东北黑土区不同土地利用方式下农田土壤微生物多样性

为探究黑龙江省黑土区不同土地利用方式下土壤微生物多样性,该研究主要采用Biolog Eco微平板法,以荒地为对照,研究了黑龙江省中部和西南部黑土区玉米、水稻、大豆及土豆4种不同土地利用方式下土壤微生物多样性的变化。结果表明：1）可培养细菌的数量从大到小依次为土豆、水稻、大豆、玉米、荒地,但群落Shannon-Wiener多样性指数从高到低依次为：荒地（2.18）、玉米（2.11）、土豆（2.00）、水稻（1.73）、大豆（1.49）;2）不同利用方式下黑土区微生物碳源利用程度大致随培养时间的延长而升高,并且氨基酸、糖类以及聚合物类是黑土微生物代谢的最主要碳源;玉米地土壤微生物的Shannon-Wiener指数（3.18）、McIntosh指数（5.96）、丰富度指数（24.89）、及Simpson指数（0.95）比其他土地利用方式土壤微生物的多样性指数高,而水稻田土壤微生物的多样性指数最低,土豆、大豆与荒地土壤微生物的多样性指数间无显著差别;3）不同土地利用方式显著影响了土壤微生物群落碳源代谢多样性,并且对土壤微生物群落代谢特征起分异作用的主要碳源类型为糖类、氨基酸类和羧酸类,其中糖类尤为突出。该研究将有助于了解黑土区土壤微生物多样性与土地利用方式之间的关系,为黑土区农业的可持续发展提供一定的科学依据。     

The influence of different types of urban land use on soil microbial biomass and functional diversity in Beijing,China

Soil microbes in urban ecosystems are affected by a variety of abiotic and biotic factors resulting from changes in land use. However, the influence of different types of land use on soil microbial properties and soil quality in urban areas remains largely unknown. Here, by comparing five types of land use: natural forest, park, agriculture, street green and roadside trees, we examined the effects of different land uses on soil microbial biomass and microbial functional diversity in Beijing, China. We found that soil properties varied with land uses in urban environments. Compared to natural forest, soil nutrients under the other four types of urban land use were markedly depleted, and accumulation of Cu, Zn, Pb and Cd was apparent. Importantly, under these four types of land use, there was less microbial biomass, but it had greater functional diversity, particularly in the roadside‐tree soils. Furthermore, there were significant correlations between the microbial characteristics and physicochemical properties, such as organic matter, total nitrogen and total phosphorus (P < 0.05), suggesting that lack of nutrients was the major reason for the decrease in microbial biomass. In addition, the larger C/N ratio, Ni concentration and pool of organic matter together with a higher pH contributed to the increase in microbial functional diversity in urban soils. We concluded that different land uses have indirect effects on soil microbial biomass and microbial community functional diversity through their influence on soil physicochemical properties, especially nutrient availability and heavy metal content.     

Phosphorus pools in soil after land conversion from silvopasture to arable and grassland use

Differences in soil P among silvopasture, grassland, and arable lands have been well established. Nevertheless, most of the reports compare soil properties under long‐term sites. Thus, there exists little information on the effect of the conversion of silvopasture to arable or grassland use on soil P pools. The objective of the study was to determine the impact of converting silvopasture system (SP) into arable cropping and grassland system on the distribution of P pools and potential P bioavailability. We compared the following systems: SP system, SP converted to arable cropland (SP‐AL), SP converted to grassland (SP‐GL), and for comparative purposes, a long‐term arable cropland (AL). The P fractionation was performed by a sequential extraction scheme, using acid and alkaline extractants on samples collected from the 0–10 and 10–20 cm soil layers. It was assumed that the large variations in soil‐P fractionations are caused by the different management practices associated with land conversion. The results of P fractionation showed a dominance of calcium‐bound P, HCl‐extractable Pi constituted up to 36% of the soil total P (TP). However, the type of land use did not affect this P fraction. On the other hand, the reduction in labile‐P_i and NaOH‐P_i fractions observed at the SP‐AL site may have led to the decline in readily available P. The soil total organic P (TP_o) content was 8% and 17% lower at SP‐AL compared to SP and SP‐GL site, respectively. Labile organic‐P (labile‐P_o) content was markedly higher at SP site compared to arable soils, and was ≈ 10% of TP_o. The NaOH‐P_o constituted the highest fraction of the organic‐P pool (55%–79% of TP_o) across all the study systems, and was positively correlated with TP_o (p < 0.01). The study indicates that conversion of SP system in temperate regions to arable cropping with conventional tillage seems to result in the reduction of P availability compared to SP, indicating SP as an important land‐use practice.     

