Root overlap and allocation of above- and belowground growth of European beech in pure and mixed stands of Douglas fir and Norway spruce

Site conditions and species identity have a combined effect on fine root growth of trees in pure and mixed stands.However,mechanisms that may contribute to this effect are rarely studied,even though they are essential to assess the potential of species to cope with climate change.This study examined fine root overlap and the linkage between fine root and stem growth of European beech(Fagus sylvatica)growing in pure and mixed stands with Douglas fir(Pseudotsuga menziesii)or Norway spruce(Picea abies)at two different study sites in northwestern Germany.The study sites represented substantially different soil and climate conditions.At each site,three stands,and at each stand,three pairs of trees were studied.In the pure beech stand,the pairs consisted of two beech trees,while in the mixed stands each pair was composed of a beech tree and a conifer.Between each pair,three evenly spaced soil cores were taken monthly throughout the growing season.In the pure beech stands,microsatellite markers were used to assign the fine roots to individual trees.Changes in stem diameter of beech were quantified and then upscaled to aboveground wood productivity with automatic high-resolution circumference dendrometers.We found that fine root overlap between neighboring trees varied independently of the distance between the paired trees or the stand types(pure versus mixed stands),indicating that there was no territorial competition.Aboveground wood productivity(wood NPP)and fine root productivity(root NPP)showed similar unimodal seasonal patterns,peaking in June.However,this pattern was more distinct for root NPP,and root NPP started earlier and lasted longer than wood NPP.The influence of site conditions on the variation in wood and root NPP of beech was stronger than that of stand type.Wood NPP was,as expected,higher at the richer site than at the poorer site.In contrast,root NPP was higher at the poorer than at the richer site.We concluded that beech can respond to limited resources not only above-but also belowground and that the negative relationship between above-and belowground growth across the study sites suggests an‘optimal partitioning’of growth under stress.

Land-use legacies affect the composition and distribution of tree species and their belowground functions in a succession from old-field to mature temperate forest

Forests undergoing ecological succession following abandonment from agricultural use(i.e.,old fields)are ubiquitous in temperate regions of the U.S.and Europe.Ecological succession in old fields involves changes in vegetation composition influenced by factors such as land-use history,soil conditions,and dispersal limitations.Species’behavioral,morphological,physiological and life-history attributes influence the outcomes of environmental and biotic filters on distribution and abundance.However,many studies have focused on aboveground attributes,while less attention has been placed on belowground species characteristics that influence community assembly and function.In this study,we used a trait-based approach to examine how aboveground plant composition and distribution vary with plant root functional traits(e.g.,mycorrhizal association)that mediate access for nutrients such as nitrogen(N)and phosphorous(P).We inventoried every tree stem(n=11,551)in a 10-ha forested area containing old-field and historical forests and matched every species with root functional traits(n=33)from established databases.We found that land-use history influences community composition and distribution in old-field forests,which also varied with belowground root functional traits.Community composition in old-field forests,which were dominated by Acer saccharum and non-native species,were largely associated with arbuscular mycorrhizae(AM)and higher root nutrient concentrations.On the other hand,community composition in historical forests–largely dominated by Tsuga canadensis–were associated with ectomycorrhiza(EcM)and more variation of root length and depth.These results suggest that changes in aboveground communities have implications for belowground ecosystem services(e.g.,nutrient cycling)which are important to forest ecosystem development.Trait-based approaches can elucidate mechanisms of community assembly,and understanding how traits influence species coexistence and interactions can inform management decisions related to biodiversity conservation and restoration efforts in disturbed or altered forests.

