Primary Forest Soils Research Articles

Temporal Variability in Soil Greenhouse Gas Fluxes and Influencing Factors of a Primary Forest on the Eastern Qinghai-Tibetan Plateau

Soil greenhouse gas (GHG) fluxes relate to soil carbon and nitrogen budgets and have a significant impact on climate change. Nevertheless, the temporal variation and magnitude of the fluxes of all three major GHGs (CO2, CH4 and N2O) and their influencing factors have not been elucidated clearly in primary forests on the eastern Qinghai-Tibetan Plateau. Herein, field chamber GHG fluxes from May to November, soil microbial community and enzyme activity were analyzed in a fir-dominated (Abies fargesii var. faxoniana) primary forest. The emission rates of CO2 and N2O ranged between 64.69–243.22 mg CO2 m−2 h−1 and 1.69–5.46 ug N2O m−2 h−1, exhibiting a temporally unimodal pattern with a peak in July. The soil acted as a CH4 sink, and the uptake rate varied between 52.96 and 84.67 μg CH4 m−2 h−1 with the higher uptake rates in June and November. The temporal variation in the CO2 flux was significantly correlated with the geometric mean of enzyme activities, suggesting that the soil CO2 flux was determined by microbial activity rather than soil microbial biomass. The soil N2O flux was positively related to nitrate concentration with marginal significance, probably because N2O was a byproduct of nitrification and denitrification processes. The soil CH4 uptake was closely associated with methanotrophic biomass (18:1ω7c). The results highlight divergent temporal dynamics of GHG fluxes owing to different driving mechanisms and an important CH4 sink in the primary forest soil, helping to evaluate the carbon and nitrogen budgets of primary forests on the eastern Qinghai-Tibetan Plateau.

Response of soil phosphorus fractions to litter removal in subalpine coniferous forest

Litter plays a crucial role in phosphorus (P) cycling, and its role in forest ecosystems may vary with different treatments and forest types. In this study, we investigated soil P fraction responses to litter removal in different forest types and how forest conversion affects the acquisition pathway of bioavailable P through an in situ controlled litter experiment. The results showed that the soil P content increased with the conversion of primary to secondary forest, which may be mostly related to the differences in nutrients and species richness between the two forest types. In addition, the main source of bioavailable P in primary forests was active organic P, while mineral P was the main bioavailable P source in secondary forests. Moreover, the three-year litter removal treatment significantly decreased the primary forest soil P fraction content while significantly increasing the secondary forest bioavailable P content. The main driving factors of the soil P fraction are also different between the two forest types, with AP activity and SOC as the major factors in the primary forest and pH as the main factor in the secondary forest.

Microbial Composition on Abandoned and Reclaimed Mining Sites in the Komi Republic (North Russia)

Restoration of anthropogenically disturbed soils is an urgent problem in modern ecology and soil biology. Restoration processes in northern environments are especially important, due to the small amounts of fertile land and low levels of natural succession. We analyzed the soil microbiota, which is one of the indicators of the succession process is the soil. Samples were obtained from three disturbed soils (self-overgrown and reclaimed quarries), and two undisturbed soils (primary and secondary forests). Primary Forest soil had a well-developed soil profile, and a low pH and TOC (total organic carbon) amount. The microbial community of this soil had low richness, formed a clear remote cluster in the beta-diversity analysis, and showed an overrepresentation of Geobacter (Desulfobacteriota). Soil formation in clay and limestone abandoned quarries was at the initial stage, and was caused by both a low rate of mineral profile formation and severe climatic conditions in the region. Microbial communities of these soils did not have specific abundant taxa, and included a high amount of sparse taxa. Differences in taxa composition were correlated with abiotic factors (ammonium concentration), which, in turn, can be explained by the parent rock properties. Limestone quarry reclaimed by topsoil coverage resulted in an adaptation of the top soil microbiota to a novel parent rock. According to the CCA analysis, the microbial composition of samples was connected with pH, TOC and ammonium nitrogen concentration. Changes in pH and TOC were connected with ASVs from Chloroflexota, Gemmatimonadota and Patescibacteria. ASVs from Gemmatimonadota also were correlated with a high ammonium concentration.