Effect of land use on forest floor and soil of a Quercus suber L. forest in Gallura (Sardinia,Italy)

In order to determine the effect of land use on forest floor and soil, two adjacent sites with different land use were investigated in Gallura (northern Sardinia, Italy). One site is a Quercus suber L. forest mainly used for cork production and the other is an open Quercus suber L. forest where livestock is put out to graze. In each site one soil profile was studied to characterize the mineral soil, and five humus profiles were opened along a vegetation transect, were studied to characterize the forest floor. Samples of L, F and H horizons of the forest floor and of the A mineral horizons were collected and analysed for each profile. In the site mainly used for cork production well‐developed ectorganic (L, F and H) horizons are always present, with a total thickness ranging from 5·2 to 9·5 cm. Humus profile is of the Moder type, while mineral soils have an A–C profile, generally 50 cm deep. Organic matter content in the forest floor ranges from 1·76–3·72 kg m⁻² and nutrients content in the mineral soil is high. In the site used chiefly for grazing the ectorganic horizons are very poorly developed, with a total thickness ranging from 1–3 cm, except for some islands under the Quercus suber L. canopy where the total thickness may reach 5·3 cm. Humus profile is of the Mull type, but the used classification system seems not appropriate when the tree density is below a critical limit. Mineral soils have an A–C profile 20–25 cm deep. The organic matter content in the forest floor ranges from 0·45 to 1·84 kg m⁻², while nutrient content in the mineral soil maintains at high level, even higher than in the former case for C, N and Ca, probably in relation with higher supply of cattle excreta. Sheet erosion is evident in the site. It is concluded that cork production will maintain a sustainable forest floor development in cork–oak forest ecosystem, whereas cattle grazing, fires and ploughing in cork–oak forests may be considered to trigger off severe soil degradation processes. Copyright © 2000 John Wiley & Sons, Ltd.     

红壤坡地不同土地利用方式土壤蒸发和植被蒸腾规律研究

为明确红壤坡地土壤水分耗散特征,通过田间定位观测,分析了农作区、茶园和桠柑园土壤水分蒸发和蒸腾过程。结果表明：蒸发、蒸腾与土壤表层含水率和植被叶面积指数关系密切,不同利用方式日蒸发量大小顺序为遮荫茶园〈对照茶园〈桠柑园〈农作区。茶树和桠柑蒸腾速率日变化曲线均呈现单峰型,桠柑日蒸腾速率比对照茶树弱,这两种土地利用方式下6—10月均以蒸腾耗水为主。遮荫可有效削弱茶园土壤蒸发及植被蒸腾。茶园蒸发受微地形条件影响较大,梯地蒸发比梯坎蒸发弱,而农作区和桠柑园土壤蒸发更多受水分条件的影响。合理的土地利用方式和适度遮荫可以有效降低红壤坡地土壤水分散失,提高水分利用效率和防治季节性干旱。     

Implications of soil substrate and land use for properties of fen soils in North-East Germany Part I: Basic soil conditions,chemical and biological properties of topsoils

