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81.
针对传统生活污水水质相对复杂,处理与回用较为困难的问题,提出在收集时排除粪便水,选择厨房、洗漱、洗澡、洗涤的污水,利用浸没式膜生物反应器(SMBR)技术实现无粪便污水的快速处理,再生水回用于冲厕.结果表明:此种污水COD、NH4+-N和TP含量低,具有良好的可生化性,可大大降低处理周期与处理成本.本技术优化的主要工艺条件为:污泥浓度范围7000~9100 mg·L-1,污泥龄(SRT)40~55 d,水力停留时间(HRT)为80min,气水比为12~15,处理效果好,微滤膜对稳定出水水质起到重要作用.在此条件下,COD、NH4+-N和TP去除率分别为85.5%、53.1%和44.9%.出水COD在20~30 mg·L-1,BOD5为1~5 mg·L-1,NH4+-N为2~3.08 mg·L-1,TP为0.59~0.9 mg·L-1,LAS为0.41~0.67 mg·L-1,去除效果较好,再生水水质可达到<城市污水再生利用城市杂用水水质>(GB/T 18920-2002)标准. 相似文献
82.
Samuel Pinna Hirondelle Varady-Szabo Patrick Boivin Eric Lucas 《Journal of Insect Conservation》2009,13(4):387-397
Urban habitats harbour considerable biological diversity. Ecologists have developed methods to select which habitats should
be conserved. The Ecological value, a method based on vegetation, has been created for the urban habitats of Montreal (Quebec, Canada). The main objective of
our study was to determine if this method was relevant to assess carabid diversity of Mount Royal Park. This index is calculated
using five criteria: uniqueness, representativeness, degree of succession, richness and rarity of the flora, each of which
can influence communities of insects. Ground beetles (Coleoptera: Carabidae) were selected because of their success as biological
indicators. Despite sampling difficulties, our results demonstrate clearly that the Ecological value method does not represent the high carabid richness of urban open habitats (tall grasses) and their specialised native carabid
species. Within forests we found nonetheless that the ecological value index has a significant positive relationship with
native carabid abundance. Moreover, maturity and structure of urban forests were positively correlated with carabid abundance
and richness. Some urban vegetation characteristics have been shown to influence entomological diversity, but the relevance
of using a global floral index to encompass the carabid community seems limited. 相似文献
83.
Mapping continuous fields of forest alpha and beta diversity 总被引:1,自引:0,他引:1
Question: How to map continuous fields of forest alpha and beta diversity in remote areas, based on easily accessible spatial data. Location: Kyrgyzstan/Central Asia. Methods: The study relied on a combination of predictive mapping and remote sensing. Punctual measurements of alpha diversity were linked to topography and reflectance using regression models. For beta diversity, ordination techniques were employed to extract major vegetation gradients. Scores on the ordination axes were regressed against topography as well as reflectance and subsequently mapped. Beta diversity was mapped as spatial turnover rate along these axes. Results: The diversity maps quantified species counts and turnover in a spatially contiguous manner while taking into account fuzzy transitions. The variance explained by regression models ranged from 51% to 61% in cross‐validation. Many of the observed differences were caused by differences in species shares. The occurrence of walnut, in particular, showed a negative relation to woody species numbers. Conclusion: Mapping biodiversity in remote areas can be based on easily accessible spatial data in combination with a set of calibration field samples. With regard to human influence on walnut dominance, a total removal of human land use would be counterproductive in terms of diversity conservation. The results of this study highlight the need for comprehensive analyses of diversity patterns that include spatially contiguous quantifications of species numbers, shares and turnover rates. 相似文献
84.
We repeatedly sampled the surface mineral soil (0–20 cm depth) in three northern temperate forest communities over an 11-year experimental fumigation to understand the effects of elevated carbon dioxide (CO2 ) and/or elevated phyto-toxic ozone (O3 ) on soil carbon (C). After 11 years, there was no significant main effect of CO2 or O3 on soil C. However, within the community containing only aspen ( Populus tremuloides Michx.), elevated CO2 caused a significant decrease in soil C content. Together with the observations of increased litter inputs, this result strongly suggests accelerated decomposition under elevated CO2. In addition, an initial reduction in the formation of new (fumigation-derived) soil C by O3 under elevated CO2 proved to be only a temporary effect, mirroring trends in fine root biomass. Our results contradict predictions of increased soil C under elevated CO2 and decreased soil C under elevated O3 and should be considered in models simulating the effects of Earth's altered atmosphere. 相似文献
85.