Changes in soil chemical properties and their spatial distribution after logging and conversion to oil palm plantation in Sabah (Borneo)

Abstract Conversion of primary forest into oil palm plantations is common in tropical countries, affecting soil properties, ecosystem services and land-use management. However, little is known about the short-range spatial soil distribution that is important for soil scientists, ecologists, entomologists, mycologists or microbiologists. In this study, seven soil properties (pH, EC (µS/m), P (mg/kg), NO3- (mg/kg), N%, C% and C:N) were measured to quantify the spatial autocorrelation across primary forest, selectively logged forest and oil palm plantation in Sabah, Malaysian Borneo. Local variograms were calculated (range ∼5 m) to determine the short-range variation, and a decision tree as well as principal component analysis were implemented to determine if the overall (global) mean differed between land uses. As hypothesised, oil palm soils deviated the most from primary forest soils, which had more fluctuating variograms and in general, a shorter range. Oil palm plantations also showed a difference in the global mean except for electrical conductivity. Selectively logged forests also differed in their short-range spatial structure; however, the global mean and variance remained similar to primary forest soil with the exception of labile phosphorus and nitrate. These results were attributed to initial plantation development, removal of topsoil, fertiliser application and topography.

Mapping Secondary Vegetation of a Region of Deforestation Hotspot in the Brazilian Amazon: Performance Analysis of C- and L-Band SAR Data Acquired in the Rainy Season

The re-suppression of secondary vegetation (SV) in the Brazilian Amazon for agriculture or land speculation occurs mostly in the rainy season. The use of optical images to monitor such re-suppression during the rainy season is limited because of the persistent cloud cover. This study aimed to evaluate the potential of C- and L-band SAR data acquired in the rainy season to discriminate SV in an area of new hotspot of deforestation in the municipality of Colniza, northwestern of Mato Grosso State, Brazil. This is the first time that the potential of dual-frequency SAR data was analyzed to discriminate SV, with an emphasis on data acquired during the rainy season. The L-band ALOS/PALSAR-2 and the C-band Sentinel-1 data acquired in March 2018 were processed to obtain backscattering coefficients and nine textural attributes were derived from the gray level co-occurrence matrix method (GLCM). Then, we classified the images based on the non-parametric Random Forest (RF) and Support Vector Machine (SVM) algorithms. The use of SAR textural attributes improved the discrimination capability of different LULC classes found in the study area. The results showed the best performance of ALOS/PALSAR-2 data classified by the RF algorithm to discriminate the following representative land use and land cover classes of the study area: primary forest, secondary forest, shrubby pasture, clean pasture, and bare soil, with an overall accuracy and Kappa coefficient of 84% and 0.78, respectively. The RF outperformed the SVM classifier to discriminate these five LULC classes in 14% of overall accuracy for both ALOS-2 and Sentinel-1 data sets. This study also showed that the textural attributes derived from the GLCM method are highly sensitive to the moving window size to be applied to the GLCM method. The results of this study can assist the future development of an operation system based on dual-frequency SAR data to monitor re-suppression of SV in the Brazilian Amazon or in other tropical rainforests.

Forest management impact on soil organic carbon: A paired-plot study in primeval and managed European beech forests

Forest soils have been recognized as important reservoirs of older stable carbon (C) in the biosphere and thus play a key role in the global C cycle. While much research has addressed the consequences of forest conversion and forest use on soil organic carbon (SOC) stocks, some controversies remain as to whether primary forest soils store significantly more SOC than soils in managed forests. Here, we explore the effect of forest management on SOC stocks in European beech (Fagus sylvatica) forests through a paired-plot study in nearby primeval and managed forests in the western Carpathians, testing the hypotheses that primeval forests store significantly more SOC especially in the topsoil and that larger biomass and deadwood amounts are important drivers. The three primeval forests stored on average 15 % more SOC (∼1.8 kg C m−2) in the organic layers and mineral soil to 50 cm depth than the managed forests prior to harvest (difference marginally significant at p = 0.09). Contrary to expectation, the difference was significant in the subsoil (30–50 cm depth) but not in the topsoil. Consequently, the primeval forests had a greater proportion of their SOC pool located in the subsoil than the managed forests. Despite considerably larger wood biomass and deadwood amounts in the primeval forests, SOC pools were neither related to biomass nor deadwood mass. PCA and correlation analyses revealed a prominent negative effect of the availability of Ca, Mg, K and P on SOC stocks, suggesting that clear-cutting has slightly (but significantly) increased nutrient supply in the managed forests, likely stimulating soil biological activity and reducing SOC storage in comparison to the primeval forests. We conclude that the primeval forest reference is important for assessing forest management effects on SOC storage, and that a long history of management likely has significantly reduced the SOC stocks of Central European beech forests.

