土地利用方式对土壤碳库影响的敏感性评价指标

综述了目前国内外在监测土地利用方式对土壤有机碳动态的影响时所采用的一些敏感性指标：微生物量碳和微生物商、CO2通量和qCO2、轻组有机质和颗粒态有机质、溶解态有机碳(DOC)。大量的研究表明，与土壤有机碳相比，微生物量碳库的周转率更大，周转时间更短，在土壤总有机碳变化可检测之前，土壤微生物部分的变化可能被检测到，是土壤碳动态的敏感性指标。轻组和颗粒态有机质是自然土壤肥力的决定因素，也是土地管理方式影响最明显的部分，对于准确评价土地利用变化对土壤碳过程的影响具有重要意义。CO2，通量和qCO2，可以综合反映土壤微生物的活性、利用土壤有机碳的效率及土壤中碳的代谢作用等，也是土壤碳动态的敏感性指标。DOC通量比全球植物和大气间碳交换量小1-2个数量级，所以生物圈碳平衡的很小变化会导致DOC的巨大变化，DOC浓度和通量是土壤温度和湿度变化的敏感指标。     

Conversion from agriculture to grassland builds soil organic matter on decadal timescales.

Soil organic matter (SOM) often increases when agricultural fields are converted to perennial vegetation, yet decadal scale rates and the mechanisms that underlie SOM accumulation are not clear. We measured SOM accumulation and changes in soil properties on a replicated chronosequence of former agricultural fields in the midwestern United States that spanned 40 years after perennial-grassland establishment. Over this time period, soil organic carbon (SOC) in the top 10 cm of soil accumulated at a constant rate of 62.0 g x m(-2) x yr(-1), regardless of whether the vegetation type was dominated by C3 or C4 grasses. At this rate, SOC contents will be equivalent to unplowed native prairie sites within 55-75 years after cultivation ceased. Both labile (short turnover time) and recalcitrant (long turnover time) carbon pools increased linearly for 40 years, with recalcitrant pools increasing more rapidly than expected. This result was consistent across several different methods of measuring labile SOC. A model that investigates the mechanisms of SOM formation suggests that rapid formation of stable carbon resulted from biochemically resistant microbial products and plant material. Former agricultural soils of the Great Plains may function as carbon sinks for less than a century, although much of the carbon stored is stable.     

SOMPROF: A vertically explicit soil organic matter model

Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to interactions with the soil temperature and moisture profile, as well as on long (years to centuries) time scale because of depth-specific stabilization mechanisms of organic matter. It is likely that a representation of the SOM profile and surface organic layers in SOM models can improve predictions of the response of land surface fluxes to climate and environmental variability. Although models capable of simulating the vertical SOM profile exist, these were generally not developed for large scale predictive simulations and do not adequately represent surface organic horizons. We present SOMPROF, a vertically explicit SOM model, designed for implementation into large scale ecosystem and land surface models. The model dynamically simulates the vertical SOM profile and organic layer stocks based on mechanistic representations of bioturbation, liquid phase transport of organic matter, and vertical distribution of root litter input. We tested the model based on data from an old growth deciduous forest (Hainich) in Germany, and performed a sensitivity analysis of the transport parameters, and the effects of the vertical SOM distribution on temporal variation of heterotrophic respiration. Model results compare well with measured organic carbon profiles and stocks. SOMPROF is able to simulate a wide range of SOM profiles, using parameter values that are realistic compared to those found in previous studies. Results of the sensitivity analysis show that the vertical SOM distribution strongly affects temporal variation of heterotrophic respiration due to interactions with the soil temperature and moisture profile.     