Abstract

The objective of the paper was to analyse the implications of the origin of peat (muck) soil substrate, the current type of land use and the state of anthropogenic soil development for the topsoil properties of fens. Chemical and biological properties of peat soils of the Rhin-Havelluch lowland and the Uckermark rural landscape were analyzed. The unit water content according to Ohde and the ash content were utilized to characterize the anthropogenic development status of peat topsoils. Several chemical properties were significantly influenced by soil substrate, in particular by the proportion and kind of the mineral component. The substrate was associated with the hydrological type of mire and the soil development state. TOC/N ratio and microbial activity were increased in cases of high lime spring mires and moorshified low ash peat. The proportion of easily soluble organic carbon increased, whereas the sulphur content decreased with the soil development state. The nitrogen content and the proportions of oxalate soluble iron and aluminium reached maxima in the moorshified state. The type of land use (grassland, forest) significantly influenced the topsoil pH and the proportion of oxalate soluble phosphorus. Soils under forest were clearly determined by topsoil acidification.     

The role of soil science in the land use negotiation process*

Abstract. The hierarchial concept of land use planning becomes less relevant in a society with continuous interactions between stakeholders, researchers, planners and politicians. In this context, land use negotiation rather than land use planning appears to be the most appropriate concept. In the negotiation process, good quality data about the land is important as land properties are, obviously, key elements to be considered. Case studies at farm and regional level have been analysed to explore answers to a number of questions. How can soil data be presented most effectively? What are the research needs? How can the large existing body of data be mobilized most effectively? Studies on regional land use in Costa Rica used methods in a logical sequence including projections, explorations and predictions of land use patterns. The work involved upscaling of data, obtained at farm level, to the regional level. Work at farm level focussed on prototyping procedures in which farming systems were ‘designed’ by close interaction between farmers and scientists, including applications of precision agriculture. Soil data demands were analysed, emphasizing the effects of using data with different degrees of detail together with the application of pedotransfer functions which effectively transform existing data into parameters that are difficult or expensive to measure directly. This not only facilitated interactions with stakeholders but also with colleague scientists in interdisciplinary teams. In addition, use of Geographical Information Systems allowed visual presentations of alternative geographical land use patterns that were associated with various scenarios, thereby facilitating the interaction processes. A plea is made to increase interaction of stakeholders and researchers by considering research programmes as vehicles for joint learning.     

Impacts of land use/cover change on soil properties in the Mediterranean region of northwestern Jordan

This study was carried out to evaluate the effects of deforestation on physical and chemical properties of soils under native forest in the Mediterranean region of northwestern Jordan. Land use/cover maps of 1953, 1978 and 2002 were interpreted and analysed within GIS to quantify the shift from forest to rainfed cultivation. Six sites were sampled in a non‐changed forest and in cultivated fields, three for each. Different soil properties of texture, bulk density, organic matter, total nitrogen, pH, cation exchange capacity (CEC), phosphorous and potassium were analysed. Results showed that many forests were changed into cultivated lands at a rate more than the reforestation. Subsequently, adverse effects on the studied physical and chemical properties were observed. The most affected properties were particle size distribution, bulk density of surface soil and subsoil. Organic matter and CEC decreased in cultivated soil as compared to the forest soil. Cultivated soils were found to exhibit a significantly lower status in physical and chemical soil properties as compared to forest soils. This general decline in the soil physical and chemical properties, in turn, contributed to soil erosion, reduction of soil fertility and land degradation. There is an urgent need to improve soil quality by developing sustainable land use practices to reduce the rate of soil degradation and to ensure long‐term sustainability of the farming system in the study area and in similar biophysical settings. Copyright © 2008 John Wiley & Sons, Ltd.     

