration in the A. ordosica shrubland on Ordos Plateau were investigated in the growing season （May-October） of 2006 and their environmental driving factors were also analyzed, Results indicated that diurnal dynamics of soil respiration rate and its temperature dependence showed some discrepancy in two different growth stages （the vegetative growth stage and the reproductive growth stage）. During the vegetative growth stage, the diurnal variation of soil respiration was slight and not correlated with the daily temperature change, but during the reproductive growth stage, the daily respiration variation was relatively large and significantly correlated with the diurnal variation of air and soil temperature. In the growing season, the peak value of soil respiration occurred at July and August because of the better soil water-heat conditions and their optimal deployment in this period. In the shrubland ecosystem, precipitation was the switch of soil respiration pulses and can greatly increase soil respiration rates after soil rewetting. Moreover, the soil respiration rates in the growing season and the air temperature and soil surface water content were closely correlated （p〈0.05） each other. The stepwise regression model indicated that the variation of soil surface moisture accounted for 41.9% of the variation in soil respiration （p〈0.05）.     

Storage of biomass and net primary productivity in desert shrubland of Artemisia ordosica on Ordos Plateau of Inner Mongolia, China

Biomass and net primary productivity （NPP） are two important parameters in determining ecosystem carbon pool and carbon sequestration. The biomass storage and NPP in desert shrubland of Artemisia ordosica on Ordos Plateau were investigated with method of harvesting standard size shrub in the growing season （June-October） of 2006. Results indicated that above- and belowground biomass of the same size shrubs showed no significant variation in the growing season （p〉0.1）, but annual biomass varied significantly （p〈 0.01）. In the A. ordosica community, shrub biomass storage was 699.76-1246.40 g.m^-2 and annual aboveground NPP was 224.09 g-m^-2·a^-1. Moreover, shrub biomass and NPP were closely related with shrub dimensions （cover and height） and could be well predicted by shrub volume using power regression.     

土壤温度和水分对长白山3种温带森林土壤呼吸的影响

为了研究土壤温度和土壤含水量对阔叶红松林(山地暗棕壤)、云冷杉暗针叶林(山地棕针叶林土壤)和岳桦林(生草森林土)的土壤呼吸的影响,于2001年9月在长白山进行了土壤实验。利用增加土壤样柱的含水量,将土壤含水量分为9%,、21%、30%、37%和43%5个等级,土壤样品分别在0、5、15、25和35的温度下保持24小时。阔叶红松林土壤在0~35范围内,土壤呼吸速率与温度呈正相关。在一定的含水量范围内(21%~37%),土壤呼吸随含水量的增加而升高,当含水量超出该范围,土壤呼吸速率则随含水量的变化而降低。土壤温度和水分对土壤呼吸作用存在明显的交互作用。不同森林类型土壤呼吸作用强弱存在显著差异,大小顺序为阔叶红松林>岳桦林>云冷杉暗针叶林.红松阔叶林土壤呼吸作用的最佳条件是土壤温度35,含水量37%;云冷杉暗针叶林下的山地棕色针叶土壤呼吸作用的最佳条件是25,21%;岳桦林土壤呼吸作用的最佳条件是35,含水量37%。但是,由于长白山阔叶红松林,云冷杉林和岳桦林处在不同的海拔带上,同期不同森林类型土壤温度各不相同,相差4~5,所以野外所测的同期的山地棕色针叶林土呼吸速率应低于暗棕色森林土呼吸速率,山地生草森林土呼吸速率应高于山地棕色针叶林土的呼吸速率。图2表1参25。     

Prescribed burning and mechanical thinning effects on belowground conditions and soil respiration in a mixed-conifer forest,California

Soil respiration (R_S) is a major carbon pathway from terrestrial ecosystems to the atmosphere and is sensitive to environmental changes. Although commonly used mechanical thinning and prescribed burning can significantly alter the soil environment, the effect of these practices on R_S and on the interactions between R_S and belowground characteristics in managed forests is not sufficiently understood. We: (1) examined the effects of burning and thinning treatments on soil conditions, (2) identified any changes in the effects of soil chemical and physical properties on R_S under burning and thinning treatments, and (3) indirectly estimated the changes in the autotrophic soil respiration (R_A) and heterotrophic soil respiration (R_H) contribution to R_S under burning and thinning treatments. We conducted our study in the Teakettle Experimental Forest where a full factorial design was implemented with three levels of thinning, none (N), understory thinning (U), and overstory thinning (O; September to October 2000 for thin burn combination and June and July 2001 for thin only treatments) and two levels of burning, none (U) and prescribed burning (B; fall of 2001). R_S, soil temperature, soil moisture, litter depth, soil total nitrogen and carbon content, soil pH, root biomass, and root nitrogen (N) concentration were measured between June 15 and July 15, 2002 at each plot. During this period, soil respiration was measured three times at each point and averaged by point. When we assumed the uniform and even contribution of R_A and R_H to R_S in the studied ecosystem without disturbances and a linear relationship of root N content and R_A, we calculated the contributions of R_A to R_S as 22, 45, 53, 48, and 45% in UU, UO, BN, BU, and BO, respectively. The results suggested that after thinning, R_S was controlled more by R_H while after burning R_S was more influenced by R_A. The least amount of R_S variation was explained by studied factors under the most severe treatment (BO treatment). Overall, root biomass, root N concentration, and root N content were significantly (p < 0.01) correlated with soil respiration with correlation coefficients of 0.37, −0.28, and 0.29, respectively. This study contributes to our understanding of how common forestry management practices might affect soil carbon sequestration, as soil respiration is a major component of ecosystem respiration.     