A process-based model of nitrogen cycling in forest plantations: Part II. Simulating growth and nitrogen mineralisation of Eucalyptus globulus plantations in south-western Australia

We applied a new version of the G’DAY ecosystem model to short-rotation plantations of Eucalyptus globulus growing under a Mediterranean climate in south-western Australia. The new version, that includes modified submodels for biomass production, water balance, litter and soil organic matter (SOM) decomposition, and soil inorganic N balance, was parameterised and applied to three experimental eucalypt sites (Mumballup, Darkan and Northcliffe) of contrasting productivity. With a common base set of parameter values, the model was able to correctly reproduce observed time series of soil water content, canopy leaf area index and stemwood data at the three sites. The model's ability to simulate soil N supply under forest plantations was tested by simulating N mineralisation at each of the three sites over the duration of the experiment (10 years). Simulated annual net N mineralisation in the litter and top 20 cm soil layer ranged from 50 to 170 kg N ha⁻¹ across the sites as a result of differences in rates of litter production, SOM and litter decomposition, and microbial N immobilisation and (re-)mineralisation. Simulations of annual soil N mineralisation were similar to measured rates over a 3-year period, except for an overestimation in 1 year at Mumballup and 2 years at Darkan. Model results indicated the importance of fine root production and turnover for N supply. As plantations age, supply of N to trees increasingly originates from litter decomposition, while the contribution from decomposition of SOM decreases. Although major soil feedbacks associated with litter production, decomposition and N availability are adequately integrated into G’DAY, further work is required in some aspects of the model, including the utility of the C-allocation submodel over a wide range of site conditions and silvicultural treatments.     

Experimental warming shows that decomposition temperature sensitivity increases with soil organic matter recalcitrance

Soil C decomposition is sensitive to changes in temperature, and even small increases in temperature may prompt large releases of C from soils. But much of what we know about soil C responses to global change is based on short-term incubation data and model output that implicitly assumes soil C pools are composed of organic matter fractions with uniform temperature sensitivities. In contrast, kinetic theory based on chemical reactions suggests that older, more-resistant C fractions may be more temperature sensitive. Recent research on the subject is inconclusive, indicating that the temperature sensitivity of labile soil organic matter (OM) decomposition could either be greater than, less than, or equivalent to that of resistant soil OM. We incubated soils at constant temperature to deplete them of labile soil OM and then successively assessed the CO2-C efflux in response to warming. We found that the decomposition response to experimental warming early during soil incubation (when more labile C remained) was less than that later when labile C was depleted. These results suggest that the temperature sensitivity of resistant soil OM pools is greater than that for labile soil OM and that global change-driven soil C losses may be greater than previously estimated.     

Temperature influences carbon accumulation in moist tropical forests

Evergreen broad-leaved tropical forests can have high rates of productivity and large accumulations of carbon in plant biomass and soils. They can therefore play an important role in the global carbon cycle, influencing atmospheric CO2 concentrations if climate warms. We applied meta-analyses to published data to evaluate the apparent effects of temperature on carbon fluxes and storages in mature, moist tropical evergreen forest ecosystems. Among forests, litter production, tree growth, and belowground carbon allocation all increased significantly with site mean annual temperature (MAT); total net primary productivity (NPP) increased by an estimated 0.2-0.7 Mg C x ha(-1) x yr(-1) x degrees C(-1). Temperature had no discernible effect on the turnover rate of aboveground forest biomass, which averaged 0.014 yr(-1) among sites. Consistent with these findings, forest biomass increased with site MAT at a rate of 5-13 Mg C x ha(-1) x degrees C(-1). Despite greater productivity in warmer forests, soil organic matter accumulations decreased with site MAT, with a slope of -8 Mg C x ha(-1) x degrees C(-1), indicating that decomposition rates of soil organic matter increased with MAT faster than did rates of NPP. Turnover rates of surface litter also increased with temperature among forests. We found no detectable effect of temperature on total carbon storage among moist-tropical evergreen forests, but rather a shift in ecosystem structure, from low-biomass forests with relatively large accumulations of detritus in cooler sites, to large-biomass forests with relatively smaller detrital stocks in warmer locations. These results imply that, in a warmer climate, conservation of forest biomass will be critical to the maintenance of carbon stocks in moist tropical forests.     

