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1.
Soil soluble organic nitrogen (SON) can play an important role in soil nitrogen (N) cycling in forest ecosystems. This study examined the effect of land-use change from a native forest (NF) to a first rotation (1R) and subsequent second rotation (2R) hoop pine (Araucaria cunninghamii) plantation on soil SON pools. The impact of residue management on SON pools was also investigated in the 2R forest, where SON was measured in tree rows (2R-T) and windrows (2R-W). Various extraction techniques were used to measure SON pool size in the 0-10, 10-20 and 20-30 cm layers of soil. The results showed that land-use change had a significant impact on soil SON pools. In the 0-10 cm layer, 3.2-8.7, 14-23, 20-28, 60-160 and 127-340 mg SON kg−1 were extracted by water, 0.5 M K2SO4, 2 M KCl, hot water and hot 2 M KCl, respectively. The size of the SON pools and the potential production of SON (PPSON) were generally highest in the NF soil and lowest in the 2R-T soil, and in all forest types decreased with soil depth. The larger SON pools in the NF soil coincided with lower soil, litter and root C:N ratios, suggesting that the difference in the size of SON pools between the NF and 1R soil may be related to differences in the quality of organic matter input under the different forest ecosystems. Differences in the size of SON pools between the 1R soil and the 2R soils and between the 2R-T soil and the 2R-W soil may be related to the quantity of organic matter input and time since disturbance. Significant relationships were found between the SON extracted by 0.5 M K2SO4 (SONps) and 2 M KCl (SONKCl), and also among the SON extracted by hot 2 M KCl (SONhKCl), hot water (SONhw) and water (SONw), suggesting that the organic N released by these groups of extracts may be at least partly from similar pools. 相似文献
2.
Zhihong Xu Sally Ward Chengrong Chen Tim Blumfield Nina Prasolova Juxiu Liu 《Journal of Soils and Sediments》2008,8(2):99-105
Background, Aims, and Scope An improved understanding of important soil carbon (C) and nutrient pools as well as microbial activities in forest ecosystems
is required for developing effective forest management regimes underpinning forest productivity and sustainability. Forest
types and management practices can have significant impacts on soil C and nutrient pools as well as biological properties
in forest ecosystems. Soil C and nutrient pools were assessed for adjacent natural forest (NF), first rotation (1R) (50-year-old),
and second rotation (2R) (1-year-old) hoop pine (Araucaria cunninghamii Ait. ex D. Don) plantations in southeast Queensland of subtropical Australia.
Materials and Methods Five transects spaced 3 m apart with 9 sampling points along each transect were selected (9.6 m × 12.0 m each site), with
45 soil cores (7.5 cm in diameter) collected and separated into 0–10 and 10–20 cm depths. These soils were analysed for total
C, total nitrogen (N), C (δ13C) and N (δ15N) isotope composition. The 0–10 cm soils were analysed for pH, CEC, exchangeable cations, total P and total K, and assayed
for microbial biomass C and N, respiration, metabolic quotient, potential mineralizable N (PMN), gross N mineralization (M) and immobilization (I).
Results Total C and N in 0–10 cm soils were higher under NF and 1R plantation than under 2R plantation, while they were highest in
10–20 cm soils under NF, followed by the 1R and then 2R plantation. δ13C was lower under NF than under the plantations, while δ15N was higher under NF than under the plantations. Total P was the highest under NF, followed by the 1R and then 2R plantation,
while total K was higher under the 2R plantation. No significant differences were detected for pH, CEC, exchangeable cations,
microbial C and N, respiration and metabolic quotient among the 3 sites. PMN and M were higher under NF, while I was the highest under the 2R plantation, followed by the NF and then 1R plantation.
Discussion Soil total C and N in 0–10 cm depth were significantly lower under 2R hoop pine plantation than those under NF and 1R hoop
pine plantation. There were significant reductions in soil total C and N from NF to 1R and from 1R to 2R hoop pine plantations
in 10–20 cm depth. This highlights potential N deficiency in the 2R hoop pine plantations, and application of N fertilizers
may be required to improve the productivity of 2R hoop pine plantations.
There were no significant differences in other soil chemical and physical properties in 0–10 cm depth among the 3 sites under
NF, 1R and 2R hoop pine plantations, except for soil total P and K.
Soil microbial biomass C, CO2 respiration and metabolic quotient did not differ among the 3 sites assessed, perhaps mainly due to these biological variables
being too sensitive to variations in soil chemical and physical properties and thereby being associated with a larger variability
in the soil biological properties. However, soil potential mineralizable N, gross N mineralization and immobilization were
rather sensitive to the conversion of NF to hoop pine plantation and forest management practices.