Toby A. Gardner Jos Barlow Robin Chazdon Robert M. Ewers Celia A. Harvey Carlos A. Peres Navjot S. Sodhi 《Ecology letters》2009,12(6):561-582
The future of tropical forest biodiversity depends more than ever on the effective management of human-modified landscapes, presenting a daunting challenge to conservation practitioners and land use managers. We provide a critical synthesis of the scientific insights that guide our understanding of patterns and processes underpinning forest biodiversity in the human-modified tropics, and present a conceptual framework that integrates a broad range of social and ecological factors that define and contextualize the possible future of tropical forest species. A growing body of research demonstrates that spatial and temporal patterns of biodiversity are the dynamic product of interacting historical and contemporary human and ecological processes. These processes vary radically in their relative importance within and among regions, and have effects that may take years to become fully manifest. Interpreting biodiversity research findings is frequently made difficult by constrained study designs, low congruence in species responses to disturbance, shifting baselines and an over-dependence on comparative inferences from a small number of well studied localities. Spatial and temporal heterogeneity in the potential prospects for biodiversity conservation can be explained by regional differences in biotic vulnerability and anthropogenic legacies, an ever-tighter coupling of human-ecological systems and the influence of global environmental change. These differences provide both challenges and opportunities for biodiversity conservation. Building upon our synthesis we outline a simple adaptive-landscape planning framework that can help guide a new research agenda to enhance biodiversity conservation prospects in the human-modified tropics. 相似文献
86.
Natalia Norden Robin L. Chazdon Anne Chao Yi-Huei Jiang Braulio Vílchez-Alvarado 《Ecology letters》2009,12(5):385-394
Understanding the recovery dynamics of ecosystems presents a major challenge in the human-impacted tropics. We tested whether secondary forests follow equilibrium or non-equilibrium dynamics by evaluating community reassembly over time, across different successional stages, and among multiple life stages. Based on long-term and static data from six 1-ha plots in NE Costa Rica, we show that secondary forests are undergoing reassembly of canopy tree and palm species composition through the successful recruitment of seedlings, saplings, and young trees of mature forest species. Such patterns were observed over time within sites and across successional stages. Floristic reassembly in secondary forests showed a clear convergence with mature forest community composition, supporting an equilibrium model. This resilience stems from three key factors co-occurring locally: high abundance of generalist species in the regional flora, high levels of seed dispersal, and local presence of old-growth forest remnants. 相似文献
87.
Erin Stewart Lindquist Ken W. Krauss Peter T. Green Dennis J. O'Dowd Peter M. Sherman and Thomas J. Smith III 《Biological reviews of the Cambridge Philosophical Society》2009,84(2):203-223
Plant populations are regulated by a diverse assortment of abiotic and biotic factors that influence seed dispersal and viability, and seedling establishment and growth at the microsite. Rarely does one animal guild exert as significant an influence on different plant assemblages as land crabs. We review three tropical coastal ecosystems–mangroves, island maritime forests, and mainland coastal terrestrial forests–where land crabs directly influence forest composition by limiting tree establishment and recruitment. Land crabs differentially prey on seeds, propagules and seedlings along nutrient, chemical and physical environmental gradients. In all of these ecosystems, but especially mangroves, abiotic gradients are well studied, strong and influence plant species distributions. However, we suggest that crab predation has primacy over many of these environmental factors by acting as the first limiting factor of tropical tree recruitment to drive the potential structural and compositional organisation of coastal forests. We show that the influence of crabs varies relative to tidal gradient, shoreline distance, canopy position, time, season, tree species and fruiting periodicity. Crabs also facilitate forest growth and development through such activities as excavation of burrows, creation of soil mounds, aeration of soils, removal of leaf litter into burrows and creation of carbon-rich soil microhabitats. For all three systems, land crabs influence the distribution, density and size-class structure of tree populations. Indeed, crabs are among the major drivers of tree recruitment in tropical coastal forest ecosystems, and their conservation should be included in management plans of these forests. 相似文献
88.
