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1.
An assessment index system including environment, socio-culture, economy and technology was established for evaluating environmental
construction level of community (objective construction), and questionnaire was designed according to paper review for evaluating
residential satisfaction (subjective satisfaction). The index system was divided into four layers: system (A), subsystems
(B), categories (C), and indicators (D), and in total of 38 indicators was established. The Xihe community, affiliated to
Nanfen district, Benxi City, Liaoning Province, China was selected as a case study. Results indicated that the community sustainability
index related to objective environmental construction was 0.4355 and was classified as class III (moderate); the community
sustainability index related to the residential satisfaction was 0.4255, belonging to class III. In conclusion, the sustainability
of Xihe community was moderate and needed to be improved. Residential satisfaction was lower than objective environmental
construction. The assessment index system established in this study is able to reflect the comprehensive sustainability of
community and can be used to evaluate other similar communities’ sustainability
Foundation items: This study was supported by the National Key Technologies R & D Program of China (2006BAD03A09), Agrifund
of China’s Ministry of Science and Technology (2006GB24910472). 相似文献
2.
The selection criteria for the first generations in the Portuguese Pinus pinaster improvement program have been the growth rate and form traits. In this work we study the consequences of this selection on wood quality traits. This study assesses genetic and phenotypic correlation between growth, wood density components, lignin content and mechanical traits (radial modulus of elasticity and radial modulus of rupture) of 46 half sib families from a progeny trail located in Leiria, Portugal, originated from seed collected in a clonal seed orchard. A total of 552 seventeen-years-old trees (about half of full rotation age) were sampled at 2 m height. Height measured at 12 years old presented a higher genetic control ( h2 = 0.34) relatively to DBH, measured at 12 and 17 years old respectively ( h2 = 0.17 and h2 = 0.15). The results of this study also showed that DBH growth is more dependent on latewood components than earlywood components and that higher growth in Mediterranean regions can be due to an increase of the period of latewood formation. Further, we can conclude genetic selection based on growth will not result in a decrease of wood density, will not affect the occurrence of spiral grain, and is possible to obtain an increase in the radial modulus of elasticity. The present study also showed that it is possible to select for increased growth with lower lignin proportion. Results also suggest that selection for growth at 12 years will probably not affect negatively the wood properties at 17 years. 相似文献
3.
In fire-prone regions, understanding the response of species to fire is a major goal in order to predict the effects on biodiversity. Furthermore, postfire management can also model this response through the manipulation of environmental characteristics of the burnt habitat. We have examined the taxonomic and functional response to fire and postfire management of a Mediterranean snail community affected by a summer fire in 2003. After the fire, the area was logged, leaving wood debris on the ground, and three alternative practices were implemented in several plots within the burnt area: subsoiling, removal of trunks having branches, total removal of trunks and branches, as well as one area not logged. Our results indicated that fire exerted a major impact on the snail community, strongly reducing diversity and species richness, particularly for forest species living in the humus and having European distribution ranges. By contrast, we found slight differences within the postfire practices, presumably because of the strong initial impact of fire and subsequent xerophilous postfire conditions. However, the area with only trunk removal showed a positive response of generalist snail species, probably due to moist microhabitats provided by the accumulation of wood debris on the ground. The effects of postfire management should be further explored due to the expected increase of fire risk associated with climate change and land-use histories. 相似文献
4.
Rainforest deforestation and subsequent reforestation not only alter above-ground vegetation, but also lead to significant changes in the physical and chemical characteristics of soil and in biochemical cycles, which in turn are likely to influence the growth of rainforest plants. However, little research has directly linked soil condition to seedling growth under different forms of rainforest restoration. 相似文献
5.
