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271.
Repeated fertilization of forests to increase biomass production is an environmentally controversial proposal, the effects
of which we assessed on breeding birds in stands of young Norway spruce (Picea abies), in an intensively managed forest area in southern Sweden. Our results show that fertilized stands had 38% more species
and 21% more individuals than unfertilized stands. Compared with stands under traditional management, the further intensification
of forestry by repeated applications of fertilizers thus seemed to enhance species richness and abundance of forest birds.
We cannot conclude at this stage whether the response in the bird community was caused by changes in food resources or increased
structural complexity in the forest canopy due to the skid roads used for the application of the fertilizers. Future studies
should focus on structural and compositional effects of fertilization processes during the entire rotation period and at assessing
its effects in a landscape context. 相似文献
272.
273.
Time series of abundance estimates are commonly used for analyses of population trends and possible shifts in growth rate.
We investigate if trends in age composition can be used as an alternative to abundance estimates for detection of decelerated
population growth. Both methods were tested under two forms of density dependence and different levels of environmental variation
in simulated time series of growth in Baltic gray seals. Under logistic growth, decelerating growth could be statistically
confirmed after 16 years based on population counts and 14 years based on age composition. When density dependence sets in
first at larger population sizes, the age composition method performed dramatically better than population counts, and a decline
could be detected after 4 years (versus 10 years). Consequently, age composition analysis provides a complementary method
to detect density dependence, particularly in populations where density dependence sets in late. 相似文献
274.
De Jaeger S Eyckmans J Rogge N Van Puyenbroeck T 《Waste management (New York, N.Y.)》2011,31(7):1429-1440
We study the impact of some local policies aimed at municipal solid waste (MSW) reduction on the cost efficiency of MSW collection and disposal. We explicitly account for differences between municipalities in background conditions by using a bootstrapped version of the Data Envelopment Analysis methodology in combination with a matching technique. Using data on 299 municipalities in Flanders, Belgium, for the year 2003, our results indicate that municipalities that are member of a waste collection joint venture, or that subscribe to a voluntary agreement to reduce MSW at the highest ambition level, collect and process MSW more efficiently than other municipalities. Weekly instead of two-weekly waste collection, or using a weight-based pricing system appears to have no impact on efficiency. Our results show that aiming at MSW reduction does not lead to lower efficiency of public service provision, even on the contrary. 相似文献
275.
Johan De Tavernier 《Journal of Agricultural and Environmental Ethics》2009,22(4):383-388
276.
Johan Eriksson Ulf Skyllberg 《Environmental pollution (Barking, Essex : 1987)》2009,157(11):3010-3015
Aniline and 2,4,6-trinitrotoluene (TNT) were equilibrated with particulate (POM) and dissolved organic matter (DOM) from an organic soil at different compositions of adsorbed major cations (Na, Al) and pH (aniline: 3.7–5.1, TNT: 4.8–5.0). After separation of POM, concentrations of 14C-labelled aniline and TNT* (including TNT degradation products) were determined in DOM size fractions using size-exclusion chromatography (SEC) and UV-detection. Concentrations in the <3.5 kDa size fraction were 2.8–6.0 and 8.5–9.5 times higher for aniline and TNT*, respectively, as compared to the >40 kDa fraction. Thus, both aniline and TNT* were preferentially associated to the smallest DOM size fraction. The significant binding to DOM (similar extent as to POM) and the fact that the <3.5 kDa DOM fraction was less susceptible to flocculation by major metals suggests that the mobility of aniline and TNT is highly affected by the solubility of soil organic matter. 相似文献
277.
Anna Christiansson Johan Eriksson Daniel Teclechiel Åke Bergman 《Environmental science and pollution research international》2009,16(3):312-321
Background, aim, and scope Decabromodiphenyl ether (DecaBDE) is used as an additive flame retardant in polymers. It has become a ubiquitous environmental
contaminant, particularly abundant in abiotic media, such as sediments, air, and dust, and also present in wildlife and in
humans. The main DecaBDE constituent, perbrominated diphenyl ether (BDE-209), is susceptible to transformations as observed
in experimental work. This work is aimed at identifying and assessing the relative amounts of products formed after UV irradiation
of BDE-209.
Materials and methods BDE-209, dissolved in tetrahydrofuran (THF), methanol, or combinations of methanol/water, was exposed to UV light for 100
or 200 min. Samples were analyzed by gas chromatography/mass spectrometry (electron ionization) for polybrominated diphenyl
ethers (PBDEs), dibenzofurans (PBDFs), methoxylated PBDEs, and phenolic PBDE products.
Results The products formed were hexaBDEs to nonaBDEs, monoBDFs to pentaBDFs, and methoxylated tetraBDFs to pentaBDFs. The products
found in the fraction containing halogenated phenols were assigned to be pentabromophenol, dihydroxytetrabromobenzene, dihydroxydibromodibenzofuran,
dihydroxytribromodibenzofuran, and dihydroxytetrabromodibenzofuran. The PBDEs accounted for approximately 90% of the total
amount of substances in each sample and the PBDFs for about 10%.