不同土壤类型和农业用地方式对土壤微生物量碳的影响

通过野外调查与室内分析,研究了山东桓台县3种土壤类型(潮土、褐土和砂姜黑土)与农业用地方式(林地、菜地和粮田)对土壤表层(0—10.cm)微生物量碳的影响。结果表明,不同农业用地方式对微生物量碳的影响较大,3种利用方式的微生物量碳含量差异显著,依次为:粮田>菜地>林地;土壤类型不同,土壤微生物量碳含量也不相同。任何一种土壤,菜地的N、P、K含量都高于粮田和林地;有机质含量粮田>菜地>林地;pH值林地>粮田>菜地。全N、有机质与土壤微生物量碳呈极显著正相关,有效P与微生物量碳呈弱负相关,速效K、pH值和微生物量碳不相关。不同用地方式下土壤养分与微生物量碳的相关程度不同。秸秆还田和施用有机肥有利于提高土壤中微生物量碳水平,施用化肥在一定程度上能够增加微生物量碳。     

不同土地利用方式对黄河三角洲盐碱地土壤理化性质的影响

采用野外调查取样和室内分析相结合的方法,分析3种不同土地利用方式对黄河三角洲河口区盐碱地土壤理化性质的影响。结果表明:1)刺槐林地土壤表层0～10 cm有机质和全氮质量分数均最高,分别为17.30和1.04g/kg,0～20 cm平均土壤密度(1.33 g/cm3)和0～100 cm平均土壤电导率(290.25μs/cm)均小于柽柳林地和棉花地,0～20 cm平均土壤孔隙度(51.91%)和黏粒质量含量(3.99%)均大于柽柳林地和棉花地;2)柽柳林地0～100cm平均土壤pH值为6.77,极显著低于刺槐林地和棉花地(P<0.01),平均土壤速效钾质量分数最高(104.47 mg/kg),极显著高于棉花地(P<0.01),而与刺槐林地差异不显著,0～100 cm平均土壤速效磷质量分数为棉花地>柽柳林地>刺槐林地;3)人工栽植的刺槐林地土壤理化性状优于天然更新的柽柳林地和人工耕作的棉花地。研究结果可为黄河三角洲河口区盐碱地土地合理利用和改良提供参考。     

不同利用方式下红壤微生物生物量及代谢功能多样性的变化

研究了不同农林利用方式下红壤微生物生物量和代谢功能多样性等土壤质量指标的变化.结果表明:不同利用方式对土壤质量各指标造成了显著的影响;稻田的微生物生物量碳、氮最高,林地和草地微生物生物量次之,旱地的微生物生物量碳、氮最低(分别是稻田利用方式的4.3% 和 13.7%);稻田的微生物代谢功能多样性最高,旱地、林地和草地的细菌代谢功能多样性较低,旱地的真菌代谢功能多样性最低;微生物生物量和代谢功能多样性可以作为反映土壤质量变化的早期敏感的指标,用来衡量管理措施的改变对土壤质量造成的影响.     

Shifts in microbial diversity through land use intensity as drivers of carbon mineralization in soil

Land use practices alter the biomass and structure of soil microbial communities. However, the impact of land management intensity on soil microbial diversity (i.e. richness and evenness) and consequences for functioning is still poorly understood. Here, we addressed this question by coupling molecular characterization of microbial diversity with measurements of carbon (C) mineralization in soils obtained from three locations across Europe, each representing a gradient of land management intensity under different soil and environmental conditions. Bacterial and fungal diversity were characterized by high throughput sequencing of ribosomal genes. Carbon cycling activities (i.e., mineralization of autochthonous soil organic matter, mineralization of allochthonous plant residues) were measured by quantifying ¹²C- and ¹³C-CO₂ release after soils had been amended, or not, with ¹³C-labelled wheat residues. Variation partitioning analysis was used to rank biological and physicochemical soil parameters according to their relative contribution to these activities. Across all three locations, microbial diversity was greatest at intermediate levels of land use intensity, indicating that optimal management of soil microbial diversity might not be achieved under the least intensive agriculture. Microbial richness was the best predictor of the C-cycling activities, with bacterial and fungal richness explaining 32.2 and 17% of the intensity of autochthonous soil organic matter mineralization; and fungal richness explaining 77% of the intensity of wheat residues mineralization. Altogether, our results provide evidence that there is scope for improvement in soil management to enhance microbial biodiversity and optimize C transformations mediated by microbial communities in soil.     