Internal conductance to CO(2) transfer from intercellular spaces to chloroplasts (g(i)) poses a major limitation to photosynthesis, but only three studies have investigated the temperature dependance of g(i). The aim of this study was to determine whether acclimation to 15 versus 30 degrees C affects the temperature response of photosynthesis and g(i) in seedlings of the evergreen tree species Eucalyptus regnans F. Muell. Six-month-old seedlings were acclimated to 15 or 30 degrees C for 6 weeks before g(i) was estimated by simultaneous measurements of gas exchange and chlorophyll fluorescence (variable J method). There was little evidence for acclimation of photosynthesis to growth temperature. In seedlings acclimated to either 15 or 30 degrees C, the maximum rate of net photosynthesis peaked at around 30 or 35 degrees C. Such lack of temperature acclimation may be related to the constant day and night temperature acclimation regime, which differed from most other studies in which night temperatures were lower than day temperatures. Internal conductance averaged 0.25 mol m(-2) s(-1) at 25 degrees C and increased threefold from 10 to 35 degrees C. There was some evidence that g(i) was greater in seedlings acclimated to 15 than to 30 degrees C, which resulted in seedlings acclimated to 15 degrees C having, if anything, a smaller relative limitation due to g(i) than seedlings acclimated to 30 degrees C. Stomatal limitations were also smaller in seedlings acclimated to 15 degrees C than in seedlings acclimated to 30 degrees C. Based on chloroplast CO(2) concentration, neither maximum rates of carboxylation nor RuBP-limited rate of electron transport peaked between 10 and 35 degrees C. Both were described well by an Arrhenius function and had similar activation energies (57-70 kJ mol(-1)). These findings confirm previous studies showing g(i) to be positively related to measurement temperature. 相似文献
6.
The rapid rate of deforestation in Cote d'Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and afforestation has been completed.However,for some species,the numbers of surviving transplants has declined.Hence,it is necessary to develop properly adapted and resilient genotypes that can effectively support the programs of forest restoration.In this context we evaluated the effects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species(Pycnanthus angolensis,Terminalia superba,Mansonia altissima and Pterygota macrocarpa).We analyzed these parameters for seeds of three provenances(Daloa,Akoupe and Daoukro) of four species and for thirty plants aged 6 months per provenance.Time to begin germination and time to reach maximum germination were similar among species,and were not influenced by either treatment or provenance.Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates,irrespective of species or provenance.The one exception was P.angolensis, for which no germination was recorded.Within species,some provenances produced higher germination percentages than did others.No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied significantly between provenances.Plant growth and morphological variability also depended greatly on provenance.Genetic factors might be implicated,therefore provenance trials should be undertaken and evaluated.Furthermore,molecular analysis should be undertaken to confirm the implications of genetic factors and allow for genetic selection. 相似文献
8.
Key message Quercus secondary forests show a gradual transition toward mixed forests, with sweet chestnut ( Castanea sativa ) becoming increasingly abundant in the western Spanish Central System. Additionally, in chestnut-dominated stands, it shows a certain resistance to competitive displacement by Quercus pyrenaica . Our results partially refute the traditional view that C. sativa is unable to recruit in the absence of cultural inputs. ContextSweet chestnut, Castanea sativa, is a component of European broadleaf forests and is one of the most managed trees. Due to a reduction in cultural inputs, chestnut-dominated stands tend to be invaded by other species, and it is unclear how chestnut is able to persist in natural mixed forests.AimsOur work aimed to identity the main factors that limit the establishment of C. sativa and to analyze the recruitment and mortality processes of C. sativa trees.MethodsThe age, growth ring patterns, regeneration density, and the spatial structure of trees and saplings in 11 plots in the Spanish Central System were analyzed.ResultsChestnut seedling density increased with C. sativa basal area, but transition toward the sapling stage appeared limited owing to light availability. In Quercus pyrenaica secondary forests, sparse canopies did not constrain chestnut regeneration, and in old chestnut stands, C. sativa showed a certain resistance to competitive displacement. By contrast, mixed young coppices showed a high mortality, most likely due to competition with other vigorous resprouters.ConclusionQuercus secondary forests showed a gradual transition toward mixed forests with sweet chestnut becoming increasingly more abundant. In old stands, C. sativa is likely to persist under a gap-phase mode of regeneration. Our results partially refute the traditional view that C. sativa is unable to recruit in the absence of cultural inputs. 相似文献
9.
The current study investigates with a multiple case study the relation between instrument design and policy success. The conclusion is that the instrument mix matters. The Flemish interventionist approach, which focuses more on traditional instruments, was not as effective as the Dutch stimulating approach, which uses a broad pallet of social and economic instruments, including many new environmental policy instruments. It is conspicuous that the government remains the most important regulator in all cases, although the importance of surrogate regulators is growing. Mostly the government is needed to stimulate or even create such surrogate regulators. Therefore, the government has a key position to decide which regulatory tasks will be transferred to surrogate regulators. This is currently restricted to capacity-building and certification. 相似文献
10.