气候变化与土壤有机质的关系(英文)

在最近的地质历史中,气候变化的速率是史无前例的,它对地球生物圈产生了巨大的影响。土壤有机质中的碳是地球碳库的重要组成部分,它参与全球碳循环。土壤有机质分解而产生的CO2和CH4是重要的温室气体。土壤有机质对气候模型的反应较敏感;其总量取决于生物量生产与分解的平衡状态,以及土壤储存有机质的能力。就全球规模来说,土壤有机质沿着降水增加和温度下降的梯度而增加。温度是支配凋落物分解速率的重要环境因素,它甚至能改变凋落物分解的动力学。     

土壤温室气体产生与排放影响因素研究进展

土壤是温室气体(如CO2、CH4和N2O)产生的重要源,土壤温室气体主要来自于微生物呼吸,植物根呼吸和土壤动物呼吸。土壤温室气体排放机制及其影响因素是研究全球碳氮循环的重要组成部分。研究表明,影响土壤呼吸的因素很多,土壤理化性质如温度、含水量、有机质含量、pH值、氧化还原电位(Eh)、土壤质地等因素都可以直接影响土壤微生物量及其生理生化过程,从而影响温室气体排放。其中,土壤温度,湿度、有机质含量是关键性因素。此外,地域气候、土地利用以及土地覆盖变化也可以通过改变土壤理化性质及呼吸底物来影响温室气体排放。文章重点论述了土壤温室气体排放机制,排放影响因素以及排放的日变化和季节变化规律。认为今后的研究方向应该是土壤微环境碳氮循环机制,土壤呼吸模型在尺度上的推延,以及注重中国陆地与近海生态系统碳固定及减少碳排放的对策和应用技术研究,特别在人工林碳固定及农业固碳减排方面加大研究力度等。     

Substrate concentration and enzyme allocation can affect rates of microbial decomposition

A large proportion of the world's carbon is stored as soil organic matter (SOM). However, the mechanisms regulating the stability of this SOM remain unclear. Recent work suggests that SOM may be stabilized by mechanisms other than chemical recalcitrance. Here, we show that the mineralization rate of starch, a plant polymer commonly found in litter and soil, is concentration dependent, such that its decomposition rate can be reduced by as much as 50% when composing less than approximately 10% of SOM. This pattern is largely driven by low activities of starch-degrading enzymes and low inducibility of enzyme production by microbial decomposers. The same pattern was not observed for cellulose and hemicellulose degradation, possibly because the enzymes targeting these substrates are expressed at constitutively high levels. Nevertheless, given the heterogeneous distribution of SOM constituents, our results suggest a novel low-concentration constraint on SOM decomposition that is independent of chemical recalcitrance. These results may help explain the stability of at least some SOM constituents, especially those that naturally exist in relatively low concentrations in the soil environment.     

Dynamics of soil organic matter in primary and secondary forest succession on sandy soils in The Netherlands: An application of the ROMUL model