Difference in Phosphorus Acquisition Strategies of N<sub>2</sub>-Fixing Plants in Shrubland and Primary Forest Soils of the Karst Regions

Difference in Phosphorus Acquisition Strategies of N<sub>2</sub>-Fixing Plants in Shrubland and Primary Forest Soils of the Karst Regions

Soil legacy effect of extreme precipitation on a tropical invader in different land use types

Land use change and extreme precipitation are the main challenges for tropical forests, and numerous studies have indicated that these changes could affect soil ecology. However, it is not yet known whether the soil legacy effect of ongoing changes could influence the invasiveness of alien plants. Two mixtures of invader and native species (Chromolaena odorata-Artemisia leucophylla and C. odorata-Desmodium sequax) were transplanted to 18 soil treatments (3 forest types × 3 pre-water supply levels × 2 microorganism treatments). The results showed that the biomass of the invader was greater while its biomass fraction was lower in secondary forest soil than in primary and rubber forest soil; the soil legacy effect of drought was positive on both the biomass and biomass fraction of C. odorata. In rubber plantation soil, the biomass and biomass fraction of C. odorata were enhanced by the pre-increased water supply level. In primary and rubber forests, compared with normal precipitation, the sterilization treatment increased the biomass of the invader under drought and increased precipitation. The nutrient cycle and microorganisms both played a crucial role in this process. Overall, our study demonstrated the pronounced soil legacy effect of land use change, extreme precipitation and their interactions on the invasion success of C. odorata.

Higher free-living N2 fixation at rock-soil interfaces than topsoils during vegetation recovery in karst soils

The widely distributed karst ecosystem in China has experienced rapid deterioration by deforestation and intensive cultivation in the last 50 years. Under the “Grain for Green” program, disturbed croplands were progressively abandoned to restore soil functions and ecosystem services, observed as discrete vegetation recovery phases: cultivated land, abandoned land and secondary forest, and compared to natural primary forest. Karst soils are naturally poor in nitrogen and cessation of nitrogen fertilizer application after abandonment presents an opportunity to explore the reemergence of indigenous soil N2 fixation mechanisms. In this study, we investigated how vegetation recovery affects key soil properties and their relationships with free-living N2 fixation (FLNF) activity and nifH gene abundance, microbial community structure and network interactions at different soil depths from the surface to the rock-soil interface at the bottom of the soil profile. Soil FLNF activity was increased slightly but not significantly after abandonment and was greatest in primary forest soils. High levels of FLNF activity in primary forest soils was facilitated directly by larger total organic carbon to total nitrogen ratios and an altered free-living diazotrophic community composition that was mainly modified by soil moisture content and pH. Higher FLNF was identified at rock-soil interfaces compared to topsoils, which was mainly driven by altered diazotrophic community composition stimulated by increases in soil pH and dissolved organic carbon to available inorganic nitrogen ratios. Diazotrophic network interactions also contributed to variations in FLNF activity, with relatively stable and competitive, while less niche-separated, diazotrophic communities supporting high FLNF activity in primary forest soils, while complex and mutualistic interactions facilitated the high FLNF at rock-soil interfaces. These results suggest that there is considerable and persistent FLNF in degraded karst landscapes at rock-soil interfaces which enables the provision of a vital biological source of nitrogen to overcome the nutrient limitations of karst rock weathering at the bottom of the soil profile.

Influence of Two Important Leguminous Trees on Their Soil Microbiomes and Nitrogen Cycle Activities in a Primary and Recovering Secondary Forest in the Northern Zone of Costa Rica

