皆伐方式对小兴安岭低质林土壤呼吸的影响

针对小兴安岭低质林分,采用不同的皆伐方式,利用LI-8100碳通量自动监测系统在春、夏、秋、冬4个季节对低质林分土壤呼吸进行观测,运用统计分析的方法,分析皆伐方式对土壤呼吸的影响和不同皆伐方式的土壤呼吸产生差异的原因.结果显示:试验区土壤呼吸夏季最大,冬季最低.春季和秋季因土壤温度和湿度差异不大使土壤呼吸相差较小;对于水平带同一条皆伐带,土壤呼吸并无显著性差异,并且不同的带宽对土壤呼吸的影响也不显著;垂直带随海拔升高土壤呼吸呈现波动性,总体趋势随海拔升高土壤呼吸逐渐降低,但是差距较小;水平带、垂直带和林窗的年土壤呼吸量分别为1.184,1.426,1.179 kgCO2·m-a-1,垂直带最高,水平带次之,林窗最低.影响垂直带土壤呼吸的关键因素是土壤温度,林窗则是土壤湿度,而水平带土壤温度和湿度的条件则介于垂直带和林窗之间.这说明在不同的皆伐方式条件下,影响土壤呼吸的关键因素并不完全相同.     

森林土壤呼吸对降雨脉冲的响应研究进展

森林生态系统的土壤碳储量是陆地生态系统碳库的重要组成部分。土壤呼吸则是土壤碳库参与陆地碳循环的主要方式,其受到诸多生物和非生物因子的综合调控。偶发性降雨会引起森林土壤湿度的瞬间增加,进而导致土壤呼吸速率的快速提高。文中介绍了森林土壤呼吸及其组分,综述了降雨脉冲效应的特征和诱导机制（包括物理替代机制、微生物代谢机制、土壤养分限制机制及光化学调控机制等）,分析了当前降雨脉冲研究存在的不足并展望了未来的研究重点,认为森林生态系统是未来开展降雨脉冲效应研究的重要方向,探究森林土壤呼吸不同组分对降雨脉冲的响应差异与机制也是潜在的重要研究方向。     

Effect of Forest Management Measures on Soil Respiration and Its Mechanism

Global warming is one of the hottest environment problems.One of the reasons is the sharp increase of CO2 in atmosphere.Soil respiration in forest ecosystems accounts to 60%-90%of total ecosystem respiration and is therefore one of the key components of the global C cycle.This paper summarized different responses of soil respiration to forest management measures,and described the relevant researches at home and abroad on the effect of management measures like harvesting,forest fertilization,soil improving(Liming),litter removal, and prescribed burning on soil respiration.     

Soil solution,foliar concentrations and tree growth response to 3-year of ammonium-nitrate addition in two boreal forests of Québec,Canada

Ammonium nitrate (NH₄NO₃) was applied monthly (from June to October) for 3 years in a balsam fir (Abies balsamea (Linné) Miller) and a black spruce (Picea mariana (Mill.) BSP) boreal forest in Québec (Canada). The design was composed of nine experimental units of 10 m × 10 m for each site. Application rates were 3 and 10 times the atmospheric N deposition measured at each site which was 6 and 3 kg ha⁻¹ year⁻¹ for the fir and the spruce sites, respectively. Soil solution composition (30 and 60 cm), tree growth, and foliar concentrations were analysed. The inorganic N in the soil solution of the control plots of both sites was low, particularly at the spruce site indicating that these forests are actively accumulating the atmospheric deposited N. Nitrogen additions regularly caused sudden and large inorganic N increases in the soil solution at both sites, both treatments and both sampling depths. However, these increases were transitory in nature and no persistent changes in inorganic N were observed. It was estimated that more than 95% of the added N was retained above the rooting zone at both sites. Nitrogen addition increased N, Ca, Mg and Mn foliar concentrations at the black spruce site but had no effects at the balsam fir site. After 3 years of N application, tree growth was similar in the control and the treated plots at both sites. Our results show that slow growing black spruce boreal forests with low ambient N deposition are responsive (in term of foliar N, Ca, Mg and Mn concentrations) to even small increases in N inputs, compared to higher growth balsam fir boreal forests with higher N deposition.     