Effects of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze-Yellow rivers, Tibetan Plateau of China

Improving our knowledge of the effects of environmental factors （e.g. soil conditions, precipitation and temperature） on belowground biomass in an alpine grassland is essential for understanding the consequences of carbon storage in this biome. The object of this study is to investigate the relative importance of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze and Yellow rivers, Tibetan Plateau. Soil organic carbon （SOC）, total nitrogen （TN） and total phosphorous （TP） contents and belowground biomass were measured at 22 sampling sites across an alpine meadow on the Tibetan Plateau. We analyzed the data by using the redundancy analysis to determine the main environmental factors affecting the belowground biomass and the contribution of each factor. The results showed that SOC, TN and TP were the main factors that influenced belowground biomass, and the contribution of SOC, TN and TP on biomass was in the range of 47.87%-72.06% at soil depths of 0-30 cm. Moreover, the combined contribution of annual mean temperature （AMT） and mean annual precipitation （MAP） on belowground biomass ranged from 0.92% to 4.10%. A potential mechanism for the differences in belowground biomass was caused by the variations in soil nitrogen and phosphorous, which were coupled with SOC. A significant correlation was observed between MAP and soil nutrients （SOC, TN and TP） at the soil depth of 0-10 cm （P〈0.05）. We concluded that precipitation is an important driving force in regulating ecosystem functioning as reflected in variations of soil nutrients （SOC, TN and TP） and dynamics of belowground biomass in alpine grassland ecosystems.

The importance of aboveground and belowground interspecific interactions in determining crop growth and advantages of peanut/maize intercropping

Intercropping of maize(Zea mays L.) and peanut(Arachis hypogaea L.) often results in greater yields than the respective sole crops. However, there is limited knowledge of aboveground and belowground interspecific interactions between maize and peanut in field. A two-year field experiment was conducted to investigate the effects of interspecific interactions on plant growth and grain yield for a peanut/maize intercropping system under different nitrogen(N) and phosphorus(P) levels. The method of root separation was employed to differentiate belowground from aboveground interspecific interactions. We observed that the global interspecific interaction effect on the shoot biomass of the intercropping system decreased with the coexistence period, and belowground interaction contributed more than aboveground interaction to advantages of the intercropping in terms of shoot biomass and grain yield. There was a positive effect from aboveground and belowground interspecific interactions on crop plant growth in the intercropping system, except that aboveground interaction had a negative effect on peanut during the late coexistence period. The advantage of intercropping on grain came mainly from increased maize yield(means 95%) due to aboveground interspecific competition for light and belowground interaction(61%–72% vs. 28%–39% in fertilizer treatments). There was a negative effect on grain yield from aboveground interaction for peanut, but belowground interspecific interaction positively affected peanut grain yield.The supply of N, P, or N + P increased grain yield of intercropped maize and the contribution from aboveground interspecific interaction. Our study suggests that the advantages of peanut/maize intercropping for yield mainly comes from aboveground interspecific competition for maize and belowground interspecific facilitation for peanut, and their respective yield can be enhanced by N and P. These findings are important for managing the intercropping system and optimizing the benefits from using this system.

Changes in the relationship between species richness and belowground biomass among grassland types and along environmental gradients in Xinjiang, Northwest China

The association between biodiversity and belowground biomass(BGB) remains a central debate in ecology.In this study, we compared the variations in species richness(SR) and BGB as well as their interaction in the top(0–20 cm), middle(20–50 cm) and deep(50–100 cm) soil depths among 8 grassland types(lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients(elevation, energy condition(annual mean temperature(AMT) and potential evapotranspiration(PET)), and mean annual precipitation(MAP)) based on a 2011–2013 survey of 379 sites in Xinjiang, Northwest China.The SR and BGB varied among the grassland types.The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths.The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition;however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths.The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth.Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition.These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.

The Relationships among Community Type, Peat Layer Thickness, Belowground Carbon Storage and Habitat Age of Mangrove Forests in Pohnpei Island, Micronesia

This paper quantifies the relationships among community type, peat layer thickness and habitat age of the mangrove forests in Pohnpei Island, Micronesia and provides a discussion concerning the primary succession and the belowground carbon storage of the main mangrove community types. The ages of the habitat were estimated from a relationship between the thickness of the mangrove peat layer and the formative period, which was decided by calibrated radiocarbon ages. Mangrove communities in the coral reef type habitat were generally arranged in the following order, from seaward to landward: 1) the Rhizophora stylosa or Sonneratia alba community (I or II communities), 2) the typical subunit of the S. alba subcommunity of the Rhizophora apiculata— Bruguiera gymnorrhiza community (III(2)a subunit) and 3) the Xylocarpus granatum subunit of the same subcommunity of the same community (III(2)b subunit). Their habitat ages were estimated to be younger than 460 years, between 360 and 1070 years and between 860 and 2300 years, respectively. Based on these results and other evidences such as photosynthetic characteristics and pollen analysis derived from the previous studies, the primary succession was inferred to have progressed in the order mentioned above. Belowground stored carbon for the main community types in the coral reef type habitat were estimated to be less than 370 t C ha-1 for the I and the II communities, between 290 and 860 t C ha-1 for the III(2)a subunit and between 700 and 1850 t C ha-1 for the III(2)b subunit.

