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1.
This study compared litter production, litter decomposition and nutrient return in pure and mixed species plantations. Dry
weight and N, P, K, Ca, Mg quantities in the litterfall were measured in one pure Cunninghamia lanceolata plantation (PC) and two mixed-species plantations of C. lanceolata with Alnus cremastogyne (MCA) and Kalopanax septemlobus (MCK) in subtropical China. Covering 6 years of observations, mean annual litter production of MCA (4.97 Mg·ha−1) and MCK (3.97 Mg·ha−1) was significantly higher than that of PC (3.46 Mg·ha−1). Broadleaved trees contributed 42% of the total litter production in MCA and 31% in MCK. Introduction of broadleaved tree
species had no significant effect on litterfall pattern. Total litterfall was greatest in the dry season from November to
March. Nutrient returns to the forest floor through leaf litter were significantly higher in both MCA and MCK than in PC (P < 0.05). The amounts of N, K, and Mg returned to the forest floor through leaf litter were highest in the MCA, and P and
Ca returns were highest in the MCK. Percent contribution of broadleaf litter to total nutrient returns ranged from 41.7% to
86.9% in MCA and from 49.3% to 74.8% in MCK. The decomposition rate of individual leaf litter increased in the order: C. lanceolata < K. septemlobus < A. cremastogyne. Litter mixing had a positive effect on decomposition rate of the more recalcitrant litter and promoted nutrient return.
Relative to mass loss of A. cremastogyne decomposing alone, higher mass loss of the mixture of C. lanceolata and A. cremastogyne was observed after 330 days of decomposition. These results indicate that mixed plantations of different tree species have
advantages over monospecific plantations with regards to nutrient fluxes and these advantages have relevance to restoration
of degraded sites.
Responsible Editor: Alfonso Escudero. 相似文献
2.
Toshiyuki Ohtsuka Wenhong Mo Takami Satomura Motoko Inatomi Hiroshi Koizumi 《Ecosystems》2007,10(2):324-334
Biometric based carbon flux measurements were conducted over 5 years (1999–2003) in a temperate deciduous broad-leaved forest
of the AsiaFlux network to estimate net ecosystem production (NEP). Biometric based NEP, as measured by the balance between
net primary production (including NPP of canopy trees and of forest floor dwarf bamboo) and heterotrophic respiration (RH),
clarified the contribution of various biological processes to the ecosystem carbon budget, and also showed where and how the
forest is storing C. The mean NPP of the trees was 5.4 ± 1.07 t C ha−1 y−1, including biomass increment (0.3 ± 0.82 t C ha−1 y−1), tree mortality (1.0 ± 0.61 t C ha−1 y−1), aboveground detritus production (2.3 ± 0.39 t C ha−1 y−1) and belowground fine root production (1.8 ± 0.31 t C ha−1 y−1). Annual biomass increment was rather small because of high tree mortality during the 5 years. Total NPP at the site was
6.5 ± 1.07 t C ha−1 y−1, including the NPP of the forest floor community (1.1 ± 0.06 t C ha−1 y−1). The soil surface CO2 efflux (RS) was averaged across the 5 years of record using open-flow chambers. The mean estimated annual RS amounted to
7.1 ± 0.44 t C ha−1, and the decomposition of soil organic matter (SOM) was estimated at 3.9 ± 0.24 t C ha−1. RH was estimated at 4.4 ± 0.32 t C ha−1 y−1, which included decomposition of coarse woody debris. Biometric NEP in the forest was estimated at 2.1 ± 1.15 t C ha−1 y−1, which agreed well with the eddy-covariance based net ecosystem exchange (NEE). The contribution of woody increment (Δbiomass + mortality)
of the canopy trees to NEP was rather small, and thus the SOM pool played an important role in carbon storage in the temperate
forest. These results suggested that the dense forest floor of dwarf bamboo might have a critical role in soil carbon sequestration
in temperate East Asian deciduous forests. 相似文献
3.