Conclusions Total C and N in the top 20 cm soil were highest under NF, followed by 1R and then 2R hoop pine plantations, indicating that
N deficiency may become a growth-limiting factor in the 2R hoop pine plantations and subsequent rotations of hoop pine plantation.
The sample size for soil δ13C seems to be much smaller than those for soil total C and N as well as δ15N. The significant reductions in soil total P from NF to 1R and then from 1R to 2R hoop pine plantations highlight that P
deficiency might become another growth-limiting factor in the second and subsequent rotations of hoop pine plantations. Soil
microbial properties may be associated with large spatial variations due to these biological properties being too sensitive
to the variations in soil chemical and physical properties in these forest ecosystems.
Recommendations and Perspectives Soil potential mineralizable N, gross N mineralization and immobilization were useful indices of soil N availability in response
to forest types and management practices. The sampling size for soil δ13C was much smaller than the other soil chemical and biological properties due to the different patterns of spatial variation
in these soil properties. 相似文献
3.
Jiao-Yan Ying Li-Mei Zhang Wen-Xue Wei Ji-Zheng He 《Journal of Soils and Sediments》2013,13(7):1223-1231
Purpose
Disturbances such as cultivation, logging, and plantation occurred widely in acid red soil area of China, yet little is known about their effects on soil microbial community which is closely related to soil function. In this study, microbial community compositions were investigated in a red soil with different long-term land utilization patterns to understand the potential effects of cultivation and vegetation successions on relevant soil functions.Materials and methods
Land utilization patterns include restoration, degradation (logging), cropland, and pine plantation. Both DNA- and phospholipid fatty acid (PLFA)-based methods were used to measure the abundance and community structure of microorganisms.Results and discussion
In general, DNA- and PLFA-based methods showed similar results of microbial composition, but for some parameters, only one approach showed significant differences between different land utilization patterns. Land utilization patterns showed significant effects on abundance of total microbial community, bacteria, fungi, and actinomycetes which were all lowest in the cropland plot either by PLFA or DNA analyses. 17:0 cyclo/16:1 ω7c and 19:0 cyclo/18:1 ω7c which are possibly associated with environmental stresses also varied among different land utilization patterns. Both PLFA and T-RFLP analyses showed that each land utilization pattern possessed a specific microbial community structure.Conclusions
These results revealed significant effects of different land utilization patterns especially cultivation and logging on soil microbial communities and suggested that we should be cautious in utilizing red soils to sustain soil properties and functions. Combination of DNA- and PLFA-based methods is effective to provide precise results of microbial composition. 相似文献4.
Chris E. Johnson Timothy J. Blumfield Sue Boyd Zhihong Xu 《Journal of Soils and Sediments》2013,13(5):854-862
Purpose
Residue retention is important for nutrient and water economy in subtropical plantation forests. We examined decomposing hoop pine (Araucaria cunninghamii Ait. Ex D. Don) residues—foliage, branches, and stem wood—to determine the changes in structural chemistry that occur during decomposition.Materials and methods
Residues were incubated in situ using 0.05 m2 microplots. We used solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to determine the structural composition of harvest residues in the first 24 months of decomposition.Results and discussion
The spectral data for branch and stem residues were generally similar to one another and showed few changes during decomposition. The lignin content of branch and foliage residues decreased during decomposition. When residues were mixed together during decomposition, the O-alkyl fraction of foliage decreased initially then increased up to 24 months, while the alkyl carbon (C) fraction exhibited the opposite pattern. The decomposition of woody hoop pine residues (branch and stem wood) is surprisingly uniform across the major C forms elucidated with 13C NMR, with little evidence of preferential decomposition. When mixed with branch and stem materials, foliage residues showed significant short- and long-term compositional changes. This synergistic effect may be due to the C/N ratio of the treatments and the structure of the microbial decomposer community.Conclusions
Twenty-four months of decomposition of hoop pine residues did not result in substantial accumulation of recalcitrant C forms, suggesting that they may not contribute to long-term C sequestration. 相似文献5.