Patterns and mechanisms of belowground carbon responses to changes in precipitation

It is well known that aboveground productivity usually increases with precipitation.However,how belowground carbon(C)processes respond to changes in precipitation remains elusive,although belowground net primary productivity(BNPP)represents more than one-half of NPP and soil stores the largest terrestrial C in the biosphere.This paper reviews the patterns of belowground C processes(BNPP and soil C)in response to changes in precipitation from transect studies,manipulative experiments,modeling and data integration and synthesis.The results suggest the possible existence of nonlinear patterns of BNPP and soil C in response to changes in precipitation,which is largely different from linear response for aboveground productivity.C allocation,root turnover time and species composition may be three key processes underlying mechanisms of the nonlinear responses to changes in precipitation for belowground C processes.In addition,microbial community structure and long-term ecosystem processes(e.g.mineral assemblage,soil texture,aggregate stability)may also affect patterns of belowground C processes in response to changes in precipitation.At last,we discuss implications and future perspectives for potential nonlinear responses of belowground C processes to changes in precipitation.

Belowground carbon balance and carbon accumulation rate in the successional series of monsoon evergreen broad-leaved forest

The balance, accumulation rate and temporal dynamics of belowground carbon in the successional series of monsoon evergreen broadleaved forest are obtained in this paper, based on long-term observations to the soil organic matter, input and standing biomass of litter and coarse woody debris, and dissolved organic carbon carried in the hydrological process of subtropical climax forest ecosystem—monsoon evergreen broad-leaved forest, and its two successional forests of natural restoration—coniferous and broad-leaved mixed forest and Pinus massoniana forest, as well as data of root biomass obtained once every five years and respiration measurement of soil, litter and coarse woody debris respiration for 1 year. The major results include: the belowground carbon pools of monsoon evergreen broad-leaved forest, coniferous and broad-leaved mixed forest, and Pinus massoniana forest are 23191 ± 2538 g·m?2, 16889 ± 1936 g·m?2 and 12680 ± 1854 g·m?2, respec- tively, in 2002. Mean annual carbon accumulation rates of the three forest types during the 24a from 1978 to 2002 are 383 ± 97 g·m?2·a?1, 193 ± 85 g·m?2·a?1 and 213 ± 86 g·m?2·a?1, respectively. The belowground carbon pools in the three forest types keep increasing during the observation period, suggesting that belowground carbon pools are carbon sinks to the atmosphere. There are seasonal variations, namely, they are strong carbon sources from April to June, weak carbon sources from July to September; while they are strong carbon sinks from October to November, weak carbon sinks from December to March.

Above-and belowground biomass in relation to envi- ronmental factors in temperate grasslands, Inner Mongolia

Above- and belowground biomasses of grasslands are important parameters for characterizing re- gional and global carbon cycles in grassland ecosystems. Compared with the relatively detailed in- formation for aboveground biomass (AGB), belowground biomass (BGB) is poorly reported at the re- gional scales. The present study, based on a total of 113 sampling sites in temperate grassland of the Inner Mongolia, investigated regional distribution patterns of AGB, BGB, vertical distribution of roots, and their relationships with environmental factors. AGB and BGB increased from the southwest to the northeast of the study region. The largest biomass occurred in meadow steppe, with mean AGB and BGB of 196.7 and 1385.2 g/m2, respectively; while the lowest biomass occurred in desert steppe, with an AGB of 56.6 g/m2 and a BGB of 301.0 g/m2. In addition, about 47% of root biomass was distributed in the top 10 cm soil. Further statistical analysis indicated that precipitation was the primary determinant factor in shaping these distribution patterns. Vertical distribution of roots was significantly affected by precipitation, while the effects of soil texture and grassland types were weak.

