Relation of Wind-induced Sand Displacement to Plant Biomass and Plant Sand-binding Capacity

Desertification is a process in which vegetation cover degrades followed by increased wind and water erosion. Plants adapted to moving sand conditions are able to reverse this process. They can stabilize die substrate. Not much data is available on the soil stabilization capacity of plants. This study was conducted to investigate the wind-induced sand displacement around plants in relation to their biomass. Sand displacement is examined in relation to the biomass allocation pattern of three different plant species. A new method was developed to experimentally investigate plant sand-binding capacity. The relationship between sand displacement and plant biomass was not linear. Apart from the amount of biomass, species-specific plant characters like the biomass allocation pattern and plant structure may be very important in determining the sand-binding capacity.

Effect of forest thinning on hydrologic nitrate exports from a Nsaturated plantation

Although several studies have assessed the effects of thinning on water quality,including nitrogen(N)exports,few have examined N-saturated plantations.This study assessed the short-term effect of thinning on N exports from a N-saturated plantation forest in northern Kyushu,western Japan,that was thinned(43%of basal area)during January-March 2012.Water levels at the gauging station were continually measured,and streamwater baseflow and stormflow samples were collected before(2011)and after(2013)forest thinning.Annual precipitation before(2469 mm)and after(2418 mm)forest thinning differed little,and annual water discharge after thinning(1641 mm)was similar to that before thinning(1609 mm).However,direct flow during stormflow periods was higher after thinning(260 mm)than before(153 mm).The concentrations of major ions in stream water did not differ before and after thinning.As a result,the high annual dissolved inorganic N(DIN)exports differed little before(35.8 kg N ha^-1 a^-1)and after(36.5 kg N ha^-1 a^-1)forest thinning.DIN exports during stormflow periods were slightly higher after(12.2 kg N ha^-1 a^-1)than before thinning(10.5 kg N ha^-1 a^-1)and were proportional to the increased direct flow after thinning(561 mm after vs.470 mm before thinning).We concluded that thinning does not affect annual N exports from the N-saturated plantation forest,but it can increase the proportion of N exported during stormflow periods in proportion to increased water volume of direct flow after thinning.

Spatial Distribution of Regenerated Woody Plants in <i>Alnus hirsuta</i>(Turcz.) var. <i>sibirica</i>Stand in Japan

The role of N2 fixation in structuring plant communities and influencing ecosystem function will be potentially large. In previous study, we investigated nodule biomass and activity, and calculated the amount of N2 fixation in a naturally established 18-year-old alder (Alnus hirsute (Turcz.) var. sibirica) stand following disturbance by road construction in Takayama, central Japan. In this study, to estimate the facilitation effects by alder on the spatial distribution of the regenerated tree species, we examined the distribution pattern of the regenerated tree species in this naturally established 18-year-old alder stand. The distribution pattern of alder and the regenerated woody species was analyzed in terms of spatial point processes and the regenerated species tended to distribute near the alder site. In particular, bird-dispersed tree species (endozoochory species) with relatively high shade tolerance showed a significant attraction to alder. These results suggest that alder will be used as roost trees and play the role of mother trees for these regenerated species at the degraded site. It was also suggested that the endozoochory species, which occupy 13 of 26 regenerated species in this stand, might regenerate faster than other species at this alder stand.

Regeneration of Nothofagus dombeyi(Mirb.)Ørst.in little to moderately disturbed southern beech forests in the Andes of Patagonia(Argentina)

Natural forests and stands subjected to little to moderate human impact are continuously declining worldwide and with these,their biodiversity and ecosystem services.Many Nothofagus forests in the south of the South American continent are in a pristine state or only moderately impacted by humans.Forest grazing by livestock,in the past and still today often practiced in a non-sustainable way is,however,increasingly under discussion to meet current environmental and socio-economic challenges.Accordingly,we investigate the regeneration of Nothofagus dombeyi,a keystone species of the Patagonian Andes,in secondary forests in Argentinian northern Patagonia,particularly addressing the role of disturbance through grazing by livestock at various intensities.We test the hypothesis that the regeneration of this tree species is favored by grazing impact and,thus,disturbance of the herb layer and soil surface.In support of our hypothesis,Nothofagus dombeyi regeneration was significantly higher in terms of individuals and height classes in moderately grazed forests.Multivariate analysis shows significant positive effects of moderate grazing pressure,herb layer cover,and the occurrence of bare soil on the regeneration of Nothofagus dombeyi.Our results show that an integration of livestock grazing and forest regeneration is possible and that agroforestry systems can be an adequate management option for stakeholders in the region.A grazing management can also be part of a forest fire prevention strategy.However,the regeneration success and grazing pressure should be continuously monitored.