Successful soil organic matter (SOM) quality assessment is needed to improve our ability to manage forest soils sustainably. Our objective was to use a multivariate data set to determine whether the land use conversion from native forest (NF) to hoop pine plantation and the following rotation and site preparation practices had altered SOM quality at three adjacent sites of NF, first (1R) and second rotation (2R, including tree planting row (2R-T) and windrow of harvest residues (2R-W)) of hoop pine plantations in southeast Queensland, Australia. Cross-polarization magic angle spinning 13C nuclear magnetic resonance (CPMAS 13C NMR) spectroscopy and sequential hot water and acid hydrolysis were conducted on SOM fractions separated by wet-sieving and density fractionation procedures to characterize SOM quantitative and qualitative relevant parameters, including carbon (C) functional groups, C and nitrogen (N) contents, C/N ratios, and C and N recalcitrant indices. Analysis of variance (ANOVA) and principal component analysis (PCA) of these multivariate parameters together indicated a complicated interaction between physical protection and biochemical recalcitrance, making the land use and management induced changes of SOM quality more complex. Knowledge of PCA based on the refined set of 41 SOM quantitative and qualitative parameters identified that principal component 1 (PC1), which explained 55.7% of the total variance, was most responsible for the management induced changes in soil processes. This was reflected by the dynamics of SOM regarding the aspects of total stock, soil basal and substrate induced respirations, gross and net N mineralization and nitrification, and microbial biomass, microbial diversity of C utilization patterns. Further, the macroaggregates (F250-2000 μm) and the C/N ratio of acid extracts of SOM physical fractions, which represented the most informative and unique variables loading on PC1, might be the most promising physical and chemical measures for SOM quality assessment of land use and management impacts in subtropical Australian forests. 相似文献
6.
The impact of land-use change on soil nitrogen (N) transformations was investigated in adjacent native forest (NF), 53 y-old first rotation (1R) and 5 y-old second rotation (2R) hoop pine (Araucaia cunninghamii) plantations. The 15N isotope dilution method was used to quantify gross rates of N transformations in aerobic and anaerobic laboratory incubations. Results showed that the land-use change had a significant impact on the soil N transformations. Gross ammonification rates in the aerobic incubation ranged between 0.62 and 1.78 mg N kg−1 d−1, while gross nitrification rates ranged between 2.1 and 6.6 mg N kg−1 d−1. Gross ammonification rates were significantly lower in the NF and the 1R soils than in the 2R soils, however gross nitrification rates were significantly higher in the NF soils than in the plantation soils. The greater rates of gross nitrification found in the NF soil compared to the plantation soils, were related to lower soil C:N ratios (i.e. more labile soil N under NF). Nitrification was found to be the dominant soil N transformation process in the contrasting forest ecosystems. This might be attributed to certain site conditions which may favour the nitrifying community, such as the dry climate and tree species. There was some evidence to suggest that heterotrophic nitrifiers may undertake a significant portion of nitrification. 相似文献
7.
Catriona A. Macdonald Nadine Thomas Kevin R. Tate John Dando 《Soil biology & biochemistry》2009,41(8):1642-1651
Afforestation and deforestation are key land-use changes across the world, and are considered to be dominant factors controlling ecosystem functioning and biodiversity. However, the responses of soil microbial communities to these land-use changes are not well understood. Because changes in soil microbial abundance and community structure have consequences for nutrient cycling, C-sequestration and long-term sustainability, we investigated impacts of land-use change, age of stand and soil physico-chemical properties on fungal and bacterial communities and their metabolic activities. This study was carried out at four sites in two geographical locations that were afforested on long-established pastures with Pinus radiata D. Don (pine). Two of the sites were on volcanic soils and two on non-volcanic soils and stand age ranged from 5 to 20 y. Microbial communities were analysed by biochemical (phospho-lipid fatty acids; PLFA) and molecular (multiplex-terminal restriction fragment length polymorphism; M-TRFLP) approaches. Both site and stand age influenced microbial properties, with changes being least detectable in the 5-y-old stand. Land use was a key factor influencing soil metabolic activities as measured by physiological profiling using MicroResp. Pasture soils had higher microbial biomass (P < 0.001), and metabolic activities (P < 0.001), and basal respiration rates were up to 2.8-times higher than in the pine soils. Microbial abundance analysis by PLFA showed that the fungal to bacterial ratio was higher in the pine soils (P < 0.01). Community analysis suggested that soil bacterial communities were more responsive to site (principal component 1; P < 0.001) than to land use (principal component 5; P < 0.001). In contrast, the fungal community was more affected by land-use change (principal component 1; P < 0.001) than by site, although site still had some influence on fungal community structure (principal component 2; P < 0.001). Redundancy analysis also suggested that bacterial and fungal communities responded differently to various soil abiotic properties, land-use change and location of sites. Overall, our results indicate that the change in land use from pasture to P. radiata stands had a direct impact on soil fungal communities but an indirect effect, through its effects on soil abiotic properties, on bacterial communities. Most of the changes in bacterial communities could be explained by altered soil physico-chemical properties associated with afforestation of pastures. 相似文献
8.