Tree species and wood ash application in plantations of short-rotation woody crops (SRWC) may have important effects on the
soil productive capacity through their influence on soil organic matter (SOM) and exchangeable cations. An experiment was
conducted to assess changes in soil C and N contents and pH within the 0–50 cm depth, and exchangeable cation (Ca2+, Mg2+, K+, and Na+) and extractable acidity concentrations within the 0–10 cm depth. The effects of different species (European larch [Larix decidua P. Mill.], aspen [Populus tremula L. × Populus tremuloides Michx.], and four poplar [Populus spp.] clones) and wood ash applications (0, 9, and 18 Mg ha−1) on soil properties were evaluated, using a common garden experiment (N = 70 stands) over 7 years of management in Michigan’s Upper Peninsula. Soils were of the Onaway series (fine-loamy, mixed,
active, frigid Inceptic Hapludalfs). The NM-6 poplar clone had the greatest soil C and N contents in almost all ash treatment
levels. Soil C contents were 7.5, 19.4, and 10.7 Mg C ha−1 greater under the NM-6 poplar than under larch in the ash-free, medium-, and high-level plots, respectively. Within the surface
layer, ash application increased soil C and N contents (P < 0.05) through the addition of about 0.7 Mg C ha−1 and 3 kg N ha−1 with the 9 Mg ha−1 ash application (twofold greater C and N amounts were added with the 18 Mg ha−1 application). During a decadal time scale, tree species had no effects—except for K+—on the concentrations of the exchangeable cations, pH, and extractable acidity. In contrast, ash application increased soil
pH and the concentration of Ca2+ (P < 0.05), from 5.2 ± 0.4 cmolc kg−1 (ash-free plots) to 8.6 ± 0.4 cmolc kg−1 (high-level ash plots), and tended to increase the concentration of Mg2+ (P < 0.1), while extractable acidity was reduced (P < 0.05) from 5.6 ± 0.2 cmolc kg−1 (ash-free plots) to 3.7 ± 0.2 cmolc kg−1 (high-level plots). Wood ash application, within certain limits, not only had a beneficial effect on soil properties important
to the long-term productivity of fast-growing plantations but also enhanced long-term soil C sequestration. 相似文献
4.
Fire in the Brazilian Amazon 2. Biomass, nutrient pools and losses in cattle pastures 总被引:3,自引:0,他引:3
Conversion to cattle pasture is the most common fate of the ≈426,000 km2 of tropical forest that has been deforested in the Brazilian Amazon. Yet little is known about the biomass, C, nutrient pools,
or their responses to the frequent fires occurring in these pastures. We sampled biomass, nutrient pools and their losses
or transformation during fire in three Amazonian cattle pastures with typical, but different, land-use histories. Total aboveground
biomass (TAGB) ranged from to 53 to 119 Mg ha−1. Residual wood debris from the forests that formally occupied the sites composed the majority of TAGB (47–87%). Biomass of
fine fuels, principally pasture grasses, was ≈16–29 Mg ha−1. Grasses contained as much as 52% of the aboveground K pool and the grass and litter components combined composed as much
as 88% of the aboveground P pool. Fires consumed 21–84% of the TAGB. Losses of C to the atmosphere ranged from 11 to 21 Mg ha−1 and N losses ranged from 205 to 261 kg ha−1. Losses of S, P, Ca, and K were <33 kg ha−1. There were no changes in surface soil (0–10 cm) nutrient concentration in pastures compared to adjacent primary forests.
Fires occur frequently in cattle pastures (i.e., about every 2 years) and pastures are now likely the most common type of
land burned in Amazonia. The first 6 years of a pastures existence would likely include the primary forest slash fire and
three pasture fires. Based upon our results, the cumulative losses of N from these fires would be 1935 kg ha−1 (equivalent to 94% of the aboveground pool of primary forest). Postfire aboveground C pools in old pastures are as low as
3% of those in adjacent primary forest. The initial primary forest slash fire and the repeated fires occurring in the pastures
result in the majority of aboveground C and nutrient pools being released via combustion processes rather than decomposition
processes.
Received: 6 January 1997 / Accepted: 2 September 1997 相似文献
5.
Altitudinal changes in carbon storage of temperate forests on Mt Changbai, Northeast China 总被引:8,自引:0,他引:8
Biao Zhu Xiangping Wang Jingyun Fang Shilong Piao Haihua Shen Shuqing Zhao Changhui Peng 《Journal of plant research》2010,123(4):439-452
A number of studies have investigated regional and continental scale patterns of carbon (C) stocks in forest ecosystems; however,
the altitudinal changes in C storage in different components (vegetation, detritus, and soil) of forest ecosystems remain
poorly understood. In this study, we measured C stocks of vegetation, detritus, and soil of 22 forest plots along an altitudinal
gradient of 700–2,000 m to quantify altitudinal changes in carbon storage of major forest ecosystems (Pinus koraiensis and broadleaf mixed forest, 700–1,100 m; Picea and Abies forest, 1,100–1,800 m; and Betula ermanii forest, 1,800–2,000 m) on Mt Changbai, Northeast China. Total ecosystem C density (carbon stock per hectare) averaged 237 t C ha−1 (ranging from 112 to 338 t C ha−1) across all the forest stands, of which 153 t C ha−1 (52–245 t C ha−1) was stored in vegetation biomass, 14 t C ha−1 (2.2–48 t C ha−1) in forest detritus (including standing dead trees, fallen trees, and floor material), and 70 t C ha−1 (35–113 t C ha−1) in soil organic matter (1-m depth). Among all the forest types, the lowest vegetation and total C density but the highest
soil organic carbon (SOC) density occurred in Betula ermanii forest, whereas the highest detritus C density was observed in Picea and Abies forest. The C density of the three ecosystem components showed distinct altitudinal patterns: with increasing altitude, vegetation
C density decreased significantly, detritus C density first increased and then decreased, and SOC density exhibited increasing
but insignificant trends. The allocation of total ecosystem C to each component exhibited similar but more significant trends
along the altitudinal gradient. Our results suggest that carbon storage and partitioning among different components in temperate
forests on Mt Changbai vary greatly with forest type and altitude. 相似文献
6.
