城市不同功能区绿地土壤理化性质及微生物生物量的分布特征

为提高城市绿地生态系统服务功能和促进城市可持续发展，本文研究了南京市不同功能区绿地表层土壤养分和微生物量的分布特征。结果显示，土壤pH整体呈碱性且容重偏大；公园绿地土壤全氮、速效磷和速效钾含量显著高于道路绿地；不同功能区绿地土壤有机质含量无显著差异，但公园绿地土壤微生物量碳含量和微生物熵显著高于居住区和道路绿地；公园绿地土壤结构和养分均优于道路绿地。土壤微生物量碳含量与有机质、全氮和速效钾含量呈极显著正相关，与速效磷含量呈显著正相关，与容重呈极显著负相关；土壤有机质与全氮和速效钾含量呈极显著正相关，与速效磷含量和pH无显著相关性，与容重呈显著负相关。因此，勤松土，合理施肥，增加枯枝落叶等凋落物覆盖，提高土壤养护管理水平对修复城市土壤生态和建设生态城市具有重要意义。     

Land‐Use Effects on Soil Nutrient Cycling and Microbial Community Dynamics in the Everglades Agricultural Area,Florida

Soil subsidence has become a critical problem since the onset of drainage of the organic soils in the Everglades Agricultural Area (EAA), which may impair current land uses in the future. The objectives of this study were to characterize soil microbial community‐level physiology profiles, extracellular enzymatic activities, microbial biomass, and nutrient pools for four land uses: sugarcane, turfgrass, pasture, and forest. Long‐term cultivation and management significantly altered the distribution and cycling of nutrients and microbial community composition and activity in the EAA, especially for sugarcane and turf fields. The least‐managed fields under pasture had the lowest microbial biomass and phosphorus (P) levels. Turf and forest had more microbial metabolic diversity than pasture or the most intensively managed sugarcane fields. Land‐use changes from sugarcane cropping to turf increased microbial activity and organic‐matter decomposition rates, indicating that changes from agricultural to urban land uses may further contribute to soil subsidence.     

嘉陵江流域不同土地利用类型土壤微生物功能多样性特征

基于2013—2015年对嘉陵江流域中游（四川段）不同土地利用类型（混交林、草甸、针叶林、阔叶林、灌丛和裸地）土壤生境的调查分析数据,利用Biolog微平板法和磷脂脂肪酸甲酯法（FAMEs）系统研究了土壤微生物多样性群落特征。不同土地利用类型土壤养分和有效养分基本表现为混交林 > 阔叶林 > 针叶林 > 灌丛 > 草甸 > 裸地。不同土地利用类型土壤微生物群落代谢平均颜色变化率（AWCD）随培养时间延长而逐渐增加,土壤微生物群落代谢活性依次是混交林 > 阔叶林 > 针叶林 > 灌丛 > 草甸 > 裸地。土壤微生物对不同种类碳源的利用强度存在较大差异,碳水化合物和羧酸类碳源是不同土地利用类型土壤微生物的主要碳源,其次为氨基酸类、酚酸类和聚合物类,胺类碳源的利用率最小。土壤微生物群落的物种丰富度指数（H）、均匀度指数（E）、优势度指数（D_s）和碳源利用丰富度指数（S）总体趋势为混交林最高,针叶林和阔叶林次之,裸地最低,优势度指数在不同土地利用类型差异并不显著（p > 0.05）。主成分分析结果表明,从31个因素中提取的与碳源利用相关的主成分1,主成分2分别能解释变量方差的65.154%和81.047%,在主成分分离中起主要贡献作用的是胺类和氨基酸类碳源;土壤微生物多样性指数与土壤养分之间呈正相关,与pH值呈负相关,而土壤全碳和全氮含量对土壤微生物多样性贡献较大,这是造成土壤微生物群落功能多样性差异的主要原因。H,E和S与土壤养分各指标的相关系数绝对值均高于D_s,说明了土壤养分对土壤微生物群落优势度指数的影响作用较小。     

Effects of Ant Mounds on the Plant and Soil Microbial Community in an Alpine Meadow of Qinghai–Tibet Plateau