Patterns of above-and belowground biomass allocation in China's grasslands:Evidence from individual-level observations

Above-and belowground biomass allocation not only influences growth of individual plants,but also influences vegetation structures and functions,and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling.However,due to sampling difficulties,a considerable amount of uncertainty remains about the root:shoot ratio(R/S),a key parameter for models of terrestrial ecosystem carbon cycling.We investigated biomass allocation patterns across a broad spatial scale.We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau.Our results indicated that the median of R/S for herbaceous species was 0.78 in China's grasslands as a whole.R/S was significantly higher in temperate grasslands than in alpine grasslands(0.84 vs.0.65).The slope of the allometric relationship between above-and belowground biomass was steeper for temperate grasslands than for alpine.Our results did not support the hypothesis that aboveground biomass scales isometrically with belowground biomass.The R/S in China's grasslands was not significantly correlated with mean annual temperature(MAT) or mean annual precipitation(MAP).Moreover,comparisons of our results with previous findings indicated a large difference between R/S data from individual plants and communities.This might be mainly caused by the underestimation of R/S at the individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys due to grazing and difficulties in identifying dead roots.Our findings suggest that root biomass in grasslands tended to have been overestimated in previous reports of R/S.

Additive effects of functionally dissimilar above- and belowground organisms on a grassland plant community

In nature,plant communities are affected simultaneously by a variety of functionally dissimilar organisms both above and below the ground.However,there is a gap of knowledge on interactive effects of functionally dissimilar organisms on plant communities that is needed to be filled to better understand and predict the general impact of biotic factors on plant communities.Methods We conducted a full-factorial mesocosm study to investigate the individual and combined impacts of above-and belowground functionally dissimilar organisms on a grassland plant community.We studied the effects of aboveground herbivores(Helix aspersa,Gastropoda),arbuscular mycorrhizal fungi(AMF;Glomus spp.,Glomeromycota)and endogeic earthworms(Aporrectodea spp.,Lumbricidae)on the diversity,structure and productivity of an experimental grassland plant community and each other.Important Findings Aboveground herbivory by snails decreased,AMF increased and earthworms had no effects on the diversity of the grassland plant community,while their combined effects were additive.The biomass of the plant community was negatively affected by snails and AMF,while no effects of earthworms or interaction effects were found.The plant species were differently affected by snails and AMF.No effects of the above-and belowground organisms on each other’s performance were detected.Since the effects of the functionally dissimilar organisms on the grassland plant community were mainly independent,the results indicate that their combined effects may be predicted by knowing the individual effects,at least under the conditions used in the present mesocosm study.

Large-diameter trees and deadwood correspond with belowground ectomycorrhizal fungal richness

Background: Large-diameter trees have an outsized influence on aboveground forest dynamics, composition, and structure. Although their influence on aboveground processes is well studied, their role in shaping belowground fungal communities is largely unknown. We sought to test if (i) fungal community spatial structure matched aboveground forest structure;(ii) fungal functional guilds exhibited differential associations to aboveground trees, snags, and deadwood;and (iii) that large-diameter trees and snags have a larger influence on fungal community richness than smaller-diameter trees. We used MiSeq sequencing of fungal communities collected from soils in a spatially intensive survey in a portion of Cedar Breaks National Monument, Utah, USA. We used random forest models to explore the spatial structure of fungal communities as they relate to explicitly mapped trees and deadwood distributed across 1.15 ha of a 15.32-ha mapped subalpine forest. Results: We found 6,177 fungal amplicon sequence variants across 117 sequenced samples. Tree diameter, dead-wood presence, and tree species identity explained more than twice as much variation (38.7% vs. 10.4%) for ectomy-corrhizal composition and diversity than for the total or saprotrophic fungal communities. Species identity and dis-tance to the nearest large-diameter tree (≥ 40.2 cm) were better predictors of fungal richness than were the identity and distance to the nearest tree. Soil nutrients, topography, and tree species differentially influenced the composition and diversity of each fungal guild. Locally rare tree species had an outsized influence on fungal community richness. Conclusions: These results highlight that fungal guilds are differentially associated with the location, size, and species of aboveground trees. Large-diameter trees are implicated as drivers of belowground fungal diversity, particularly for ectomycorrhizal fungi.