《Geoderma》2007,137(3-4):401-413
Land-use history – the number, type, and duration of previous land uses – is relevant to many questions regarding land-use effects on soil carbon, but is infrequently reported. We examine the importance of land-use history variables, as well as topographic and edaphic variables, on soil C in a range of forest types – native forest, pine plantations, secondary forest and rehabilitated forest – at three contrasting locations in south eastern Australia. Our comparisons include a novel forest conversion of exotic pine plantations to native, broadleaf forest.Using nested ANOVAs, we detected few differences in soil C concentration indices (total C, microbial biomass C, K2SO4–C) and C content among eucalypt-dominated vegetation and pine plantations within each location (0–10 cm depth). However, planned contrasts indicated a 30% decrease in soil C content with conversion of native forest to pine plantation of age 37 years. The reverse land-use change – pine plantation to native, broadleaf forest – was associated with a decrease in soil C concentration and content at one location (40%; age 12–13 years) and no detectable changes at another (to age 7 years). Variable effect between locations of this novel land-use change on soil C could be due to differences in potential productivity, conifer species, and plantation age.We used correlation coefficients and general linear models to identify widely applicable variables for predicting soil C concentration and content at local scales (≤ 20 km2). Within-location relationships with topographic variables were weak and infrequent relative to those with edaphic and land-use history variables. Soil texture was strongly correlated with soil C at each location, although the relative significance of different particle size fractions differed among locations. Electrical conductivity appeared more widely applicable since it was included in C models at two locations. Combining land-use history and edaphic variables produced strong predictive models for soil C concentrations and content at two locations (total r2 0.83 to 0.95). Positive relationships were indicated between soil C and ‘age of current vegetation’ at one location, and negative relationships were indicated with ‘number of land uses’ at another. These data highlight a potential predictive role for land-use history variables in local-scale assessments of soil C in forested landscapes. 相似文献
9.
The influence of soil properties on the structure of bacterial and fungal communities across land-use types 总被引：3，自引：1，他引：3
Christian L. Lauber Michael S. Strickland Mark A. Bradford Noah Fierer 《Soil biology & biochemistry》2008,40(9):2407
Land-use change can have significant impacts on soil conditions and microbial communities are likely to respond to these changes. However, such responses are poorly characterized as few studies have examined how specific changes in edaphic characteristics do, or do not, influence the composition of soil bacterial and fungal communities across land-use types. Soil samples were collected from four replicated (n = 3) land-use types (hardwood and pine forests, cultivated and livestock pasture lands) in the southeastern US to assess the effects of land-use change on microbial community structure and distribution. We used quantitative PCR to estimate bacterial–fungal ratios and clone libraries targeting small-subunit rRNA genes to independently characterize the bacterial and fungal communities. Although some soil properties (soil texture and nutrient status) did significantly differ across land-use types, other edaphic factors (e.g., pH) did not vary consistently with land-use. Bacterial–fungal ratios were not significantly different across the land-uses and distinct land-use types did not necessarily harbor distinct soil fungal or bacterial communities. Rather, the composition of bacterial and fungal communities was most strongly correlated with specific soil properties. Soil pH was the best predictor of bacterial community composition across this landscape while fungal community composition was most closely associated with changes in soil nutrient status. Together these results suggest that specific changes in edaphic properties, not necessarily land-use type itself, may best predict shifts in microbial community composition across a given landscape. In addition, our results demonstrate the utility of using sequence-based approaches to concurrently analyze bacterial and fungal communities as such analyses provide detailed phylogenetic information on individual communities and permit the robust assessment of the biogeographical patterns exhibited by soil microbial communities. 相似文献
10.
