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1.
This paper examines interactive change and adaptation of human and natural systems in two pioneer forest settlements in the Philippines. The forest ecosystem was converted by logging, further resource extraction by settlers, and cultivation — factors usually associated with systems degradation. Natural succession, however, was rapid because of high rainfall and abundant forest seed stocks; and because of high rainfall, weeds, insect pests, and poor soil — annual cereal and cash cropping was not profitable or sustainable and farmers turned to root and mixed perennial cropping. This naturally developing, more sustainable agroforestry was initially financed by boom-and-bust incomes from small scale logging and charcoal making, and took place in spite of the settlers' formation of factions and an us before them attitude towards resource use.  相似文献   

2.
Prunus cerasoides D. Don has been identified as a framework species for restoring evergreen forest in seasonally dry climates. The aim of this study was to develop criteria to select parent trees for supplying seed to forest restoration projects based on seedling performance in the nursery and in the field. Seed progenies were collected from 50 individual parent trees; 13 in Doi Inthanon National Park; 14 in Doi Ang Khang; and 23 in Doi Suthep-Pui National Park. Criteria were developed for the selection of superior parent seed trees based on nursery and field performance, and a provisional selection of parent seed trees for forest restoration projects has been made based on these criteria. Four standards for selection of superior seed trees were recognised: (i) 70% or greater seedling survival in the field, (ii) a seedling height of 100 cm or taller after the first growing season in the field, (iii) 40% or greater germination in the nursery and (iv) 70% or higher seedling survival in the nursery. Twenty one seed trees met these standards.  相似文献   

3.
We measured photosynthetically active radiation (PAR) beneath the forest canopy, understory species richness and diversity, and biomass in a Larix leptolepis plantation in central Korea 4 years after thinning. Four different thinning intensities (control, 10%, 20%, and 40% stocking reduction) were applied in 1997. Mean annual intercepted PAR at 30cm and 1m above ground level was significantly different among the thinning intensities and strongly correlated with the number of stems remaining after thinning. Understory species richness and diversity were lowest in the unthinned stands and increased with thinning intensity, and there were significant correlations between the total number of understory species or diversity index (Shannons diversity index, H) and the number of stems per hectare after thinning. Also understory above-ground biomass was significantly increased with thinning intensity in both sampling months (June and August 2001). Thinning increased light inputs to the ground and resulted in higher species richness and diversity and above-ground biomass. These results suggested that light availability and understory responses to thinning at a comparable intensity are likely to last well beyond the 4 years of this study.  相似文献   

4.
Pakkad  Greuk  James  Celia  Torre  Franck  Elliott  Stephen  Blakesley  David 《New Forests》2004,27(2):189-200
Prunus cerasoides D. Don has been identified as an excellent framework tree species for restoring evergreen forest in seasonally dry tropical forestlands. Here we describe the level of microsatellite variation in P. cerasoides trees within and among three National Parks in northern Thailand: Doi Suthep-Pui, Doi Inthanon and Doi Ang Khang, using published primers developed for peach, sweet cherry and sour cherry. The five microsatellite loci employed detected a total of 41 alleles, with the average number of alleles per locus per study site ranging from 2.7 to 8.0 (n = 82). The value of F ST over the three sites was 0.115, indicating that while the majority of genetic diversity may be contained within sites, they should be considered as genetically distinct. The implications of this for seed collection of this species for forest restoration are discussed.  相似文献   

5.
The CIES/Consortium was created in 1992 for increasing the personnel capability and conducting research in natural resources, sustainable development, and human health in the Chiapas region of Mexico. Research is being conducted in four principal study areas: Highlands of Chiapas, the Lacandon rain forest, Soconusco, and El Ocote Reserve. There are four research departments: Conservation of Natural Resources, Alternative Production Systems, Health and Population, and Agroecological Technology. Agroforestry research, within the Department of Alternative Production Systems, includes agroforestry systems diagnosis in the highlands of Chiapas, ethnobotanical survey of potentially useful woody plants, silvicultural evaluation of woody forage species, management alternatives for the fallow vegetation in the Lacandon rain forest, and forest regeneration ecology and biomass dynamics in the Highlands of Chiapas and Lacandon rain forest after human interference. The CIES/Consortium researchers are also involved in the training of professionals and supervision of bachelor- and master- theses in their respective study areas. In January 1994, CIES/Consortium started a Postgraduate program in Natural Resources and Rural Development.Centro de Investigaciones Ecológicas del Sureste; since October 19, 1994 the name has changed to El Colegio de la Frontera Sur (ECOSUR).  相似文献   