The role of phosphorus in growing tomatoes in near water-saturated soil

Abstract

High-yielding, waterlogged cultivations with considerable nitrogen input are widely practiced in Kyushu Island, Japan. Our objective was to determine the role of available phosphorus in relation to nitrogen and soil microorganisms on tomato growth in such systems. Tomato seedlings were grown in a pasteurized soil with ample KNO₃ in addition to different amounts of sodium or potassium phosphates to assess effects of phosphorus on growth enhancement and water-use efficiency in the seedlings grown with copious soil water (>－0.7?kPa). Both monobasic and dibasic phosphates applied at 40?mM to near-saturated soil markedly promoted seedling growth when fertilized with 120?mM KNO₃ or NH₄Cl, but not in the soil without nitrogen. The final concentration of NO₃^－ near the soil surface was maximized in the nitrated soil with no added PO₄^3－ but declined significantly when fertilized with any phosphates except Na₂HPO₄. No significant accumulation of NO₃^－ was detected in the water-saturated bottom soils regardless of soil fertilization with any plant minerals. Increased seedling growth was accompanied by lower dry root/shoot ratios and marked increases in evapotranspiration efficiency. Such positive effects of PO₄^3－ were greater with NO₃^－ than NH₄^＋ but diminished with increased concentrations of Na^＋ up to 160?mM. Nonetheless, growth promotions by ample NO₃^－ with PO₄^3－ were nearly negated in the non-pasteurized soil. Apparently, the activities of indigenous soil microbes were more significant than soil nitrogen and phosphorus in limiting the growth potential of tomato plants in near-saturated soils.     

Conversion of cropland into grassland: Implications for soil organic‐carbon stocks in two soils with different texture

Soil organic‐carbon (SOC) stocks are expected to increase after conversion of cropland into grassland. Two adjacent cropland and grassland sites—one with a Vertisol with 23 y after conversion and one with an Arenosol 29 y after conversion—were sampled down to 60 cm depth. Concentrations of SOC and total nitrogen (N_tot) were measured before and after density fractionation in two light fractions and a mineral‐associated fraction with C adsorbed on mineral surfaces. For the soil profiles, SOC stocks and radiocarbon (¹⁴C) concentrations of mineral associated C were determined. Carbon stocks and mineral‐associated SOC concentrations were increased in the upper 10 cm of the grassland soil compared to the cropland. This corresponded to the root‐biomass distribution, with 59% and 86% of the total root biomass at 0–5 cm soil depth of the grasslands. However, at the Arenosol site, at 10–20 cm depth, C in the mineral‐associated fraction was lost 29 y after the conversion into grassland. Over all, SOC stocks were not significantly different between grassland and cropland at both sites when the whole profile was taken into account. At the Arenosol site, the impact of land‐use conversion on SOC accumulation was limited by low total clay surface area available for C stabilization. Subsoil C (30–50 cm) at cropland of the Vertisol site comprised 32% of the total SOC stocks with high ¹⁴C concentrations below the plowing horizon. We concluded that fresh C was effectively translocated into the subsoil. Thus, subsoil C has to be taken into account when land‐use change effects on SOC are assessed.     