Ching-Yu Huang Shih-Hao Jien Tsai-Huei Chen Guanglong Tian Chih-Yu Chiu 《Journal of Soils and Sediments》2014,14(6):1061-1070
Purpose
Moso bamboo (Phyllostachys edulis), an important economic crop, is distributed from low- to medium-elevation mountains in Taiwan. Bamboo is a fast-growing herbaceous species with an extensive rhizome structure. With the hypothesis that the characteristics of soil organic matter and microbes might change after long-term bamboo plantation, we investigated different fractions of organic C and N as well as soil microbial biomass and activities in five moso bamboo plantations along an elevation gradient in Central Taiwan.Materials and methods
Five soil samples (top 10 cm of soil) were collected from each bamboo plantation (600, 800, 1,000, 1,200, and 1,400 m above sea level (asl)) in January 2011. Soil was processed and analyzed for soil total C and N contents, biologically available C, potentially mineralizable N, soil microbial biomass and soil respiration (CO2). Two extraction methods (2 M KCl and hot-water extraction) were used to estimate soil soluble organic C and N (SbOC and SbON) and soil inorganic N (NH4 + and NO3 ?) concentrations to evaluate the relationship with soil organic matter and microbe characteristics in bamboo plantations.Results and discussion
Soil total C and N contents as well as soil microbial biomass and soil respiration (CO2) of the bamboo plantations increased along the elevation gradient. Temperature changes along elevation contributed to such variations observed among the selected bamboo plantations. The SbON in hot-water extracts was highest in the 1,200-m plantation, then in the 1,400-m plantation, and lowest in the low-elevation plantations (600, 800, and 1,000 m). However, SbON in 2 M KCl extracts did not differ by elevation. The SbON was strongly correlated with soil total N in both 2 M KCl and hot-water extracts, but only SbON in hot-water extracts was strongly correlated with microbial biomass N and potentially mineralizable N. SbOC was strongly correlated with soil total C content, microbial biomass C, and biologically available C in both 2 M KCl and hot-water extracts.Conclusions
Soil total C and N, SbOC and SbON, and microbial biomass characteristics increased in the moso bamboo plantations with increasing elevation. No altitudinal difference in specific soil respiration (CO2) rate suggested that the enhanced potentially mineralizable N and soil respiration (CO2) in the high-elevation plantations were associated with increased microbial biomass rather than microbial activities. 相似文献11.
Shane S. Tutua Zhihong Xu Chengrong Chen Timothy J. Blumfield 《Journal of Soils and Sediments》2013,13(9):1573-1578
Purpose
This study evaluated the potential of using hot water extractable phosphorus (P) pools as a method to assess the impacts of harvest residue management on the bioavailability of P in an exotic pine plantation of southeast Queensland, Australia.Materials and methods
This study was carried out under three harvest residue management regimes: (1) residue removal, RR0; (2) single-level residue retention (operational level), RR1; and (3) double level of residue retention, RR2, established immediately following clear-cut harvesting in a randomised complete block experiment. Soil was sampled after 24 months of the residue management regimes applied and analysed for hot water extractable inorganic P (HWEIP), hot water extractable organic P (HWEOP) and total P (HWETP), in relation to hot water extractable organic C (HWEOC) and N (HWEON), calcium chloride extractable P (CaCl2_P), bicarbonate extractable P (NaHCO3_P) and fluoride extractable P (Bray1_P).Results and discussion
The HWEIP and CaCl2_P concentrations showed no significant variations amongst the treatments, while Bray1_P, NaHCO3_P and the HWEOP P pools were only significantly greater in the RR2 treatment than the RR0 treatment. In contrast, the HWETP pool showed highly significant (p?<?0.005) differences amongst all the treatments. In addition, both the HWEOP and HWETP were significantly related to the HWEOC and the total C, in contrast to the lack of such relationships with soil total P, suggesting their association with the HWEOC released through residue decomposition.Conclusions
This study showed that HWETP is a more sensitive measure of labile soil P and has the potential to be used as an indicator of management practices, particularly in cases where high spatial variations in soil P concentrations might confound P responses. 相似文献12.