Inga edulis and Pentaclethra macroloba are dominant N-fixing forest trees in Costa Rica, likely important for recovery of soil N and C after deforestation, yet little is known of their soil microbiomes nor how land use impacts them. Soils from both trees in a primary and secondary forest were assessed for N-cycle metrics and DNA sequence-based composition of total bacterial, potential N-fixing bacterial, and potential ammonium oxidizing bacterial genera. The compositions of the functional groups of bacteria, but not their total relative abundance of DNA, were different across the soils. The P. macroloba soils had greater NO3− levels and richness of both functional groups, while I. edulis soils had greater NH4+ levels, consistent with its NH4+ preference for root nodule development. The bacterial communities were different by habitat, as secondary forest I. edulis microbiomes were less rich, more dominant, possibly more affected by the disturbance, or reached equilibrium status quicker than the richer, less dominant P. macroloba microbiomes, which may be developing slower along with secondary forest succession, or were less affected by the disturbance. Functional redundancy and switching of 10 N-cycle bacterial genera was evident between the primary and secondary forest soils, likely to maintain stable levels of N-cycle activity following disturbance. In summary, the two tree soil microbiomes are different, land use differentially affects them, and, thus, both tree species should be used during forest regeneration strategies in this region.

The persistence of bacterial diversity and ecosystem multifunctionality along a disturbance intensity gradient in karst soil

Extensive, progressive rock emergence causes localized variations in soil biogeochemical and microbial properties that may influence the capacity for the regeneration of degraded karst ecosystems. It is likely that karst ecosystem recovery relies on the persistence of soil functions at the microbial scale, and we aimed to explored the role of interactions between soil bacterial taxa and identify keystone species that deliver key biogeochemical functions, i.e. carbon (C) and nutrient (nitrogen, N and phosphorus, P) cycling. We applied high-throughput sequencing and phylogenetic molecular ecological network approaches to topsoils sampled at rock-soil interfaces and adjacent bulk soil along an established gradient of land-use intensity in the Chinese Karst Critical Zone Observatory. Bacterial α-diversity was greater under increased perturbation and at the rock-soil interface compared to bulk soils under intensive cultivation. However, bacterial ecological networks were less intricate and connected fewer keystone taxa as human disturbance increased and at the rock-soil interface. Co-occurrence within the bacterial community in natural primary forest soils was 13% larger than cultivated soils. The relative abundances of keystone taxa Acidobacteria, Bacteroidetes and Chloroflexi increased with land-use intensity, while Proteobacteria, Actinobacteria and Verrucomicrobia decreased by up to 6%. In general, Bacteroidetes, Verrucomicrobia and Chlorobi were related to C-cycling, Proteobacteria, Actinobacteria and Chloroflexi were related to N-cycling, and Actinobacteria and Nitrospirae were related to both N- and P-cycling. Proteobacteria and Chlorobi affected C-cycling and multiple functionality indexes in the abandoned land. We conclude that increasing land-use intensity changed the soil bacterial community structure and decreased bacterial interactions. However, increases in α-diversity at the rock-soil interface in cultivated soils indicated that major soil functions related to biogeochemical cycling were maintained within keystone taxa in this microenvironment. Our study provides foundations to test the success of different regeneration practices in restoring soil microbial diversity and the multifunctionality of karst ecosystems.

Variations in soil chemical and physical properties explain basin-wide Amazon forest soil carbon concentrations

Abstract. We investigate the edaphic, mineralogical and climatic controls of soil organic carbon (SOC) concentration utilising data from 147 primary forest soils (0–30 cm depth) sampled in eight different countries across the Amazon Basin. Sampled across 14 different World Reference Base soil groups, our data suggest that stabilisation mechanism varies with pedogenetic level. Specifically, although SOC concentrations in Ferralsols and Acrisols were best explained by simple variations in clay content – this presumably being due to their relatively uniform kaolinitic mineralogy – this was not the case for less weathered soils such as Alisols, Cambisols and Plinthosols for which interactions between Al species, soil pH and litter quality are argued to be much more important. Although for more strongly weathered soils the majority of SOC is located within the aggregate fraction, for the less weathered soils most of the SOC is located within the silt and clay fractions. It thus seems that for highly weathered soils SOC storage is mostly influenced by surface area variations arising from clay content, with physical protection inside aggregates rendering an additional level of protection against decomposition. On the other hand, most of the SOC in less weathered soils is associated with the precipitation of aluminium–carbon complexes within the fine soil fraction, with this mechanism enhanced by the presence of high levels of aromatic, carboxyl-rich organic matter compounds. Also examined as part of this study were a relatively small number of arenic soils (viz. Arenosols and Podzols) for which there was a small but significant influence of clay and silt content variations on SOM storage, with fractionation studies showing that particulate organic matter may account for up to 0.60 of arenic soil SOC. In contrast to what were in all cases strong influences of soil and/or litter quality properties, after accounting for these effects neither wood productivity, above-ground biomass nor precipitation/temperature variations were found to exert any significant influence on SOC stocks. These results have important implications for our understanding of how Amazon forest soils are likely to respond to ongoing and future climate changes.