Short-term effects of nitrogen deposition on soil respiration components in two alpine coniferous forests,southeastern Tibetan Plateau

Nitrogen (N) deposition to alpine forest ecosystems is increasing gradually, yet previous studies have seldom reported the effects of N inputs on soil CO2 flux in these ecosystems. Evaluating the effects of soil respiration on N addition is of great significance for understanding soil carbon (C) budgets along N gradients in forest ecosystems. In this study, four levels of N (0, 50, 100, 150 kg N ha^-1 a^-1) were added to soil in a Picea baifouriana and an Abies georgei natural forest on the Tibetan Plateau to investigate the effect of the N inputs on soil respiration. N addition stimulated total soil respiration (Rt) and its components including heterotrophic respiration (Rh) and autotrophic respiration (Ra);however, the promoted effects declined with an increase in N application in two coniferous forests. Soil respiration rate was a little greater in the spruce forest (1.05 μmol CO2 m^-2 s^-1) than that in the fir forest (0.97 μmol CO2 m^-2 s^-1). A repeated measures ANOVA indicated that N fertilization had significant effects on Rt and its components in the spruce forest and Rt in the fir forest, but had no obvious effect on Rh or Ra in the fir forest. Rt and its components had significant exponential relationships with soil temperature in both forests. N addition also increased temperature sensitivity (Q10) of Rt and its components in the two coniferous forests, but the promotion declined as N in put increased. Important, soil moisture had great effects on Rt and its components in the spruce forest (P<0.05), but no obvious impacts were observed in the fir forest (P>0.05). Following N fertilization, Ra was significantly and positively related to fine root biomass, while Rh was related to soil enzymatic activities in both forests. The mechanisms underlying the effect of simulated N deposition on soil respiration and its components in this study may help in forecasting C cycling in alpine forests under future levels of reactive N deposition.     

旅游开发对若尔盖自然保护区土壤养分和物理性状的影响

对高原湿地若尔盖国家级自然保护区不同旅游开发强度下土壤养分和物理性状进行研究的结果表明：（1）不同旅游开发强度（强度等级）对若尔盖高原湿地花湖景区土壤养分含量（有机质、氮、磷、钾）有着较大差异。（2）不同旅游开发强度对土壤理化性质的影响表现为：随着放牧干扰强度的增加,样地土壤容重逐渐增大、孔隙度逐渐减小。干扰导致土壤持水量和含水量下降,重度和中度干扰下土壤持水量和含水量与无放牧干扰时相比均有显著下降（P〈0.05）。放牧压实造成土壤表层孔隙度下降,致使土壤初渗速率、稳渗速率下降,其中稳渗速率下降最为明显,轻度、中度和重度放牧干扰下土壤稳渗速率比未受放牧干扰时分别下降了49.81%,81.89%和92.34%。（3）旅游活动、过牧超载等人为干扰活动是引起生态退化的主要原因。气候寒冷造成土壤利用性能受限,植被生长缓慢且破坏后难于恢复,湿地中伴随着水的大量流失和进而引发的湿地功能的的丧失对若尔盖及附近地区乃至全球生态环境的形成与演变产生重大影响。应对若尔盖湿地自然生态环境进行保护。严禁挖沟排水和过度无序旅游,乃是保护土壤,稳定若尔盖湿地高原生态环境的重要措施。只有这样,保护土壤生态系统才有依托,才有物质基础。     

Effects of landscape restoration on soil water storage and water use in the Loess Plateau Region,China

Large-scale vegetation restoration in China's Loess Plateau has been initiated by the central government for controlling soil and water losses in the past three decades. However, there is virtually no guidance for plant species selection for the restoration purpose. We investigated the effects of planting trees and shrubs, land-use conversions from croplands to pastures and native grasslands on soil water dynamics and water stresses by using long-term field measurements from 1986 to 1999 in the semi-arid loess hilly area. Our research has led to the following three major findings. Firstly, the amount of soil water storage within a 100 cm depth decreased as measured at both the beginning and the ending point of growing seasons regardless land cover types. The soil water replenishment by rainfall during rainy seasons was not sufficient to fully recharge the soil water storage. Landscape restoration through shrub planting may help retain more soil water than other land cover types. Secondly, the ratio of actual evapotranspiration (ET) and pan evaporation (PET) generally declined for all land cover types during the study period. Shrub lands had the largest ET/PET ratio, followed by native grassland, cropland/alfalfa, and pine woodland. The ET/PET ratio of native grasslands declined fastest, followed by pine woodlands, shrub lands, alfalfa, and croplands. Pine woodland's low ET/PET ratios were mainly caused by its higher runoff due to soil compaction resulted from soil desiccation. Lastly, we found that the soil water storage at the beginning of growing season was important in determining the ET/PET ratios. This study suggested that pine plantations may not be appropriate for landscape restoration in such a semi-arid loess hilly area while shrubs may be highly recommended.