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991.
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
992.
Ryoma Kamikawa Shoko Hosoi-Tanabe Sadaaki Yoshimatsu Kenichi Oyama Isao Masuda Yoshihiko Sako 《Journal of applied phycology》2008,20(2):153-159
Although the molecular data currently used for identifying dinoflagellates are generally limited to nuclear ribosomal RNA
genes, some dinoflagellates cannot be identified by their gene sequence or morphotype, suggesting that additional effective
molecular makers are required. We report here a novel species-specific marker on the mitochondrial (mt) genome of dinoflagellates
belonging to six Alexandrium spp., namely, A. tamarense, A. catenella, A. tamiyavanichii, A. affine, A. hiranoi, and A. pseudogonyaulax. This new mt marker was able to clearly differentiate these six species. PCR analysis using a primer set for the A. tamarense-specific sequence confirmed that this sequence is conserved in A. tamarense strains but not in other dinoflagellate species. We also sequenced the mt genome containing the developed molecular marker
using a single cell from a field sample, which suggests that this marker is a powerful tool for identifying unculturable dinoflagellates.
The sequenced molecular region was also used to identify Alexandrium-like cells isolated from environmental seawater as A. tamarense and A. affine. 相似文献
993.
Pseudomonas putida CSV86 utilizes naphthalene (Nap), salicylate (Sal), benzyl alcohol (Balc), and methylnaphthalene (MN) preferentially over
glucose. Methylnaphthalene is metabolized by ring-hydroxylation as well as side-chain hydroxylation pathway. Although the
degradation property was found to be stable, the frequency of obtaining Nap−Sal−MN−Balc− phenotype increased to 11% in the presence of curing agents. This property was transferred by conjugation to Stenotrophomonas maltophilia CSV89 with a frequency of 7 × 10−8 per donor cells. Transconjugants were Nap+Sal+MN+Balc+ and metabolized MN by ring- as well as side-chain hydroxylation pathway. Transconjugants also showed the preferential utilization
of aromatic compounds over glucose indicating transfer of the preferential degradation property. The transferred properties
were lost completely when transconjugants were grown on glucose or 2YT. Attempts to detect and isolate plasmid DNA from CSV86
and transconjugants were unsuccessful. Transfer of degradation genes and its subsequent loss from the transconjugants was
confirmed by PCR using primers specific for 1,2-dihydroxynaphthalene dioxygenase and catechol 2,3-dioxygenase (C23O) as well
as by DNA–DNA hybridizations using total DNA as template and C23O PCR fragment as a probe. These results indicate the involvement
of a probable conjugative element in the: (i) metabolism of aromatic compounds, (ii) ring- and side-chain hydroxylation pathways
for MN, and (iii) preferential utilization of aromatics over glucose. 相似文献
994.
Gayathri Babarenda Gamage Carol Boyle Sarah J. McLaren Jake McLaren 《The International Journal of Life Cycle Assessment》2008,13(5):401-411
Background, aims and scope The environmental aspects of companies and their products are becoming more significant in delivering competitive advantage.
Formway Furniture, a designer and manufacturer of office furniture products, is a New Zealand-based company that is committed
to sustainable development. It manufactures two models of the light, intuitive, flexible and environmental (LIFE) office chair:
one with an aluminium base and one with a glass-filled nylon (GFN) base. It was decided to undertake a life cycle assessment
(LCA) study of these two models in order to: (1) determine environmental hotspots in the life cycle of the two chairs (goal
1); (2) compare the life cycle impacts of the two chairs (goal 2); and (3) compare alternative potential waste-management
scenarios (goal 3). The study also included sensitivity analysis with respect to recycled content of aluminium in the product.
Materials and methods The LIFE chair models consist of a mix of metal and plastic components manufactured by selected Formway suppliers according
to design criteria. Hence, the research methodology included determining the specific material composition of the two chair
models and acquisition of manufacturing data from individual suppliers. These data were compiled and used in conjunction with
pre-existing data, specifically from the ecoinvent database purchased in conjunction with the SimaPro7 LCA software, to develop
the life cycle inventory of the two chair models. The life cycle stages included in the study extended from raw-material extraction
through to waste management. Impact assessment was carried out using CML 2 baseline 2000, the methodology developed by Leiden
University’s Institute for Environmental Sciences.
Results This paper presents results for global warming potential (GWP100). The study showed a significant impact contribution from
the raw-material extraction/refinement stage for both chair models; aluminium extraction and refining made the greatest contribution
to GWP100. The comparison of the two LIFE chair models showed that the model with the aluminium base had a higher GWP100 impact
than the model with the GFN base. The waste-management scenario compared the GWP100 result when (1) both chair models were
sent to landfill and (2) steel and aluminium components were recycled with the remainder of the chair sent to landfill. The
results showed that the recycling scenario contributed to a reduced GWP100 result. Since production and processing of aluminium
was found to be significant, a sensitivity analysis was carried out to determine the impact of using aluminium with different
recycled contents (0%, 34% and 100%) in both waste-management scenarios; this showed that increased use of recycled aluminium
was beneficial. The recycling at end-of-life scenarios was modelled using two different end-of-life allocation approaches,
i.e. consequential and attributional, in order to illustrate the variation in results caused by choice of allocation approach.