Soil microbiomes associated with two dominant Costa Rican tree species, and implications for remediation: A case study from a Costa Rican conservation area

It is now widely accepted that the majority of tropical landscapes are in transition from disturbance to recovery. Remediation efforts are occurring in Central and South America, attempting to recuperate the soils, often using indigenous nitrogen (N)-fixing tree species. Tree species-generated soil microbial heterogeneity might be important in facilitating regeneration of forest vegetation growth and, although some work has identified these efforts may enhance the soil carbon (C), there have been few studies conducted on how these trees are affecting the below-ground soil biological dynamics in these regions. Here, we explored how and to what extent individual plant effects of a native N-fixing and non-N-fixing plant has affected the below-ground soil C and N metrics and soil bacterial and fungal community composition. To begin to address this, we examined if there were differences in various soil abiotic factors (ToC, TN, C:N ratio, Cmic, NH4+, NO3−, pH, and % moisture) and in the soil bacterial and fungal community composition associated with soil of a native non-N-fixer, Dipteryx panamensis and a native N-fixer, Pentaclethra macroloba, and in comparison to the primary forest bulk-soil in which these tree species occur. We found that primary forest-soils had the greatest amounts of soil NH4+ and Cmic, followed by Pentaclethra-soils. Dipteryx-soils had the least amount of soil Cmic and NH4+, but the greatest amounts of soil NO3−. The PERMANOVA results indicated that the Bray-Curtis soil bacterial and fungal community compositions were significantly different between N-fixing and non-N-fixing tree-soils, and also to that of the primary forest-soils. Our results also demonstrated that soil NH4+ best explained the variation observed in the soil Cmic patterns (39.2%), and, both the soil bacterial (22.8%) and fungal community composition (18.1%). Furthermore, we provide evidence that the N-fixer Pentaclethra-soils stimulates the production of more soil Cmic than the non-N-fixer Dipteryx-soils. It is clear that these tree species are important in creating changes in the soil microbial community composition, and that NH4+ may be associated with a shift in a functional response that may have implications for CUE and remediation in this region.

Interactive effects of land-use change and topography on asymbiotic nitrogen fixation in the Brazilian Atlantic Forest

The conversion of tropical forests to other land use forms is known to affect biogeochemical processes, but its influence on asymbiotic nitrogen fixation (ANF) remains poorly understood. In this study, we investigate patterns of soil ANF and its biogeochemical controls across multiple land uses and topographic positions in the Brazilian Atlantic Forest. We report ANF rates derived from observational and manipulative laboratory experiments using 15N-labeled dinitrogen (15N2) incubations of soils from primary forest, secondary forest, eucalypt plantations and pastures sampled at three hillslope positions (summit, backslope, and footslope). Our field observations revealed significant interactions between land use and topography on ANF rates, which among 14 measured soil parameters were primarily correlated with total nitrogen and available iron (explaining 69% of ANF variance). Complex non-linear relationships were observed between ANF and (mineral and organic) nutrient pools in forest soils, whereas simple positive linear relationships were found between ANF and total soil nitrogen in managed pastures and plantations. Consistent with this observation, experiments with nitrogen and phosphorus addition did not affect ANF rates in pasture or plantation soils, possibly as a result of previous fertilization and homogenization of plant and microbial communities, but variable positive and negative ANF responses were measured in primary and secondary forest soils depending on hillslope position. These findings show that ANF can be simultaneously affected by multiple variables that are sensitive to environmental conditions and demonstrate the need for considering land-use change and topography to improve predictions of terrestrial biogeochemical cycles.

