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1.
Aims
Soil respiration in forest plantations can be greatly affected by management practices such as irrigation. In northwest China, soil water is usually a limiting factor for the development of forest plantations. This study aims to examine the effects of irrigation intensity on soil respiration from three poplar clone plantations in this arid area.Methods
The experiment included three poplar clones subjected to three irrigation intensities (without, low and high). Soil respiration was measured using a Li-6400-09 chamber during the growing season in 2007.Results
Mean soil respiration rates were 2.92, 4.74 and 3.49 μmol m?2 s?1 for control, low and high irrigation treatments, respectively. Soil respiration decreased once soil water content was below a lower (14.8 %) or above an upper (26.2 %) threshold. When soil water content ranged from 14.8 % to 26.2 %, soil respiration increased and correlated with soil temperature. Fine root also played a role in the significant differences in soil CO2 efflux among the three treatments. Furthermore, the three poplar hybrid clones responded differently to irrigation regarding fine root production and soil CO2 efflux.Conclusions
Irrigation intensity had a strong impact on soil respiration of the three poplar clone plantations, which was mainly because fine root biomass and microbial activities were greatly influenced by soil water conditions. Our results suggest that irrigation management is a main factor controlling soil carbon dynamics in forest plantation in arid regions. 相似文献2.
Tommaso Chiti Elisa Grieco Lucia Perugini Ana Rey Riccardo Valentini 《Plant and Soil》2014,375(1-2):47-59
Background and aims
In the Jomoro district in Ghana, tree plantations were the first cause of deforestation in the past, drastically reducing the area occupied by primary forests. The aim of this study was to quantify soil organic carbon (SOC) losses due to a change in land use from primary forest to tree plantations (cocoa, coconut, rubber, oil palm) on the different substrates of the district. Secondary forests and mixed plantations were also included in the study.Methods
Soils were sampled at different depths up to 100 cm along a series of chronosequences in each of the three substrates (Granite, Lower Birrimian and Tertiary Sands) present in the area.Results
The highest SOC losses in the 0–30 cm layer were caused by the conversion of primary forests to tree plantations: cocoa ?61 % of the original SOC stock, coconut ?55 %, rubber ?35 % and oil palm 28 %, while mixed plantations and secondary forests showed a loss of 23 % and 21 % of the original SOC stock, respectively. C losses were less apparent from the entire profile (to a depth of 100 cm).Conclusions
All conversions to tree plantations caused substantial SOC losses, comparable to the conversion of forests to agricultural systems. Secondary forests and mixed plantations were the only sustainable land uses that restricted SOC losses considerably. 相似文献3.
Aims
Major changes to rainfall regimes are predicted for the future but the effect of such changes on terrestrial ecosystem function is largely unknown. We created a rainfall manipulation experiment to investigate the effects of extreme changes in rainfall regimes on ecosystem functioning in a grassland system.Methods
We applied two rainfall regimes; a prolonged drought treatment (30 % reduction over spring and summer) and drought/downpour treatment (long periods of no rainfall interspersed with downpours), with an ambient control. Both rainfall manipulations included increased winter rainfall. We measured plant community composition, CO2 fluxes and soil nutrient availability.Results
Plant species richness and cover were lower in the drought/downpour treatment, and showed little recovery after the treatment ceased. Ecosystem processes were less affected, possibly due to winter rainfall additions buffering reduced summer rainfall, which saw relatively small soil moisture changes. However, soil extractable P and ecosystem respiration were significantly higher in rainfall change treatments than in the control.Conclusions
This grassland appears fairly resistant, in the short term, to even the more extreme rainfall changes that are predicted for the region, although prolonged study is needed to measure longer-term impacts. Differences in ecosystem responses between the two treatments emphasise the variety of ecosystem responses to changes in both the size and frequency of rainfall events. Given that model predictions are inconsistent there is therefore a need to assess ecosystem function under a range of potential climate change scenarios. 相似文献4.