Single and combined eff ects of fertilization,ectomycorrhizal inoculation,and drought on container-grown Japanese larch seedlings

Climate change can intensify drought in many regions of the world and lead to more frequent drought events or altered cycles of soil water status.Therefore,it is important to enhance the tolerance to drought and thus health,vigor,and success of transplantation seedlings used in the forestry by modifying fertilization and promoting mycorrhization.Here,we sowed seeds of Japanese larch(Larix kaempferi)in 0.2-L containers with 0.5 g(low fertilization;LF)or 2 g(high fertilization;HF)of slow-release fertilizer early in the growing season.One month later,we irrigated seedlings with non-sterilized ectomycorrhizal inoculum(ECM)or sterilized solution(non-ECM),and after about 2 months,plants were either kept well watered(WW;500 mL water/plant/week)or subjected to drought(DR;50 mL water per plant/week)until the end of the growing season.HF largely stimulated plant growth and above-and belowground biomass production,eff ects that are of practical signifi cance,but caused a small decrease in stomatal conductance(Gs 390)and transpiration rate(E 390),which in practice is insignifi cant.ECM treatment resulted in moderate inhibition of seedling growth and biomass and largely canceled out the enhancement of biomass and foliar K content by HF.DR caused a large decrease in CO 2 assimilation,and enhanced stomatal closure and induced senescence.DR also largely depleted foliar Mg and enriched foliar K.Although DR caused a large decrease in foliar P content in LF,it moderately increased P in HF.Likewise,DR increased foliar K in HF but not in LF,and decreased foliar P in ECM plants but not in non-ECM plants.Conversely,ECM plants exhibited a large enrichment in foliar P under WW and had a lower water potential under DR when grown in LF.These results indicate that the drought tolerance and health and vigor of Japanese larch seedlings can be modifi ed by soil fertility and soil microorganisms.This study provides a basis for new multifactorial research programs aimed at producing seedlings of superior quality for forestation under climate change.

Equations for estimating the above-ground biomass of Larix sibirica in the forest-steppe of Mongolia

Biomass functions were established to estimate above-ground biomass of Siberian larch （Larix sibirica） in the Altai Mountains of Mon- golia. The functions are based on biomass sampling of trees from 18 different sites, which represent the driest locations within the natural range ofL. sibirica. The best performing regression model was found for the equations y = （D2 H）/（a＋bD） for stem biomass, y = aDb for branch biomass, and y=aDb Hc for needle biomass, where D is the stem diameter at breast height and H is the tree height. The robustness of the biomass functions is assessed by comparison with equations which had been previously published from a plantation in Iceland. There, y=aDb Hc was found to be the most significant model for stem and total above-ground biomasses. Applying the equations from Iceland for estimating the above-ground biomass of trees from Mongolia resulted in the underesti- mation of the biomass in large-diameter trees and the overestimation of the biomass in thin trees. The underestimation of thick-stemmed trees is probably attributable to the higher wood density, which has to be ex- pected under the ultracontinental climate of Mongolia compared to the euoceanic climate of Iceland. The overestimation of the biomass in trees with low stem diameter is probably due to the high density of young growth in the not systematically managed forests of the Mongolian Altai Mountains, which inhibits branching, whereas the plantations in Iceland are likely to have been planted in lower densities.