Ants are important soil engineers, affecting the structure and function of ecosystems. To address the impacts of ants (Camponotus herculeanus ) on the properties of an alpine meadow ecosystem of Qinghai–Tibet Plateau, we investigated the effects of ant mounds on plant biomass, soil physicochemical properties, microbial diversity, and functions. We found that the total biomass of plant community was significantly greater in ant mound periphery. Plant species richness in ant mounds was reduced compared with that of control plots without ant mounds. Significant changes in physicochemical properties of soil were also observed. Soil organic matter, total nitrogen, available phosphorous, total potassium, and available potassium increased in ant mound soil due to the excavation activities by ants as well as the accumulation of organic matter and other nutrients during mound construction. For example, roots/soil contents (g/g) and soil moisture in ant mound soils were lower than those in controls. Microbial community composition and microbial biomass were clearly changed in ant mound soils. BIOLOG analysis further indicated that the functional diversity of the microbial community of ant mound soil increased and differed from that of controls. This study indicates that ant‐induced modification of soil properties indirectly influences plant biomass and species composition, and ant mounds have different microbial communities from those of control soil. Copyright © 2016 John Wiley & Sons, Ltd.     

Land-use intensification and agroforestry in the Kenyan highland: Impacts on soil microbial community composition and functional capacity

This study investigates microbial communities in soil from sites under different land use in Kenya. We sampled natural forest, forest plantations, agricultural fields of agroforestry farms, agricultural fields with traditional farming and eroded soil on the slopes of Mount Elgon, Kenya. We hypothesised that microbial decomposition capacity, biomass and diversity (1) decreases with intensified cultivation; and (2) can be restored by soil and land management in agroforestry. Functional capacity of soil microbial communities was estimated by degradation of 31 substrates on Biolog EcoPlates™. Microbial community composition and biomass were characterised by phospholipid fatty acid (PLFA) and microbial C and N analyses. All 31 substrates were metabolised in all studied soil types, i.e. functional diversity did not differ. However, both the substrate utilisation rates and the microbial biomass decreased with intensification of land use, and the biomass was positively correlated with organic matter content. Multivariate analysis of PLFA and Biolog EcoPlate™ data showed clear differences between land uses, also indicated by different relative abundance of PLFA markers for certain microorganism groups. In conclusion, our results show that vegetation and land use control the substrate utilisation capacity and microbial community composition and that functional capacity of depleted soils can be restored by active soil management, e.g. forest plantation. However, although 20–30 years of agroforestry farming practises did result in improved soil microbiological and chemical conditions of agricultural soil as compared to traditional agricultural fields, the change was not statistically significant.     

红壤微生物生物量C周转及其研究

采用14 C底物标记技术测定了三种不同质地 (红砂土菜地、黄筋泥桔园和茶籽园 )的红壤微生物生物量C的周转期。结果表明 ,在 2 5℃、5 0 %田间持水量培养条件下 ,三种红壤微生物生物量C的周转期分别为 80天、1 39天和 1 70天。周转期与粘粒含量关系较为密切 ,砂质土壤的周转期较粘粒土壤短 ,提示砂质土壤有机质易被微生物降解 ,有利于养分的迅速释放 ,而粘粒土壤则更有利于养分的持留。周转期与利用方式、pH以及有机质含量无明显相关。红壤微生物生物量C周转期总体上较报道的其他类型土壤微生物生物量C周转期短 ,表明热带—亚热带地区酸性红壤有机质和养分周转相对较快 ,这有可能是造成红壤养分贫瘠的一个原因。根据周转期估算 ,通过微生物年周转的C量 (即年流通量 )为微生物生物量C的 2倍以上     