Background and aims
Across the world, about 264 million ha forest plantations are monospecific. This practice has been found to cause site productivity and soil fertility decline in the regions where forests have been harvested several times. To mitigate these problems, mixed-species plantations, especially with broadleaved and coniferous species, are preferred. Understanding the effects of introducing broadleaved tree in monospecific coniferous plantation on ecosystem carbon (C) storage and soil organic C (SOC) stability is critical to improve our understanding of forest C sequestration and C cycle.Methods
Plots were established in subtropical plantations with a randomized block design to examine the influence of introducing Michelia macclurei trees into pure Cunninghamia lanceolata plantation on biomass C storage, SOC storage of total, labile, and recalcitrant fractions (0–40 cm depth), and SOC stability.Results
Introducing M. macclurei trees increased biomass C by 17.9 % and 14.2 % compared with monospecific C. lanceolata and M. macclurei plantations, respectively. Storage of different SOC fractions was not significantly different between monospecific C. lanceolata and mixed plantations. SOC stability in bulk soils was not affected, although it differed in 10–20 cm and 20–40 cm soil depth among three plantations.Conclusions
Mixed species plantations can increase C sequestration, and in the subtropical forest ecosystem examined this was mainly attributed to an increase in biomass C. 相似文献5.
Timothy J. Fahey Joseph B. Yavitt Ruth E. Sherman Peter M. Groffman Guoliang Wang 《Plant and Soil》2013,367(1-2):379-389
Background and aims
Trees allocate a high proportion of assimilated carbon belowground, but the partitioning of that C among ecosystem components is poorly understood thereby limiting our ability to predict responses of forest C dynamics to global change drivers.Methods
We labeled sugar maple saplings in natural forest with a pulse of photosynthetic 13C in late summer and traced the pulse over the following 3 years. We quantified the fate of belowground carbon by measuring 13C enrichment of roots, rhizosphere soil, soil respiration, soil aggregates and microbial biomass.Results
The pulse of 13C contributed strongly to root and rhizosphere respiration for over a year, and respiration comprised about 75 % of total belowground C allocation (TBCA) in the first year. We estimate that rhizosphere carbon flux (RCF) during the dormant season comprises at least 6 % of TBCA. After 3 years, 3.8 % of the C allocated belowground was recovered in soil organic matter, mostly in water-stable aggregates.Conclusions
A pulse of carbon allocated belowground in temperate forest supplies root respiration, root growth and RCF throughout the following year and a small proportion becomes stabilized in soil aggregates. 相似文献6.
Background and Aims
Mangrove forests are globally important sites of carbon burial that are increasingly exposed to nutrient pollution. Here we assessed the response of soil respiration, an important component of forest carbon budgets, to nutrient enrichment over a wide range of mangrove forests.Methods
We assessed the response of soil respiration to nutrient enrichment using fertilization experiments within 22 mangrove forests over ten sites. We used boosted regression tree (BRT) models to determine the importance of environmental and plant factors for soil respiration and its responsiveness to fertilizer treatments.Results
Leaf area index explained the largest proportion of variation in soil respiration rates (LAI, 45.9 %) followed by those of site, which had a relative influence of 39.9 % in the BRT model. Nutrient enrichment enhanced soil respiration only in nine out of 22 forests. Soil respiration in scrub forests showed a positive response to nutrient addition more frequently than taller fringing forests. The response of soil respiration to nutrient enrichment varied with changes in specific leaf area (SLA) and stem extension, with relative influences of 14.4 %, 13.6 % in the BRT model respectively.Conclusions
Soil respiration in mangroves varied with LAI, but other site specific factors also influenced soil respiration and its response to nutrient enrichment. Strong enhancements in aboveground growth but moderate increases in soil respiration with nutrient enrichment indicated that nutrient enrichment of mangrove forests has likely increased net ecosystem production. 相似文献7.