We examined the association between habitat variables and the relative impacts of topographic microclimates as a valuable tool for restoration and conservation of Abies pinsapo in southern Spain. We used presence–absence data from A. pinsapo and 79 environmental variables and biomod species distribution models to describe the current and future species habitat across the Sierra de las Nieves Natural Park (southern Spain). A. pinsapo habitat was most strongly associated with microtopographic (solar incidence) and temperature variables, indicating climate-driven changes in microhabitat use. Most of the temperature variation among the study site was attributable to topographic microclimates rather than regional temperature differences, such that differences in microhabitat associations occurred principally between north- and south-facing slopes within the same region. The current potential distribution suggests that around 8.7% (56.44 km2) of the study area is highly suitable for A. pinsapo, with 9.7% (62.84 km2) being moderately suitable. Under different global circulation models and climate change scenarios, the net decrease in suitable habitat is predicted to be 93% of the current distribution by 2040, disappearing altogether by 2099. Our findings also show a sharp reduction of potential restoration areas (1.8% of the current areas). Microclimatic variation generated by the topography offers the microclimate-driven locations of habitat suitability which could shape species’ distribution restoration actions and their responses to environmental change. The approach presented here can provide a rapid assessment of the future conservation status of other important forest tree species in Spain, improving our understanding of the vulnerability of endangered species under climate change, and can be an effective tool for biodiversity conservation, restoration, and management. 相似文献
11.
Ant–aphid mutualisms, in which ants tend aphids, which in turn provide honeydew to the ants, are widespread and have been shown to affect plant growth. In boreal forests the effect of ant–aphid mutualism on tree growth can vary with stand age, because forest clear-cutting harms the ecologically most dominant ant partner in such mutualisms, wood ants ( Formica rufa group). We studied whether the mutualism between wood ants and Cinara aphids affects the growth of boreal Norway spruces ( Picea abies L. Karst.) in stands of different ages. In boreal forests, conifers, unlike deciduous trees, have only few defoliating insects, and therefore we expected the growth loss of conifers due to sap sucking by aphids not to be compensated by reduced insect herbivory due to predation by wood ants. The study was conducted in medium-fertile spruce-dominated stands in eastern Finland. We used stands of four different age classes (5, 30, 60 and 100 years) and selected ten spruces heavily visited and ten spruces lightly visited by ants around five medium-sized ant mounds in each stand age class. The access of ants was blocked on half of the trees in both groups. In the 5-year-old stands, the mean annual height growth of individual heavily visited seedlings was 16.3% greater than in the ones where ant traffic was blocked, but this difference was not significant. In the 30-year-old stands, the mean annual radial growth of the heavily visited spruces was 7.3% smaller than in trees where ant traffic was blocked, and this difference was significant. The mutualism had no significant effect on the radial growth in the 60- and 100-year-old stands. In the 60-year-old stands, however, the spruces that were visited heavily prior to the beginning of the study grew significantly less relative to their past growth than the initially lightly visited trees during the study. This suggests that the ant–aphid mutualism may have long-term effects on tree growth. The ant–aphid mutualism had no significant effect on the growth at the stand level. The results indicate that ant–aphid mutualism can have a significant effect on the growth of individual spruces, but the effect is negligible at ecosystem level. 相似文献
12.
The effect of harvest residue management options on biomass and nutrient accumulation in understory vegetation, as well as the contribution of understory to nutrient cycling, were assessed during the early rotation stage of a Eucalyptus globulus Labill. plantation in Central Portugal. The effects of residue management options on early tree growth were also evaluated. Treatments established at the time of plantation and replicated four times in a simple completely randomised design included removal of harvest residues (R), incorporation of residues into the soil by harrowing (I) and maintenance of residues on the soil surface (S). Understory biomass was sampled in the spring between 2002 and 2006, and every 2 months between March 2006 and March 2007. The latter samples were stratified into biomass, standing dead mass and litter for net above ground primary production (NAPP) assessment. Samples were oven dried, weighed and analysed for nutrient contents. Results showed that understory standing biomass strongly increased from the first to the third year and that quantities of nutrients accumulated in ground vegetation followed similar patterns between the three treatments. Nutrient accumulation in ground vegetation was greater than in tree biomass until at least the second spring after plantation. Bimonthly sampling revealed treatment R to have the largest amounts of standing biomass, standing dead mass, litter and nutrient immobilisation, while treatment S exhibited the lowest values. NAPP (4th–5th year) was 639, 511 and 362 g m −2 year −1, respectively in R, I and S, corresponding the standing biomass increase to 277, 183 and 143 g m −2 year −1. These values are comparable to those observed for litter fall in similar stands (age and tree density) in the same area. The contribution of ground vegetation to nutrient accumulation in the system was unaffected by harvest residue management methods, but further research is necessary in order to establish whether slash management options influence long term tree growth and vegetation dynamics. 相似文献
13.