6.
In Belgium, the current distribution and abundance of Xylosandrus germanus (Coleoptera, Scolytidae), a relatively new species to the Belgian fauna, is poorly known. Therefore, data on the range and population levels of this ambrosia beetle, on a regional and local scale respectively, are presented. Based on those results, the beetles range is discussed. Among the analysed biotic and abiotic factors that could influence the species settlement and population levels, climatic ones, and temperature in particular, seem to exert a crucial influence.  相似文献   

7.
Balancing timber production and conservation in tropical forests requires an understanding of the impacts of silvicultural manipulations on specific groups of organisms. Lianas are characteristic of many tropical forests, where they contribute to species diversity, ecosystem functioning, and biomass. However, lianas can also impede timber production by increasing logging damage and slowing tree growth. Cutting lianas prior to logging can mitigate the negative effects, but may adversely affect a forest's value for conservation. To evaluate the effects of forest management activities on lianas, this study assessed the impacts of logging, both with and without pre-logging liana cutting, on the relative abundance and population structure of five species of lianas that differed in primary reproductive strategies.Inventories of the five study species were conducted 10 years following logging in 4.4 ha plots in three adjacent treatment areas: (1) an old-growth forest reserve, (2) a selectively-logged forest that used conventional practices for the region, and (3) a forest that was logged using reduced-impact logging (RIL) techniques including complete liana cutting prior to logging. Liana species responses to logging varied according to their primary modes of reproduction. Croton ascendens, a pioneer species with a persistent seed bank, had a higher abundance in the two logging treatments relative to the old-growth forest, while Serjania caracasana, an early successional species lacking a persistent seed bank, showed abundant regeneration following conventional logging but negligible regeneration following RIL. In contrast, Acacia multipinnata, also an early successional species, showed abundant regeneration following RIL owing to the sprouting of persistent prostrate stems present on the forest floor prior to logging. In both logged areas, Bauhinia guianensis recruited abundant climbing stems from self-supporting seedlings that were present prior to logging, but it showed greatly reduced seedling density following RIL. By sprouting profusely from both fallen stems and stumps, Memora schomburgkii recruited abundant small-diameter climbing stems in both of the logging treatments. The results of this study demonstrate that there are interspecific differences in liana responses to different types of logging and that knowing species’ primary modes of reproduction is a valuable first step toward predicting those responses.  相似文献   

8.
This study presents data on the biomass and net aerial primaryproductivity (NAPP) of two contrasting East Anglian salt marshes.One site was at Tollesbury, Essex where the marshes are of theestuarine type and are subject to marsh degradation and erosionwhile the other site was 130 km to the north at Stiffkey, Norfolkwhere the barrier-type marshes are still actively developing withno signs of erosion. The NAPP was determined by the method ofSmalley with quadrats being harvested monthly with replacement.At the lowest levels at Tollesbury there was Pioneer Marshwhich was dominated by a mixture of Salicornia spp. and Astertripolium. At higher levels at Tollesbury there was LowerMarsh which was dominated by a mixture of Atriplex portulacoides andPuccinellia maritima. Over the four years of the studyPuccinellia became the dominant species following a markeddecrease in the extent and vigour of Atriplex. At Stiffkey theMiddle Marsh was at a much higher level and the vegetation waspredominantly a short dense sward with Atriplex portulacoides,Puccinellia maritima and Limonium vulgare together with smallerquantities of Armeria maritima and Plantago maritima. The meanNAPPs over three years of the Pioneer and Lower Marsh atTollesbury (467 & 519 g m-2 yr-1respectively) were similar butin 1993 the NAPPs recorded at Tollesbury were higher than thoserecorded at Stiffkey (625 & 583 compared with 458 g m-2yr-1).Smalleys method is difficult to apply to communities wherespecies dominance is variable, especially when dominance isshared between species with markedly different growth patterns.The results for NAPP obtained from the salt marshes at Tollesburyand Stiffkey are discussed in relation to results obtained byother workers from comparable areas in England and theNetherlands. Attention is also drawn to the possibly largerbelow-ground component of production that is frequentlyoverlooked. The importance of salt marshes in relation to othercoastal communities lies in the export of a proportion of theorganic matter produced and this mainly depends on theabove-ground production.  相似文献   