Background and aims
The knowledge of individual tree species impacts on soil respiration based on rigorous experimental designs is limited, but is crucial to help guide selection of species for reforestation and carbon (C) management purposes.Methods
We assessed monthly soil respiration and its components, litterfall input, fine root production and mortality under 19-year-old native coniferous Cunninghamia lanceolata and broadleaved Mytilaria laosensis plantations in sub-tropical China.Results
Total soil respiration from October 2011 to March 2013 was significantly lower under the C. lanceolata than the M. laosensis plantation. The difference in respiration rates derived from fine roots and the litter layer explained much of the variation of total soil respiration between the two tree species. We used an exponential equation and base temperature (10 °C) to normalize soil respiration rate and its components (R10) and determined the correlation between R10 and soil moisture. Although soil moisture had a positive relationship with R10 derived from roots or litter under both C. lanceolata and M. laosensis forests, these positive correlations were masked by negative relationships between soil moisture and R10 derived from root-free soil, which resulted in a neutral correlation between total R10 and soil moisture under C. lanceolata forests. Monthly litterfall input was associated with variation in concurrent total soil respiration rate under the M. laosensis plantation and respiration rate lagging 3 months behind under the C. lanceolata plantation, which may suggest that litterfall input from M. laosensis can more rapidly produce C substrates for microbial respiration than litterfall from C. lanceolata.Conclusions
This study highlighted that tree species-induced variation in the quality and quantity of fine roots and litterfall can impact not only the soil respiration rate but also the seasonal variation model of forest soil respiration. 相似文献8.
J. A. Ramírez J. D. León-Peláez D. Craven D. A. Herrera C. M. Zapata M. I. González-Hernández J. Gallardo-Lancho W. Osorio 《Plant and Soil》2014,378(1-2):215-226
Background and aims
Exotic coniferous species have been used widely in restoration efforts in tropical montane forests due to their tolerance to adverse conditions and rapid growth, with little consideration given to the potential ecological benefits provided by native tree species. The aim of this study was to elucidate differences in litterfall and nutrient flow between a montane oak forest (Quercus humboldtii Bonpl.) and exotic coniferous plantations of pine (Pinus patula Schltdl. & Cham.) and cypress (Cupressus lusitanica Mill.) in the Colombian Andes.Methods
Litter production, litter decomposition rate, and element composition of leaf litter were monitored during 3 years.Results
Litter production in the oak forest and pine plantation was similar, but considerably lower in the cypress plantation . Similar patterns were observed for nutrient concentrations in litterfall, with the exception of Ca which was three times higher in the cypress plantation. The annual decay rate of litter was faster in the montane oak forest than in either of the exotic coniferous plantations. The potential and net return of nutrients to the forest floor were significantly higher in oak forest than in the exotic coniferous plantations.Conclusions
Future restoration programs should consider new species that can emulate the nutrient flow of native broadleaf species instead of exotic species that tend to impoverish soil nutrient stocks in tropical montane forests. 相似文献9.
Mirco Rodeghiero Galina Churkina Cristina Martinez Thomas Scholten Damiano Gianelle Alessandro Cescatti 《Plant and Soil》2013,364(1-2):55-68
Aims
The partitioning of the total soil CO2 efflux into its two main components: respiration from roots (and root-associated organisms) and microbial respiration (by means of soil organic matter (SOM) and litter decomposition), is a major need in soil carbon dynamics studies in order to understand if a soil is a net sink or source of carbon.Methods
The heterotrophic component of the CO2 efflux was estimated for 11 forest sites as the ratio between the carbon stocks of different SOM pools and previously published (Δ14C derived) turnover times. The autotrophic component, including root and root-associated respiration, was calculated by subtracting the heterotrophic component from total soil chamber measured CO2 efflux.Results
Results suggested that, on average, 50.4 % of total soil CO2 efflux was derived from the respiration of the living roots, 42.4 % from decomposition of the litter layers and less than 10 % from decomposition of belowground SOM.Conclusions
The Δ14C method proved to be an efficient tool by which to partition soil CO2 efflux and quantify the contribution of the different components of soil respiration. However the average calculated heterotrophic respiration was statistically lower compared with two previous studies dealing with soil CO2 efflux partitioning (one performed in the same study area; the other a meta-analysis of soil respiration partitioning). These differences were probably due to the heterogeneity of the SOM fraction and to a sub-optimal choice of the litter sampling period. 相似文献10.