• Introduction
Stem taper equations have been widely used for volume estimation to varied top diameter limits or for biomass calculations.
However, their main drawback is that specific calibration is often necessary for each species or clone, and accounting for
genetic and environmental effects is often a challenge. 相似文献
14.
Key message For an optimal deployment of poplar resistance to the gall-inducing aphid Phloeomyzus passerinii , a laboratory susceptibility assay has been developed. The nature of aphid–tree interactions during compatible and incompatible situations has been studied in detail. This should help at identifying specific resistance markers and at testing effects of site conditions on tree–pest interactions. Context P. passerinii is a major pest of poplar plantations in Europe, and the plantation of resistant poplar genotypes is regarded as the best long-term management strategy for this pest. This requires a sound knowledge of the interactions among the pest, its host and their environment.AimsHere, we review the recent advances aiming at developing an optimal deployment of host resistance versus P. passerinii.ResultsInvestigations on aphid-host interactions demonstrated that P. passerinii induces pseudogalls within the bark of susceptible hosts. This results in a reduction of starch bark content during aphid outbreaks, which could be involved in tree death. The constitutive level of starch in the bark could be related to the tolerance level of trees. A susceptibility test has been designed for poplar genotypes, discriminating three categories of susceptibility depending on tree’s ability to totally or partially inhibit pseudogall induction. The test still has several limitations however. It neither takes into account the large level of individual genetic diversity of the aphid in France, nor the environmental modulation of tree resistance and tolerance, while water deficit and fertilization could potentially affect these parameters.ConclusionThe hypotheses drawn regarding the processes leading to tree death or resistance should help at identifying resistance markers, and at testing effects of site conditions on tree–pest interactions. 相似文献
15.
Swidden cultivation is the traditional agricultural system in most parts of the Amazonian rain forest. In a remote area in
the Manu National Park, Peru, this system was analysed in two indigenous Matsiguenka communities. Diversity of cultivated
plants on fields and in homegardens are presented in the current study. Cultivated plants were noted on two to four plots
per field on 46 fields, making a total of 126 survey plots. Nineteen homegardens were studied as well. Dominating species
cultivated on fields is cassava ( Manihot esculenta). Fruit trees such as the peach palm ( Bactris gasipaes), guava ( Psidium guajava) or Inga edulis, but also cotton ( Gossypium barbadense) and a medicinal plant ( Cyperus sp.) predominate in more than 75 % of the homegardens analysed. Species diversity increases steadily from 18 and 24 species
on 1- and 2-year-old fields to 26, 29 and 66 species in young, medium old and old homegardens, respectively. Seventy-one different
species in total were found in all homegardens analysed and 25 in swidden fields. Diversity of species cultivated in homegardens
is low compared to other studies in the rain forest of the Amazon. This seems to be due to their remoteness from the next
urban centre and to the fact that they are native communities with still low external exchange of information. These findings
are in contrast to the hypothesis that remoteness from urban centres increases species richness because subsistence production
is based on a broad variety of species. In contrast to species richness in homegardens, differences in species richness in
swidden fields between the present and other studies could not be found. 相似文献
16.
Context In tropical areas, studies based on the retrospective analysis of tree development have focused principally on growth ring research. The interpretation of primary growth markers is overlooked although it opens perspectives to provide long time-series on tree-crown development. Aims This study focused on Parkia velutina, an emergent tree of neotropical rain forests. Our objectives were (1) to characterize the phenological cycle of this species, and (2) to identify temporally interpretable morphological and anatomical markers. Methods We collected dominant branches in 14 adult trees and identified growth markers that limit longitudinal and radial increments. We coupled this approach with a 2-year phenological survey of 20 trees. Results Leaf shedding, growth unit elongation and growth ring formation define the phenological cycle. At tree scale, this cycle is synchronous and affects all axes. At population scale, trees can be desynchronized. This cycle is annual despite some slight variability. Successive growth units and growth rings are easily identifiable. Conclusion Dating a branch by counting the number of growth units or growth rings is possible in many years with a reasonable error. Nevertheless, estimating their precise month of formation in order to study climatic influences remains difficult. 相似文献
17.