We applied the simulation model ROMUL of soil organic matter dynamics in order to analyse and predict forest soil organic matter (SOM) changes following stand growth and also to identify gaps of data and modelling problems. SOM build-up was analysed (a) from bare sand to forest soil during a primary succession in Scots pine forest and (b) on mature forest soil under Douglas fir plantations as an example of secondary succession in The Netherlands. As some of the experimental data were unreliable we compiled a set of various scenarios with different soil moisture regime, initial SOM pools and amount and quality of above and below ground litter input. This allowed us to find the scenarios that reflect the SOM dynamics more realistically. In the Scots pine forest, total litter input was estimated as 0.50 kg m⁻² year⁻¹. Two scenarios were defined for the test runs: (a) forest floor moisture regimes—‘dry, mesic and hydric’ and (b) augmenting a root litter pool with three ratios of needles and branches to roots: 1:1, 1:1.5 and 1:2.0. The scenario finally compiled had the following characteristics: (a) climate for dry site with summer drought and high winter moisture of forest floor; (b) a litter input of 0.25 kg m⁻² year⁻¹ above ground and 0.50 kg m⁻² year⁻¹ below ground; (c) a low nitrogen and ash content in all litter fall fractions. The test runs for the estimation of the initial SOM pools and the amount and proportion of above and below ground litter fall were also performed in the Douglas fir plantation. The inputs of above ground litter tested in various combinations were 0.30 and 0.60 kg m⁻² year⁻¹, and below ground litter 0.30, 0.60 and 0.90 kg m⁻² year⁻¹. The scenario that fitted the experimental data had an SOM pool of 20–25 kg m⁻², an aboveground litter input of 0.6 kg m⁻² year⁻¹and a below ground litter input of 0.9 kg m⁻² year⁻¹. The long-term simulation corresponded well with the observed patterns of soil organic matter accumulation associated with the forest soil development in primary and secondary succession. During primary succession in Scots pine forest on dry sand there is a consistent accumulation of a raw humus forest floor. The soil dynamics in the Douglas fir plantation also coincide with the observed patterns of SOM changes during the secondary succession, with SOM decreasing significantly under young forest, and SOM being restored in the older stands.     

Estimating soil carbon turnover using radiocarbon data: A case-study for European Russia

Turnover rates of soil carbon for 20 soil types typical for a 3.7 million km² area of European Russia were estimated based on ¹⁴C data. The rates are corrected for bomb radiocarbon which strongly affects the topsoil ¹⁴C balance. The approach is applied for carbon stored in the organic and mineral layers of the upper 1 m of the soil profile. The turnover rates of carbon in the upper 20 cm are relatively high for forest soils (0.16–0.78% year⁻¹), intermediate for tundra soils (0.25% year⁻¹), and low for grassland soils (0.02–0.08% year⁻¹) with the exception of southern Chernozems (0.32% year⁻¹). In the soil layer of 20–100 cm depth, the turnover rates were much lower for all soil types (0.01–0.06% year⁻¹) except for peat bog soils of the southern taiga (0.14% year⁻¹). Combined with a map of soil type distribution and a dataset of several hundred soil carbon profiles, the method provides annual fluxes for the slowest components of soil carbon assuming that the latter is in equilibrium with climate and vegetation cover. The estimated carbon flux from the soil is highest for forest soils (12–147 gC/(m² year)), intermediate for tundra soils (33 gC/(m² year)), and lowest for grassland soils (1–26 gC/(m² year)). The approach does not distinguish active and recalcitrant carbon fractions and this explains the low turnover rates in the top layer. Since changes in soil types will follow changes in climate and land cover, we suggest that pedogenesis is an important factor influencing the future dynamics of soil carbon fluxes. Up to now, both the effect of soil type changes and the clear evidence from ¹⁴C measurements that most soil organic carbon has a millennial time scale, are basically neglected in the global carbon cycle models used for projections of atmospheric CO₂ in 21st century and beyond.     

Soil metabolic pulses: water, substrate, and biological regulation

Pulses of metabolic activity are a common ecological response to intermittently available resources, and in soils these pulses often occur in response to wetting. To better understand variation in soil pulses, we conducted a distributed field experiment at seven sites along a 2200-m elevation transect in southern California, USA. Treatments included both water and water + substrate additions and two measurements of soil respiration within one hour. These experiments were repeated 11 times throughout 2009-2010. Additions of substrate led to consistently higher pulse fluxes, exceeding 10 micromol CO2 x m(-2( x s(-1), than additions of water alone. These results support a sequential limitation by two resources where an initial limiting resource acts as a switch and, after activation, processes are regulated by a second resource. In contrast to general expectations of increasing pulses with higher soil organic matter (SOM), pulses exhibited strong scale dependencies. Pulses during the summer period and SOM were correlated positively within sites and negatively between sites. This cross-scale divergence implies that, at low elevations, the proportion of SOM available for pulse metabolism was a much larger fraction than at higher elevations. With expected climate changes leading to more frequent drying-wetting cycles, regulation of metabolic pulses will increasingly influence long-term biogeochemical dynamics.     