DeXiang Chen YiDe Li HePing Liu Han Xu WenFa Xiao TuShou Luo Zhang Zhou MingXian Lin 《中国科学:生命科学英文版》2010,53(7):798-810
Biometric inventories for 25 years, from 1983 to 2005, indicated that the Jianfengling tropical mountain rain forest in Hainan,
China, was either a source or a modest sink of carbon. Overall, this forest was a small carbon sink with an accumulation rate
of (0.56±0.22) Mg C ha−1yr−1, integrated from the long-term measurement data of two plots (P9201 and P8302). These findings were similar to those for
African and American rain forests ((0.62±0.23) Mg C ha−1yr−1). The carbon density varied between (201.43±29.38) Mg C ha−1 and (229.16±39.2) Mg C ha−1, and averaged (214.17±32.42) Mg C ha−1 for plot P9201. Plot P8302, however, varied between (223.95±45.92) Mg C ha−1 and (254.85±48.86) Mg C ha−1, and averaged (243.35±47.64) Mg C ha−1. Quadratic relationships were found between the strength of carbon sequestration and heavy rainstorms and dry months. Precipitation
and evapotranspiration are two major factors controlling carbon sequestration in the tropical mountain rain forest. 相似文献
7.
Soil carbon storage, litterfall and CO2 efflux in fertilized and unfertilized larch (Larix leptolepis) plantations 总被引:1,自引:0,他引:1
Choonsig Kim 《Ecological Research》2008,23(4):757-763
This study evaluated the effects of forest fertilization on the forest carbon (C) dynamics in a 36-year-old larch (Larix leptolepis) plantation in Korea. Above- and below-ground C storage, litterfall, root decomposition and soil CO2 efflux rates after fertilization were measured for 2 years. Fertilizers were applied to the forest floor at rates of 112 kg
N ha−1 year−1, 75 kg P ha−1 year−1 and 37 kg K ha−1 year−1 for 2 years (May 2002, 2003). There was no significant difference in the above-ground C storage between fertilized (41.20 Mg C
ha−1) and unfertilized (42.25 Mg C ha−1) plots, and the C increment was similar between the fertilized (1.65 Mg C ha−1 year−1) and unfertilized (1.52 Mg C ha−1 year−1) plots. There was no significant difference in the soil C storage between the fertilized and unfertilized plots at each soil
depth (0–15, 15–30 and 30–50 cm). The organic C inputs due to litterfall ranged from 1.57 Mg C ha−1 year−1 for fertilized to 1.68 Mg C ha−1 year−1 for unfertilized plots. There was no significant difference in the needle litter decomposition rates between the fertilized
and unfertilized plots, while the decomposition of roots with 1–2 mm diameters increased significantly with the fertilization
relative to the unfertilized plots. The mean annual soil CO2 efflux rates for the 2 years were similar between the fertilized (0.38 g CO2 m−2 h−1) and unfertilized (0.40 g CO2 m−2 h−1) plots, which corresponded with the similar fluctuation in the organic carbon (litterfall, needle and root decomposition)
and soil environmental parameters (soil temperature and soil water content). These results indicate that little effect on
the C dynamics of the larch plantation could be attributed to the 2-year short-term fertilization trials and/or the soil fertility
in the mature coniferous plantation used in this study. 相似文献
8.