Human activities have fundamentally changed global nitrogen (N) cycling, leading to elevated N deposition in most parts of the world. The fate of deposited N, whether being retained to sustain plant growth or causing ecosystem N saturation, is critical to the global carbon (C) cycling and local environment. In a short-term laboratory experiment, we used 15N-labeled NH 4+ and NO 3− to study the fate of N inputs in forest soils and what regulates N retention. Soils with a wide range of organic matter content and other attributes were collected from a 70-year-old plantation containing monotypic stands of Norway spruce ( Picea abies), red pine ( Pinus resinosa), sugar maple ( Acer saccharum), and red oak ( Quercus rubra), and separated into 0-5 cm and 5-15 cm layers. Nitrogen added to the soil was either immediately extracted (Time 0: T0) with K 2SO 4 solution, or incubated for 7 d (T7) and then extracted. Retention of 15N into the non-extractable soil pool at T0 was limited; but after the 7-d incubation, between 20 and 70% of the 15NH 4+ was retained. Nitrification transformed on average 50% of the 15NH 4+ into 15NO 3− during the incubation while retention of 15NO 3− at T7 remained low (7.40 ± 1.08%). Retention of 15NH 4+ into non-extractable soil at T7 was positively correlated to the percentage of soil organic matter (SOM) ( r2 = 0.323, P < 0.001), and was significantly higher ( P < 0.001) in the high-SOM 0-5 cm layer than in the low-SOM 5-15 cm layer. Conversion of 15NH 4+ to 15NO 3− during incubation significantly reduced the 15NH 4+ retention ( P < 0.001). Our results suggest that the variations of SOM and other soil attributes play strong roles in the retention of newly deposited inorganic N and could affect forest ecosystem responses to chronic N deposition. 相似文献
18.
? It is agreed that climate (precipitation and temperature) influences the distribution of plant species. Near the margins of a species’ natural range, climate becomes limiting to physiological processes. There, climate change may be expected to have a significant impact on tree growth and the species’ ranges may be altered. ? In order to assess what influence climate change could exert on the distribution of pine species at their margin, radial growth trends in ring-width chronologies over the last century were analysed. In the French Mediterranean area where climate change is characterized by increased temperature, forest plots were selected along an altitudinal transect on the north-facing slope of the Sainte-Baume mountain (Bouches-du-Rhône, France) where the ranges of Pinus sylvestris and Pinus halepensis overlap. ? Two growth patterns were identified. For P. halepensis, radial growth has increased at all altitudes indicating that climate change has improved growth conditions of this species near the margin of its ecological range. For P. sylvestris, radial growth has increased only at low altitudes and even decreased at high altitudes. ? It must be deduced that the growth changes observed cannot be generalised either at the species level or at the geographical level and must be interpreted with great caution. 相似文献
20.
Nitrogen (N) deposition exceeds the critical loads for this element in most parts of Switzerland apart from the Alps. At 17
sites (8 broadleaved stands, 8 coniferous stands, and 1 mixed stand) of the Swiss Long-term Forest Ecosystem Research network,
we are investigating whether N deposition is associated with the N status of the forest ecosystems. N deposition, assessed
from throughfall measurements, was related to the following indicators: (1) nitrate leaching below the rooting zone (measured
on a subset of 9 sites); (2) the N nutrition of the forest stand based on foliar analyses (16 sites); and (3) crown defoliation,
a non specific indicator of tree vitality (all 17 sites). Nitrate leaching ranging from about 2 to 16 kg N ha −1 a −1 was observed at sites subjected to moderate to high total N deposition (>10 kg ha −1 a −1). The C/N ratio of the soil organic layer, or, when it was not present, of the upper 5 cm of the mineral soil, together with
the pool of organic carbon in the soil, played a critical role, as previous studies have also found. In addition, the humus
type may need to be considered as well. For instance, little nitrate leaching (<2 kg N ha −1 a −1) was recorded at the Novaggio site, which is subjected to high total N deposition (>30 kg ha −1 a −1) but characterized by a C/N ratio of 24, large organic C stocks, and a moder humus type. Foliar N concentrations correlated
with N deposition in both broadleaved and coniferous stands. In half of the coniferous stands, foliar N concentrations were
in the deficiency range. Crown defoliation tended to be negatively correlated with N concentrations in the needles. In the
majority of the broadleaved stands, foliar N concentrations were in the optimum nutritional range or, on one beech plot with
high total N deposition (>25 kg ha −1 a −1), above the optimum values. There was no correlation between the crown defoliation of broadleaved trees and foliar concentrations. 相似文献
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