新疆艾比湖地区不同土地利用方式土壤养分、酶活性及微生物特性研究

新疆艾比湖地区在我国内陆荒漠自然生态系统中具有典型性和较高研究价值,通过对不同土地利用方式土壤进行采样和分析,系统地研究和比较了不同土地利用方式土壤酶活性及微生物特性(土壤微生物量和微生物数量)。结果表明:新疆艾比湖不同土地利用方式土壤机械组成不尽一致,黏粒含量占主导地位,粗砂粒含量相对较低,土壤总孔隙度与土壤容重变化趋势相反。不同土地利用方式对土壤养分具有较大影响,不同土地利用方式下土壤养分(有机碳、全氮、全磷)和有效养分(有效磷、有效氮、有效钾、有效锌、有效铁含量)均呈现出一致性规律,大致表现为林地草地耕地未利用地,土壤全磷在不同土地利用方式下差异均不显著(p0.05);与耕地相比,土壤微生物量碳和氮、土壤微生物数量(细菌、真菌和放线菌),土壤酶活性(土壤蔗糖酶、脱氢酶、脲酶、酸性磷酸酶活性)均有明显的增加,大致表现为:林地草地耕地未利用地;相关性分析表明,土壤微生物量碳和氮、细菌、放线菌和真菌数量、蔗糖酶、脱氢酶、脲酶和磷酸酶活性均呈显著或者极显著的负相关(p0.05,p0.01);土壤有机质和全氮与蔗糖酶、脱氢酶、磷酸酶和细菌数量呈极显著正相关(p0.01),土壤有效养分与土壤微生物量碳、细菌数量和蔗糖酶活性呈显著或极显著正相关(p0.05,p0.01),说明土壤微生物量碳仍是有效养分的主要来源,其中土壤容重对土壤微生物量、微生物数量和酶活性贡献为负,土壤养分对土壤微生物量、微生物数量和酶活性贡献为正,这是造成不同土地利用方式土壤微生物量、微生物数量和酶活性差异的重要原因,其中有机质和全氮是土壤微生物量、微生物数量和酶活性的主要养分来源。     

不同土地利用方式下围垦海涂微生物群落和土壤酶特征

利用DGGE技术,从微生物多样性的角度,结合土壤酶活性研究不同农林利用方式对围垦海涂养分特征的影响。结果表明:未利用海涂盐分含量最高,而有机质和碱解氮含量最低;相比于蔬菜地和林地,棉花地和水稻田的有机质、碱解氮、过氧化氢酶和蛋白酶活性更高。四种利用方式土壤的脲酶和磷酸酶活性差异不显著。细菌是土壤中的主要种群,其数量与土壤有机质、碱解氮等养分特征呈显著正相关,表现为水稻田、棉花地>蔬菜地、林地>未利用。DGGE图谱分析结果显示未利用土壤shannon多样性指数最高为2.81,与水稻田、棉花地较为接近,其次为蔬菜地和林地,分别为2.52和2.38。围垦利用引起土壤中的Gaetbulibacter marinus与Gillisia mitskevichiae种属变化。围垦利用后土壤质量优于未利用海涂。相比而言,种植水稻对提高土壤肥力水平,维持土壤质量较为有利。     

Changes in soil microbial community structure following the abandonment of agricultural terraces in mountainous areas of Eastern Spain

In Eastern Spain, almond trees have been cultivated in terraced orchards for centuries, forming an integral part of the Mediterranean forest scene. In the last decades, orchards have been abandoned due to changes in society. This study investigates effects of changes in land use from forest to agricultural land and the posterior land abandonment on soil microbial community, and the influence of soil physico-chemical properties on the microbial community composition (assessed as abundances of phospholipids fatty acids, PLFA). For this purpose, three land uses (forest, agricultural and abandoned agricultural) at four locations in SE Spain were selected. Multivariate analysis showed a substantial level of differentiation in microbial community structure according to land use. The microbial communities of forest soils were highly associated with soil organic matter content. However, we have not found any physical or chemical soil property capable of explaining the differences between agricultural and abandoned agricultural soils. Thus, it was suggested that the cessation of the perturbation caused by agriculture and shifts in vegetation may have led to changes in the microbial community structure. PLFAs indicative of fungi and ratio of fungal to bacterial PLFAs were higher in abandoned agricultural soils, whereas the relative abundance of bacteria was higher in agricultural soils. Actinomycetes were generally lower in abandoned agricultural soils, while the proportions of vesicular–arbuscular mycorrhyzal fungi were, as a general trend, higher in agricultural and abandoned agricultural soils than in forests. Total microbial biomass and richness increased as agricultural < abandoned agricultural < forest soils.     