Emissions of nitrous oxide from three tropical forests in Southern China in response to simulated nitrogen deposition 总被引:2,自引:0,他引:2
Wei Zhang Jiangming Mo Guirui Yu Yunting Fang Dejun Li Xiankai Lu Hui Wang 《Plant and Soil》2008,306(1-2):221-236
Emissions of nitrous oxide (N2O) from the soil following simulated nitrogen (N) deposition in a disturbed (pine), a rehabilitated (pine and broadleaf mixed)
and a mature (monsoon evergreen broadleaf) tropical forest in southern China were studied. The following hypotheses were tested:
(1) addition of N will increase soil N2O emission in tropical forests; and (2) any observed increase will be more pronounced in the mature forest than in the disturbed
or rehabilitated forest due to the relatively high initial soil N concentration in the mature forest. The experiment was designed
with four N treatment levels (three replicates; 0, 50, 100, 150 kg N ha−1 year−1 for C (Control), LN (Low-N), MN (Medium-N), and HN (High-N) treatment, respectively) in the mature forest, but only three
levels in the disturbed and rehabilitated forests (C, LN and MN). Between October 2005 to September 2006, soil N2O flux was measured using static chamber and gas chromatography methodology. Nitrogen had been applied previously to the plots
since July 2003 and continued during soil N2O flux measurement period. The annual mean rates of soil N2O emission in the C plots were 24.1 ± 1.5, 26.2 ± 1.4, and 29.3 ± 1.6 μg N2O–N m−2 h−1 in the disturbed, rehabilitated and mature forest, respectively. There was a significant increase in soil N2O emission following N additions in the mature forest (38%, 41%, and 58% when compared to the C plots for the LN, MN, and
HN plots, respectively). In the disturbed forest a significant increase (35%) was observed in the MN plots, but not in the
LN plots. The rehabilitated forest showed no significant response to N additions. Increases in soil N2O emission occurred primarily in the cool-dry season (November, December and January). Our results suggest that the response
of soil N2O emission to N deposition in tropical forests in southern China may vary depending on the soil N status and land-use history
of the forest. 相似文献
9.
Response of soil respiration to simulated N deposition in a disturbed and a rehabilitated tropical forest in southern China 总被引:3,自引:1,他引:2
Jiangming Mo Wei Zhang Weixing Zhu Yunting Fang Dejun Li Ping Zhao 《Plant and Soil》2007,296(1-2):125-135
Responses of soil respiration (CO2 emission) to simulated N deposition were studied in a disturbed (reforested forest with previous understory and litter harvesting)
and a rehabilitated (reforested forest with no understory and litter harvesting) tropical forest in southern China from October
2005 to September 2006. The objectives of the study were to test the following hypotheses: (1) soil respiration is higher
in rehabilitated forest than in disturbed forest; (2) soil respiration in both rehabilitated and disturbed tropical forests
is stimulated by N additions; and (3) soil respiration is more sensitive to N addition in disturbed forest than in rehabilitated
forest due to relatively low soil nutrient status in the former, resulting from different previous human disturbance. Static
chamber and gas chromatography techniques were employed to quantify the soil respiration, following different N treatments
(Control, no N addition; Low-N, 5 g N m−2 year−1; Medium-N, 10 g N m−2 year−1), which had been applied continuously for 26 months before the respiration measurement. Results showed that soil respiration
exhibited a strong seasonal pattern, with the highest rates observed in the hot and wet growing season (April–September) and
the lowest rates in winter (December–February) in both rehabilitated and disturbed forests. Soil respiration rates exhibited
significant positive exponential relationship with soil temperature and significant positive linear relationship with soil
moisture. Soil respiration was also significantly higher in the rehabilitated forest than in the disturbed forest. Annual
mean soil respiration rate in the rehabilitated forest was 20% lower in low-N plots (71 ± 4 mg CO2-C m−2 h−1) and 10% lower in medium-N plots (80 ± 4 mg CO2-C m−2 h−1) than in the control plots (89 ± 5 mg CO2-C m−2 h−1), and the differences between the control and low-N or medium-N treatments were statistically significant. In disturbed forest,
annual mean soil respiration rate was 5% lower in low-N plots (63 ± 3 mg CO2-C m−2 h−1) and 8% lower in medium-N plots (61 ± 3 mg CO2-C m−2 h−1) than in the control plots (66 ± 4 mg CO2-C m−2 h−1), but the differences among treatments were not significant. The depressed effects of experimental N deposition occurred
mostly in the hot and wet growing season. Our results suggest that response of soil respiration to elevated N deposition in
the reforested tropical forests may vary depending on the status of human disturbance.
Responsible Editor: Hans Lambers. 相似文献
10.