Precipitation variability does not affect soil respiration and nitrogen dynamics in the understorey of a Mediterranean oak woodland 总被引:1,自引:0,他引:1
Marjan Jongen Xavier Lecomte Stephan Unger David Fangueiro João Santos Pereira 《Plant and Soil》2013,372(1-2):235-251
Background and aims
Future climate scenarios for the Mediterranean imply increasing precipitation variability. This study presents a large-scale water manipulation experiment simulating changes in precipitation variability, aiming at a better understanding of the effects of rainfall patterns on soil C and N cycling and understorey productivity in a Mediterranean oak woodland.Methods
We used rain-out shelters to achieve (1) a normal dry period (7 days), and (2) a dry period increased three-fold (21 days), without altering total annual precipitation inputs.Results
The temporal patterns of soil respiration (R s) and soil inorganic N were not affected by treatment. However, water infiltration and N leaching increased with large infrequent watering events. R s and soil NH4 +-N correlated with soil temperature, with soil NO3 ?-N being influenced by leaching.Conclusions
The lack of significant treatment effects on either R s or soil inorganic N can be explained by (1) minor differences in plant productivity between the treatments, suggesting equal plant N demand, and (2) the absence of moisture dependence of R s and soil NH4 +-N. Increased N leaching with large infrequent precipitation events may have longer-term consequences for ecosystem functioning. Our results contribute to an improved understanding of possible climate change effects on key ecosystem processes in Mediterranean ecosystems. 相似文献11.
Adam P. Coble Alisha Autio Molly A. Cavaleri Dan Binkley Michael G. Ryan 《Trees - Structure and Function》2014,28(1):1-15
Key message
Across sites in Brazil and Hawaii, LMA and N mass were strongly correlated with height and shade index, respectively, which may help simplify canopy function modeling of Eucalyptus plantations.Abstract
Within tree canopies, leaf mass per area (LMA) and leaf nitrogen per unit area (N area) commonly increase with height. Previous research has suggested that these patterns occur as a strategy to optimize carbon gain by allocating available resources to upper canopy leaves that are exposed to greater light availability. We tested three hypotheses about the influences of height, shade index (a proxy for light), and stand age on LMA and leaf nitrogen for even-aged Eucalyptus saligna and Eucalyptus grandis × urophylla plantations in Brazil and Hawaii, USA, spanning most of the environmental conditions found across 19.6 million ha of Eucalyptus spp. plantations around the world. Shade index was developed by incorporating canopy depth (inner-crown shading) and a tree height ratio relative to neighbor trees (shading from other trees). Across all sites and ages, leaf height accounted for 45 % of the variation in LMA, whereas shade index accounted for only 6 %. A combination of both factors was slightly better in accounting for LMA variation than height alone. LMA–height relationships among sites were strongest under greater light availability and in older stands. Leaf nitrogen per unit mass (N mass) consistently decreased with shade index, whereas N area showed no consistent pattern with height or shade index. These relationships indicate that N mass is primarily driven by light, while height is the primary driver for LMA. The general relationships between LMA and leaf N mass across all sites may simplify canopy function modeling of E. saligna and E. grandis × urophylla plantations. 相似文献12.
Background and aims
Soil CO2 emissions can dominate gaseous carbon losses from forested wetlands (swamps), especially those positioned in coastal environments. Understanding the varied roles of hydroperiod, salinity, temperature, and root productivity on soil respiration is important in discerning how carbon balances may shift as freshwater swamps retreat inland with sea-level rise and salinity incursion, and convert to mixed communities with marsh plants.Methods
We exposed soil mesocosms to combinations of permanent flooding, tide, and salinity, and tracked soil respiration over 2½ growing seasons. We also related these measurements to rates from field sites along the lower Savannah River, Georgia, USA. Soil temperature and root productivity were assessed simultaneously for both experiments.Results
Soil respiration from mesocosms (22.7–1678.2 mg CO2 m?2 h?1) differed significantly among treatments during four of the seven sampling intervals, where permanently flooded treatments contributed to low rates of soil respiration and tidally flooded treatments sometimes contributed to higher rates. Permanent flooding reduced the overall capacity for soil respiration as soils warmed. Salinity did reduce soil respiration at times in tidal treatments, indicating that salinity may affect the amount of CO2 respired with tide more strongly than under permanent flooding. However, soil respiration related greatest to root biomass (mesocosm) and standing root length (field); any stress reducing root productivity (incl. salinity and permanent flooding) therefore reduces soil respiration.Conclusions
Overall, we hypothesized a stronger, direct role for salinity on soil respiration, and found that salinity effects were being masked by varied capacities for increases in respiration with soil warming as dictated by hydrology, and the indirect influence that salinity can have on plant productivity. 相似文献13.