Evaluating land use/land cover changes and fragmentation in the Camili forest planning unit of northeastern Turkey from 1972 to 2005

Changes in land use/land cover have important consequences on the management of natural resources including soil and water quality, global climatic systems and biodiversity. This study analysed the spatial and temporal pattern of land use/land cover change in the Camili forest planning unit that includes the Camili Biosphere Reserve Area within the Caucasian hotspot, in the northeast corner of Turkey. To assess the patterns during a 33‐year period, the necessary data were obtained from forest stand maps and evaluated with Geographic Information Systems and FRAGSTATS. Results showed that the total forested areas increased from 19 946·5 ha (78·6% of the study area) in 1972 to 20 797·3 ha (81·9 per cent) in 2005 with a slight net increase of 851 ha. Softwood cover types (411·8 ha) completely transitioned to other cover types over 33‐year period. In terms of spatial configuration, the total number of forest fragments increased from 172 to 608, and mean size of forest patch (MPS) decreased from 147·7 ha to 41·8 ha during the period. Nearly 84 per cent of the patches in 1972 and 93 per cent of them in 2005 generally seem to concentrate into 0–100 ha patch size class, indicating more fragmented landscape over time that might create a risk for the maintenance of biodiversity of the area. There were apparent trends in the temporal structure of forest landscape, some of which may issue from mismanagement of the area, social conflict, and illegal utilization of forest resources due to ineffective forest protection measurements. The study revealed that it is important to understand both spatial and temporal changes of land use/land cover and their effects on landscape pattern to disclose the implications for land use planning and management. Copyright © 2007 John Wiley & Sons, Ltd.     

基于网格搜索随机森林算法的工矿复垦区土地利用分类

为提高工矿复垦区遥感影像土地利用分类精度,为土地复垦监测工作提供数据支持,该文探讨了基于网格搜索(Grid-Search)的随机森林(random forest)复垦区土地利用分类方法。研究利用GF-1影像、DEM(digital elevation model)和野外调查等数据,以随机森林分类算法为框架,采用基于OOB(Out-of-Bag)误差的网格搜索法对算法进行参数寻优,结合影像光谱、地形、纹理、空间信息,计算选取了33个特征变量,构建了4种变量组合模型开展随机森林分类试验,4个组合模型的分类精度分别达到82.79%、84.91%、86.75%、88.16%。为去除33个特征变量中的冗余信息、降低影像波段变量维度、缩短分类执行时间并保证影像分类精度,试验分别利用变量重要性估计和Relief F方法进行特征选择后再次执行随机森林分类,将分类结果与不同组合模型、不同分类方法进行比较,结果表明:基于网格搜索参数寻优的随机森林算法在多特征变量的影像分类中可以达到88.16%的分类精度,在利用不同方法降维后依然可以将分类精度保持在85%以上,精度优于相同特征变量下的SVM(support vector machine)和MLC(maximum likelihood classification)分类方法;在效率方面,随机森林分类方法执行时间优于SVM,并且在处理多维特征变量时能力更强。由此可见,采用基于网格搜索的随机森林方法对工矿复垦区土地利用信息进行分类提取可以得到较高的精度,基于该方法开展遥感影像解译可为土地复垦监测工作提供技术支持和理论参考。     

华北农牧交错带土地沙漠化成因与土地利用调整对策

从气候变化、土地利用等角度对华北农牧交错带典型区——内蒙古多伦县的土地沙漠化形成机制进行分析。对干湿指数、最大可能蒸散量等指标的分析表明该区域近30a来气候变化在一定程度上有利于沙化土地的恢复。1985年和2000年两期土地沙漠化、土地利用监测数据空间叠加和地统计分析表明,该区域15a来不存在明显的开荒和毁林等土地利用方式转型现象,利用方式未变化的土地占总土地的95.98%。严重沙化土地的91.39%发生在利用方式未变化的草地、耕地和未利用土地,三者沙化程度加重分别占该区所有沙化程度加重土地的55.16%、25.92%和10.31%。实地调查和遥感、统计等相关数据分析表明,耕地沙化主要是秋耕和农业大机械的应用为风蚀创造了条件,连年耕作和经济作物的种植促进了耕地退化;草地和未利用土地沙漠化主要因为载畜量过重和草原交通对草场的破坏。针对以上土地利用强度过大等造成土地沙漠化的原因提出华北农牧交错带土地利用调整策略。     