Biodiversity and belowground interactions mediate community invasion resistance against a tall herb invader

Aims Species-rich plant communities are hypothesized to be more resistant against plant invasions because they use resources in a more efficient way.However,the relative contributions of aboveground competition and belowground interactions for invasion resistance are still poorly understood.Methods We compared the performance of Knautia arvensis transplants growing in plots differing in plant diversity both under full competition and with shoots of neighbors tied back to determine the relative strength of aboveground competition in suppressing this test invader without the confounding effect of shading.In addition,we assessed the effects of belowground competition and soil-borne pathogens on transplant performance.Important Findings Both aboveground competition and plant species richness strongly and independently affected invader performance.Aboveground biomass,height,leaf mass per area and flowering of transplanted individuals of K.arvensis decreased with increasing species richness of the host community.Species-rich and species-poor communities both imposed equally strong aboveground competition on K.arvensis.However,belowground interactions(especially belowground root competition)had strong negative effects on transplant performance.In addition,the presence of grasses in a plant community further reduced the performance of K.arvensis.Our results suggest that belowground competition can render species-rich host communities more suppressive to newly arriving species,thus enhancing community invasion resistance.

Issues and prospects of belowground ecology with special reference to global climate change

The theory of ecology is based on over 100 a of research and investigation, all centered on aboveground pat-terns and processes. However, as contemporary ecologists are increasingly acknowledging, belowground structures, func-tions, and processes are some of the most poorly understood areas in ecology. This lack of understanding of belowground ecological processes seriously restricts the advance of global change research. The interdisciplinary field of belowground ecology began to flourish in the 1990s, along with the expan-sion of global change research, and quickly gained momen-tum. Belowground ecology aims to investigate belowground structures, functions, and processes, as well as their rela-tionships with corresponding aboveground features, empha-sizing the responses of belowground systems under global change conditions. Key research areas include root ecology, belowground animals, and soil microorganisms. This review summarizes and analyzes the relationships between above- and belowground ecosystems, root ecology, root biogeogra-phy, belowground biodiversity, as well as research areas with particular challenges and progress. This commentary em-phasizes certain theoretical issues concerning the responses of belowground processes to global change, and concludes that belowground ecology is a critical research priority in the 21st century.

植物物候研究进展

植物物候是指植物受周围环境影响而呈现周期性变化的自然现象。为总结植物物候研究进展,展望植物物候研究的未来发展,本文总结了主要环境因素(如气候、土壤等)及其变化对植物物候的影响,分析比较了研究植物物候不同方法的优缺点,揭示了植物物候研究中存在的问题及潜在的解决方案。综述植物物候研究进展能够为理解环境变化条件下植物物候动态、物种共存以及生态系统结构稳定提供参考。

不同海拔梯度高寒草地地下生物量与环境因子的关系

以新疆天山南坡的巴音布鲁克高寒草地为对象,研究了不同海拔梯度高寒草地地下生物量的变化及其与环境因子的关系.结果表明:随着海拔的升高,高寒草原、高寒草原化草甸和高寒草甸的地下生物量逐渐增大,二者呈极显著正相关(P<0.01).地下生物量从表层至底层逐渐递减,呈"T"形分布.高寒草原、高寒草原化草甸和高寒草甸0～10cm土层的地下生物量分别占总地下生物量的68.1%、84.1%和86.7%.地下生物量与大气温度呈极显著负相关,与相对湿度和土壤含水量呈极显著正相关(P<0.01),而与有机质、速效氮和pH等无显著相关.

