共查询到20条相似文献,搜索用时 15 毫秒
1.
Are silvopastoral systems compatible with forest regeneration? An integrative approach in southern Patagonia 总被引:1,自引:1,他引:0
Rosina Soler Guillermo Martínez Pastur Pablo Peri María Vanessa Lencinas Fernando Pulido 《Agroforestry Systems》2013,87(6):1213-1227
We used an integrated approach to analyze the influence of silvopastoral management on the biotic and abiotic factors influencing on the natural recruitment of native forests in Tierra del Fuego (Argentina). The probabilities of transition from flowers to seeds to seedlings were estimated in forests with silvopastoral management (i.e., stands that had been both grazed and thinned), secondary growth stands, and unmanaged old-growth areas. Pre-dispersal losses were caused by microclimate and insect predation acting on flowers and immature fruits. Post-dispersal losses resulted from the impact of reduced litterfall and microclimate. But the most critical stage of the overall cycle was seedling establishment. Silvopastoral practices and stand age modified the main drivers of regeneration. While flowering was unaffected by management, fruiting and seed production were more successful in unmanaged forests. Seedling establishment and survival were favored by canopy cover reduction in silvopastoral stands. The increase of solar radiation and soil moisture in managed forests positively influenced the seedling establishment and survival, while in second-growth forests it was limited by suitable micro-site availability. Thinning practices aimed at increasing the understory heterogeneity in mature forests and restoring canopy complexity of second-growth stands could be suitable for sustainable management of these temperate forests. 相似文献
2.
• Context
Landscape structure is crucial for forest conservation in regions where the natural forest is fragmented. Practical conservation is currently shifting from local stands to a landscape perspective, although few studies have tested the relative effects of different spatial scales on plant species composition and diversity in forests. 相似文献3.
Gerhard Langenberger Georg Cadisch Konrad Martin Shi Min Hermann Waibel 《Agroforestry Systems》2017,91(3):577-596
The last decades brought along a tremendous expansion of rubber plantations as well as respective socio-economic transformations. This paper reviews the historical development of rubber cultivation with special reference to intercropping and illustrates the major development steps. The agronomic challenges of intercropping are analyzed and a management classification scheme is suggested. Though the topic of labor always accompanied rubber management, it is nowadays of even higher relevance due to alternative income options, be it due to competing crops such as oil palm, or be it off-farm income opportunities. This development challenges labor intensive permanent intercropping systems. It can thus be concluded that the permanent integration of additional plants needs either to be highly profitable or at least be labor extensive to be adopted on a considerable scale. Given the large area of rubber plantations the latter seems to be more realistic. In this context timber trees might offer promising options if tree selection is properly adapted to site and plantation conditions. Nevertheless, without external interventions, such as land-use planning and implementation, or incentives, the development will be difficult to control. 相似文献
4.
Vincent Oeba Larwanou Mahamane Samuel CJ Otor James B Kung’u Muchiri N Mbae 《Southern Forests》2017,79(2):117-124
The introduction of carbon finance as an incentive in forestry farming has a potential of increasing the amount of carbon sequestered. However, this has created a daunting task among investors in forestry to optimise the joint production of wood and carbon sequestration. For instance, investors might find it profitable to give up some timber returns in exchange for carbon credits. This study evaluated expected income from growing Cupressus lusitanica Mill., Pinus patula Schiede ex Schltdl. & Cham., Eucalyptus saligna Sm. and Juniperus procera Hochst. ex Endl. for wood and/or the carbon market in central Kenya. The global average unit price of carbon and stumpage royalty were used to estimate expected returns from sale of carbon credits and wood, respectively. There were significant differences (p < 0.01) in the expected amount of income from sale of carbon and wood among the four species. Specifically, at economic rotation of 30 years with stand density of 532 trees ha?1 P. patula and C. lusitanica yielded US$28 050 and US$23 650, respectively, from sale of carbon compared with US$59 000 and US$51 000, respectively, from sale of wood. This was twice the value investors receive from clear-felling as compared with sales from carbon. Similarly, at economic rotation of 33 years with stand density of 150 trees ha?1, a forest investor in E. saligna would earn US$15 400 from sale of carbon compared with US$33 000 from sale of wood. Overall, the amount expected to be realised from sale of carbon was lower compared with that from sale of wood. This demonstrates that the price dynamics of carbon offsets in the voluntary and the compliance markets need to remain competitive and attractive for the forest owners to give up some timber returns in exchange for carbon income or to modify forest management regulation in order to increase carbon sequestration. 相似文献
5.
