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1.
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
2.
Litterfall dynamics in carbonate and deltaic mangrove ecosystems in the Gulf of Mexico 总被引:1,自引:0,他引:1
Carlos Coronado-Molina H. Alvarez-Guillen J. W. DayJr. E. Reyes B. C. Perez F. Vera-Herrera R. Twilley 《Wetlands Ecology and Management》2012,20(2):123-136
From 1996 to 2002, we measured litterfall, standing litter crop, and litter turnover rates in scrub, basin, fringe and riverine
forests in two contrasting mangrove ecosystems: a carbonate-dominated system in the Southeastern Everglades and a terrigenous-dominated
system in Laguna de Terminos (LT), Mexico. We hypothesized that litter dynamics is driven by latitude, geomorphology, hydrology,
soil fertility and soil salinity stress. There were significant temporal patterns in LT with litterfall rates higher during
the rainy season (2.4 g m−2 day−1) than during the dry season (1.8 g m−2 day−1). Total annual litterfall was significantly higher in the riverine forest (12.8 Mg ha−2 year−1) than in the fringe and basin forests (9.7 and 5.2 Mg ha−2 year−1, respectively). In Southeastern Everglades, total annual litterfall was also significantly higher during the rainy season
than during the dry season. Spatially, the scrub forest had the lowest annual litterfall (2.5 Mg ha−2 year−1), while the fringe and basin had the highest (9.1 and 6.5 Mg ha−2 year−1, respectively). In LT, annual standing litter crop was 3.3 Mg ha−1 in the fringe and 2.2 Mg ha−1 in the basin. Litter turnover rates were significantly higher in the fringe mangrove forest (4.1 year−1) relative to the basin forests (2.2 year−1). At Southeastern Everglades there were significant differences in annual standing litter crop: 1.9, 3.3 and 4.5 Mg ha−1 at scrub, basin and fringe mangrove sites, respectively. Furthermore, turnover rates were similar at both basin and fringe
mangrove types (2.1 and 2.0 year−1, respectively) but significantly higher than scrub mangrove forest (1.3 year−1). These findings suggest that litter export is important in regulating litter turnover rates in frequently flooded riverine
and fringe forests, while in infrequently flooded basin forests, in situ litter decomposition controls litter turnover rates. 相似文献
3.
Modelling soil C sequestration in spruce forest ecosystems along a Swedish transect based on current conditions 总被引:1,自引:1,他引:0
The change of current pools of soil C in Norway spruce ecosystems in Sweden were studied using a process-based model (CoupModel).
Simulations were conducted for four sites representing different regions covering most of the forested area in Sweden and
representing annual mean temperatures from 0.7°C to 7.1°C. The development of both tree layer and field layer (understory)
was simulated during a 100-year period using data on standing stock volumes from the Swedish Forest Inventory to calibrate
tree growth using different assumptions regarding N supply to the plants. The model successfully described the general patterns
of forest stand dynamics along the Swedish climatic transect, with decreasing tree growth rates and increasing field layer
biomass from south to north. However, the current tree growth pattern for the northern parts of Sweden could not be explained
without organic N uptake and/or enhanced mineralisation rates compared to the southern parts. Depending on the assumption
made regarding N supply to the tree, different soil C sequestration rates were obtained. The approach to supply trees with
both mineralised N and organic N, keeping the soil C:N ratio constant during the simulation period was found to be the most
realistic alternative. With this approach the soils in the northern region of Sweden lost 5 g C m−2 year−1, the soils in the central region lost 2 g C m−2 year−1, and the soils in the two southern regions sequestered 9 and 23 g C m−2 year−1, respectively. In addition to climatic effects, the feedback between C and N turnover plays an important role that needs
to be more clearly understood to improve estimates of C sequestration in boreal forest ecosystems. 相似文献
4.
Rae-Hyun Kim Yowhan Son Jong Hwan Lim Im Kyun Lee Kyung Won Seo Jin Woo Koo Nam Jin Noh Soung-Ryoul Ryu Sun Kee Hong Byung Sun Ihm 《Ecological Research》2006,21(6):819-827
Coarse woody debris (CWD) is an essential component of forests. However, quantification of both the mass and nutrient content
of CWD within a given environment tends to be a fairly labor-intensive proposition that requires long-term studies to be conducted
for viable data to be obtained. As a result, various aspects of CWD in forest ecosystems remain somewhat poorly understood.