Changes in microbial community characteristics and soil organic matter with nitrogen additions in two tropical forests

Microbial communities and their associated enzyme activities affect the amount and chemical quality of carbon (C) in soils. Increasing nitrogen (N) deposition, particularly in N-rich tropical forests, is likely to change the composition and behavior of microbial communities and feed back on ecosystem structure and function. This study presents a novel assessment of mechanistic links between microbial responses to N deposition and shifts in soil organic matter (SOM) quality and quantity. We used phospholipid fatty acid (PLFA) analysis and microbial enzyme assays in soils to assess microbial community responses to long-term N additions in two distinct tropical rain forests. We used soil density fractionation and 13C nuclear magnetic resonance (NMR) spectroscopy to measure related changes in SOM pool sizes and chemical quality. Microbial biomass increased in response to N fertilization in both tropical forests and corresponded to declines in pools of low-density SOM. The chemical quality of this soil C pool reflected ecosystem-specific changes in microbial community composition. In the lower-elevation forest, there was an increase in gram-negative bacteria PLFA biomass, and there were significant losses of labile C chemical groups (O-alkyls). In contrast, the upper-elevation tropical forest had an increase in fungal PLFAs with N additions and declines in C groups associated with increased soil C storage (alkyls). The dynamics of microbial enzymatic activities with N addition provided a functional link between changes in microbial community structure and SOM chemistry. Ecosystem-specific changes in microbial community composition are likely to have far-reaching effects on soil carbon storage and cycling. This study indicates that microbial communities in N-rich tropical forests can be sensitive to added N, but we can expect significant variability in how ecosystem structure and function respond to N deposition among tropical forest types.     

长期施肥对土壤有机质积累的影响

20年的NPK施肥定位试验,有利于深刻揭示土壤肥力特征与营养平衡规律。以位于黄淮海平原的中国科学院禹城综合试验站为例,探讨和估算了长期定量施肥对冬小麦（TriticuspaestvumL．）、夏玉米（ZeaMaysL．）生长和土壤有机质（SOM）的影响。结果表明,长期的N、P肥配施或N、P、K均衡施肥,可显著增加SOM储量,并且后者要优于前者;SOM增加主要集中在0-20cm深度的土层,40-60cm基本不变;生物量对SOM储量变化影响明显,NPK,NP处理作物生长良好,作物残体输人明显优于其他处理;0-40cm可以代表该区用以计算土壤固碳潜力,并且在N、P、K均衡施肥条件下,0-40cm土层中SOM储量长期以来持续增加,并未达到上限,每年的平均固碳速率（以C计）达182．8kg·hm-1,约是全球平均水平的1．5倍,全国平均水平的1．1倍。华北平原若按N、P、K均衡施肥,农田土壤每年固碳潜力将达到1．6-2．4Tg·a-1。     

Soil C and N changes with afforestation of grasslands across gradients of precipitation and plantation age