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。     

渭北旱塬区不同坡向土地利用类型对土壤性质的影响

为了研究不同坡向土地利用类型对土壤性质的影响,以渭北旱塬区5种土地利用类型(不同坡向)为研究对象,系统分析该区不同坡向土地利用类型剖面土壤物理、化学和生物性质的差异。结果表明:(1)除土壤pH和土壤颗粒组成外,5种土地利用类型土壤含水量、总孔隙度、有机质、全氮、微生物量碳和氮含量总体随土层加深呈下降趋势,土壤容重则相反。(2)0-30cm土层,阳坡农用地土壤含水量、黏粒含量和pH最高,粉粒和全氮含量最低;人工草地砂粒和全氮含量最高,黏粒含量最低;人工林地土壤总孔隙度、土壤有机质、微生物量碳和氮含量最高,土壤含水量、土壤容重和pH最低;天然草地土壤容重和粉粒含量最高,总孔隙度和砂粒含量最低;退耕地有机质、微生物量碳和氮含量最低。阴坡农用地土壤含水量、粉粒含量和pH最高,黏粒和全氮含量最低;人工草地土壤容重、黏粒和微生物量氮含量最高,土壤总孔隙度、粉粒、砂粒和有机质含量最低;人工林地有机质含量和微生物量碳含量最高;天然草地土壤总孔隙度、砂粒和全氮含量最高,土壤容重和pH最低;退耕地土壤含水量、微生物量碳和氮含量最低。(3)5种土地利用类型中,土壤容重、细黏粒、粗黏粒、细粉粒、粗砂粒、土壤pH和有机质(退耕地除外)表现为阳坡阴坡,土壤含水量(退耕地和农用地除外)、总孔隙度、粗粉粒、细砂粒、土壤质地粗化度、全氮(人工草地除外)、土壤微生物量碳和氮含量则为阴坡阳坡。     

Long‐term changes of aggregate‐associated and labile soil organic carbon and nitrogen after conversion from forest to grassland and cropland in northern Turkey

Soil management systems can have great effect on soil chemical, physical and biological properties. Conversion of forest to grassland and cropland can alter C and N dynamics. The objective of this study was to evaluate the changes in aggregate‐associated and labile soil organic C and N fractions after conversion of a natural forest to grassland and cropland in northern Turkey. This experiment was conducted on plots subject to three different adjacent land uses (forest, grassland and cropland). Soil samples were taken from 0–5, 5–15 and 15–30 cm depths from each land use. Some soil physical (soil texture, bulk density), chemical (soil pH, soil organic matter, lime content, total organic C and N, inorganic N, free and protected organic C) and biological (microbial biomass C and N, mineralizable C and N) properties were measured. The highest and lowest bulk densities were observed in grassland (1.41 g cm⁻³) and cropland (1.14 g cm⁻³), respectively. Microbial biomass C and total organic C in forest were almost twice greater than grassland and four‐times greater than cropland. Cultivation of forest reduced total organic N, mineralizable N and microbial biomass N by half. The great portion of organic C was stored in macroaggregates (>250 µm) in all the three land uses. Free organic C comprised smaller portion of soil organic C in all the three land uses. Thus, this study indicated that long‐term conversion of forest to grassland and cropland significantly decreased microbial biomass C, mineralizable C and physically protected organic C and the decreases were the greatest in cropland. Copyright © 2011 John Wiley & Sons, Ltd.     

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.     

Microbial Biomass,Community Diversity,and Enzyme Activities in Response to Urea Application in Tea Orchard Soils

To improve yield and quality in tea orchards, a large amount of nitrogen (N) fertilizer is usually applied. Our objective was to evaluate the effect of N application on microbial community and activity in tea orchard soils and assess the relative importance of fertilizer application versus land use in structuring the soil microbial community. Urea application caused significant decreases in soil microbial biomass and enzyme activities in the three tea orchards. For the wasteland and forest, soil microbial biomass and enzyme activities significantly increased as a result of N fertilizer application. Urea application caused significant decreases in microbial functional and genetic diversity indices of the three tea orchards. Moreover, the bacterial and fungal phospholipid fatty acids were found to be changed with urea application. Multivariate analyses consistently showed that land use had a greater effect on soil microbial community diversity than urea application.     