The results using the consequential approach showed that recycling at end-of-life was beneficial, while use of the attributional
method led to a similar GWP100 as that seen for the landfill scenario.
Discussion The results show that the main hotspot in the life cycle is the raw-material extraction/refinement stage. This can be attributed
to the extraction and processing of aluminium, a material that is energy intensive. The LIFE chair model with the aluminium
base has a higher GWP100 as it contains more aluminium. Sensitivity analysis pertaining to the recycled content of aluminium
showed that use of aluminium with high recycled content was beneficial; this is because production of recycled aluminium is
less energy intensive than production of primary aluminium. The waste-management scenario showed that recycling at end-of-life
resulted in a significantly lower GWP100 than landfilling at end-of-life. However, this result is dependent upon the modelling
approach used for recycling.
Conclusions With respect to goal 1, the study found that the raw-material extraction/refinement stage of the life cycle was a significant
factor for both LIFE chair models. This was largely due to the use of aluminium in the product. For goal 2, it was found that
the LIFE chair model with the aluminium base had a higher GWP100 than the GFN model, again due to the material content of
the two models. Results for goal 3 illustrated that recycling at end-of-life is beneficial when using a system expansion (consequential)
approach to model recycling; if an attributional ‘cut-off’ approach is used to model recycling at end-of-life, there is virtually
no difference in the results between landfilling and recycling. Sensitivity analysis pertaining to the recycled content of
aluminium showed that use of higher recycled contents leads to a lower GWP100 impact.
Recommendation and perspectives Most of the GWP100 impact was contributed during the raw-material extraction/refinement stage of the life cycle; thus, the
overall impact of both LIFE chair models may be reduced through engaging in material choice and supply chain environmental
management with respect to environmental requirements. The study identified aluminium components as a major contributor to
GWP100 for both LIFE chair models and also highlighted the sensitivity of the results to its recycled content. Thus, it is
recommended that the use of aluminium in future product designs be limited unless it is possible to use aluminium with a high
recycled content. With respect to waste management, it was found that a substantial reduction in the GWP100 impact would occur
if the chairs are recycled rather than landfilled, assuming an expanding market for aluminium. Thus, recycling the two LIFE
chair models at end-of-life is highly recommended. 相似文献
995.
One simple but efficient carbon-supplying device was designed and developed, and the correlative carbon-supplying technology was described. The absorbing characterization of this device was studied. The carbon-supplying system proved to be economical for large-scale cultivation of Spirulina sp. in an outdoor raceway pond, and the gaseous carbon dioxide absorptivity was enhanced above 78%, which could reduce the production cost greatly. 相似文献
996.
Alternative strategies to sustain N-fertility in acid and calcaric beech forests: Low microbial N-demand versus high biological activity 总被引:1,自引:0,他引:1
A.M. Kooijman M.M. Kooijman-Schouten G.B. Martinez-Hernandez 《Basic and Applied Ecology》2008,9(4):410-421
To challenge the “conventional wisdom” that rates of net N-mineralization increase with pH, we measured net N-mineralization, respiration and/or microbial C and N in four Luxembourg beech forests with similar litter input, but different soil types, using laboratory incubation experiments. Litter input and fungal/bacterial colony ratios were also measured. To test whether the results could be explained by existing theoretical models, equations of C and N dynamics were reformulated to allow estimation of microbial growth efficiency, gross C and N release and microbial uptake, based on measured values of net N-mineralization, respiration and C:N ratios of substrate and microbes.Instead of an increase, net N-mineralization rates showed a significant sevenfold decrease from acid to calcaric soil in the organic layer, and a fourfold decrease in the mineral topsoil. At the same time, microbial N-demand increased with pH, as indicated by the significant decrease in net N-mineralization per unit microbe or unit C respired. These results could be explained by theoretical models. In organic layer and mineral topsoil, despite high gross N-release, net N-mineralization rates decreased with pH because of higher microbial immobilization. Increase in microbial N-demand was associated with a decrease in fungal/bacterial colony ratio: the more the bacteria, the higher the microbial N-demand.Acid and calcaric soils seem to have different strategies to sustain ecosystem N-fertility. In calcaric soil, N-availability to the vegetation seems indeed supported by high biological activity and gross N-release, which is needed to compensate for the potentially high immobilization by bacteria. In acid soil, however, despite low gross N-release, N-availability to the vegetation may not be lower than in calcaric soil, due to high amounts of fungi and low microbial N-demand. 相似文献
997.