Falin Chen Hua Zheng Kai Zhang Zhiyun Ouyang Yongfu Wu Qian Shi Huailin Li 《Journal of Soils and Sediments》2013,13(5):887-894
Purpose
Although it is generally accepted that planting exotic plant species alters metabolic function of soil microbial communities, its temporal dynamic is often ignored when evaluating ecological effects of associated land use changes. To investigate the dynamic impacts of successive Eucalyptus planting on carbon metabolic activities of soil microbial communities, we studied community-level physiological profiles of soil microbial communities in different generations of Eucalyptus plantations.Materials and methods
We studied community-level physiological profiles of soil microbial communities, using the Biolog? Ecoplates incubation, in adjacent first (G1), second (G2), third (G3), and fourth (G4) generation Eucalyptus plantations that were, respectively, aged 3, 8, 14, and 19 years in Guangxi province, southern China. We used the ‘space-for-time substitution’ approach to investigate the impact of stand age of exotic Eucalyptus plantations on carbon metabolic diversity and activities of soil microbial communities. For each Eucalyptus plantation generation, three experimental plots were randomly selected. In each plot, one composite soil sample from 0 to 10 cm in depth was obtained for the analyses.Results and discussion
Single carbon source utilization varied with Eucalyptus plantation stand age. Among preselected 31 carbon sources, utilization of 17 carbon sources changed significantly, which was best described by a quadratic function (ten carbon sources) and an exponential function (seven carbon sources). As a result, cumulative averaged metabolic activity and metabolic diversity of soil microbial communities showed quadratic and exponential changes relative to Eucalyptus plantation stand age. The order of cumulative averaged carbon metabolic activity and metabolic diversity were G1?>?G4, G3?>?G2 and G1?>?G2?>?G3, G4 (p?<?0.05), respectively. The factors contributing to carbon source utilization structure of soil microbial communities for different stand ages of Eucalyptus plantations were shrub richness, soil organic carbon content, microbial biomass carbon, C-to-N ratio, and N-to-P ratio.Conclusions
Eucalyptus plantation stand age has inconsistent non-linear impacts on two aspects of soil microbial metabolic function: (1) quadratic impacts on carbon metabolic efficiency and (2) exponential impacts on carbon metabolic diversity. The decreasing carbon metabolic diversity has no significant impact on carbon metabolic efficiency during successive Eucalyptus plantings. The results show that the importance of assessing long-term impacts of land use changes on soil microbial communities from exotic plantations by quantifying multi-aspect non-linear changes on soil microbial metabolic function. 相似文献13.
Restoration of forests poses a major challenge globally,particularly in the tropics,as the forests in these regions are more vulnerable to land-use change.We studied land-use change from natural forest (NF) to degraded forest (DF),and subsequently to either Jatropha curcas plantation (JP) or agroecosystem (AG),in the dry tropics of Uttar Pradesh,India,with respect to its impacts on soil microbial community composition as indicated by phospholipid fatty acid (PLFA) biomarkers and soil organic carbon (SOC) content.The trend of bacterial PLFAs across all land-use types was in the order:NF ＞ JP ＞ DF＞ AG.In NF,there was dominance of gram-negative bacterial (G-) PLFAs over the corresponding gram-positive bacterial (G+) PLFAs.The levels of G-PLFAs in AG and JP differed significantly from those in DF,whereas those of G+ PLFAs were relatively similar in these three land-use types.Fungal PLFAs,however,followed a different trend:NF ＞ JP ＞ DF =AG.Total PLFAs,fungal/bacterial (F/B) PLFA ratio,and SOC content followed trends similar to that of bacterial PLFAs.Across all land-use types,there were strong positive relationships between SOC content and G-,bacterial,fungal,and total microbial PLFAs and F/B PLFA ratio.Compared with bacterial PLFAs,fungal PLFAs appeared to be more responsive to land-use change.The F/B PLFA ratio,fungal PLFAs,and bacterial PLFAs explained 91％,94％,and 73％ of the variability in SOC content,respectively.The higher F/B PLFA ratio in JP favored more soil C storage,leading to faster ecosystem recovery compared to either AG or DF.The F/B PLFA ratio could be used as an early indicator of ecosystem recovery in response to disturbance,particularly in relation to land-use change. 相似文献
14.
江西退化红壤人工重建森林土壤微生物碳源代谢功能研究 总被引：5，自引：0，他引：5
应用MicroResp方法研究4种重建森林土壤微生物对不同类型碳源的代谢特征,自然恢复地为对照处理。结果表明,不同培养时间(6 h和继续培养18 h)和不同土壤深度(0~10和10~20 cm),土壤微生物对单一碳源的利用能力差异显著。4种重建森林土壤微生物对碳源利用能力有显著差异,表现为:自然恢复地阔叶混交林阔叶纯林针阔混交林针叶纯林。多样性指数和均匀度指数表明4种重建森林土壤微生物群落多样性的变化趋势为:自然恢复地阔叶混交林阔叶纯林针阔混交林针叶纯林,除自然恢复地外,土壤微生物的多样性和均匀度在4种不同重建森林类型之间差异不显著。主成分分析结果表明,所选15种碳源能够阐述4种不同重建森林土壤微生物功能多样性的差异,森林土壤微生物的敏感碳源主要为糖类。 相似文献
15.