Discussion BDE-209 is a source of PBDEs primarily present in OctaBDEs but also to some extent in PentaBDEs, both being commercial products
now banned within the EU and in several states within the USA. It is notable that OH-PBDFs have not been identified or indicated
in any of the photolysis studies performed to date. Formation of OH-PBDFs, however, may occur as pure radical reactions in
the atmosphere.
Conclusions Photolysis of decaBDE yields a wide span of products, from nonaBDEs to hydroxylated bromobenzenes. It is evident that irradiation
of decaBDE in water and methanol yields OH-PBDFs and MeO-PBDFs, respectively. BDE-202 (2,2′,3,3′,5,5′,6,6′-octabromodiphenyl
ether) is identified as a marker of BDE-209 photolysis.
Recommendations and perspectives BDE-209, the main constituent of DecaBDE, is primarily forming debrominated diphenyl ethers with higher persistence which
are more bioaccumulative than the starting material when subjected to UV light. Hence, DecaBDE should be considered as a source
of these PBDE congeners in the environment.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
278.
Evaluation of land-use regression models used to predict air quality concentrations in an urban area
Markey Johnson V. Isakov J.S. Touma S. Mukerjee H. Özkaynak 《Atmospheric environment (Oxford, England : 1994)》2010,44(30):3660-3668
Cohort studies designed to estimate human health effects of exposures to urban pollutants require accurate determination of ambient concentrations in order to minimize exposure misclassification errors. However, it is often difficult to collect concentration information at each study subject location. In the absence of complete subject-specific measurements, land-use regression (LUR) models have frequently been used for estimating individual levels of exposures to ambient air pollution. The LUR models, however, have several limitations mainly dealing with extensive monitoring data needs and challenges involved in their broader applicability to other locations. In contrast, air quality models can provide high-resolution source–concentration linkages for multiple pollutants, but require detailed emissions and meteorological information. In this study, first we predicted air quality concentrations of PM2.5, NOx, and benzene in New Haven, CT using hybrid modeling techniques based on CMAQ and AERMOD model results. Next, we used these values as pseudo-observations to develop and evaluate the different LUR models built using alternative numbers of (training) sites (ranging from 25 to 285 locations out of the total 318 receptors). We then evaluated the fitted LUR models using various approaches, including: 1) internal “Leave-One-Out-Cross-Validation” (LOOCV) procedure within the “training” sites selected; and 2) “Hold-Out” evaluation procedure, where we set aside 33–293 tests sites as independent datasets for external model evaluation. LUR models appeared to perform well in the training datasets. However, when these LUR models were tested against independent hold out (test) datasets, their performance diminished considerably. Our results confirm the challenges facing the LUR community in attempting to fit empirical response surfaces to spatially- and temporally-varying pollution levels using LUR techniques that are site dependent. These results also illustrate the potential benefits of enhancing basic LUR models by utilizing air quality modeling tools or concepts in order to improve their reliability or transferability. 相似文献
279.
On the decline of ground lichen forests in the Swedish boreal landscape: Implications for reindeer husbandry and sustainable forest management 总被引:1,自引:0,他引:1
Per Sandström Neil Cory Johan Svensson Henrik Hedenås Leif Jougda Nanna Borchert 《Ambio》2016,45(4):415-429
Lichens are a bottleneck resource for circumpolar populations of reindeer, and as such, for reindeer husbandry as an indigenous Sami land-use tradition in northern Sweden. This study uses ground lichen data and forest information collected within the Swedish National Forest Inventory since 1953, on the scale of northern Sweden. We found a 71 % decline in the area of lichen-abundant forests over the last 60 years. A decline was observed in all regions and age classes and especially coincided with a decrease of >60 year old, open pine forests, which was the primary explanatory factor in our model. The effects of reindeer numbers were inconclusive in explaining the decrease in lichen-abundant forest. The role that forestry has played in causing this decline can be debated, but forestry can have a significant role in reversing the trend and improving ground lichen conditions.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-015-0759-0) contains supplementary material, which is available to authorized users. 相似文献280.
Tomas Lundmark Johan Bergh Annika Nordin Nils Fahlvik Bishnu Chandra Poudel 《Ambio》2016,45(2):203-213
Continuous-cover forestry (CCF) has been recognized for the production of multiple ecosystem services, and is seen as an alternative to clear-cut forestry (CF). Despite the increasing interest, it is still not well described how CCF would affect the carbon balance and the resulting climate benefit from the forest in relation to CF. This study compares carbon balances of CF and CCF, applied as two alternative land-use strategies for a heterogeneous Norway spruce (Picea abies) stand. We use a set of models to analyze the long-term effects of different forest management and wood use strategies in Sweden on carbon dioxide emissions and carbon stock changes. The results show that biomass growth and yield is more important than the choice of silvicultural system per se. When comparing CF and CCF assuming similar growth, extraction and product use, only minor differences in long-term climate benefit were found between the two principally different silvicultural systems. 相似文献