Consequences of forest conversion to pasture and fallow on soil microbial biomass and activity in the eastern Amazon

The main change in soil use in Amazonia is, after slash and burn deforestation followed by annual crops, the establishment of pastures. This conversion of forest to pasture induces changes in the carbon cycle, modifies soil organic matter content and quality and affects biological activity responsible for numerous biochemical and biological processes essential to ecosystem functioning. The aim of this study was to assess changes in microbial biomass and activity in fallow and pasture soils after forest clearing. The study was performed in smallholder settlements of eastern Brazilian Amazonia. Soil samples from depths of 0–2, 2–5 and 5–10 cm were gathered in native forest, fallow land 8–10 yr old and pastures with ages of 1–2, 5–7 and 10–12 yr. Once fallow began, soil microbial biomass and its activity showed little change. In contrast, conversion to pasture modified soil microbial functioning significantly. Microbial biomass and its basal respiration decreased markedly after pasture establishment and continued to decrease with pasture age. The increase in metabolic quotient in the first years of pasture indicated a disturbance in soil functioning. Our study confirms that microbial biomass is a sensitive indicator of soil disturbance caused by land‐use change.     

How different reforestation approaches affect red soil properties in southern China

Significant differences were found in soil physicochemical and biological effects between various forest restoration approaches of a hilly red‐soil region, southern China. Soil quality was the highest in natural secondary forest (0·95), while in sites revegetated with tea‐oil camellia (Camellia oleifera), Chinese fir (Cunninghamia lanceolata) and slash pine (Pinus elliottii) and control sites, integrated soil quality indices were 0·68, 0·55, 0·36 and 0·04 respectively. The lower soil quality of plantations and controls resulted from increased disruption of soil physical structure, lower quality litter fall, lower litter fall production, reduction in microbial biomass, decline of microbial function and loss of soil nutrients due to periodically artificial tending and accelerated soil erosion. Improvement in soil physicochemical properties and enhanced soil microbial function at a natural secondary forest site demonstrated the inherent restoration of these soils. Hence, natural restoration, as well as reducing human disturbance, is a better approach to improving soil properties than returning farmland to planted woodlands. Copyright © 2005 John Wiley & Sons, Ltd.     

Land use change and soil nutrient transformations in the Los Haitises region of the Dominican Republic

We characterized soil cation, carbon (C) and nitrogen (N) transformations within a variety of land use types in the karst region of the northeastern Dominican Republic. We examined a range of soil pools and fluxes during the wet and dry seasons in undisturbed forest, regenerating forest and active agricultural sites within and directly adjacent to Los Haitises National Park. Soil moisture, soil organic matter (SOM), soil cations, leaf litter C and pH were significantly greater in regenerating forest sites than agricultural sites, while bulk density was greater in active agricultural sites. Potential denitrification, microbial biomass C and N, and microbial respiration g⁻¹ dry soil were significantly greater in the regenerating forest sites than in the active agricultural sites. However, net mineralization, net nitrification, microbial biomass C, and microbial respiration were all significantly greater in the agricultural sites on g⁻¹ SOM basis. These results suggest that land use is indirectly affecting microbial activity and C storage through its effect on SOM quality and quantity. While agriculture can significantly decrease soil fertility, it appears that the trend can begin to rapidly reverse with the abandonment of agriculture and the subsequent regeneration of forest. The regenerating forest soils were taken out of agricultural use only 5-7 years before our study and already have soil properties and processes similar to an undisturbed old forest site. Compared to undisturbed mogote forest sites, regenerating sites had smaller amounts of SOM and microbial biomass N, as well as lower rates of microbial respiration, mineralization and nitrification g⁻¹ SOM. Initial recovery of soil pools and processes appeared to be rapid, but additional research must be done to address the long-term rate of recovery in these forest stands.     