Approximately 30% of global soil organic carbon (SOC) is stored in subtropical and tropical ecosystems but it is being rapidly lost due to continuous deforestation. Tree plantations are advocated as a C sink, however, little is known about rates of C turnover and sequestration into soil organic matter under subtropical and tropical tree plantations. We studied changes in SOC in a chronosequence of hoop pine (Araucaria cunninghamii) plantations established on former rainforest sites in seasonally dry subtropical Australia. SOC, δ13C, and light fraction organic C (LF C<1.6 g cm−3) were determined in plantations, secondary rainforest and pasture. We calculated loss of rainforest SOC after clearing for pasture using an isotope mixing model, and used the decay rate of rainforest-derived C to predict input of hoop pine-derived C into the soil. Total SOC stocks to 100 cm depth were significantly (P<0.01) higher under rainforest (241 t ha−1) and pasture (254 t ha−1) compared to hoop pine (176-211 t ha−1). We calculated that SOC derived from hoop pine inputs ranged from 32% (25 year plantation) to 61% (63 year plantation) of total SOC in the 0-30 cm soil layer, but below 30 cm all C originated from rainforest. These results were compared to simulations made by the Century soil organic matter model. The Century model simulations showed that lower C stocks under hoop pine plantations were due to reduced C inputs to the slow turnover C pool, such that this pool only recovers to within 45% of the original rainforest C pool after 63 years. This may indicate differences in soil C stabilization mechanisms under hoop pine plantations compared with rainforest and pasture. These results demonstrate that subtropical hoop pine plantations do not rapidly sequester SOC into long-term storage pools, and that alternative plantation systems may need to be investigated to achieve greater soil C sequestration. 相似文献
16.
《Communications in Soil Science and Plant Analysis》2012,43(9):1291-1302
The microbial activity of soil plays an important role in the regulation of the transformation of carbon (C) and phosphorus (P). However, the activity of soil microbes is strongly related to the type of land-use system. The present work aimed to compare the microbial activity and metabolic responses of three different land-use systems to P (0 to 600 mg kg?1 of dry soil) and C additions in an Oxisol of the Brazilian savannah. The land-use systems studied were savannah vegetation (SV), 32-year-old pine plantation (PP), and 11-year-old no-tillage system (NT). The following analyses were carried out: amount of C carbon dioxide (CO2) evolved, total organic carbon (TOC), total glucose (TG), microbial biomass carbon (MBC), and metabolic yields (Y) from P and C additions to the soil. The different land-use systems affected the respiratory activity of microbiota, indicating an increase in SV and a decrease in PP when compared to the SV system under incubation for 17 days. The addition of P resulted in an increase of respiratory activity. The responses were adjusted by the Michaelis–Menten equation for all three land-use systems. The greatest TOC and lowest MBC were observed in NT and PP, respectively, when compared to SV. However, a lower content of TG was observed in NT in comparison to SV. Under bioassay conditions, the results confirm the greater microbial demand for P in PP and SV than in NT. The NT system showed greater metabolic yields when glucose was applied to the soil, suggesting that the response of microbiota in this system depends on easily available forms of C, as shown by the sugar content. The results showed expressive metabolic differences among the systems, suggesting that different soil uses change the dynamic of the responses of soil microorganisms. 相似文献
17.
Jiangbing Xu Youzhi Feng Yanling Wang Xiaosan Luo Jianwu Tang Xiangui Lin 《Journal of Soils and Sediments》2016,16(3):916-923
Purpose
The extract of Stevia residue is an ideal substitute for cultivation of the purple nonsulfur bacterium, like Rhodopseudomonas palustris (R. palustris). But the influence of R. palustris grown under residue extract on its downstream application is still not well-characterized. The objective of this study was to assess the effect of foliar spray of R. palustris grown under Stevia residue extract on the plant growth and soil microbial properties.Materials and methods
A pot experiment was carried out under the greenhouse condition, consisting of four treatments varying in the sprayed substances: sterilized water (control), R. palustris grown under the chemical medium supplemented with L-tryptophan (SyT), R. palustris grown under Stevia residue extract supplemented with L-tryptophan (ExT), and R. palustris grown under Stevia residue extract supplemented with NH4Cl (ExT). The net photosynthesis rate of the uppermost leaves was measured with a portable photosynthesis system. Soil microbial activity was analyzed by microcalorimetry. Soil bacterial community components were determined by real-time quantitative PCR (qPCR) and high-throughput sequencing techniques.Results and discussion
Compared with SyT, the R. palustris grown under Stevia residue extract not only improved the plant biomass and the net photosynthetic rate to a large extent, but also increased soil microbial metabolic activity and altered community compositions as well. The treatments receiving R. palustris, especially ExT and ExN, increased the relative abundances of some functional guilds involved in C turnover and nutrient cycling in soil, including Acidobacteria, Actinobacteria, Proteobacteria, Gemmatimonadaetes, Nitrospirae, and Planctomycetes.Conclusions
R. palustris grown under the Stevia residue extract showed advantages over that under the chemical medium on both plant growth and soil microbial properties. One of the possible reasons could result from the increases in microbial activity and several bacterial keystone guilds involved into C and nutrient cycling, both of which potentially contribute to the improved plant growth. The results would be conducive to the downstream application of R. palustris in an economical way.18.