Deforestation decreases spatial turnover and alters the network interactions in soil bacterial communities

Despite important progress in understanding the influence of deforestation on the bacterial α diversity and community structure at local scales, little is known about deforestation impacts in terms of spatial turnover and soil bacterial community network interactions, especially at regional or global scales. To address this research gap, we examined the bacterial spatial turnover rate and the species networks in paired primary and secondary forest soils along a 3700-km north-south transect in eastern China using high-throughput 16S rRNA gene sequencing. The spatial turnover rate of bacterial communities was higher in primary forests than in secondary, suggesting deforestation increased biotic homogenization at a large geographic scale. Multiple regression on matrices analysis revealed that both geographic distance and soil properties (especially soil pH and organic matter availability) strongly affected bacterial spatial turnover. Through the phylogenetic molecular ecological network approach, we demonstrate that the bacterial network of primary forests was more intricate than in secondary forests. This suggests that microbial species have greater niche-sharing and more interactions in primary forests as compared to secondary forests. On the other hand, the bacterial network in secondary forests was more modular, and the taxa tended to co-occur, with positive correlations accounting for 82% of all potential interactions. In conclusion, our findings demonstrate that anthropogenic deforestation has clear effects on bacterial spatial turnover and network interactions, with potential for serious consequences such as microbial diversity loss in primary forests.

Role and Variation of the Amount and Composition of Glomalin in Soil Properties in Farmland and Adjacent Plantations with Reference to a Primary Forest in North-Eastern China.

The glycoprotein known as glomalin-related soil protein (GRSP) is abundantly produced on the hyphae and spores of arbuscular mycorrhizal fungi (AMF) in soil and roots. Few studies have focused on its amount, composition and associations with soil properties and possible land-use influences, although the data hints at soil rehabilitation. By choosing a primary forest soil as a non-degraded reference, it is possible to explore whether afforestation can improve degraded farmland soil by altering GRSP. In this paper, close correlations were found between various soil properties (soil organic carbon, nitrogen, pH, electrical conductivity (EC), and bulk density) and the GRSP amount, between various soil properties and GRSP composition (main functional groups, fluorescent substances, and elements). Afforestation on farmland decreased the EC and bulk density (p < 0.05). The primary forest had a 2.35–2.56-fold higher GRSP amount than those in the plantation forest and farmland, and GRSP composition (tryptophan-like and fulvic acid-like fluorescence; functional groups of C–H, C–O, and O–H; elements of Al, O, Si, C, Ca, and N) in primary forest differed from those in plantation forest and farmland (p < 0.05). However, no evident differences in GRSP amount and composition were observed between the farmland and the plantation forest. Our finding highlights that 30 years poplar afforestation on degraded farmland is not enough to change GRSP-related properties. A longer period of afforestation with close-to-nature managements may favor the AMF-related underground recovery processes.

A comparison of the wet and dry season DNA-based soil invertebrate community characteristics in large patches of the bromeliad Bromelia pinguin in a primary forest in Costa Rica

In Costa Rica, the Maquenque National Wildlife Refuge (MNWLR) contains a unique habitat gradient ranging from primary old growth forests, grasslands, pastures, to various ages of secondary forests. Within these primary old growth forests are extremely dense naturally occurring Bromelia pinguin (Bromeliaceae) patches that often grow with densities up to 2 plants per square meter. A previous study found that anti-fungal activity of this particular plant appears to be altering the fungal community in soils adjacent to these plants. No work has been previously conducted on the possible effects of this plant community on soil faunal communities and if seasonality contributes to changes in soil invertebrate populations along a moisture gradient. Thus, a study was conducted to assess the effects of this specialized plant community on soil invertebrates with respect to season, and if these changes in soil fauna guild structure could prove to be valid candidates as indicators of ecosystem condition with changes in precipitation. In addition, a meta-analysis was done to determine how the bromeliad-associated soil invertebrate communities differ from those in adjacent primary forest soils. Therefore, comparisons were determined from previous primary forest soil invertebrate environmental DNA (eDNA) to the current wet season bromeliad soil invertebrate eDNA. Roche 454 pyro-sequencing was conducted on the 650bp fragment of the cytochrome oxidase subunit I (COI) gene of invertebrates to obtain and characterize soil invertebrate sequence composition. To determine relationships among soil fauna guilds across seasons, relative abundance of the sequences were calculated, and used in conjunction with EcoSim niche overlap and co-occurrence values. From the bromeliad seasonal soil fauna eDNA study, it appears certain invertebrate guilds are driven by moisture as indicated by fluctuations in relative abundance of each invertebrate guild across seasons in bromeliad patch soils, as well as indicated by EcoSim niche overlap values. In particular, Guilds 1, 4, and 5, should warrant further investigation as indicators of habitat condition. The meta-analysis showed that a naturally occurring modified environment (the bromeliad patches), can result in differences in relative abundance and partitioning of a limited resource between invertebrate guild structure. Those guilds associated with microbivorous and complex decomposition activities (i.e. Guilds 3 and 4), are more abundant in primary forest soils than bromeliad patch soils and could potentially used for bioindicators of habitat perturbations.