Afforestation, the conversion of unforested lands to forests, is a tool for sequestering anthropogenic carbon dioxide into plant biomass. However, in addition to altering biomass, afforestation can have substantial effects on soil organic carbon (SOC) pools, some of which have much longer turnover times than plant biomass. An increasing body of evidence suggests that the effect of afforestation on SOC may depend on mean annual precipitation (MAP). The goal of this study was to test how labile and bulk pools of SOC and total soil nitrogen (TN) change with afforestation across a rainfall gradient of 600-1500 mm in the Rio de la Plata grasslands of Argentina and Uruguay. The sites were all former grasslands planted with Eucalyptus spp. Overall, we found that afforestation increased (up to 1012 kg C x ha(-1) x yr(-1)) or decreased (as much as 1294 kg C x ha(-1) x yr(-1)) SOC pools in this region and that these changes were significantly related to MAP. Drier sites gained, and wetter sites lost, SOC and TN (r2 = 0.59, P = 0.003; and r2 = 0.57, P = 0.004, respectively). Labile C and N in microbial biomass and extractable soil pools followed similar patterns to bulk SOC and TN. Interestingly, drier sites gained more SOC and TN as plantations aged, while losses reversed as plantations aged in wet sites, suggesting that plantation age in addition to precipitation is a critical driver of changes in soil organic matter with afforestation. This new evidence implies that longer intervals between harvests for plantations could improve SOC storage, ameliorating the negative trends found in humid sites. Our results suggest that the value of afforestation as a carbon sequestration tool should be considered in the context of precipitation and age of the forest stand.     

土壤磷素微生物作用的研究进展

土壤中许多微生物(包括菌根真菌)能够通过产生质子和有机酸溶解土壤不溶态无机磷，通过分泌磷酸酶水解有机磷，但微生物的这种作用受土壤供磷与植物对磷需求间平衡的控制。土壤微生物量中的磷是土壤有机磷最为活跃的部分，由于其周转快、极易矿化为植物有效磷而成为土壤有效磷的活性库。目前，测定土壤微生物量中的磷的方法并不统一，而熏蒸提取法的应用最为广泛。文章阐述了土壤微生物在提高土壤磷素有效性磷中所起的作用，介绍了土壤微生物量中的磷周转及其对土壤磷素有效性调节的重要性，并总结分析了熏蒸提取法测定土壤微生物量中的磷的实用性和局限性。     

Litter decomposition and nitrogen mineralization from an annual to a monthly model

The forest litter decomposition model (FLDM) described in this paper provides an important basis for assessing the impacts of forest management on seasonal stream water quality and export of dissolved organic carbon (DOC). By definition, models with annual time steps are unable to capture seasonal, within-year variation. In order to simulate seasonal variation in litter decomposition and DOC production and export, we have modified an existing annual FLDM to account for monthly dynamics of decomposition and residual mass in experimental litterbags placed in 21 different forests across Canada.The original annual FLDM was formulated with three main litter pools (fast, slow, and very slow decomposing litter) to address the fact that forest litter is naturally composed of a mixture of organic compounds that decompose at different rates. The annual FLDM was shown to provide better simulations than more complex models like CENTURY and SOMM.The revised monthly model retains the original structure of the annual FLDM, but separates litter decomposition from nitrogen (N) mineralization. In the model, monthly soil temperature, soil moisture, and mean January soil temperature are shown to be the most important controlling variables of within-year variation in decomposition. Use of the three variables in a process-based definition of litter decomposition is a significant departure from the empirical definition in the annual model. The revised model is shown to give similar calculations of residual mass and N concentration as the annual model (r² = 0.91, 0.78), despite producing very different timeseries of decomposition over six years. It is shown from a modelling perspective that (i) forest litter decomposition is independent of N mineralization, whereas N mineralization is dependent on litter decomposition, and (ii) mean January soil temperature defines litter decomposition in the summer because of winter-temperatures’ role in modifying forest-floor microorganism community composition and functioning in the following summer.     