Effect of agricultural land use change on community composition of bacteria and ammonia oxidizers 总被引：1，自引：0，他引：1
Rong Sheng Delong Meng Minna Wu Hongjie Di Hongling Qin Wenxue Wei 《Journal of Soils and Sediments》2013,13(7):1246-1256
Purpose
Soil microbial communities can be strongly influenced by agricultural practices, but little is known about bacterial community successions as land use changes. The objective of this study was to determine microbial community shifts following major land use changes in order to improve our understanding of land use impacts on microbial community composition and functions.Materials and methods
Four agricultural land use patterns were selected for the study, including old rice paddy fields (ORP), Magnolia nursery planting (MNP), short-term vegetable (STV), and long-term vegetable (LTV) cultivation. All four systems are located in the same region with same soil parent material (alluvium), and the MNP, STV, and LTV systems had been converted from ORP for 10, 3, and 30 years, respectively. Soil bacteria and ammonia oxidizer community compositions were analyzed by 454 pyrosequencing and terminal restriction fragment length polymorphism, respectively. Quantitative PCR was used to determine 16S rRNA and amoA gene copy numbers.Results and discussion
The results showed that when land use was changed from rice paddy to upland systems, the relative abundance of Chloroflexi increased whereas Acidobacteria decreased significantly. While LTV induced significant shifts of bacterial composition, MNP had the highest relative abundance of genera GP1, GP2, and GP3, which were mainly related to the development of soil acidity. The community composition of ammonia-oxidizing bacteria (AOB) but not ammonia-oxidizing archaea was strongly impacted by the agricultural land use patterns, with LTV inducing the growth of a single super predominant AOB group. The land use changes also induced significant shifts in the abundance of 16S rRNA and bacterial amoA genes, but no significant differences in the abundance of archaea amoA was detected among the four land use patterns. Soil total phosphorous, available phosphorous, NO3 ?, and soil organic carbon contents and pH were the main determinants in driving the composition of both bacteria and AOB communities.Conclusions
These results clearly show the significant impact of land use change on soil microbial community composition and abundance and this will have major implications on the microbial ecology and nutrient cycling in these systems, some of which is unknown. Further research should be directed to studying the impacts of these microbial community shifts on nutrient dynamics in these agroecosystems so that improved nutrient management systems can be developed. 相似文献19.
Purpose
The purposes of this study were to identify the influence of a severe drought period on the impact of a subsequent heat–drought disturbance on the microbial community of a Mediterranean agricultural soil and particularly to highlight the long-term effects on the microbial catabolic profiles.Materials and methods
We performed an experiment in microcosms and applied the MicroResp? method on soil microbial communities.Results and discussion
A 21-day combined heat–drought disturbance had less impact on soil microbial communities pre-exposed to a 73-day severe drought than on those that were not pre-exposed. These differences were observed not only for biomass and physiological traits (basal respiration, qCO2), but also for catabolic microbial structure evolution during the recovery time.Conclusions
These observations suggest that the physiological stress imposed by the initial severe drought changed the microbial catabolic structure or physiological state and favoured a portion of the microbial community best adapted to cope with the final heat–drought disturbance. Consequently, the initial severe drought may have induced a community tolerance to the subsequent heat wave. In this study, we also note that resilience was, more than resistance, an indicator of pre-exposure to stress. In the context of assessing the effects of extreme climatic events on soil microbial processes, these results suggest that future studies should take into account the historic stress of habitats and resilience parameters.20.
Kai Wang Jie Zhang Zhiqiang Zhu Huagang Huang Tingqiang Li Zhenli He Xiaoe Yang Ashok Alva 《Journal of Soils and Sediments》2012,12(7):1089-1099