In this review, we have compiled all available estimates of CWD mass and nutrients from both coniferous and deciduous forests
in Korea. The CWD mass data varied substantially by forest type, age, location, and sampling time, ranging from 1.5 to 24.5 Mg ha−1, and for the amount (kg ha−1) of nutrients in the CWD, ranging from 3.5 to 23.6 for nitrogen (N), 0.8 to 4.7 for phosphorus (P), 3.9 to 13.3 for potassium
(K), 25.9 to 30.9 for calcium (Ca), 1.4 to 4.2 for magnesium (Mg), and 0.1 to 0.6 for sodium (Na). The mass of CWD transferred
from live trees to the forest floor ranged between 0.1 and 4.9 Mg ha−1 year−1, and these values were roughly equivalent to 26–42% of the annual litterfall inputs (2.5–10.8 Mg ha−1 year−1) for mixed Quercus spp. forests within the relevant region. Annual nutrients inputs (kg ha−1 year−1) through CWD decomposition were 0.7–1.6 for N, 0.04–0.3 for P, 0.3–1.0 for K, 1.7–3.1 for Ca, and 0.1–0.3 for Mg. Consequently,
these results revealed that the ecological value of CWD for C and nutrient cycling was relatively insignificant. However,
only a limited number of studies have been conducted on CWD in different coniferous or mixed deciduous forests in the region.
As a direct result of this paucity of data, further long-term studies on CWD mass and nutrients in a variety of forest types
are required in order to be able to evaluate accurately the ecological value of CWD on biodiversity and physical properties
in Korean forest ecosystems. 相似文献
5.
Mark S. Castro Keith N. Eshleman Louis F. Pitelka Geoff Frech Molly Ramsey William S. Currie Karen Kuers Jeffrey A. Simmons Bob R. Pohlad Carolyn L. Thomas David M. Johnson 《Biogeochemistry》2007,84(3):333-348
The objective of this study was to evaluate the nitrogen (N) biogeochemistry of an 18–22 year old forested watershed in western
Maryland. We hypothesized that this watershed should not exhibit symptoms of N saturation. This watershed was a strong source
of nitrate (NO3
−) to the stream in all years, with a mean annual export of 9.5 kg N ha−1 year−1 and a range of 4.4–18.4 kg N ha−1 year−1. During the 2001 and 2002 water years, wet deposition of inorganic N was 9.0 kg N ha−1 year−1 and 6.3 kg N ha−1 year−1, respectively. Watershed N export rates in 2001 and 2002 water years were 4.2 kg N ha−1 year−1 and 5.3 kg N ha−1 year−1, respectively. During the wetter water years of 2003 and 2004, the watershed exported 15.0 kg N ha−1 year−1 and 18.4 kg N ha−1 year−1, rates that exceeded annual wet deposition of N by a factor of two (7.5 kg N ha−1 year−1 in 2003) and three (5.5 kg N ha−1 year−1 in 2004). Consistent with the high rates of N export, were high concentrations (2.1–3.3%) of N in foliage, wood (0.3%) and
fine roots, low C:N ratios in the forest floor (17–24) and mineral soil (14), high percentages (83–96%) of the amount of mineralized
N that was nitrified and elevated N concentrations (up to 3 mg N l−1) in soil solution. Although this watershed contained a young aggrading forest, it exhibited several symptoms of N saturation
commonly observed in more mature forests. 相似文献
6.
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
7.