Carbon sequestration and soil fertility of tropical tree plantations and secondary forest established on degraded land 总被引:1,自引:0,他引:1
Purpose
Much tropical land requires rehabilitation but the capacity of reforestation with plantations or naturally regenerating secondary forests for overcoming soil degradation remains unclear. We hypothesised that desirable effects, including improved soil fertility and carbon sequestration, are achieved to a greater extent in Acacia mangium plantations and secondary forests than in Eucalyptus urophylla plantations.Methods
We tested our hypothesis across soil and climate gradients in Vietnam with linear mixed-effect models and other, comparing A. mangium and E. urophylla plantations, secondary forests and pasture.Results
A. mangium plantations and secondary forests showed a positive correlation between biomass production and desirable soils properties including increased soil carbon, nitrogen and phosphorus, and reduced bulk density. All plantations, but not secondary forests, caused increases in soil acidity. Eight-year old A. mangium plantations contained most carbon in biomass+soil, and secondary forests and pastures had similar or higher soil carbon. E. urophylla plantations had the lowest soil carbon status, raising doubt about their sequestration capacity in current 6–8 year rotations.Conclusions
The study demonstrates that appropriate reforestation enhances soil fertility and promotes carbon sequestration on degraded tropical lands and that unmanaged secondary forests are effective at improving soil fertility and sequestering carbon at low cost. 相似文献14.
Background and aims
Partitioning of soil respiration is a challenging task when resolving the C cycling in forest ecosystems. Our aim was to partition the respiration of newly grown extramatrical ectomycorrhizal mycelium (ECM) and fine roots (and their associated microorganisms) in a young Norway spruce forest.Methods
Ingrowth mesh bags of 16 cm diameter and 12 cm height were placed in the upper soil and left for 12–16 months in 2010 and 2011. The 2 mm mesh size allowed the ingrowth of ECM and fine roots whereas a 45 μm mesh size allowed only the ingrowth of ECM. The mesh bags were filled with either homogenized EA horizon soil, pure quartz sand (QS) or crushed granite (CG, only 2011), each with five replicates. Controls without any ingrowth were established for each substrate by solid plastic tubes (2010) and by 1 μm mesh bags (2011). Fluxes of CO2 from the mesh bags and controls were measured biweekly during the growing season by the closed chamber method.Results
The contribution of ECM to soil respiration was largest in the QS treatments, reaching cumulatively 1.2 and 2.2 Mg C ha?1 6 months?1 in 2010 and 2011, respectively. For EA and CG treatments, the cumulative respiration from ECM was larger than from controls, however the differences being not statistically significant. The respiration of newly grown fine roots in QS amounted to 1.0 Mg C ha?1 in 2010, but could not be identified in 2011 since fluxes from 2 mm and 45 μm mesh bags were similar. The correlation of total root length in single QS mesh bags to CO2 fluxes was poor. The contribution of fine root respiration was also not detectable in the EA and CG treatment. No correlation was found between the autumnal biomass of newly grown ECM and its cumulative respiration.Conclusion
Our results suggest a substantial contribution of newly grown ECM to soil respiration. Respiration of ECM might be larger than respiration of fine roots. 相似文献15.