Vitality variation and population structure of a riparian forest in the lower reaches of the Tarim River,NW China

Since 2000, the Chinese government has implemented emergency water diversion measures to restore the damaged riparian forest ecosystem with dominant tree species Euphrat poplar(Populus euphratica Oliv.)at the lower reaches of the Tarim River. In the present study, comparative analysis of variations in the vitality of P. euphratica trees were made using 2005 and 2010 data to illustrate the revitalization process of riparian forest. Poplar trees within 300 m of the riverbed were positively revitalized, while the vitality of trees farther than 300 m from the river decreased. Population structure was studied to demonstrate the development of poplar community. In the first belt, the class structure for the diameter at breast height(DBH) of P. euphratica fit a logistic model, and the 2nd, 3rd and 4th belt curve fittings were close to a Gaussian model; in other plots they were bimodal. Cluster analysis of the composition of the DBH class of poplar trees demonstrated that those within 16–36 cm DBH were the most abundant(58.49% of total) in study area, under 16 cm of DBH were second(31.36%), and trees >40 cm DBH were the least abundant(10.15%). More than 80% of the trees were young and medium-sized, which means that the poplar forest community in the vicinity of the lower Tarim River is at a stable developmental stage. The abundance of juvenile trees of P. euphratica in the first and second measuring belts was 12.13% in 2005 and increased to 25.52% in 2010, which means that the emergency water transfer had a positive impact on the generation of young P. euphratica trees in the vicinity of the river.

Effects of six years of simulated N deposition on gross soil N transformation rates in an old-growth temperate forest

Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing’an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory usingN tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH~+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO~-) was primarily produced via oxidation of NH~+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO~- consumption rates,resulting in a build-up of NO~-, which highlights the high risk of N losses via NO~- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation.

Interactive influence of rainfall manipulation and livestock grazing on species diversity of the herbaceous layer community in a humid savannah in Kenya

Changes in rainfall regime and grazing pressure affect vegetation composition and diversity with ecological implications for savannahs. The savannah in East Africa has experienced increased livestock grazing and rainfall variability but the impacts associated with those changes on the herbaceous layer have rarely been documented. We investigated the effect of livestock grazing, rainfall manipulation and their interaction on the composition and diversity of the herbaceous community in the savannah for two years in Lambwe, Kenya. Rainfall manipulation plots were set up for vegetation sampling;these plots received either 50% more or 50% less rainfall than control plots. Simpson’s diversity and Bergere Parker indices were used to determine diversity changes and dominance respectively. The frequency of species was used to compute their abundance and their life forms as determined from the literature. Grazing significantly increased species diversity through suppression of dominant species. Rainfall manipulation had no significant impact on plant diversity in fenced plots, but rainfall reduction significantly reduced diversity in grazed plots. In contrast, rainfall manipulation had no impact on dominance in either fenced or grazed plots. The interaction of grazing and rainfall manipulation is complex and will require additional survey campaigns to create a complete picture of the implications for savannah structure and composition.

AGE STRUCTURES OF MODULES OF CLONAL PEATLAND SEDGE Carex middendorffii

Age structure of a plant population carries important information on population dynamics. The traditional age classification of individuals by development phases could not explain the generation relationship neither between individuals nor between modules, and it could not accurately predict the future of population or the tendency of peatland evolution. In a peatland of the Xiao Hinggan Mountains, China, at the middle of the growth season, the age structures of 3 modules, ramets, active buds and rhizomes of a Carex middendorffii clonal population were investigated, with the method of classifying age classes of ramets and active buds by counting generation quantity of tiller nodes, and classifying age classes of rhizomes by their real survival time. The quantity of vegetative ramets was dominant. Tiller nodes of ramets can propagate vegetatively for a maximum of 3 generations. The population of ramets consisted of 3 age classes of ramets at the middle of the growth season, and showed a stable age structure. In the two sampling events, there was no significant difference between quantities and age structure of the population. The maximum age of an excavated rhizome was 12 years old. Rhizomes were classified in 8 age classes, and age classes 4-6 contributed most to the total biomass. There was no significant difference in total length and total biomass per unit area, or in biomass per unit length in rhizomes between the two samplings. Four age classes of active buds were recognized, and their number increased from July to August. The Carex middendorffii clonal population achieved regeneration by budding from the tiller nodes of ramets. The age structures of the 3 modules suggested that the Carex middendorffii clonal population could persist in the early development phase of the oligotrophic peatland in the Xiao Hinggan Mountains, but it could not be dominant. It also faces the risk to disappear from the community as the peatland develops further.