Bernhard Beinhofer 《European Journal of Forest Research》2010,129(5):921-934
This study analysed whether the production of high-quality assortments, saw timber and pulpwood in Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) stands leads to effects of risk compensation. Mixtures of conventionally treated pruned and non-pruned stands, as well as
mixtures of stands which had been optimized concerning the occurrence of assortments and financial criteria were considered.
The price simulation was done by bootstrapping to avoid the assumption of a certain distribution of timber prices, and to
preserve the correlations of the timber prices from different assortments. The financial valuation was carried out with annuities
within a Monte Carlo simulation with 10,000 repetitions. To quantify the effect of natural hazards, the calculations were
repeated with and without this factor. Minimum risk portfolios were determined and optimization performed using both a utility
function as well as the value-at-risk approach. The mixtures with minimum risk were dominated by pine stands, as they are
less affected by natural hazards and prices for pine timber have a lower volatility, although pine timber prices are generally
lower compared to that of spruce timber. These pine dominated portfolios showed risk reductions up to 92% compared to the
riskiest single stand, but the annuities were reduced even more. In contrast to this, the portfolios optimized with the utility
function and the value-at-risk approach consisted of spruce stands. These spruce portfolios showed an efficient risk reduction
of up to 60%. Additionally, higher annuities and larger diversification effects occurred in the portfolios containing the
optimized stands. Integrating the risk of natural hazards, the annuities decreased, as did the correlation of the annuities
of the different stands, while risk increased. Altogether these effects led to higher relative risk reductions when forming
optimal portfolios. These results indicate that producing different assortments of spruce and pine leads to risk compensation,
especially when considering portfolios consisting of optimized stands. 相似文献
6.
Do environmental diversity approaches lead to improved site selection? A comparison with the multi-species approach 总被引:2,自引:0,他引:2
Artti Juutinen Mikko Mnkknen Markku Ollikainen 《Forest Ecology and Management》2008,255(11):3750-3757
This paper suggests a new approach to select conservation areas cost-effectively according to the concept of complementarity and representation of focal natural features. The suggested environmental diversity (ED) site selection model maximizes ecological diversity, measured via ordination of the chosen taxa communities. Given their fundamental role in ecosystem functioning, vascular plants are chosen as the indicator taxa. We test the ED indicator model by contrasting it to the conventional site selection indicator (MS model), which maximizes the representation of species number in the indicator taxa. We demonstrate that the ED model is more cost-effective than the MS model. More importantly, while the ED selection is operative over the whole range of species, the MS selection does not work beyond the range of species, where all vascular plants become protected. Beyond that point MS indicator model cannot guide conservation efforts, which is a serious drawback. The ED model outperforms MS model also in terms of habitat conservation and taxonomic diversity. Thus, it provides an interesting selection framework for biodiversity. 相似文献
7.
Panama has the highest rate of change in the area of primary forests within Central America. However, to meet growing timber
demands, it became popular over the last decades to establish plantations made up of foreign species such as Tectona
grandis or Pinus spp. In the majority of the cases the species used are well known; their characteristics such as growth performance have
been reviewed intensively and can be accessed in numerous publications. Characteristics of Panama’s native tree species of
commercial relevance such as Hieronyma
alchorneoides, Swietenia
macrophylla and Terminalia
amazonia are largely unknown and have been investigated within the study at hand. Using valuation methods of financial mathematics,
the competitive position of these three indigenous species was assessed, the results compared to those of T. grandis stands in the same area. Land costs and taxes were not considered, as they would be the same for all species. Financial estimates
for indigenous species will enlarge their acceptance for use in reforestation and plantation projects. Using the NPV method
and applying the standard scenario, the profitability of T. grandis is lower than that of T. amazonia and S. macrophylla and lies only slightly above the profitability calculated for H. alchorneoides. This result clearly indicates that the investigated native tree species are comparable with T. grandis regarding their economic profitability. Besides its ecological impact, growing native tree species is now also economically
legitimate. By calculating land expectation values for all tree species, ideal rotation lengths could be determined. For these
species, considerable flexibility exists regarding the optimal rotation length. 相似文献
8.
Juan Andrés Oria-de-Rueda María Hernández-Rodríguez Pablo Martín-Pinto Valentín Pando Jaime Olaizola 《Forest Ecology and Management》2010
The aim of this work was to study and describe fungal communities in different habitats in dry Mediterranean areas. The objective was to determine whether artificial reforestations can develop fungal communities as productive and diverse as those found in natural stands. The results could provide ecological and economical implications for forest management in marginal areas, in order to recover the original forest dominated by Quercus, establishing as intermediate stage new forest stands dominated by Pinus which might play an essential role in restoring some type of degraded or marginal areas. 相似文献
9.