Natalia P. Kosykh Natalia G. Koronatova Natalia B. Naumova Argenta A. Titlyanova 《Wetlands Ecology and Management》2008,16(2):139-153
We measured phytomass stock and production in Western Siberian mire ecosystems (palsa, ridge, oligotrophic and mesotrophic
hollows, fen). To determine the contribution of different phytomass fractions into total production, we developed a method
to estimate below-ground production (BNP). Standing crop of living above-ground phytomass on treeless plots varied from 300
to 660 g m−2, reaching maximum on palsa, where 81% of phytomass consisted of Sphagnum mosses and lichens. In the hollows and the fen, Sphagnum percentage varied from 70 to 95%. Standing crop of living below-ground phytomass varied from 325 to 1,210 g m−2. It consisted of woody stems, stem bases, rhizomes and roots, with the latter contributing from 30 to 60%. Total production
of mire ecosystems in northern taiga of Western Siberia ranged from 350 to 960 g m−2 year−1 and depended on microtopography of the ecosystem (the presence of permafrost and water table depth). Production of treeless
plant communities located on the elevated sites depended on the presence of permafrost: in comparison with the ridge, palsa
production was lower. Production on the low sites increased with increase pH and reached maximum (960 g m−2 year−1) in poor fens. Bryophytes were the major producers above ground. Their production varied from 100 to 272 g m−2 year−1 and reached maximum on ridges. BNP contributed 37–66%, increasing due to increased contribution of sedges. 相似文献
8.
Woody encroachment into herbaceous ecosystems is emerging as an important ecological response to global change. A primary
concern is alterations in C and N cycling and associated variations across a variety of ecosystems. We quantified seasonal
variation in litterfall and litter N concentration in Morella cerifera shrub thickets to assess changes in litterfall and associated N input after shrub expansion on an Atlantic coast barrier
island. We also used the natural abundance of 15N to estimate the proportion of litterfall N originating from symbiotic N fixation. Litterfall for shrub thickets ranged from
8,991 ± 247 to 3,810 ± 399 kg ha−1 year−1 and generally declined with increasing thicket age. Litterfall in three of the four thickets exceeded previous estimates
of aboveground annual net primary production in adjacent grasslands by 300–400%. Leaf N concentration was also higher after
shrub expansion and, coupled with low N resorption efficiency and high litterfall, resulted in a return of as much as 169 kg N ha−1 year−1 to the soil. We estimated that ∼70% of N returned to the soil was from symbiotic N fixation resulting in an ecosystem input
of between 37 and 118 kg ha−1 year−1 of atmospheric N depending on site. Considering the extensive cover of shrub thickets on Virginia barrier islands, N fixation
by shrubs is likely the largest single source of N to the system. The shift from grassland to shrub thicket on barrier islands
results in a substantial increase in litterfall and foliar N concentration that will likely have a major impact on the size
and cycling of ecosystem C and N pools. Increasing C and N availability in these nutrient-poor soils is likely to permanently
reduce cover of native grasses and alter community structure by favoring species with greater N requirements. 相似文献
9.
Yuji Isagi 《Ecological Research》1994,9(1):47-55
Gross production and carbon cycling in aPhyllostachys bambusoides stand in Kyoto Prefecture, central Japan, were determined, and then a compartment model showing the carbon stock and cycling
within the ecosystem was developed. Aboveground carbon stock was 52.3 tC ha−1, increasing at a rate of 3.6 tC ha−1 year−1. Belowground carbon stock was 20.8 tC ha−1 in the root system and 92.0 tC ha−1 in the soil. Aboveground net production was 11.2 tC ha−1 year−1. Belowground net production was crudely estimated at 4.5 tC ha−1 year−1. The gross production was estimated at 41.8 tC ha−1 year−1 by summing the amount of outflow to the environment and the increment in biomass. Leaves consumed 13.7 tC ha−1 year−1 by respiration; the rest (41.8−13.7=28.1 tC ha−1 year−1) was surplus production of the leaves and flowed into the other compartments. The amounts of construction and maintenance
respiration of the aboveground compartments were 3.4 and 18.5 tC ha−1 year−1, respectively. The annual amount of soil respiration was 11.2 tC ha−1 year−1. Soil respiration levels of 4.3 and 3.1 tC ha−1 year−1 were estimated for the flow of root respiration and root detritus. The proportion of net to gross production was 37%, which
fell within the range of young and mature forests. A shorter life span of culms, compared to tree trunks, resulted in smaller
biomass accumulation ratio (biomass/net production) in the ecosystem, of 4.66. 相似文献
10.