Effects of soil nutrient availability and ozone on container-grown Japanese larch seedlings and role of soil microbes

The interactive eff ects of ozone,soil nutrient availability and root microorganisms on physiological,growth,and productivity traits were studied for the fi rst time for Japanese larch(Larix kaempferi)seedlings grown in containers over a growing season,using a free air ozoneconcentration enrichment exposure system.High nutrient availability altered leaf and root nutrient dynamics and enhanced plant growth;however,it also enhanced seedling susceptibility to damping-off disease compared to low nutrient availability.Negative eff ects of elevated ozone,as compared with ambient ozone,on leaf gas exchange and plant stem form were neither off set nor exacerbated by soil nutrient availability and root colonizers.Such negative eff ects suggest that elevated ozone may have implications for ecological health even when plant vigor is limited by factors other than ozone.Inoculation of roots with ectomycorrhizae had negligible infl uence on the eff ects of either soil nutrient availability or ozone.However,this lack of eff ect may be upon impeded formation of complete mycorrhizal root tips due to factors other than the manipulated variables.B and Na appeared to have an important role in stress responses,so further studies to examine their link with physiological mechanisms as a function of time.This study provides an important perspective for designing forestry practices to enhance seedling health.

Evaluation of Parametric Limitations in Simulating Greenhouse Gas Fluxes from Irish Arable Soils Using Three Process-Based Models

Globally a large number of process-based models have been assessed for quantification of agricultural greenhouse gas (GHG) emissions. Modelling approaches minimize the presence of spatial variability of biogeochemical processes, leading to improved estimates of GHGs as well as identifying mitigation and policy options. The comparative performance of the three dynamic models (e.g., DNDC v9.4, DailyDayCent and ECOSSE v5+) with minimum numbers of common input parameters was evaluated against measured variables. Simulations were performed on conventionally-tilled spring barley crops receiving N fertilizer at 135 - 159 kg·N·ha-1·yr-1 and crop residues at 3 t·ha-1·yr-1. For surface soil nitrate (0 - 10 cm), the ECOSSE and DNDC simulated values showed significant correlations with measured values (R2 = 0.31 - 0.55, p 0.05). Only the ECOSSE-simulated N2O fluxes showed a significant relationship (R2 = 0.33, p 0.05) with values measured from fertilized fields, but not with unfertilized ones. The DNDC and DailyDayCent models significantly underestimated seasonal/annual N2O fluxes compared to ECOSSE, with emission factors (EFs), based on an 8-year average, were 0.09%, 0.31% and 0.52%, respectively. Predictions of ecosystem respiration by both DailyDayCent and DNDC showed reasonable agreement with Eddy Covariance data (R2 = 0.34 - 0.41, p 0.05). Compared to the measured value (3624 kg·C·ha-1·yr-1), the ECOSSE underestimated annual heterotrophic respiration by 7% but this was smaller than the DNDC (50%) and DailyDayCent (24%) estimates. All models simulated CH4 uptake we

岩溶区砂糖桔短期种植对土壤氮转化过程的影响

利用15N同位素成对标记法并结合MCMC数值模型,研究岩溶区乔灌地开垦种植砂糖桔4年后土壤氮转化特征。结果显示:乔灌地开垦种植砂糖桔后,土壤有机氮矿化速率由2.93 mg N·kg^(−1)·d^(−1)显著下降至0.60 mg N·kg^(−1)·d^(−1),土壤无机氮的供应能力降低,土壤有机氮矿化速率与土壤有机碳、全氮和全钙含量呈显著正相关性,与铁、铝、钾和黏粒比例呈显著负相关性;土壤铵态氮微生物同化速率由1.76 mg N·kg^(−1)·d^(−1)显著降低为0.10 mg N·kg^(−1)·d^(−1),在砂糖桔地铵态氮微生物同化速率与有机氮矿化速率的比值仅为0.17。乔灌地土壤自养硝化速率高达11.06 mg N·kg^(−1)·d^(−1),而硝态氮微生物同化作用微弱,硝态氮异化还原速率仅为0.64 mg N·kg^(−1)·d^(−1),导致硝态氮净产生速率达到10.42 mg N·kg^(−1)·d^(−1)。由于土壤铵态氮浓度的降低和施肥导致土壤酸化不利于硝化细菌的活动,自养硝化速率显著降低至1.68 mg N·kg^(−1)·d^(−1)。岩溶区乔灌地开垦种植砂糖桔4年后土壤氮转化速率呈下降趋势。

Dynamics of non-structural carbohydrates following a full masting event reveal a role for stored starch in relation to reproduction in Fagus crenata