森林经营措施对土壤呼吸的影响机理

全球变暖是当今世界最热的环境问题之一, 其主要原因是大气中CO₂浓度剧增。而森林土壤呼吸占生态系统呼吸总量的60%~90%, 是全球碳循环的一个关键组成部分。文中综述主要森林经营措施对土壤呼吸造成影响的程度及方向, 详尽总结采伐、林地施肥、土壤改良、凋落物移除和火烧等措施对土壤呼吸影响的国内外相关研究。     

The effect of fire disturbance on short-term soil respiration in typical forest of Greater Xing’an Range,China

We investigated the effect of fire disturbance on short-term soil respiration in birch （Betula platyphylla Suk.） and larch （Larix gmelinii Rupr.） forests in Greater Xing’an range, northeastern China for further understanding of its effect on the carbon cycle in ecosystems. Our study show that post-fire soil respiration rates in B. platyphylla and L. gmelinii forests were reduced by 14%and 10%, respectively. In contrast, the soil heterotrophic respiration rates in the two types of forest were similar in post-fire and control plots. After fire, the contribution of root respiration to total soil respiration was dramatically reduced. Variation in soil respiration rates was explained by soil moisture （W） and soil tem-perature （T） at a depth of 5 cm. Exponential regression fitted T and W models explained Rs rates in B. platyphylla control and post-fire plots （83.1% and 86.2%） and L. gmelinii control and post-fire plots （83.7%and 88.7%）. In addition, the short-term temperature coefficients in B.     

森林土壤酶活性对氮沉降的响应

近年来,大气氮沉降日益增加,已对森林生态系统产生了不可忽视的影响,而土壤酶活性反映了土壤肥力及土壤环境质量,因而可以用来评价氮沉降对森林土壤造成的影响。关于氮沉降对森林生态系统酶活性的影响已开展了一系列的研究,然而尚缺少系统总结。文中从森林土壤酶种类和林分类型角度总结了氮沉降对土壤酶活性的影响,并从氮沉降水平、氮种类形态、氮沉降与环境的交互作用等方面探讨了土壤酶活性对氮沉降的响应机制,提出未来研究热点是氮沉降对不同类型的森林土壤酶影响、不同森林类型土壤酶的氮沉降临界值、氮沉降对土壤酶活性影响的长期定位研究以及氮沉降与CO₂浓度、温度、降雨、磷添加的交互作用对土壤酶活性影响,以期为未来森林土壤管理提供参考。     

两广地区主要森林类型的年土壤呼吸及空间分布研究

研究根据广东和广西(两广)地区森林类型分布图、主要森林类型的年土壤呼吸数据库以及中国日值格点气温、降水数据,建立线性模型预测两广地区主要森林类型的年土壤呼吸速率和年土壤呼吸通量。结果表明,两广地区主要森林类型年土壤呼吸速率为常绿阔叶林864.18 gC/m~2/yr>其他森林811.03 gC/m~2/yr>针叶林791.43 gC/m~2/yr>灌木林780.18 gC/m~2/yr>落叶阔叶林758.80 gC/m~2/yr>竹林731.49 gC/m~2/yr>针阔混交林684.91 gC/m~2/yr。两广地区森林年土壤呼吸通量为204.41 TgC/yr,其中常绿阔叶林最大,为77.41 TgC/yr,针叶林次之,为56.81 TgC/yr,具体为常绿阔叶林>针叶林>灌木林>落叶阔叶林>针阔混交林>竹林>其他森林,顺序与各种森林类型面积大小一致。各森林类型的土壤呼吸通量主要与森林面积有关,森林面积越大土壤呼吸通量越大。     

环境与生物因子对土壤呼吸及其组分的影响

生态系统呼吸中土壤呼吸的不确定性最大。文中阐述了环境与生物因子如土壤温度、湿度、理化性质、大气CO₂浓度、生物因子及人类活动对土壤呼吸及其组分产生的影响, 并对未来相关领域的研究进行了展望。     

森林生态系统土壤碳库对氮沉降的响应

从土壤碳含量的输入和输出两方面综述了N沉降胁迫对土壤碳库的影响方式和过程,分析了目前N沉降对凋落物分解、细根生物量、土壤呼吸的影响的研究进展及其作用机制,但由于N沉降对土壤碳库的影响是一个复杂的综合作用过程,N沉降对森林土壤碳库的总效应尚需要更深入的研究.     