We model plant species diversity globally by country to show that future plant diversity capacity has a strong dependence on changing climate and carbon dioxide concentration. CO2 increase, through its impact on net primary production and warming is predicted to increase regional diversity capacity, while warming with constant CO2 leads to decreases in diversity capacity. Increased CO2 concentrations are unlikely to counter projected extinctions of endemic species, shown in earlier studies to be more strongly dependent on changing land use patterns than climate per se. Model predictions were tested against (1) contemporary observations of tree species diversity in different biomes, (2) an independent global map of contemporary species diversity and (3) time sequences of plant naturalisation for different locations. Good agreements between model, observations and naturalisation patterns support the suggestion that future diversity capacity increases are likely to be filled from a 'cosmopolitan weed pool' for which migration appears to be an insignificant barrier. 相似文献
998.
To explore the importance of 12 elements in litter production and decomposition, we fertilized 36 1600 m2 -plots with combinations of N, P, K, or micronutrients (i.e. B, Ca, Cu, Fe, Mg, Mn, Mo, S, Zn) for 6 years in a lowland Panamanian forest. The 90% of litter falling as leaves and twigs failed to increase with fertilization, but reproductive litter (fruits and flowers) increased by 43% with N. K enhanced cellulose decomposition; one or more micronutrients enhanced leaf-litter decomposition; P enhanced both. Our results suggest tropical forests are a non-Liebig world of multiple nutrient limitations, with at least four elements shaping rates of litterfall and decomposition. Multiple metallomic enzymes and cofactors likely create gradients in the break down of leaf litter. Selection favours individuals that make more propagules, and even in an N-rich forest, N is a non-substitutable resource for reproduction. 相似文献
999.
Information on movement patterns of marine fishes between estuarine populations and stocks at sea is fundamental to understanding their population dynamics, life history tactics and behavior. Furthermore, understanding estuarine habitat use by marine fishes is crucial for their effective conservation and integrated estuarine management. Although large numbers of young marine fish make use of temperate estuaries in highly predictable abundance patterns, very little is known about how estuarine populations interact with the populations at sea. Recruitment of sand goby Pomatoschistus minutus (Pallas, 1770) into the low salinity zone of the Scheldt estuary (Belgium) was reconstructed over an entire year by means of an isotopic clock. These results were combined with a growth model to yield age and length at immigration. Sand gobies entered the upper Scheldt estuary almost continuously from May onwards, except in July when they appeared to avoid the estuary due to warm summer temperatures. About 70% of the fish caught in the upper estuary resided there for less than 1 month, which indicates a strong temporal overlap of immigration and emigration. This complex migration pattern suggests that estuarine residence is caused by trade-offs made at the individual level, whereby migration is probably triggered by temperature. The high turnover of individuals in the estuarine population leads us to question the functional role of the estuary for marine fishes. Sand gobies entering the upper estuary had a wide range of ages and body sizes, although they were at least 2 months old and had a minimum standard length of approximately 20 mm. This study shows that the use of an isotopic clock strongly complements catch data and is useful to describe the connectivity between populations. 相似文献
1000.
δ13C values of C3 plants are indicators of plant carbon–water relations that integrate plant responses to environmental conditions. However,
few studies have quantified spatial variation in plant δ13C at the landscape scale. We determined variation in leaf δ13C, leaf nitrogen per leaf area (Narea), and specific leaf area (SLA) in April and August 2005 for all individuals of three common woody species within a 308 × 12-m
belt transect spanning an upland–lowland topoedaphic gradient in a subtropical savanna in southern Texas. Clay content, available
soil moisture, and soil total N were all negatively correlated with elevation. The δ13C values of Prosopis glandulosa (deciduous N2-fixing tree legume), Condalia hookeri (evergreen shrub), and Zanthoxylum fagara (evergreen shrub) leaves increased 1–4‰ with decreasing elevation, with the δ13C value of P. glandulosa leaves being 1–3‰ higher than those of the two shrub species. Contrary to theory and results from previous studies, δ13C values were highest where soil water was most available, suggesting that some other variable was overriding or interacting
with water availability. Leaf Narea was positively correlated with leaf δ13C of all species (p < 0.01) and appeared to exert the strongest control over δ13C along this topoedaphic gradient. Since leaf Narea is positively related to photosynthetic capacity, plants with high leaf Narea are likely to have low p
I/p
a ratios and therefore higher δ13C values, assuming stomatal conductance is constant. Specific leaf area was not correlated significantly with leaf δ13C. Following a progressive growing season drought in July/August, leaf δ13C decreased. The lower δ13C in August may reflect the accumulation of 13C-depleted epicuticular leaf wax. We suggest control of leaf δ13C along this topoedaphic gradient is mediated by leaf Narea rather than by stomatal conductance limitations associated with water availability. 相似文献