The montane ecosystems of northern California have been subjected to repeated manipulation and active fire suppression for over a century, resulting in changes in community structure that contribute to increased wildfire hazard. Ecosystem restoration via reduction of stand density for wildfire hazard mitigation has received substantial attention in recent years; however, many ecological questions remain unanswered. This study compares belowground effects of two alternative forest thinning treatments designed to restore the large, old tree component of late‐seral structure, one of which focuses on restoring Pinus ponderosa dominance (Pine‐preference) and the other of which promotes development of large trees regardless of species (Size‐preference). We evaluated forest floor and soil chemical and microbial parameters in six experimental thinning treatment units of 40 ha each in the Klamath National Forest of northern California 5–6 years after thinning. Inorganic N availability, soil organic C content, phenol oxidase activity, and forest floor C:N ratio were greater in the Size‐preference treatment, whereas forest floor N and soil pH were greater in the Pine‐preference treatment. Our results indicate that these two thinning strategies produce differences in the soil environment that has the potential to affect growth rates of trees that remain, as well as the growth and survivorship of newly established seedlings. Thus, which species/individuals are removed during structural restoration of these mixed‐conifer forests matters both to the belowground components of the ecosystem today and the vegetation and productivity of the ecosystem in future decades. 相似文献
89.
ERIKA MARIN-SPIOTTA WHENDEE L. SILVER CHRISTOPHER W. SWANSTON† REBECCA OSTERTAG‡ 《Global Change Biology》2009,15(6):1584-1597
Our research takes advantage of a historical trend in natural reforestation of abandoned tropical pastures to examine changes in soil carbon (C) during 80 years of secondary forest regrowth. We combined a chronosequence approach with differences in the natural abundance of 13 C between C3 (forest) and C4 (pasture) plants to estimate turnover times of C in the bulk soil and in density fractions. Overall, gains in secondary forest C were compensated for by the loss of residual pasture-derived soil C, resulting in no net change in bulk soil C stocks down to 1 m depth over the chronosequence. The free light fraction (LF), representing physically unprotected particulate organic matter, was most sensitive to land-use change. Reforestation replenished C in the free LF that had been depleted during conversion to pastures. Turnover times varied with model choice, but in general, soil C cycling rates were rapid for the 0–10 cm depth, with even the heavy fraction (HF) containing C cycling in decadal time scales. Turnover times of C in the free LF from the 0–10 cm depth were shorter than for the occluded and HFs, highlighting the importance of physical location in the soil matrix for residence time in the soil. The majority of the soil C pool (82±21%) was recovered in the mineral-associated density fraction. Carbon-to-nitrogen ratios and differences in natural abundance 15 N of soil organic matter (SOM) showed an increasing degree of decomposition across density fractions with increasing mineral association. Our data show that the physical distribution of C in the soil has a large impact on soil C turnover and the ability of soils to maintain SOM stocks during land-use and land-cover change. 相似文献
90.
N. DELPIERRE †‡ K. SOUDANI †‡ C. FRANÇOIS †‡ B. KÖSTNER§ J.-Y. PONTAILLER †‡ E. NIKINMAA¶ L. MISSON M. AUBINET C. BERNHOFER§ A. GRANIER†† T. GRÜNWALD§ B. HEINESCH B. LONGDOZ†† J.-M. OURCIVAL S. RAMBAL T. VESALA¶ E. DUFRÊNE †‡ 《Global Change Biology》2009,15(6):1455-1474
Temperate and boreal forests undergo drastic functional changes in the springtime, shifting within a few weeks from net carbon (C) sources to net C sinks. Most of these changes are mediated by temperature. The autumn 2006–winter 2007 record warm period was followed by an exceptionally warm spring in Europe, making spring 2007 a good candidate for advances in the onset of the photosynthetically active period. An analysis of a decade of eddy covariance data from six European forests stands, which encompass a wide range of functional types (broadleaf evergreen, broadleaf deciduous, needleleaf evergreen) and a wide latitudinal band (from 44° to 62°N), revealed exceptional fluxes during spring 2007. Gross primary productivity (GPP) of spring 2007 was the maximum recorded in the decade examined for all sites but a Mediterranean evergreen forest (with a +40 to +130 gC m?2 anomaly compared with the decadal mean over the January–May period). Total ecosystem respiration (TER) was also promoted during spring 2007, though less anomalous than GPP (with a +17 to +93 gC m?2 anomaly over 5 months), leading to higher net uptake than the long‐term mean at all sites (+12 to +79 gC m?2 anomaly over 5 months). A correlative analysis relating springtime C fluxes to simple phenological indices suggested spring C uptake and temperatures to be related. The CASTANEA process‐based model was used to disentangle the seasonality of climatic drivers (incoming radiation, air and soil temperatures) and biological drivers (canopy dynamics, thermal acclimation of photosynthesis to low temperatures) on spring C fluxes along the latitudinal gradient. A sensitivity analysis of model simulations evidenced the roles of (i) an exceptional early budburst combined with elevated air temperature in deciduous sites, and (ii) an early relief of winter thermal acclimation in coniferous sites for the promotion of 2007 spring assimilation. 相似文献