Jiangming Mo Sandra Brown Jinghua Xue Yunting Fang Zhian Li Dejun Li Shaofeng Dong 《Ecological Research》2007,22(4):649-658
The effects of simulated N deposition on changes in mass, C, N and P of decomposing pine (Pinus massoniana) needles in a disturbed and a rehabilitated forest in tropical China were studied during a 24-month period. The objective
of the study was to test the hypothesis that litter decomposition in a disturbed forest is more sensitive to N deposition
rate than litter decomposition in a rehabilitated forest due to the relatively low nutrient status in the former as a result
of constant human disturbance (harvesting understory and litter). The litterbag method and N treatments (control, no N addition;
low-N, 5 g N m−2 year−1; medium-N, 10 g N m−2 year−1) were employed to evaluate decomposition. The results revealed that N addition increased (positive effect) mass loss rate
and C release rate but suppressed (negative effect) the release rate of N and P from decomposing needles in both disturbed
and rehabilitated forests. The enhanced needle decomposition rate by N addition was significantly related to the reduction
in the C/N ratio in decomposing needles. However, N availability is not the sole factor limiting needle decomposition in both
disturbed and rehabilitated forests. The positive effect was more sensitive to the N addition rate in the rehabilitated forest
than in the disturbed forest, however the reverse was true for the negative effect. These results suggest that nutrient status
could be one of the important factors in controlling the response of litter decomposition and its nutrient release to elevated
N deposition in reforested ecosystems in the study region. 相似文献
11.
Monopolization of litter processing by a dominant land crab on a tropical oceanic island 总被引:3,自引:0,他引:3
Litter processing by macroinvertebrates typically involves suites of species that act together to determine rates of breakdown
and decomposition. However, tropical oceanic islands and coastal fringes on continents are often dominated by one or a few
species of omnivorous land crabs that consume leaf litter. We used an exclusion experiment, together with other leaf removal
and litter decomposition studies, to assess the role of a single dominant species, the red crab (Gecarcoidea natalis), in litter dynamics in rain forest on Christmas Island, Indian Ocean. In the presence of red crabs, litter cover and biomass
varied seasonally, from almost complete cover and high biomass at the end of the dry season to almost total absence of litter
at the end of each wet season. When crabs were excluded from both the shaded understory and light gaps in rain forest, litter
increased rapidly to almost complete cover, which was then maintained year round. Leaf tether experiments, and measures of
litter input and standing crops, indicated that red crabs monopolize litter processing, removing between 39 and 87% of the
annual leaf fall from the forest floor. Rates of litter turnover were over twice as high in the presence of land crabs: the
decomposition constant, k, was 2.6 in the understory exclusion plots, but rose to 6.0 in the presence of crabs. Red crabs occur at biomass densities
(114 g m−2) far greater than those reported elsewhere for entire litter faunas. They significantly reduced the abundance of other litter
invertebrates, but we did not detect any change in the relative frequencies of the major invertebrate groups (mites, collembolans,
pulmonate snails, ants, psocopterans, and spiders). Wherever omnivorous land crabs are abundant, their activities may be paramount
in litter decomposition and in regulating the rate of nutrient cycling. In monopolizing litter processing, they may also be
important physical “ecosystem engineers”, translocating organic matter and nutrients into the soil and reducing available
habitat for other animals.
Received: 19 August 1998 / Accepted: 11 January 1999 相似文献
12.
The dynamics of aboveground big woody organs over 10 cm diameter was studied at a mature foothill dipterocarp forest in West
Sumatra. The biomass of big woody organs was estimated to be 519 m3 ha−1 or 408 metric ton ha−1 by means of a pipe model theory. The diameter distribution showed a convex curve and the mode was found at a diameter of
about 20 cm. The standing mass of big dead woody litter on the forest floor was 116 m3 ha−1, which accounted for 22% by voume or 9.5% by weight of the biomass of living organs respectively. Thedbh observation with two 1-ha plots for 4 yr and 5 yr respectively revealed that the average net production rate was 9.5 ton
ha−1 yr−1. The death rate (7.9 ton ha−1 yr−1) accounted for 83% of the net production rate and was nearly equivalent to the decay rate (7.5 ha−1 yr−1) of dead wood on the forest floor. The balance between the death and decay rates was confirmed for each diameter class. Average
turnover periods for big woody organs and dead woody litter were estimated to be 43 and 8.1 yr, respectively. Standing masses
of live anddead woody materials accumulated in the study forest were approximately equal to those obtained in a mature tropical
lowland rainforest, whereas the flow rates were lower, being only 70% of the corresponding values. 相似文献
13.