Woody debris contribution to the carbon budget of selectively logged and maturing mid-latitude forests 总被引:3,自引:0,他引:3
Liu WH Bryant DM Hutyra LR Saleska SR Hammond-Pyle E Curran D Wofsy SC 《Oecologia》2006,148(1):108-117
Woody debris (WD) is an important component of forest C budgets, both as a C reservoir and source of CO2 to the atmosphere. We used an infrared gas analyzer and closed dynamic chamber to measure CO2 efflux from downed coarse WD (CWD; diameter≥7.5 cm) and fine WD (FWD; 7.5 cm>diameter≥2 cm) to assess respiration in a selectively logged forest and a maturing forest (control site) in the northeastern USA. We developed two linear regression models to predict WD respiration: one based on WD temperature, moisture, and size (R
2=0.57), and the other on decay class and air temperature (R
2=0.32). WD respiration (0.28±0.09 Mg C ha−1 year−1) contributed only ≈2% of total ecosystem respiration (12.3±0.7 Mg C ha−1 year−1, 1999–2003), but net C flux from CWD accounted for up to 30% of net ecosystem exchange in the maturing forest. C flux from CWD on the logged site increased modestly, from 0.61±0.29 Mg C ha−1 year−1 prior to logging to 0.77±0.23 Mg C ha−1 year−1 after logging, reflecting increased CWD stocks. FWD biomass and associated respiration flux were ≈7 times and ≈5 times greater, respectively, in the logged site than the control site. The net C flux associated with CWD, including inputs and respiratory outputs, was 0.35±0.19 Mg C ha−1 year−1 (net C sink) in the control site and −0.30±0.30 Mg C ha−1 year−1 (net C source) in the logged site. We infer that accumulation of WD may represent a small net C sink in maturing northern hardwood forests. Disturbance, such as selective logging, can enlarge the WD pool, increasing the net C flux from the WD pool to the atmosphere and potentially causing it to become a net C source.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
11.
Julie C. Pett-Ridge 《Biogeochemistry》2009,94(1):63-80
The input of phosphorus (P) through mineral aerosol dust deposition may be an important component of nutrient dynamics in
tropical forest ecosystems. A new dust deposition calculation is used to construct a broad analysis of the importance of dust-derived
P to the P budget of a montane wet tropical forest in the Luquillo Mountains of Puerto Rico. The dust deposition calculation
used here takes advantage of an internal geochemical signal (Sr isotope mass balance) to provide a spatially integrated longer-term
average dust deposition flux. Dust inputs of P (0.23 ± 0.08 kg ha−1 year−1) are compared with watershed-average inputs of P to the soil through the conversion of underlying saprolite into soil (between
0.07 and 0.19 kg ha−1 year−1), and with watershed-average losses of soil P through leaching (between 0.02 and 0.14 kg ha−1 year−1) and erosion (between 0.04 and 1.38 kg ha−1 year−1). The similar magnitude of dust-derived P inputs to that of other fluxes indicates that dust is an important component of
the soil and biomass P budget in this ecosystem. Dust-derived inputs of P alone are capable of completely replacing the total
soil and biomass P pool on a timescale of between 2.8 ka and 7.0 ka, less than both the average soil residence time (~15 ka)
and the average landslide recurrence interval (~10 ka). 相似文献
12.
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
13.
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
14.
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
15.
Reliable information about soil conservation capacities of different natural ecosystems is an important reference for the
design of targeted erosion and sediment control strategies. The objective of this paper is to quantify the soil conservation
capacities of different natural ecosystems that can represent different climatic zones. The 137Cs technique has been used to estimate soil redistribution rates in different natural ecosystems over the past 40 years in
Wolong Nature Reserve. The reserve, transiting from the Chengdu plain to the Qinghai-Tibet plateau, maintains rich ecosystems
from subtropical to frigid. The net soil erosion rates of 5 selected ecosystems that represent a warm coniferous-broadleaf-mixed
forest, a cold-resistant deciduous taiga forest, a cold-resistant shrub, an evergreen cold-resistant taiga forest, and an
alpine meadow are 0.17, 0.16, 0.13, 0.11 and 0.06 kg·m−2·a−1, respectively. Their soil conservation capacities are reversed in order. The reference inventories for 137Cs in different ecosystems range from 1658 to 3707 Bq·m−2 with the altitude. Results of this study indicate that any attempt to develop effective erosion and sediment strategies in
areas with similar climates should consider natural ecosystem types.