氮磷沉降对森林土壤生化特性影响研究进展

人类活动引起的氮磷沉降给土壤带来严重影响。外源性氮可以直接增加土壤全氮和碱解氮的含量,提高土壤磷的有效性,减少全磷含量;外源性磷可以促进树木对土壤氮的吸收,可能造成土壤全氮含量下降。外源性氮对微生物群落存在促进、抑制和没有影响3种情况。外源性磷通常可增加微生物生物量,改变原有的森林微生物群落组成;氮沉降可以提高、降低或无影响土壤酶的活性。氮磷沉降对不同土壤酶种类的影响效果各异。氮沉降的影响也与土壤深度及酶的种类有关。对磷沉降影响土壤酶的研究甚少。未来氮磷沉降的研究热点包括热带氮磷沉降、土壤氮磷比和氮磷沉降交互作用对土壤的影响,不同地形、森林类型、林龄条件下氮磷沉降的对比分析,生态系统中缓冲氮磷沉降作用的关键因子及全球气候变化下氮磷沉降对土壤的影响。     

基于全球数据库的森林土壤呼吸模型研究

森林土壤呼吸在陆地生态系统的碳平衡中发挥了重要作用,准确估算森林土壤呼吸量对于了 解陆地碳平衡的变化至关重要。这项研究以全球气候数据、全球森林土壤呼吸数据库为基础数据,通过 开发人工神经网络（ANN）模型建立由年平均气温（MAT）、年平均降水（MAP）、森林类型驱动的土壤 呼吸模型,预测全球森林土壤呼吸变化。模型估算的结果表明,从 1960 年到 2017 年,全球森林平均年 土壤呼吸量为 40.10±0.48 Pg C yr-1,全球森林土壤对全球土壤呼吸的贡献在 40.9% - 49.8% 之间。人工神 经网络模型预测的准确度达到 0.63,进一步改善了全球森林土壤呼吸模型预测的精度。     

Fluxes,stocks and availability of nitrogen in evergreen broadleaf and fir forests: similarities and differences

In this study,nitrogen fluxes or flows in litterfall,nitrogen stocks and available nitrogen in soils of two plots representing evergreen broadleaf and Bulgarian fir forests were assessed.Both plots are in good quality sites and for this reason,the litterfall quantities and nitrogen fluxes were relatively high.The woody litterfall flux of nitrogen was significantly higher in the fir forest than in the evergreen broadleaf one.The total nitrogen stock was higher in the soil under the fir forest.However,the percentage of the available nitrogen(ammonium+nitrates) was significantly higher in the upper 20 cm soil layer of the evergreen broadleaf forest in spite of the higher average C/N ratios in the foliar litterfall of the broadleaf forest and insignificant difference of the C/N ratios in all soil layers of the two ecosystems.The microclimatic conditions(higher soil temperatures in the evergreen broadleaf forest) is probable possible cause for this difference.The available nitrogen in the soils and its retranslocation from senescing leaves cover the nitrogen requirements of trees.It is hypothesized that trees may also take up nitrogen from deeper soil layers.     

Nitrogen budgets for Scots pine and Norway spruce ecosystems 12 and 7 years after the end of long-term fertilisation

The magnitude of nitrogen storage and its temporal change in forest ecosystems are important when analysing global change. For example, the accelerated growth of European forests has been linked to increased nitrogen deposition, but the changes in the N inputs that cause long-term changes in ecosystems have not yet been identified. We used two Swedish forest optimum nutrition experiments with Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) to study the long-term fate of N applied to these forest ecosystems. In the pine experiment, in addition to fertiliser (NPK) application, soil acidity was manipulated by application of lime and dilute sulphuric acid. From the spruce experiment, we selected treatments with similar fertiliser doses as in the pine experiment and with and without lime addition.We quantified various terms in the N budget 12 years (pine) and 7 years (spruce) after the last N addition. In the pine stand the NPK-treatment was the only treatment to produce a significant increase in N in the tree biomass (97% above control), whereas in the spruce stand the N additions increased tree N in all treatment combinations (207% above control). In the pine stand the relative distribution of nitrogen between trees and soil did not vary across treatments, with trees containing around 12% of ecosystem N and humus containing around 44% of soil N. The increases in N stocks in the pine stands were mainly in the soil. In contrast, in the spruce ecosystem trees accumulated most of the added N and the increase in the soil was restricted to the humus layer.In the pine ecosystem, large losses of added N (between 254 and 738 kg ha⁻¹ out of 1040 kg ha⁻¹ added as fertiliser) occurred, whereas in the spruce ecosystem we recovered more N than could be accounted for by inputs (between 250 and 591 kg ha⁻¹). There was no clear pattern in the interaction between acidification/liming and N additions.     

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.     