Soil Nutrients Limit Fine Litter Production and Tree Growth in Mature Lowland Forest of Southwestern Borneo 总被引:1,自引:0,他引:1
Efforts to improve models of terrestrial productivity and to understand the function of tropical forests in global carbon
cycles require a mechanistic understanding of spatial variation in aboveground net primary productivity (ANPP) across tropical
landscapes. To help derive such an understanding for Borneo, we monitored aboveground fine litterfall, woody biomass increment
and ANPP (their sum) in mature forest over 29 months across a soil nutrient gradient in southwestern Kalimantan. In 30 (0.07 ha)
plots stratified throughout the watershed (∼340 ha, 8–190 m a.s.l.), we measured productivity and tested its relationship
with 27 soil parameters. ANPP across the study area was among the highest reported for mature lowland tropical forests. Aboveground
fine litterfall ranged from 5.1 to 11.0 Mg ha−1 year−1 and averaged 7.7 ± 0.4 (mean ± 95 C.I.). Woody biomass increment ranged from 5.8 to 23.6 Mg ha−1 year−1 and averaged 12.0 ± 2.0. Growth of large trees (≥60 cm dbh) contributed 38–82% of plot-wide biomass increment and explained
92% of variation among plots. ANPP, the sum of these parameters, ranged from 11.1 to 32.3 Mg ha−1 year−1 and averaged 19.7 ± 2.2. ANPP was weakly related to fine litterfall (r
2 = 0.176), but strongly related to growth of large trees at least 60 cm dbh (r
2 = 0.848). Adjusted ANPP after accounting for apparent “mature forest bias” in our sampling method was 17.5 ± 1.2 Mg ha−1 year−1.Relating productivity measures to soil parameters showed that spatial patterning in productivity was significantly related
to soil nutrients, especially phosphorus (P). Fine litterfall increased strongly with extractable P (r
2 = 0.646), but reached an asymptote at moderate P levels, whereas biomass increment (r
2 = 0.473) and ANPP (r
2 = 0.603) increased linearly across the gradient. Biomass increment of large trees was more frequently and strongly related to
nutrients than small trees, suggesting size dependency of tree growth on nutrients. Multiple linear regression confirmed the
leading importance of soil P, and identified Ca as a potential co-limiting factor. Our findings strongly suggest that (1)
soil nutrients, especially P, limit aboveground productivity in lowland Bornean forests, and (2) these forests play an important,
but changing role in carbon cycles, as canopy tree logging alters these terrestrial carbon sinks.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
Soil respiration and carbon balance in a subtropical native forest and two managed plantations 总被引:3,自引:0,他引:3
Yu-Sheng Yang Guang-Shui Chen Jian-Fen Guo Jin-Sheng Xie Xiao-Guo Wang 《Plant Ecology》2007,192(1):71-84
From 1999 to 2003, a range of carbon fluxes was measured and integrated to establish a carbon balance for a natural evergreen
forest of Castanopsis kawakamii (NF) and adjacent monoculture evergreen plantations of C. kawakamii (CK) and Chinese fir (Cunninghamia lanceolata, CF) in Sanming Nature Reserve, Fujian, China. Biomass carbon increment of aboveground parts and coarse roots were measured
by the allometric method. Above- and belowground litter C inputs were assessed by litter traps and sequential cores, respectively.
Soil respiration (SR) was determined by the alkaline absorbance method, and the contribution from roots, above- and belowground litters was separated
by the DIRT plots. Annual SR averaged 13.742 t C ha−1 a−1 in the NF, 9.439 t C ha−1 a−1 in the CK, and 4.543 t C ha−1 a−1 in the CF. For all forests, SR generally peaked in later spring or early summer (May or June). The contribution of root respiration ranged from 47.8% in
the NF to 40.3% in the CF. On average, soil heterotrophic respiration (HR) was evenly distributed between below- (47.3∼54.5%) and aboveground litter (45.5%–52.7%). Annual C inputs (t C ha−1 a−1) from litterfall and root turnover averaged 4.452 and 4.295, 4.548 and 2.313, and 2.220 and 1.265, respectively, in the NF,
CK, and CF. As compared to HR, annual net primary production (NPP) of 11.228, 13.264, and 6.491 t C ha−1 a−1 in the NF, CK, and CF brought a positive net ecosystem production (NEP) of 4.144, 7.514, and 3.677 t C ha−1 a−1, respectively. It suggests that native forest in subtropical China currently acts as an important carbon sink just as the
timber plantation does, and converting native forest to tree plantations locally during last decades might have caused a high
landscape carbon loss to the atmosphere. 相似文献
15.