Antonio D. del Campo Tarcísio J. G. Fernandes Antonio J. Molina 《European Journal of Forest Research》2014,133(5):879-894
Hydrology-oriented silviculture might adapt Mediterranean forests to climatic changes, although its implementation demands a better understanding and quantification on the water fluxes. The influence of thinning intensity (high, medium, low and a control) and its effect on the mid-term (thinned plots in 1998 and 2008) on the water cycle (transpiration, soil water and interception) and growth [basal area increment (BAI)] were investigated in 55-year-old Aleppo pine trees. Thinning enhanced a lower dependence of growth on climate fluctuations. The high-intensity treatment showed significant increases in the mean annual BAI (from 4.1 to 17.3 cm2) that was maintained in the mid-term. Thinning intensity progressively increased the sap flow velocity (v s) in all cases with respect to the control. In the mid-term, an increased functionality of the inner sapwood was also observed. Mean daily tree water use ranged from 5 (control) to 18 (high intensity) l tree?1. However, when expressed on an area basis, daily transpiration ranged from 0.18 (medium) to 0.30 mm (control), meaning that in spite of the higher transpiration rates in the remaining trees, stand transpiration was reduced with thinning. Deep infiltration of water was also enhanced with thinning (about 30 % of rainfall) and did not compete with transpiration, as both presented opposite seasonal patterns. The changes in the stand water relationships after 10 years were well explained by the forest cover metric. The blue to green water ratio changed from 0.15 in the control to 0.72 in the high-intensity treatment, with the remaining treatments in the 0.34–0.48 range. 相似文献
10.
Heike Kawaletz Inga Mölder Peter Annighöfer André Terwei Stefan Zerbe Christian Ammer 《Annals of Forest Science》2014,71(3):337-347
Context
Identifying the traits of exotic species may explain their invasiveness and help control the negative impacts of these species on native ecosystems. In this study, we investigated root competition as an important driver for the competitiveness of two exotic tree species in the seedling stage.Aims
In a pot experiment, carried out in Central Europe, we studied the effect of root competition of two exotic tree species (Prunus serotina Ehrh. and Robinia pseudoacacia L.) on biomass allocation of two native ones (Quercus robur L. and Carpinus betulus L.).Methods
Seedlings of these species were exposed to intra- and interspecific mixtures with and without the effect of root competition. For this, belowground plastic partitions were installed in the pots.Results
Competition intensity in the pots increased over time, irrespective of mixture type. However, this increase was much higher for the native species if mixed with the exotic species compared to monocultures or inter-native mixtures. In addition to ontogeny, competition affected biomass allocation patterns. Under root competition by the exotic species, the native species preferentially allocated their biomass to the roots. A higher allocation to the roots was mainly achieved at the expense of leaf and branch biomass.Conclusion
Root competition of P. serotina and R. pseudoacacia may be a reason for the lack of Q. robur and C. betulus in the seedling stage in natural environments where all four species occur. 相似文献11.
Maxime Réjou-Méchain Adeline FayolleRobert Nasi Sylvie Gourlet-FleuryJean-Louis Doucet Michel GallyDidier Hubert Alexandra PasquierAlain Billand 《Forest Ecology and Management》2011,261(2):187-194
In this paper we seek to identify the floristic determination biases contained in large-scale commercial inventories conducted by logging companies and to determine whether this impacts on the observed patterns of alpha and beta diversity. The study focused on floristic data recently collected by industrial timber companies in the tropical forests of the Central African Republic (28,229 0.5-ha plots spread over 14,000 km2). A subset of these plots (n = 1107) was later re-sampled for controlling purposes by experienced botanists. The proportion of agreement between the two samplings was assessed for each species and independently for small and large trees, and at genus and family resolutions. Unsurprisingly, large trees and common species were more accurately identified than small trees and rare species. We found that the quality of the floristic determination increased slightly from species to families. We also detected a significant variation between concessions in the quality of the floristic determination that was more dependent on working conditions during forest inventories than on field workers. Contrary to a widespread belief, we did not find a strong bias toward commercial species, showing that commercial inventory data could also be valid for non-commercial species in ecological studies. Finally, we found that both alpha and beta diversity patterns in commercial inventories were highly consistent with those of the re-sampled inventory. This latter result shows that commercial inventories are well suited to detect large-scale patterns of floristic variation. Large-scale commercial inventories could thus play an important role in the identification of large-scale patterns in tropical tree diversity. This could enhance our ability to manage tropical forests by designing representative reserve networks and developing management plans that integrate diversity patterns at the landscape scale. 相似文献
12.