Supported by the National Natural Science Foundation of China (Grant No. 40321101) 相似文献
16.
Structure and Function of an Age Series of Eucalypt Plantations in Central Himalaya. I. Dry Matter Dynamics 总被引:2,自引:1,他引:1
The biomass and net primary productivity (NPP) of 2- to 8-year-oldplantations of Eucalyptus tereticornis Sm. (= E. hybrid) growingin the tarai (a level area of superabundant water) region ofCentral Himalaya were estimated. Allometric equations for allthe above-ground and below-ground components of trees and shrubswere developed for each stand. Understorey, forest floor biomassand litter fall were also estimated from stands. Shrubs appearedfirst at 5-year-old plantation. The biomass of vegetation, forestfloor littermass, tree litter fall and net primary productivity(NPP) of trees and shrubs increased with the increase in plantationage, whereas herb biomass and NPP significantly (P < 0·01)decreased with the increase in plantation age. The total plantationbiomass increased from 7·7 t ha1 in the 2-year-oldto 126·7 t ha1 in the 8-year-old plantation andNPP from 8·6 t ha1 year1 in the 2-year-oldto 23·4 t ha1 year1 in the 8-year-old plantation.The biomass accumulation ratio ranged from 0·81 to 5·93. Eucalyptus tereticornis Sm, plantation, biomass, forest floor, litter fall, net primary productivity, biomass accumulation ratio 相似文献
17.
Patches of common juniper (Juniperus communis L.) shrubs potentially facilitate the formation of fertile islands in heath tundra ecosystems thereby influencing the long-term
resilience of these ecosystems. Although the role of juniper in the formation of such ‘islands of fertility’ has been studied
in semiarid landscapes, there has been little attention paid to the importance of juniper in other ecosystems. In this study
we contrast the soil fertility and rates of N fixation under juniper shrubs with that in open heath tundra in northern Sweden.
Plots were established at several individual sites in alpine heath tundra in Northern Sweden and mineral soils to a depth
of 10 cm were characterized for available N and P and total C, N, P, Ca, Mg, K, Fe, Mn, Zn, and Cu. Nitrogen fixation rates
were measured by acetylene reduction in feather mosses under juniper canopies and contrasted with N fixation in both feather
mosses and surface soils in the open heath. Soils under juniper had concentrations of total P greatly in excess of P in open
heath, furthermore, juniper islands had the highest concentrations of bioavailable P. Nitrogen fixation rates in the feather moss Pleurozium schreberi (Bird.) Mitt were approximately 150 μmol acetylene reduced m−2 d−1 under the juniper canopy compared to less than 10 μmol acetylene reduced m−2 d−1 in the open heath. Feather mosses under the juniper canopy also fixed N at a significantly higher rate (on an aerial basis)
than that of surface cores from the open heath that included lichen, mosses, and soil crusts. Juniper facilitates the formation
of islands of soil fertility that may in turn facilitate the growth of other plants and positively influence the long term
recovery of heath tundra ecosystems following disturbance. 相似文献
18.