Although mature trees have substantial non-structural carbohydrate(NSC)storage that is well documented with respect to its capacity to buffer the asynchrony of supply and demand at the whole-plant level,its role in reproduction remains poorly understood,especially in mast seeding species.In order to elucidate whether masting depletes the whole-tree NSC storage pool,seasonal and inter-annual variations in starch and soluble sugar(SS)concentrations in branchlets,stems and coarse roots of Fagus crenata were measured in two stands over 5 years after a full masting event.Full masting reduced individual storage pools to 72% and 49% of the maxima in the two stands;this was observed 2-3 years after full masting.In addition,temporary reduction in starch concentration in summer due to moderate fruiting was found in roots and deep sapwood cores of stems,representing tree rings formed 20 years ago,but not in branchlets.Together with a higher starch storage pool in roots than in branchlets,these results indicate that starch stored in roots and stems is available and supports life-history traits,such as masting events,that occur irregularly.Moreover,limited rainfall in the late growing season caused a reduction in both organ NSC concentration and individual storage irrespective of masting,which further complicated the masting-NSC relationship.These findings have important implications for interpreting the role of carbon resources in masting events.

Microtopography causes small-scale variation in harvest and forage quality of high-yielding silage grassland in northern Germany

Background:Local sward dieback,especially in grasslands on peat soil,in response to the extreme 2018/2019 drought demonstrates climate vulnerability of intensive grasslands in northern Central Europe.Methods:We explore the influence of microtopography,that is,the within-field mosaic of depressions and elevated patches,on soil volumetric moisture content,standing biomass and biomass crude protein(CP)andfibre content in intensively managed grassland on peat soil in a moist year(2021)and a dry year(2022)for quantifying small-scale spatial heterogeneity within afield.Results:We found high within-field variation in soil moisture,biomass and forage quality and a moisture dependence of productivity that was stronger in the dry year.CP ranged from 10%to 25%within afield,being lower in moist depressions than elevated patches in the wet(but not in the dry)summer.Conclusions:The moister depressions help to limit the overall productivity decline in dry summers,whereas,in moist summers,the higher dry patches produce more protein-rich forage than the depressions,where productivity is higher but quality is lower.We recommend adapting grassland management to this heterogeneity through spatially differentiated management regimes in order to better cope with an increasingly drier and more variable climate.

两种亚热带榕属乔木切枝后的叶效率及其对生长的影响

榕 ( Ficusmicrocarpa L.)和黄桷树 ( Ficus virens Ait.Var.sublanceolata( Miq.) Corner)是在三峡库区大量栽植的优良绿化树种。因种苗培育和植株管理的需要 ,对榕和黄桷树进行切枝的现象常有发生。切枝引起的叶组织损失可能使植株的总光合生产下降 ,生长减弱。因此 ,叶的净生产能力 ,即叶效率 ,对榕和黄桷树植株切枝后的生长和损伤恢复至关重要。由于切枝引起的光合组织 (叶组织 )损失大于非光合组织损失 (因为切枝并不影响植株的主茎和根组织 ) ,植株切枝后平均每单位叶面积要提供比切枝前更多的同化产物用于呼吸消耗 ,因而切枝后植株的叶效率有可能下降。为探明切枝是否会影响榕和黄桷树的叶效率以及可能的叶效率变化对植株生长的影响 ,设计了包括 2个处理季节 (春季和秋季 )和 4个处理强度 ( 0 %、2 0 %、5 0 %和 70 %切枝 )的切枝实验 ,对榕和黄桷树进行了切枝处理。实验结果表明 ,切枝不会降低榕和黄桷树的叶效率 ,相反 ,切枝后植株的叶效率会增高 (榕春季切枝处理除外 ) ,切枝对叶效率的增高效应不会因切枝季节和切枝强度的不同而变化。研究发现 ,不同切枝季节对榕和黄桷树叶效率的影响不一样。秋季切枝使叶效率增高的程度大于春季切枝。秋季切枝后 。