Soil carbon and related soil properties along a soil type and land‐use intensity gradient,New South Wales,Australia

The aim of this study was to systematically quantify differences in soil carbon and key related soil properties along a replicated land‐use intensity gradient on three soil landscapes in northwest New South Wales, Australia. Our results demonstrate consistent land‐use effects across all soil types where C, N and C:N ratio were in the order woodland > unimproved pasture = improved pasture > cultivation while bulk density broadly showed the reverse pattern. These land‐use effects were largely restricted to the near surface soil layers. Improved pasture was associated with a significant soil acidification, indicating that strategies to increase soil carbon through pasture improvement in these environments might also have associated soil degradation issues. Total soil carbon stocks were significantly larger in woodland soils, across all soil types, compared with the other land‐uses studied. Non‐wooded systems, however, had statistically similar carbon stocks and this pattern persisted whether or not carbon quantity was corrected for equivalent mass. Our results suggest that conversion from cultivation to pasture in this environment would yield between 0.06 and 0.15 t C/ha/yr which is at the lower end of predicted ranges in Australia and well below values measured in other cooler, wetter environments. We estimate that a 10% conversion rate (cultivation to pasture) across NSW would yield around 0.36 Mt CO₂‐e/yr which would contribute little to emission reductions in NSW. We conclude that carbon accumulation in agricultural soils in this environment might be more modest than current predictions suggest and that systematically collected, regionally specific data are required for the vegetation communities and full range of land‐uses before accurate and reliable predictions of soil carbon change can be made across these extensive landscapes.     

抛荒土地不同处理及利用方式对喀斯特地区土壤微生物的影响

土壤微生物特性是土壤养分的储存库,土壤养分也影响土壤微生物活性,了解两者的相互作用机制对土地利用与管理提供理论依据,而喀斯特地区不同土地利用方式相关研究较少。基于喀斯特峰丛洼地火烧、刈割、刈割除根、封育、种植玉米、种植桂牧1号杂交象草6种坡面典型的土地利用方式的动态监测样地建设与调查,该文分析了不同土地利用方式下土壤微生物特性,揭示其与土壤养分相互作用机制。结果表明,不同土地利用方式对土壤养分的影响不同,土壤有机质（soil organic matter,SOM）、全氮（total nitrogen,TN）、全磷（total phosphorus,TP）、碱解氮（available nitrogen,AN）等沿封育、火烧、刈割、刈割除根、种植桂牧1号、种植玉米等土地利用方式的转变而减少;不同土地利用方式土壤微生物生物量各不同,土壤微生物量碳（microbial biomass carbon, MBC）：244.98～1 246.89 mg/kg、土壤微生物量氮（microbial biomass nitrogen,MBN）：35.44～274.69 mg/kg、土壤微生物量磷（microbial biomass phosphorus,MBP）：30.88～64.72 mg/kg,其中,种植玉米土壤微生物生物量均最低,其土壤质量退化现象严重;不同土地利用方式土壤微生物种群数量及组成影响不同,种植玉米和桂牧1号杂交象草细菌占绝对优势,而火烧、刈割、刈割除根及封育均以放线菌占绝对优势,真菌的比例很少;不同土地利用方式土壤微生物特性与土壤养分之间相互作用关系不同：火烧的土壤TP和MBP、全钾（total potassium,TK）与MBC、TN与放线菌作用最强且均呈正相关,刈割的土壤TN与MBC呈正相关,刈割除根的速效磷（available phosphorus,AP）与MBN正相关,封育的pH值与MBC、真菌负相关,种植玉米的TN、TK与MBP负相关,种植桂牧1号杂交象草的pH值与真菌负相关、与放线菌正相关;聚类分析可以将喀斯特峰丛洼地6种土地利用方式划分为4类,其中封育和火烧最好。