Herb-layer diversity in deciduous forests: Raised by tree richness or beaten by beech? 总被引:3,自引:0,他引:3
Andreas Mlder Markus Bernhardt-Rmermann Wolfgang Schmidt 《Forest Ecology and Management》2008,256(3):272
Where natural production capacity permits, modern silvicultural management in Central Europe frequently aims at the development of mixed broadleaved stands, instead of pure European beech (Fagus sylvatica) stands. It is crucial to study the effects of these tree-layer diversity variations on herb-layer vegetation, since herb-layer vegetation contributes significantly to ecosystem functioning in forests. In Hainich National Park (Thuringia, Germany), we conducted observational research in deciduous stands to investigate whether herb-layer diversity was related to canopy-layer diversity, and to ascertain possible causal mechanisms. We found that herb-layer vegetation of deciduous forest stands rich in canopy species appeared to be more diverse than herb-layer vegetation of beech-dominated stands. We surmise that herbaceous understorey diversity was indirectly influenced by canopy tree species through the medium of the altered environmental factors soil pH and litter layer thickness. Apparently, lower beech proportion had a more profound effect than the number of secondary tree species. There were no correlations between herb-layer diversity and light transmissibility of the canopy layer, indicating that the light factor was not crucial for herb-layer diversity. At least for the Hainich research sites, our results indicated that small-scale light and soil heterogeneity is insignificant for herb-layer diversity. We found several herb-layer species whose occurrence was particularly correlated with tree-layer diversity and environmental factors. Remarkably, all species positively correlated with soil pH were important for the phytosociological classification of the research sites. Beech-dominated research sites showed high tree-layer volumes, whereas research sites with high tree-layer diversity tended to feature lower tree-layer volumes. These findings could be the result of differing former silvicultural systems and varying soil clay contents affecting tree species composition. In contrast, herb-layer biomass was positively correlated with tree-layer diversity. Herb-layer productivity might be promoted in more diverse research sites by increased nutrient supply and base saturation. It is also possible that greater beech proportion interfered with herb-layer productivity. However, herb-layer biomass was also positively correlated with herb-layer diversity. Hence, our study hints that positive diversity-functioning relationships might occur in the herb-layer of the deciduous forest under investigation. 相似文献
13.
14.
Complexity in modelling forest ecosystems: How much is enough? 总被引:1,自引:0,他引:1
James P. Kimmins Juan A. Blanco Brad Seely Clive Welham Kim Scoullar 《Forest Ecology and Management》2008
The levels-of-integration concept in ecology suggests that while the population and community levels of biological organization provide understanding, they do not provide an adequate basis for predicting future states of populations, communities or ecosystems. Empirical models of populations and communities are implicitly ecosystem level because they are based on measures of the results of all past determinants that affected the populations and communities in question. They can be good predictors under unchanging conditions, but they are not able to predict for changing conditions, which requires the explicit representation of those ecological processes that are anticipated to change. The question addressed in this paper is: how does the performance of a “simple” stand-level model change as representations of these processes are added, and how much complexity is enough? Examples are given of change in performance of the ecosystem management model FORECAST run as a light competition model as nutrient regulation of growth and understory interactions are added singly or in combination. These examples are framed in comparisons of simulations for a white spruce stand in the in boreal mixedwood region in northern British Columbia, for a long-term thinning-fertilization trial in a Douglas-fir stand on southern Vancouver Island, and for yield decline in Chinese fir in south eastern China. It is concluded that the effect of adding complexity on the predictions of this model depends on the time scale of the simulation and the management or natural disturbance regime that is being simulated. The results supported Occam's razor: that models should be as simple as possible but as complex as necessary. 相似文献
15.
16.
In Sweden, management of moose is important due to considerable values as well as costs associated with this game species. An overarching question is how much moose Sweden should have. This short communication is delimited to the question of what the hunting value of moose is and what the hunting value would be given alternative levels of moose population density and allowed harvest. It is based on data from a mail contingent valuation survey that involved randomly selected hunters from a national register. The results showed that moose was the economically most important game species in Swedish hunting. The results also suggested that the hunting value would increase, but at a decreasing rate, if the moose population density and allowed harvest were increased – and vice versa. The findings should be of considerable interest in the context of adaptive moose management. 相似文献
17.