西藏那曲地区高寒草地地下生物量

矮嵩草草甸、藏北嵩草草甸及紫花针茅草原是那曲地区主要的草地类型,通过对其地下生物量的分布特征、地下/地上生物量的关系及其对土壤环境影响的研究发现:(1)这三类植物群落的地下生物量表现为总的T字形趋势下的锯齿状分布,主要分布在0～10cm的草皮层中,而且不同的退化草地,其地下的生物量也不同;(2)各群落的地下生物量和地上生物量密切相关,相关性均呈显著正相关.地下/地上生物量的比值越大,地上生物量就越高.地上生物量的变化不大,而地下生物量变化显著;(3)在高山草甸土中,矮嵩草草甸的地下生物量和土壤的有机质,全N,碱解N的含量及土壤的容重呈相关关系,而与其他的土壤因子相关性不显著.(4)各群落的地下生物量的垂直分布特征及与土壤环境的关系是植物长期适宜高寒生境条件的结果和反映.

中国森林的地下碳分配

通过收集国内33个森林样地的土壤呼吸和年凋落物量数据,分析中国森林地下碳分配(TBCA)模式。结果表明,中国森林土壤呼吸年通量与年凋落物量呈显著的线性相关(R2=0.3319,P=0.000),其中成熟林土壤呼吸与年凋落物量间呈显著的线性相关(R2=0.3245,P=0.004),但未成熟林土壤呼吸与年凋落物量间的线性相关不显著(R2=0.3485,P=0.092)。中国森林的地下碳分配变化范围1.460～25.100tChm-2a-1,平均值为9.217tChm-2a-1;中国森林的TBCA与年均气温相关关系不显著(P=0.196),但与年均降水量则呈显著正相关(R=0.480,P=0.021)。中国森林TBCA和凋落物对土壤呼吸的平均贡献分别为74.2%和25.8%;中国森林TBCA对土壤呼吸的贡献随土壤呼吸增大而增大,而凋落物对土壤呼吸的贡献则随土壤呼吸的增大而降低。

内蒙古温带草地植被的碳储量

草地生态系统在全球碳循环中起着极为重要的作用。大部分草地碳储存在地下,但是实测数据十分匮乏,因此准确估算温带草地植被碳储量对评价草地生态系统碳循环具有重要意义。作为一个区域性资料积累工作,作者对内蒙古温带草地的碳储量进行了大范围的实测研究,以估算该地区草地植被的碳储量。主要结果如下:(1)内蒙古温带草地总面积为58.46×106hm2,总植被碳储量为226.0±13.27Tg C(1 Tg=1012g),平均碳密度为3.44Mg C.hm-2;(2)地下根系储存的碳是地上碳储量的6倍左右,地上、地下生物量碳储量分别为33.22±1.75和193.88±12.6 Tg C,平均碳密度分别是0.51和2.96 MgC.hm-2;(3)不同草地类型的碳储量差异较大,典型草原最大(113.25 Tg C),占草地总碳储量的50%,其次是草甸和草甸草原,荒漠草原碳储量最低(15.37 Tg C)。

放牧对草原生态系统地下生产力及生物量的影响

放牧作为一种人类活动的干扰因子,主要通过动物的采食、践踏及其排泄物的输入对草原生态系统产生影响,这些影响直接作用于草原生态系统的地上部分和土壤,从而影响草原生态系统的物质生产和分配,进而影响到地下生产力和生物量.以蒙古克氏针茅 Stipakrylovii -冷蒿 Artemisiafrigida 草原为研究对象,对自由放牧区和围栏禁牧封育区草原生态系统地下生产力、生物量进行了比较研究.结果表明:自由放牧区草原生态系统地下生产力为147.6g·m-2·y-1,围栏禁牧封育区地下生产力达187.3g·m-2·y-1,二者地下生产力差异显著 α=0.05 ,说明封育保护可以提高过牧草原生态系统的地下生产力.地下生物量在自由放牧区为2032.6g·m-2,其中活地下生物量占54.9%,死地下生物量占45.1%;在围栏禁牧封育区平均为2071.8g·m-2,其中活地下生物量占56.4%,死地下生物量占43.6%,两者没有明显差异.地下生物量在土壤中垂直分布规律在两个试验区均表现为自地表向下呈指数函数减小,主要集中分布在0～30cm的土层.