不同土地覆被下岩溶表层系统CO2体积分数研究

对重庆金佛山林地、裸地表层岩溶生态系统CO2体积分数进行了野外监测,揭示了CO2体积分数变化规律,这种变化与土壤温度有密切的关系。林地与裸地各个层次土壤的CO2体积分数与土温呈一致性变化,随着土温的升高或降低而相应的增加或减少。文章进一步揭示了林地植被平抑这种动态效应,而裸地则响应于温度变化;这种不同植被系统下的动态差异在解释岩溶沉积记录和讨论岩溶作用与碳循环的关系时值得充分注意。     

A process-based model of nitrogen cycling in forest plantations: Part I. Structure,calibration and analysis of the decomposition model

We present a new decomposition model of C and N cycling in forest ecosystems that simulates N mineralisation from decomposing tree litter. It incorporates a mechanistic representation of the role of soil organisms in the N mineralisation-immobilisation turnover process during decomposition. We first calibrate the model using data from decomposition of ¹⁴C-labelled cellulose and lignin and ¹⁴C-labelled legume material and then calibrate and test it using mass loss and N loss data from decomposing Eucalyptus globulus residues. The model has been linked to the plant production submodel of the G’DAY ecosystem model, which previously used the CENTURY decomposition submodel for simulating C and N cycling. The key differences between this new decomposition model and the previous one, based on the CENTURY model, are: (1) growth of microbial biomass is the process that drives N mineralisation-immobilisation, and microbial succession is simulated; (2) decomposition of litter can be N-limited, depending on soil inorganic N availability relative to N requirements for microbial growth; (3) ‘quality’ of leaf and fine root litter is expressed in terms of biochemically measurable fractions; (4) the N:C ratio of microbial biomass active in decomposing litter is a function of litter quality and N availability; and (5) the N:C ratios of soil organic matter (SOM) pools are not prescribed but are instead simulated output variables defined by litter characteristics and soil inorganic N availability. With these modifications the model is able to provide reasonable estimates of both mass loss and N loss by decomposing E. globulus leaf and branch harvest residues in litterbag experiments. A sensitivity analysis of the decomposition model to selected parameters indicates that parameters regulating the stabilisation of organic C and N, as well as those describing incorporation of soil inorganic N in Young-SOM (biochemical immobilisation of N) are particularly critical for long-term applications of the model. A parameter identifiability analysis demonstrates that simulated short-term C and N loss from decomposing litter is highly sensitive to three model parameters that are identifiable from the E. globulus litterbag data.     

基于Meta分析的土壤呼吸对凋落物输入的响应

凋落物输入是影响土壤呼吸的一个重要因素,然而从国内外目前研究结果来看,土壤呼吸响应凋落物输入的影响因素尚不清楚。利用国内外已发表的30篇研究论文共1393对有效数据,通过Meta分析,从凋落物管理措施、气候、植被、地形、土壤理化性质等因素揭示凋落物输入对土壤呼吸的影响程度。研究发现:与清除凋落物处理相比较而言,(1)凋落物输入后显著增加了土壤呼吸,且土壤呼吸的增加程度呈现出倍增凋落物处理是自然凋落物处理的1.33倍;(2)不同气候条件下的土壤呼吸增加程度呈现出强降雨(>1000 mm)是微弱降雨(<1000 mm)的1.34倍,以及高温气候(>20℃)是低温气候(<20℃)的1.7倍;(3)土壤呼吸的增加程度在不同植被带下呈现出针叶林带(34.1%)>阔叶林带(28%)>混交林带(22%)>草地(17.3%)的趋势;(4)不同海拔梯度条件下土壤呼吸的增加程度呈现出高海拔(59.6%)>中海拔(34.2%)>低海拔(26.7%)的趋势;(5)不同土壤理化性质条件下的土壤呼吸增量呈现出低容重(77.5%)分别是中容重(26.9%)和高容重(18.0%)的2.9倍和4.3倍,同时中性土壤(79.6%)的呼吸增量远远大于酸性(28.2%)和碱性(24.1%)土壤的呼吸增量,以及高土壤碳氮比(81.2%)的土壤呼吸增量远远大于低土壤碳氮比(19.4%)和中土壤碳氮比(29.6%)的土壤呼吸增量。由此可见,凋落物输入后会导致土壤呼吸的显著增加,但是不同气候、不同植被、不同地形、不同土壤理化性质等条件下其土壤呼吸增加的幅度不同。