The need to carry out biological conservation outside protected areas requires avoiding, minimizing or mitigating impacts brought about by habitat transformation upon the biota. Usually, forest plantations hold fewer species than the original forest. However, structurally complex plantations support more species and individuals than simpler ones. Here we test if this phenomenon occurs in amphibian and reptilian assemblages, analyzing information regarding their richness and abundance in forestry plantations from 14 countries and 72 case studies which compare species richness and abundance in plantations and forests. Among amphibians, species richness is lower in plantations than in forests while among reptiles there is no significant difference. The abundance of reptiles increases in plantations. Three studies dealt with reptile assemblages in relation to structural complexity of plantation, which suggest that species richness and abundance is higher in complex plantations. Despite accounting for 50 % of the terrestrial vertebrates, herpetological studies account for 15 % of the research available regarding the impact of plantation upon vertebrates, information deficiency that hampers decision-making on the conservation of herpetozoans outside protected areas. 相似文献
18.
Great interest is currently centred on the biologic activities of pycnogenol a standardized plant extract obtained from the bark of the French maritime pine Pinus pinaster (formerly known as Pinus maritima), Aiton, subspecies Atlantica des Villar (Pycnogenol®, Horphag Research Ltd., UK, Geneve, Switzerland), which grows in the coastal southwest France. The quality of this extract is specified in the United States Pharmacopeia (USP 28). Between 65% and 75% of Pycnogenol are procyanidins comprising of catechin and epicatechin subunits with varying chain lengths. Other constituents are polyphenolic monomers, phenolic or cinnamic acids and their glycosides. As many studies indicate, pycnogenol components are highly bioavailable. Uniquely, pycnogenol displays greater biologic effects as a mixture than its purified components do individually indicating that the components interact synergistically. Pycnogenol is now utilized throughout the world as a nutritional supplement and as a phytochemical remedy for various diseases ranging from chronic inflammation to circulatory dysfunction, including several impaired psycho-physiological functions. Owing to the basic chemical structure of its components, the most obvious feature of pycnogenol is its strong antioxidant activity. In fact, phenolic acids, polyphenols, and in particular flavonoids, are composed of one (or more) aromatic rings bearing one or more hydroxyl groups and are therefore potentially able to quench free radicals by forming resonance-stabilized phenoxyl radicals. 相似文献
19.
Mezzetti Bruno Smagghe Guy Arpaia Salvatore Christiaens Olivier Dietz-Pfeilstetter Antje Jones Huw Kostov Kaloyan Sabbadini Silvia Opsahl-Sorteberg Hilde-Gunn Ventura Vera Taning Clauvis Nji Tizi Sweet Jeremy 《Journal of pest science》2021,94(4):1555-1555
Journal of Pest Science - A correction to this paper has been published: https://doi.org/10.1007/s10340-021-01393-0 相似文献
20.
Fude Liu Wenjie Yang Ming Zhang Yuhong Liu Jianwei Zheng Wenjin Wang Shiting Zhang Zhongsheng Wang Shuqing An 《European Journal of Forest Research》2010,129(6):1093-1108
In order to test whether the strategy of resource acquisition varies with life form, leaf texture and canopy gradient, we
measured light-saturated net photosynthetic capacity (A
max-mass) and leaf nitrogen and phosphorus concentrations (N
mass and P
mass) for 127 woody species of understory (small shrubs and tree seedlings) and 47 woody species of canopy (large shrubs and tree
adults) in a tropical montane rain forest of Hainan Island, South China. Photosynthetic nitrogen use efficiency (PNUE) and
photosynthetic phosphorus use efficiency (PPUE) were studied by taking into account functional groups, which classified by
either life form (FG1) or leaf texture (FG2). For FG1, there were significant (P < 0.05) differences between trees and shrubs in A
mass, N
mass and P
mass, but not in PNUE and PPUE; whereas for FG2, there were significant (P < 0.05) differences between the papery-leaved species and those with leathery leaves in the measured leaf traits inclusive
of PNUE and PPUE. Within the same classification systems, significant allometric scaling relationships were found in the leaf
trait pairs of A
mass-N
mass and A
mass-P
mass. Considered separately, the slope and y-intercept of the linear regression between A
mass and N
mass did not differ among functional groups nor between understory and canopy, but those for the linear regression between A
mass and P
mass differed significantly (P = 0.001) between understory and canopy species regardless of functional groups. The results of phylogenetic comparative analyses
were in accordance with the observed positive scaling relationships. The overall results indicate that there are no fundamentally
different nitrogen capture strategies in tropical woody species regardless of their life form, leaf texture and canopy gradient.
However, the strategies of phosphorus acquisition of tropical woody species differ with canopy layer increases. This variation
may correspond to the special soil conditions in this ecosystem, as phosphorus is an element limiting plant growth in tropical
areas. 相似文献