冰雪灾害对森林土壤性质的影响

冰雪灾害是一种常见的自然灾害,易对森林造成巨大破坏。在全球变化加剧的背景下,冰雪灾害发生的频率和强度呈现上升趋势。文中综述了冰雪灾害后森林土壤物理性质、土壤化学性质、土壤微生物群落和土壤酶活性的变化,以便为受损森林生态系统的修复提供参考。今后的研究热点是加强对灾后森林养分循环、土壤微生物和土壤种子库的长期研究,开展土壤微生物群落、土壤呼吸和土壤理化性质相互关系及作用机理研究,运用3S技术监测不同立地条件下土壤灾后动态变化、建立更科学精准的受灾森林生态系统评估体系,以及建立生态修复模型预测冰雪灾害后的森林恢复过程。     

浅谈森林采伐对土壤呼吸的影响

阐述了森林生态系统土壤呼吸的概念及研究意义,探讨了影响森林土壤呼吸的因子,并着重论述了森林采伐对土壤呼吸的影响,同时指出确定土壤呼吸对森林生态系统不同经营方式的反馈作用,对选取适当的森林经营措施具有重要的指导意义。     

杉木林地土壤微生物研究进展

杉木是我国主要造林树种之一,具有生长快、产量高、材质好的优点。土壤微生物与杉木林地土壤理化性质、土壤肥力以及植物根系之间有密切的关联。文中概述了不同林分条件下杉木林地土壤微生物的群落特征及其与土壤质量之间的响应机制,尤其是与植物根系共生关系方面的研究进展,以期为实现杉木林质量的精准提升提供理论参考。天然林和阔叶林较杉木人工林有更丰富的微生物群落,在杉木林生长发育过程中,中龄阶段各微生物指标最低。杉木林土壤微生物群落组成、生物量和活性等均与土壤酸碱性、通气状况、养分含量等存在密切的响应关系。杉木林菌根真菌主要属于球囊霉属,国内对杉木林下菌根真菌的研究仍处于初级阶段。未来土壤微生物的研究热点包括土壤微生物的时空演变规律、土壤微生物在提升土壤肥力上的机理和途径、菌根真菌在土壤养分高效利用中的机制等。     

Antagonistic effects of species on C respiration and net N mineralization in soils from mixed coniferous plantations

Mixtures of litter from different plant species often show non-additive effects on decomposition and net N release (i.e., observed effects in mixtures differ from predictions based on litter of the component species), with positive non-additive (i.e., synergistic effects) being most common. Although large amounts of C and N reside in soil organic matter that contribute significantly to the overall C and N cycle, only a few studies have compared species monoculture vs. mixture effects on soil C and N dynamics. We studied the interactive effects of black spruce (Picea mariana), tamarack (Larix laricina), and white pine (Pinus strobus) on soil C respiration and net N mineralization in a plantation in northern Minnesota, USA. The trees were planted in monoculture and in all three possible two-species combinations (mixtures). After 10 years, we measured aboveground plant biomass and soil C respiration and net N mineralization rates in long-term (266 days) and short-term (13 days) laboratory incubations, respectively. Soil C respiration and net N mineralization were significantly lower in mixtures with tamarack than would be predicted from the monocultures of the two component species. Possibly, mixing of lignin rich litter from black spruce or white pine with N rich litter from tamarack suppressed the formation of lignolytic enzymes or formed complexes highly resistant to microbial degradation. However, these antagonistic effects on soil C respiration and net N mineralization in mixtures with tamarack did not result in reduced aboveground biomass in these plots after 10 years of growth. It remains to be seen if these antagonistic effects will affect long-term forest productivity and dynamics in boreal forests.     

采伐对幕布山区毛竹林土壤呼吸的影响

利用LI-COR-8100土壤CO2通量自动测量系统测定了湖北赤壁幕布山区采伐毛竹林土壤表面CO2通量及5 cm深度的土壤温度、湿度,研究了采伐对毛竹林土壤呼吸的影响,并用壕沟法区分各组分呼吸。结果表明:采伐显著增加了毛竹林的土壤温度,但对土壤湿度无显著影响;采伐能增加土壤呼吸、凋落物呼吸与矿质呼吸,但降低了根系呼吸;土壤总呼吸及组分呼吸与土壤温度呈指数相关(R2=32.63%84.50%),与土壤湿度呈线性相关(R2=40.60%93.50%),运用土壤温度、湿度复合模型能提高预测土壤呼吸的准确性(R2=41.40%96.20%)。采伐毛竹林土壤呼吸的增加主要因为采伐后土壤温度升高所致。