Microbial biomass activities in urban soils in two consecutive years

Ecological soil functions are protected in Germany. Thus, for the sustainable use of urban soil resources data on the function of soils to serve as a habitat are required. Soil microbial biomass and activities were studied in two surface horizons in two consecutive years at nine sites in Stuttgart, Germany, differing in land use. Microbial biomass (chloroform‐fumigation extraction, substrate‐induced respiration) and microbial activities (potential N mineralization, potential ammonium oxidation, and enzyme activities of dehydrogenase, urease, arylsulfatase, and phosphatase) were determined in 2001 and 2002. DIN/ISO standard methods were applied as far as they were available. Furthermore, soil chemical properties were determined in the 2001‐samples. Large differences in chemical and microbiological properties among surface horizons were found. Concentrations of microbial biomass and microbial activities were, however, often comparable to agricultural or forest surface soils. The lowest microbial biomass and activities were observed at a highly disturbed railway area where vegetation was missing and total organic C (TOC) had been altered by anthropogenic organic particles. In contrast, microorganisms were promoted at vegetated sites and where organic impurities were negligible. As TOC was altered by obscure organic matter, total N (TN) and not TOC closely correlated with soil microbiological properties. Biomass and activity generally decreased with depth, but mixing of organic matter resulted in more uniform depth distribution of microbial properties in one garden soil. In 2002, microbial biomass and activity were often lower compared to 2001, but interpretation of this difference hampered as the number of samples taken was probably not sufficient to address the spatial variability in soil properties. Additional studies are needed to develop simple and cost‐effective procedures for the evaluation of ecological quality of urban soils by combined efforts of city planners and soil scientists.     

Assessment of soil quality in different ecosystems (with soils of Podolsk and Serpukhov districts of Moscow oblast as examples)

The values of the soil-ecological index and microbiological parameters (the carbon of microbial biomass C_mic, its ratio to the total organic carbon C_mic/C_org, and basal respiration) were determined for the soddy-podzolic, soddy-gley, bog-podzolic, meadow alluvial, and gray forest soils under different land uses (forest, fallow, cropland, and urban areas) in the Podolsk and Serpukhov districts of Moscow oblast (237 and 45 sampling points, respectively). The soil sampling from the upper 10 cm (without the litter horizon) was performed in September and October. To calculate the soil-ecological index, both soil (physicochemical and agrochemical) and climatic characteristics were taken into account. Its values for fallow, cropland, and urban ecosystems averaged 70.2, 72.8, and 64.2 points (n = 90, 17, and 24, respectively). For the soils of forest ecosystems, the average value of the soil-ecological index was lower (54.4; n = 151). At the same time, the micro-biological characteristics of the studied forest soils were generally higher than those in the soils of fallow, cropland, and urban ecosystems. In this context, to estimate the soil quality in different ecosystems on the basis of the soil-ecological index, the use of a correction coefficient for the biological properties of the soils (the C_mic content) was suggested. The ecological substantiation of this approach for assessing the quality of soils in different ecosystems is presented in the paper.     

黄土丘陵区不同土地利用方式对土壤微生物量碳氮磷的影响

为探讨植被区与土地利用方式对土壤微生物量的影响,在陕西省延河流域森林区、森林草原区和草原区采集5种土地利用方式下的土壤剖面样品(0-10cm,10-30cm),并对其微生物量碳(SMBC)、微生物量氮(SMBN)和微生物量磷(SMBP)及土壤理化性质进行了分析。结果表明,微生物量磷的含量在3个植被区中均是在农地、撂荒地中相对较高,微生物量碳、氮在森林区表现为:乔木林地>农地在森林草原区表现为:灌木林地>天然草地>乔木林地>农地>撂荒地在草原区表现为:天然草地>乔木林地>灌木林地>农地>撂荒地。相同土地利用方式下,土壤养分和微生物量在森林区最高,森林草原区次之,草原区最低。相关分析表明,微生物量碳、氮、磷、代谢熵、微生物量碳氮比与土壤养分相关性极为密切。因此,土壤微生物量能够作为评价土壤质量的生物学指标。不同植被区不同土地利用方式对土壤质量的改善作用不同,林地和天然草地作用效果好,对土壤微生物量的提高有明显的促进作用。