Impact of Ecosystem Management on Microbial Community Level Physiological Profiles of Postmining Forest Rehabilitation 总被引:1,自引:0,他引:1
We investigated the impacts of forest thinning, prescribed fire, and contour ripping on community level physiological profiles
(CLPP) of the soil microbial population in postmining forest rehabilitation. We hypothesized that these management practices
would affect CLPP via an influence on the quality and quantity of soil organic matter. The study site was an area of Jarrah
(Eucalyptus marginata Donn ex Sm.) forest rehabilitation that had been mined for bauxite 12 years previously. Three replicate plots (20 × 20 m) were established
in nontreated forest and in forest thinned from 3,000–8,000 stems ha−1 to 600–800 stems ha−1 in April (autumn) of 2003, followed either by a prescribed fire in September (spring) of 2003 or left nonburned. Soil samples
were collected in August 2004 from two soil depths (0–5 cm and 5–10 cm) and from within mounds and furrows caused by postmining
contour ripping. CLPP were not affected by prescribed fire, although the soil pH and organic carbon (C), total C and total
nitrogen (N) contents were greater in burned compared with nonburned plots, and the coarse and fine litter mass lower. However,
CLPP were affected by forest thinning, as were fine litter mass, soil C/N ratio, and soil pH, which were all higher in thinned
than nonthinned plots. Furrow soil had greater coarse and fine litter mass, and inorganic phosphorous (P), organic P, organic
C, total C, total N, ammonium, microbial biomass C contents, but lower soil pH and soil C/N ratio than mound soil. Soil pH,
inorganic P, organic P, organic C, total C and N, ammonium, and microbial biomass C contents also decreased with depth, whereas
soil C/N ratio increased. Differences in CLPP were largely (94%) associated with the relative utilization of gluconic, malic
(greater in nonthinned than thinned soil and mound than furrow soil), l-tartaric, succinic, and uric acids (greater in thinned than nonthinned, mound than furrow, and 5–10 cm than 0–5 cm soil).
The relative utilization of amino acids also tended to increase with increasing soil total C and organic C contents but decreased
with increasing nitrate content, whereas the opposite was true for carboxylic acids. Only 45% of the variance in CLPP was
explained using a multivariate multiple regression model, but soil C and N pools and litter mass were significant predictors
of CLPP. Differences in soil textural components between treatments were also correlated with CLPP; likely causes of these
differences are discussed. Our results suggest that 1 year after treatment, CLPP from this mined forest ecosystem are resilient
to a spring prescribed fire but not forest thinning. We conclude that differences in CLPP are likely to result from complex
interactions among soil properties that mediate substrate availability, microbial nutrient demand, and microbial community
composition. 相似文献
16.
Estimates of biomass and primary productivity in a high-altitude maple forest of the west central Himalayas 总被引:4,自引:0,他引:4
S. C. Garkoti 《Ecological Research》2008,23(1):41-49
The paper describes the biomass and productivity of maple (Acer cappadocicum) forest occurring at an altitude of 2,750 m in the west central Himalayas. Total vegetation biomass was 308.3 t ha−1, of which the tree layer contributed the most, followed by herbs and shrubs. The seasonal forest-floor litter mass varied
between 5.4 t ha−1 (in rainy season) and 6.6 t ha−1 (in winter season). The annual litter fall was 6.2 t ha−1, of which leaf litter contributed the largest part (59% of the total litter fall). Net primary productivity of total vegetation
was 19.5 t ha−1 year−1. The production efficiency of leaves (net primary productivity/leaf mass) was markedly higher (2.9 g g−1 foliage mass year−1) than those of the low-altitude forests of the region. 相似文献
17.
Structure, above-ground biomass and dynamics of mangrove ecosystems: new data from French Guiana 总被引:5,自引:0,他引:5
The article presents new results on the structure and the above-ground biomass of the various population types of mangroves
in French Guiana. Nine mangrove stands were studied, each composed of three to ten adjoining plots with areas that varied
depending on the density of the populations. Structural parameters and indices were calculated. Individuals representative
of the three groups of taxa present were felled:Avicennia germinans (L) Stearn, Rhizophora spp., and Laguncularia racemosa (L) Gaertn. The trunks, branches and leaves were sorted and weighed separately. The biomass was obtained by determining the
allometric relationships, the general equation selected being of the type y = a
o
x
a1, where the diameter (x) is the predictive variable. The total above-ground biomass varied from 31 t ha−1 for the pioneer stages to 315 t ha−1 for mature coastal mangroves, but with large variations depending on the structural characteristics at each site. The results
place the Guianese mangroves among those with high biomass, although lower than those reported for Asia. Based on the relationships
between structural parameters and standing biomass, in particular with the use of the “self-thinning rule”, population dynamics
models are proposed.
Received: 16 August 1996 / Accepted 17 January 1998 相似文献
18.