Responses of soil fungi to logging and oil palm agriculture in Southeast Asian tropical forests.

Human land use alters soil microbial composition and function in a variety of systems, although few comparable studies have been done in tropical forests and tropical agricultural production areas. Logging and the expansion of oil palm agriculture are two of the most significant drivers of tropical deforestation, and the latter is most prevalent in Southeast Asia. The aim of this study was to compare soil fungal communities from three sites in Malaysia that represent three of the most dominant land-use types in the Southeast Asia tropics: a primary forest, a regenerating forest that had been selectively logged 50years previously, and a 25-year-old oil palm plantation. Soil cores were collected from three replicate plots at each site, and fungal communities were sequenced using the Illumina platform. Extracellular enzyme assays were assessed as a proxy for soil microbial function. We found that fungal communities were distinct across all sites, although fungal composition in the regenerating forest was more similar to the primary forest than either forest community was to the oil palm site. Ectomycorrhizal fungi, which are important associates of the dominant Dipterocarpaceae tree family in this region, were compositionally distinct across forests, but were nearly absent from oil palm soils. Extracellular enzyme assays indicated that the soil ecosystem in oil palm plantations experienced altered nutrient cycling dynamics, but there were few differences between regenerating and primary forest soils. Together, these results show that logging and the replacement of primary forest with oil palm plantations alter fungal community and function, although forests regenerating from logging had more similarities with primary forests in terms of fungal composition and nutrient cycling potential. Since oil palm agriculture is currently the mostly rapidly expanding equatorial crop and logging is pervasive across tropical ecosystems, these findings may have broad applicability.