E. D. Schulze D. Nicolle A. Boerner M. Lauerer G. Aas I. Schulze 《Trees - Structure and Function》2014,28(4):1125-1135
Key message
Eucalyptus and Acacia species were surprisingly similar with respect to variations in δ 13 C, δ 15 N. Both genera respond with speciation and associated changes in leaf structure to drought.Abstract
Stable carbon and nitrogen isotope ratios (δ13C and δ15N) in leaves of eucalypts (Corymbia and Eucalyptus) and Acacia (and some additional Fabaceae) species were investigated together with specific leaf area (SLA), leaf nitrogen (N) and leaf phosphorous (P) concentration along a north–south transect through Western Australia covering winter- and summer-dominated rainfall between 100 and 1,200 mm annually. We investigated 62 eucalypts and 78 woody Fabaceae species, mainly of the genus Acacia. Leaf δ13C values of Eucalyptus and Acacia species generally increased linearly with latitude from ?29.5 ± 1.3 ‰ in the summer-dominated rainfall zone (15°S–18°S) to about ?25.7 ± 1.1 ‰ in the winter-dominated rainfall zone (29°S–31°S). δ15N increased initially with southern latitudes (0.5 ± 1.6 ‰ at 15°S; 5.8 ± 3.3 ‰ at 24–29°S) but decreased again further South (4.6 ± 3.5 ‰ at 31°S). The variation in δ13C and δ15N was probably due to speciation of Eucalyptus and Acacia into very local populations. There were no species that were distributed over the whole sampling area. The variation in leaf traits was larger between species than within species. Average nitrogen concentrations were 11.9 ± 1.05 mg g?1 in Eucalyptus, and were 18.7 ± 4.1 mg g?1 in Acacia. Even though the average nitrogen concentration was higher in Acacia than Eucalyptus, δ15N gave no clear indication for N2 fixation in Acacia. In a multiple regression, latitude (as a surrogate for rainfall seasonality), mean rainfall, leaf nitrogen concentration, specific leaf area and nitrogen fixation were significant and explained 69 % of the variation of δ13C, but only 36 % of the variation of δ15N. Higher nitrogen and phosphorus concentration could give Acacia an advantage over Eucalyptus in arid regions of undefined rainfall seasonality. 相似文献16.
Key message
Physiological characteristics except WUE of H. ammodendron have obvious response to rainfall pulses of 6–12 mm, and rainfall in this range at least is “effective” precipitation for H. ammodendron.Abstract
In water-limited ecosystems, pulses of rainfall can trigger a cascade of plant physiological responses. Small precipitation events account for a large proportion of the precipitation received in arid regions. Their potential ecological importance, however, has previously been ignored. Here the responses of the physiological characteristics of Haloxylon ammodendron (H. ammodendron) to rainfall were evaluated by rainfall manipulative experiments during the growing season of 2012 in the desert region of Northwestern China. Net Photosynthesis rate (P n), transpiration (Tr), water use efficiency (WUE), stomatal conductance (G s), internal concentration of CO2 (C i), sap flow, leaf water potential (Ψ), and soil volumetric water content (SVWC) were monitored throughout the experimental period. The results showed that the water status of H. ammodendron is highly sensitive to rainfall pulses. P n, Tr, and G s increased with rainfall and then decreased gradually after rainfall. WUE decreases after rainfall and increases in times of increasing drought, although within a narrow range. H. ammodendron has a special buffering ability induced by harsh environmental conditions, particularly the rainfall patterns. Collectively, a 6-mm or greater rainfall amount is “effective” precipitation for H. ammodendron from the perspective of plant physiology. This study result is essential to the theories and practice of combating desertification. 相似文献17.