Baker TR Honorio Coronado EN Phillips OL Martin J van der Heijden GM Garcia M Silva Espejo J 《Oecologia》2007,152(3):495-504
The stocks and dynamics of coarse woody debris (CWD) are significant components of the carbon cycle within tropical forests.
However, to date, there have been no reports of CWD stocks and fluxes from the approximately 1.3 million km2 of lowland western Amazonian forests. Here, we present estimates of CWD stocks and annual CWD inputs from forests in southern
Peru. Total stocks were low compared to other tropical forest sites, whether estimated by line-intercept sampling (24.4 ± 5.3 Mg ha−1) or by complete inventories within 11 permanent plots (17.7 ± 2.4 Mg ha−1). However, annual inputs, estimated from long-term data on tree mortality rates in the same plots, were similar to other
studies (3.8 ± 0.2 or 2.9 ± 0.2 Mg ha−1 year−1, depending on the equation used to estimate biomass). Assuming the CWD pool is at steady state, the turnover time of coarse
woody debris is low (4.7 ± 2.6 or 6.1 ± 2.6 years). These results indicate that these sites have not experienced a recent,
large-scale disturbance event and emphasise the distinctive, rapid nature of carbon cycling in these western Amazonian forests. 相似文献
19.
Microclimatic parameters influencing nitrogen fixation in the phyllosphere in a Costa Rican premontane rain forest 总被引:1,自引:0,他引:1
Elke Freiberg 《Oecologia》1998,117(1-2):9-18
The acetylene reduction method was used to measure nitrogen fixation in the phyllosphere of attached leaves of different
phorophytes under natural conditions in a premontane rain forest in Costa Rica. Maximum rates of nitrogen fixation (26 ng N · cm−2 leaf area · h−1) – mainly due to the activity of two species of Scytonema (Cyanobacteria) – were measured in the rainy season in bright sunlight. Rates of nitrogen fixation were correlated with the
leaf area covered by Scytonema. In periods without precipitation the fixation activity decreased to zero within 2–3 days. As long as the epiphylls were sufficiently
supplied with water, other microclimatic factors like temperature and light intensity also influenced nitrogen fixation rates,
but to a lesser extent. Relative humidity and species of phorophyte showed no direct influence. It was concluded that the
most important factor for nitrogen fixation in the phyllosphere was the availability of liquid water. Linking these results
to meteorological data, the input of nitrogen by biological nitrogen fixation in the phyllosphere in the investigation area
was estimated to be as much as 1.6 ± 0.8 kg N · ha−1 · year−1 per unit of leaf area index (LAI). For an LAI of 2 for the understory the nitrogen input would vary between 2 and 5 kg N ·
ha−1 · year−1. This work also demonstrates the importance of detailed knowledge of variation in microclimate throughout the year as a basis
for extrapolation of the annual nitrogen input.
Received: 21 December 1997 / Accepted: 14 June 1998 相似文献
20.
Litter Decomposition and Nutrient Dynamics in a Phosphorus Enriched Everglades Marsh 总被引:3,自引:0,他引:3
A field study was conducted in a nutrient-impacted marsh in Water Conservation Area 2A (WCA-2A) of the Everglades in southern
Florida, USA, to evaluate early stages of plant litter (detritus) decomposition along a well-documented trophic gradient,
and to determine the relative importance of environmental factors and substrate composition in governing decomposition rate.
Vertically stratified decomposition chambers containing native plant litter (cattail and sawgrass leaves) were placed in the
soil and water column along a 10-km transect coinciding with a gradient of soil phosphorus (P) enrichment. Decomposition rate
varied significantly along the vertical water–soil profile, with rates typically higher in the water column and litter layer
than below the soil surface, presumably in response to vertical gradients of such environmental factors as O2 and nutrient availability. An overall decrease in decomposition rate occurred along the soil P gradient (from high- to low-impact).
First-order rate constant (k) values for decomposition ranged from 1.0 to 9.2 × 10−3 day−1 (mean = 2.8 ×10−3 day−1) for cattails, and from 6.7 × 10−4 to 3.0 × 10−3 day−1 (mean = 1.7 × 10−3 day−1) for sawgrass. Substantial N and P immobilization occurred within the litter layer, being most pronounced at nutrient-impacted
sites. Nutrient content of the decomposing plant tissue was more strongly correlated to decomposition rate than was the nutrient
content of the surrounding soil and water. Our experimental results suggest that, although decomposition rate was significantly
affected by initial substrate composition, the external supply or availability of nutrients probably played a greater role
in controlling decomposition rate. It was also evident that nutrient availability for litter decomposition was not accurately
reflected by ambient nutrient concentration, e.g., water and soil porewater nutrient concentration. 相似文献