Kristell Hergoualc’h Ute Skiba Jean-Michel Harmand Catherine Hénault 《Biogeochemistry》2008,89(3):329-345
The objective of this study was to evaluate the effect of N fertilization and the presence of N2 fixing leguminous trees on soil fluxes of greenhouse gases. For a one year period, we measured soil fluxes of nitrous oxide
(N2O), carbon dioxide (CO2) and methane (CH4), related soil parameters (temperature, water-filled pore space, mineral nitrogen content, N mineralization potential) and
litterfall in two highly fertilized (250 kg N ha−1 year−1) coffee cultivation: a monoculture (CM) and a culture shaded by the N2 fixing legume species Inga densiflora (CIn). Nitrogen fertilizer addition significantly influenced N2O emissions with 84% of the annual N2O emitted during the post fertilization periods, and temporarily increased soil respiration and decreased CH4 uptakes. The higher annual N2O emissions from the shaded plantation (5.8 ± 0.3 kg N ha−1 year−1) when compared to that from the monoculture (4.3 ± 0.1 kg N ha−1 year−1) was related to the higher N input through litterfall (246 ± 16 kg N ha−1 year−1) and higher potential soil N mineralization rate (3.7 ± 0.2 mg N kg−1 d.w. d−1) in the shaded cultivation when compared to the monoculture (153 ± 6.8 kg N ha−1 year−1 and 2.2 ± 0.2 mg N kg−1 d.w. d−1). This confirms that the presence of N2 fixing shade trees can increase N2O emissions. Annual CO2 and CH4 fluxes of both systems were similar (8.4 ± 2.6 and 7.5 ± 2.3 t C-CO2 ha−1 year−1, −1.1 ± 1.5 and 3.3 ± 1.1 kg C-CH4 ha−1 year−1, respectively in the CIn and CM plantations) but, unexpectedly increased during the dry season. 相似文献
19.
Culm recruitment, standing crop biomass, net production and carbon flux were estimated in mature (5 years after last harvest)
and recently harvested bamboo (Dendrocalamus strictus (Roxb.) Nees) savanna sites in the dry tropics. During the 2 study years bamboo shoot recruitment was 1711–3182 and 1432–1510
shoots ha−1 in harvested and mature sites, respectively. Corresponding shoot mortality was 66–93% and 62–69%, respectively. Total biomass
was 34.9 t ha−1 at the harvested site and 47.4 t ha−1 at the mature site. Harvesting increased the relative contribution of belowground bamboo biomass. Annual litter input to
soil was 2.7 and 5.9 t ha−1 year−1 at the harvested and mature sites, respectively. The bulk of the annual litterfall (78–88%) occurred in the cool dry season
(November to February). The mean litter mass on the savanna floor ranged from 3.1 to 3.3 t ha−1; at the harvested site wood litter contributed 70% of the litter mass and at the mature site leaves formed 77% of the litter
mass. The mean total net production (TNP) for the two annual cycles was 15.8 t ha−1 year−1 at the harvested site and 19.3 t ha−1 year−1 at the mature site. Nearly half (46–57%) of the TNP was allocated to the belowground parts. Short lived components (leaves
and fine roots) contributed about four-fifths of the net production of bamboo. Total carbon storage in the system was 64.4
t ha−1 at the harvested site and 75.4 t ha−1 at the mature site, of which 23–28% was distributed in vegetation, 2% in litter and 70–75% in soil. Annual net carbon deposition
was 6.3 and 8.7 t ha−1 year−1 at harvested and mature sites, respectively. 相似文献
20.
Kyung Won Seo Su Jin Heo Yowhan Son Nam Jin Noh Sue Kyoung Lee Chun Gyeong Yoon 《Landscape and Ecological Engineering》2011,7(1):93-99
This study was conducted to examine the influences of soil-moisture conditions on soil nitrogen (N) dynamics, including in
situ soil N mineralization, N availability, and denitrification in a pure Alnus japonica forest located in Seoul, central Korea. The soil N mineralization, N availability, and denitrification were determined using
the buried bag incubation method, ion exchange resin bag method, and acetylene block method, respectively. The annual net
N mineralization rate (kg N ha−1 year−1) and annual N availability (mg N bag−1) were 40.26 and 80.65 in the relatively dry site, −5.43 and 45.39 in the moist site, and 7.09 and 39.17 in the wet site,
respectively. The annual net N mineralization rate and annual N availability in the dry site were significantly higher than
those in the moist and wet sites, whereas there was no significant difference between the moist and wet sites. The annual
mean denitrification rate (kg N ha−1 year−1) in the dry, moist, and wet sites was 2.37, 2.76, and 1.59, respectively. However, there was no significant difference among
sites due to the high spatial and temporal variations. Our results indicate that soil-moisture condition influenced the in
situ N mineralization and resin bag N availability in an A. japonica forest, and treatments of proper drainage for poorly drained sites would increase soil N mineralization and N availability
and consequently be useful to conserve and manage the A. japonica forest. 相似文献