岩溶区农业种植对土壤有机氮矿化的影响

土壤有机氮矿化是供应无机氮的主导过程,研究其变化对于认识土壤氮素有效性和指导氮肥施用具有重要意义。本研究分别在云南建水、蒙自和勐腊岩溶区选取脐橙地、玉米地和橡胶地作为研究对象,并以临近未受人为扰动的草地或原始林地作为对照,采用15N同位素标记方法,研究了岩溶区草地或原始林地开垦种植农作物后石灰土有机氮矿化(MNorg)速率变化,并区分了易分解有机氮矿化(MNlab)和难分解有机氮矿化(MNrec)对MNorg的贡献。结果表明,原始林地土壤MNorg(8.94 mg N∙kg^-1 d^-1)显著高于草地(1.41~2.46 mg N·kg^-1 d^-1),且均以MNlab为主。其中,草地MNlab对MNorg贡献率可达80.6%~93.1%,而在原始林地中该贡献率达到62.2%。岩溶区草地或林地开垦种植经济作物显著降低MNorg速率,其MNorg速率为0.53~0.89 mg N∙kg^-1 d^-1,下降比例达62.5%~90.1%。这种差异主要受MNlab和MNrec影响,由草地开垦种植脐橙和玉米后土壤MNorg下降主要归于MNlab速率下降,而MNrec并未发生显著变化;原始林地开垦种植橡胶后土壤MNorg下降主要归于MNlab和MNrec速率的共同下降。岩溶区草地或原始林地开垦种植农作物后土壤有机碳、全氮、全磷、全钙和全镁含量及土壤田间持水量、pH、阳离子交换量均显著降低,且与土壤MNorg和MNlab呈显著正相关,表明农业种植对土壤理化性质的改变是影响矿化速率的重要因素。

岩溶区和碎屑岩区林地和农田土壤氮矿化过程对比研究

通过^(15)N标记法和MCMC氮素转化模型,研究了岩溶区(石灰性土壤)和碎屑岩区(红壤)林地和农田土壤易分解有机氮矿化(M_易)、难分解有机氮矿化(M_难)和总有机氮矿化(M_总)速率。结果发现,土壤矿化速率受土壤类型和土地利用方式的显著影响。林地石灰性土壤M_总(3.71mg N/kg)显著低于林地红壤(5.57mg N/kg),石灰性土壤M_(Nlab)(1.81mg N/kg)与M_(Nrec)(1.90mg N/kg)相近,而红壤M_易(4.60mg N/kg)显著高于M_难(0.96mg N/kg)。林地变为农田后,石灰性土壤M_总显著提高,而红壤显著降低。与林地相比,岩溶区农田土壤M_易提高了72.5%,而M_难下降了33.7%。碎屑岩区农田土壤M_易和M_难分别降低至2.47和0.46mg N/kg。岩溶区土壤CaO和MgO含量与M_易呈显著负相关,而与M_难呈显著正相关,表明岩溶区土壤钙镁含量是影响氮矿化速率的重要因素。

Temporal Variability in Soil CO_2 Emission in an Orchard Forest Ecosystem

Temporal variability in soil CO2 emission from an orchard was measured using a dynamic open-chamber system for measuring soil CO2 effiux in Heshan Guangdong Province, in the lower subtropical area of China. Intensive measurements were conducted for a period of 12 months. Soil CO2 emissions were also modeled by multiple regression analysis from daily air temperature, dry-bulb saturated vapor pressure, relative humidity, atmospheric pressure, soil moisture, and soil temperature. Data was analyzed based on soil moisture levels and air temperature with annual data being grouped into either hot-humid season or relatively cool season based on the precipitation patterns. This was essential in order to acquire simplified exponential models for parameter estimation. Minimum and maximum daily mean soil CO2 effiux rates were observed in November and July, with respective rates of 1.98 ± 0.66 and 11.04 ± 0.96 μmol m^-2 s^-1 being recorded. Annual average soil CO2 emission （FCO2） was 5.92 μmol m^-2 s^-1. Including all the weather variables into the model helped to explain 73.9% of temporal variability in soil CO2 emission during the measurement period. Soil CO2 effiux increased with increasing soil temperature and soil moisture. Preliminary results showed that Q10, which is defined as the difference in respiration rates over a 10 ℃ interval, was partly explained by fine root biomass. Soil temperature and soil moisture were the dominant factors controlling soil CO2 effiux and were regarded as the driving variables for CO2 production in the soil. Including these two variables in regression models could provide a useful tool for predicting the variation of CO2 emission in the commercial forest Soils of South China .