9.
Summary Preliminary investigations of the interaction occurring between different timber species and various types of steel used for sawblade manufacture, have indicated clearly the practical importance of the process of stress corrosion cracking (Krilov 1986). Based on eight timber species and four types of steel, these have confirmed the previous findings, indicating that the losses of material can be very extensive. The results of the combined effects of corrosion and wear produced steel losses ranging from 3.3 to 8.4 g/m2/h in weight and 0.0008 to 0.002 mm/h in thickness of the sawblade. The interaction between timber species and the types of steel was highly significant. The corrosion losses caused by the stringybark species, Eucalyptus obliqua, E. muellerana and E. macrorhynca were >37% greater than those produced by species not belonging to this botanical classification. Both timber and steels were ranked by Duncan's multiple-range test according to their corrosive properties, which differed at 5% probability level. These findings have practical applications in the woodworking industry and related fields.  相似文献   

10.
A field study was conducted in the Western Ghats of peninsular India to test the following two hypotheses: (1) lower floristic diversity for the cardamom hill reserves (CHR —a traditional agroforestry system of the tropics) compared to undisturbed evergreen forests and (2) a truncated vegetation structure for shade trees in the cardamom areas. The experimental sites involved three CHRs and an evergreen forest site.The CHRs, regardless of their locations, were characterized by lower floristic diversity and density than the evergreen forest site. The undisturbed forest site at Ayyappancoil registered the highest floristic richness and diversity (Simpson's floristic diversity index, D=0.93), followed by the well-managed CHR site, suggesting that managerial interventions may have a strong bearing on the floristic diversity of CHRs. The current suite of species in the CHRs included both heliophilic as well as shade-tolerant components. However, dominant tree species, their density and relative abundance exhibited marked variations among the CHR sites, albeit about one-third of the species were common at all sites.Stand physiognomy was characterized by the dominance of a single layer of trees in the CHRs, while the wet evergreen forest exhibited a multilayered canopy structure. Some of the lower height classes were poorly represented in the cardamom areas, whereas the evergreen forests depicted an inverse J shaped height distribution pattern. Implicit in the truncated stand structure of the CHR is the poor regeneration status, due to systematic removal of the lower size classes.  相似文献   

11.
Blakesley  David  Pakkad  Greuk  James  Celia  Torre  Franck  Elliott  Stephen 《New Forests》2004,27(1):89-100
Castanopsis acuminatissima (Bl.) A. DC. is one of a number of framework species which are being planted to restore seasonally dry tropical forests in northern Thailand. This study describes the level of microsatellite variation within and among three populations of this species in three National Parks in northern Thailand: Doi Suthep-Pui, Doi Inthanon and Jae Sawn, using published primers developed for Castanopsis cuspidata var. sieboldii Nakai. The five microsatellite loci employed in this study detected a total of 54 alleles (n = 72). The informativeness of the microsatellite loci varied from six to 18 alleles, with an average of 10.8 alleles found over all loci. The mean observed heterozygosities in the three populations showed no significant deviations from Hardy-Weinberg expectations. The vast majority of genetic diversity was contained within the populations, with no significant differentiation between them (FST = 0.006). Algorithms were designed to capture microsatellite diversity, and the rationale for using microsatellite markers to inform genetic conservation is discussed. The implications for seed collection of C. acuminatissima for forest restoration are also discussed.  相似文献   

12.
Rossi  Pekka 《New Forests》1999,18(2):161-177
The effect of length of cuttings, 10 to 50 cm long, on establishment and productivity of short-rotation plantations was investigated in five trials, for periods of 2 to 9 years. The trials were established on abandoned agricultural fields planted with unrooted Salix Aquatica cuttings. The effect of cutting length was very similar in all five trials: the longer the cuttings (up to 30–50 cm), the better the survival and growth. In most trials the greatest difference in survival was between cutting lengths of 10 and 20 cm, especially in unfavorable growing conditions. In an annually harvested trial during the 9-year test period, a cutting length up to 30 cm affected biomass production per stool positively. In two trials grown with 5-year rotation, the longest cuttings produced 7 times the above-ground biomass of the shortest ones. Results of these trials also emphasize the importance of establishment for the future success of willow plantations.  相似文献   

13.
Aphalo  Pedro  Rikala  Risto 《New Forests》2003,25(2):93-108
Silver birch seedlings were grown in two types of trays differing incell volume. For each kind of tray, three different spacings were achieved bygrowing seedlings in all, half or one quarter of the cells. The planting-stockso produced was out-planted at two forest sites and growth followed for fiveyears. Container size had a large effect on seedling morphology and on fieldperformance. Density also had a large effect on seedling morphology, but littleinfluence on performance. The tightest relationship of field performance was tothe mean dry weight of the stems of the planting stock (R2 = 0.94).Mean height and sturdiness index, defined as diameter ÷height, were not correlated with performance. Of the non-destructivemeasurements, mean root-collar diameter was the most closely correlated withperformance.  相似文献   