喀斯特峰丛洼地不同生态系统的土壤肥力变化特征

PDF HTML阅读 XML下载 导出引用 引用提醒 喀斯特峰丛洼地不同生态系统的土壤肥力变化特征 DOI: 10.5846/stxb201208161154 作者: 作者单位: 中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,江西农业大学,广西大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院西部行动计划资助项目（KZCX2-XB3-10）；国家科技支撑计划资助项目（2011BAC09B02）；中国科学院战略性先导科技专项资助项目（XDA05070404，XDA05050205）；国家自然科学基金资助项目（31370485，31370623，U1033004，31100329）；桂科攻（1123001-9C）资助项目；广西“特聘专家”资助项目 Characteristics of soil fertility in different ecosystems in depressions between karst hills Author: Affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences,,Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences,,,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:基于喀斯特峰丛洼地坡耕地、草丛、灌丛、人工林、次生林、原生林6种典型生态系统的土壤主要养分、矿质养分和微生物这3组变量共计20个指标的调查、取样和分析，运用多重比较分析、主成分分析和典范相关分析探讨了其土壤肥力变化特征、主要影响因子及两两之间的相互关系。结果表明，喀斯特峰丛洼地土壤pH值为6.60-7.75，土壤主要养分、微生物种群数量和微生物生物量明显高于同纬度地区地带性红壤，矿质养分含量相对较低，其中SiO2、Al2O3、Fe2O3占矿质全量的90%以上。土壤肥力的总体趋势为原生林 > 次生林 > 灌丛 > 草丛 > 坡耕地 > 人工林。喀斯特石漠化地区实行林草结合的退耕还林还草模式更有利于土壤生态系统的环境改善，坡耕地应多施有机肥和氮肥，人工林应多施氮肥。原生林植物与养分之间达到了良好的平衡状态，主要应加强森林抚育管理，改善森林环境，保障植物、土壤养分及微生物之间的良好协调关系。确保土壤资源的合理利用，促进喀斯特峰丛洼地乃至整个西南喀斯特区域植被的迅速恢复和生态重建。 Abstract:The main soil nutrients, soil mineral nutrients, and soil microbes were investigated, sampled, and analyzed in farmland, grassland, scrub, plantation forest, secondary forest, and primary forest in depressions between karst hills. Multiple comparison analysis, principal component analysis, and canonical correlation analysis were used to study the soil characteristics and the main factors affecting soil fertility as well as the relationships between those three factors: the main soil nutrients, soil mineral content, and soil microbes. Soil pH ranged from 6.60 to 7.75 in depressions between karst hills. Across the different ecological systems, from farmland to primary forest soil, pH varied from acidic to alkaline. The soil nutrient content varied in different ecological systems, and changes in soil nutrient content can be modeled during the process of ecological succession. In the process of secondary succession soil organic matter (SOM), total nitrogen (TN), total phosphorous (TP), available nitrogen (AN), and available phosphorous (AP) content increased gradually. The soil nutrient levels were highest in primary forest and follow the sequence of primary forest > secondary forest > shrub > grassland. The soils of these habitats were all significantly or very significantly different. When the landuse type was changed from a landscape with natural secondary succession to farmland or plantation forests, soil TP and TK content increased significantly. The content of the main soil nutrients (SOM, TN, TP, TK, AN, AP, AK), microbial populations, and the soil content of C, N, and P in microbial biomass (Cmic, Nmic, Pmic, respectively), were obviously higher in the karst area than that in the red soil region at the same latitudes. The content of mineral nutrients was relatively low and the sum of SiO2, Al2O3, and Fe2O3 accounted for more than 90% of the total mineral nutrients. Although the supply of Ca and Mg were adequate, serious shortages of other mineral nutrients limited plant growth and development. Many types of ecological systems in depressions between karst hills were not obviously showing signs of rocky desertification, although a strong potential for rocky desertification still exists. All ecosystems studied here had high soil microbial populations, and primary forest had highest total microbial populations, bacteria populations and Actinomyces population while plantation forest had the lowest. Soil fertility can be ranked in the order of primary forest > secondary forest > scrub > grassland > farmland > plantation forest. The landscape in this karst area is strongly heterogeneous; the ecological systems are complex because numerous factors affect the ecosystems and different ecological systems are influenced by different factors. Therefore, the practice of returning farmland to forests or grassland tends to improve the soil ecosystem environment in karst areas which have undergone rocky desertification. Farmland requires more organic and nitrogenous fertilizers and plantation forests require more nitrogenous fertilizer than other ecosystems. In the primary forest, plants and soil nutrients reach a state of dynamic equilibrium, and land management should focus on strengthening and improving the forest environment and balancing the relationships among plants, soil nutrients and microbes. Assuring that soil resources are used rationally will be helpful in improving the results of ecological restoration and accelerate vegetation rehabilitation in depressions between karst hills or even in the entire karst region of southwest China. 参考文献 相似文献 引证文献

Effects of eucalyptus and coniferous plantations on soil properties in Gambo District, southern Ethiopia

Plantation establishment using exotic species on disturbed cultivated and undisturbed primary forest soils is common in Gambo district, southern Ethiopia, but their effects on soil properties are not fully known. This study investigated the effects of plantation species on major soil physical and chemical properties and further evaluated the soil quality under different land uses. Soil samples in triplicates, collected under different plantations, were analysed for their physical and chemical properties. Based on these soil properties, an integrated soil quality index was determined. The soil bulk density (BD) varied from 0.72 to 0.80 cm−3 in plantations established on primary forest land and natural forest and from 0.86 to 1.14 g cm−3 in those plantations established on cultivated soils. Also significantly lower pore volume and infiltration rate were observed under plantations established on cultivated lands than those on primary forest soils. Higher water volume (% at −1500 kPa matric potential) was obtained in soils under Juniperus procera and natural forest compared with that under the rest of the plantations investigated. The concentration of soil organic carbon (SOC) varied from 3.4 to 10.2%, N from 0.3 to 1.0% and Av.P from 1.5 to 7.0% in soils under plantations and natural forest. Exchangeable cations generally showed a decreasing trend with depth in all land use types with minor exceptions. The concentrations of exchangeable Ca+2 varied from 6.5 to 22.7 cmol kg−1 and were significantly higher under Juniperus procera than under Eucalyptus species. The soil under plantations on previously cultivated lands showed soil quality index below 0.5 (the baseline value), while those established on undisturbed forest soil were generally above that value. The study results suggest that selecting species such as Juniperus procera and prolonging the harvesting period would improve and maintain the quality of soil properties.