Seasonal and within-event dynamics of rainfall and throughfall chemistry in an open tropical rainforest in Rondônia,Brazil 总被引:1,自引:0,他引:1
Sonja Germer Christopher Neill Alex V. Krusche Sergio C. Gouveia Neto Helmut Elsenbeer 《Biogeochemistry》2007,86(2):155-174
Prolonged dry periods, and increasingly the generation of smoke and dust in partially-deforested regions, can influence the chemistry of rainfall and throughfall in moist tropical forests. We investigated rainfall and throughfall chemistry in a palm-rich open tropical rainforest in the southwestern Brazilian Amazon state of Rondônia, where precipitation averages 2300 mm year?1 with a marked seasonal pattern, and where the fragmentation of remaining forest is severe. Covering the transition from dry to wet season (TDWS) and the wet season (WS) of 2004–2005, we sampled 42 rainfall events on event basis as well as 35 events on a within-event basis, and measured concentrations of DOC, Na+, K+, Ca2+, Mg2+, NH 4 + , Cl?, SO 4 2? , NO 3 ? and pH in rainfall and throughfall. We found strong evidence of both seasonal and within-event solute rainfall concentration dynamics. Seasonal volume-weighted mean (VWMS) concentrations in rainfall of DOC, K+, Ca2+, Mg2+, NH 4 + , SO 4 2? and NO 3 ? were significantly higher in the TDWS than the WS, while VWMS concentrations in throughfall were significantly higher for all solutes except DOC. Patterns were generally similar within rain events, with solute concentrations declining sharply during the first few millimeters of rainfall. Rainfall and throughfall chemistry dynamics appeared to be strongly influenced by forest and pasture burning and a regional atmosphere rich in aerosols at the end of the dry season. These seasonal and within-event patterns of rainfall and throughfall chemistry were stronger than those recorded in central Amazônia, where the dry season is less pronounced and where regional deforestation is less severe. Fragmentation and fire in Rondônia now appear to be altering the patterns in which solutes are delivered to remaining moist tropical forests. 相似文献
18.
Background and aims
Conversion of natural forests to plantations often results in a considerable loss of plant species and thus likely a reduction in quantity and quality of plant debris entering the soil. Larch plantation is widespread in northeastern China, but its ecological impacts receive little attention. This study aimed to assess soil quality under larch stands against the secondary forest stands using a suite of soil chemical and microbiological properties.Methods
Four pairs of larch plantations and secondary forests were randomly selected from a mountainous area and mineral soils of top 15 cm were collected from each field.Results
Soil carbon (C) and nitrogen (N) concentrations, microbial biomass, C and N mineralization and the activities of hydrolytic enzymes were significantly lower in the larch plantations than those in the secondary forests. However, light fraction C as a proportion of soil C was greater in the larch plantations, suggesting less accumulation and stabilization of soil C to heavy fraction in the larch plantations compared to the secondary forests. We also used δ15N records in light and heavy fractions to derive the relative stability of soil C and found that soil C stability was lower in the larch plantations. This was supported by Fourier transform infrared spectroscopy analysis because carboxylate stretching, which might result from microbial oxidation, was less abundant in the larch plantations.Conclusions
The differences in soil organic matter quality between the larch plantations and the secondary forests were reliably reflected in soil microbial properties and microbially-mediated processes. Our results indicated that the larch plantations reduced soil quality as well as nutrient cycling rate. 相似文献19.
Christopher J. Phillips Michael Marden Suzanne Lambie Alex Watson Craig Ross Scott Fraser 《Plant and Soil》2013,363(1-2):33-48
Aims
Radiata pine (Pinus radiata D. Don) plantations are widely used to control erosion in New Zealand. However, other species with similar growth but longer rotation lengths and ability to coppice may offer future alternatives to radiata pine. Comparing performance of alternative species to radiata thus becomes important if policy is to be developed to promote them.Methods
The below-ground characteristics (roots) of young redwood (Sequoia sempervirens (D. Don) Endl.) trees from two established plantations in New Zealand were examined and compared with those of radiata pine, and selected poplar and New Zealand native species.Results
Roots with diameters less than 10 mm comprised over 99 % of total root length in 3-yr-old trees and 98 % of total root length in 4-yr-old trees. For roots greater than 2 mm in diameter, total root length of young redwood trees was greater than that of young radiata pine, poplar and the best performing New Zealand native plant. Total root length at a given root collar diameter for young (1–4 year old) redwood trees was significantly greater than for radiata pine trees. Roots of redwoods were finer and more numerous than for radiata but the below-ground biomass for a given root collar diameter showed no statistical difference between the two species.Conclusions
Redwood, because of its comparable growth rate and the production of many fine lateral roots, has the potential to become a keystone erosion-control species in New Zealand, especially on steep lands where there is an increased risk of post-harvest landsliding associated with moderate to severe rainstorm events. 相似文献20.
Changes in water content of two agricultural soils does not alter labile P and C pools 总被引:1,自引:0,他引:1
Clayton R. Butterly Ann M. McNeill Jeff A. Baldock Petra Marschner 《Plant and Soil》2011,348(1-2):185-201