14.
In Italy, new agroforestry cultural models could play an important role in the diffusion of plantation forestry timber species. We studied the stem growth rates and leaf water potentials () of common walnut (Juglans regia L.), and gravimetric soil moisture (DW) depletion during the third and fourth growing seasons in an agroforestry trial in central Italy. Since the establishment of experimental plots in 1992, walnut was intercropped with alfalfa (Medicago sativa L.), with or without polyethylene (PE) mulching along tree rows. By the end of the study period, the unmulched-intercropped walnut was almost 68% smaller in stem diameter and height than the sole-unmulched control, demonstrating walnuts sensitivity to alfalfa competition. The competitive effect of alfalfa on walnut stem growth was effectively controlled/reduced by PE mulching. Stem growth rates of mulched-intercropped walnut were always lower than the control, but much higher (ca. 235% in stem diameter and height) than those of unmulched-intercropped walnut. The higher field performance of mulched-intercropped walnut compared to the un- mulched-intercropped treatment was associated with higher soil moisture and predawn and midday values during the summers driest periods. The presence of PE mulching was also associated with lower levels of soil moisture during the early and late growing season, but this did not negatively affect walnut and growth rates. These results suggest that in the climatic conditions of central Italy, competition for soil moisture between young common walnut trees and alfalfa can be substantially lowered, but not completely eliminated, by PE mulching.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

15.
This work deals with the experimental management of secondary succession in a tropical forest region in Uxpanapa, Veracruz, México. The goal is to establish a system of diversified units, which will maintain production and biodiversity while obtaining valuable products, primarily for self-sufficiency, and secondarily as cash crops. Three different diversifield units of production have been identified: a) the traditional milpa, maize polyculture, b) the diversified home orchard and c) the enriched fallows. These units were established in three secondary forests areas, where once thinned or cleared, valuable annual and perennial species were introduced.Total biomass and product yields were analyzed, also labour invested on each production unit was recorded, units were compared on an efficiency basis. Maize yield of polyculture is low but total production is more than twice that of maize monoculture. Efficiency in the polyculture is also higher and its weeds were better controlled. After three years the milpa has become an orchard with more than 150 individual fruit trees belonging to 10 different species. Enriched secondary forests show the highest biomass production in the open treatment, 68% transmittance, and the highest survivorship in the moderate shade treatment, 37%.Schizolobium parahybum andCordia alliodora were the most successful forest species due to their fast growth.  相似文献   

16.
The purpose of this work was to determine the most efficient methods of inoculation to significantly improve nodulation and growth of Acacia senegal and Acacia nilotica, grown under greenhouse conditions. Our results showed that inoculation using dissolved alginate beads containing rhizobia significantly improved the growth of both acacia species better than the growth of plants in other treatments. The experiment with A. nilotica was conducted in two unsterilised soils from different areas. Plants grown in soil from Bel Air were well-nodulated and showed better growth than plants grown in soil from Sangalkam. However, no difference between these soils was shown between the several methods of inoculation and their effect on the nodulation and growth of plants. An interaction between A. senegal and A. nilotica provenances and the effect of inoculation with rhizobia was also demonstrated. Bel Air provenance of A. senegal, Dahra and RIM provenances of A. nilotica grew best of several provenances tested. These results suggest that (1) it may be possible to improve growth and yield of A. senegal and A. nilotica by careful selection of each symbiotic partner; and (2) nursery-grown seedlings of A. senegal and A. nilotica should be inoculated, just after sowing, with dissolved alginate beads containing a mixture of selected rhizobia. Résumé. Lobject de notre travail était de déterminer la méthodologie dinoculation la plus efficace pour améliorer significativement la nodulation et la croissance dAcacia senegal et dAcacia nilotica poussant dans des conditions de serre. Nos résultats ont montré que linoculation utilisant des billes dalginate dissoutes améliorait significativement la croissance des deux espèces dAcacia par rapport à celle des plantes des autres traitements. Lexpérience avec A. nilotica a été faite dans deux types de sol non stériles. Nous avons observé que les plants poussant dans le sol de Bel Air étaient plus nodulés et mieux développés que ceux poussant dans le sol de Sangalkam. Cependant, aucune différence significative entre les deux sols na été mise en évidence en termes deffet des différentes méthodologies dinoculation sur la nodulation et la croissance des plantes. Il a aussi été démontré lexistence dune interaction entre les provenances dA. senegal et dA. nilotica et leffet de linoculation avec rhizobium. Cest ainsi que les provenances Bel Air dA. senegal, Dahra et RIM dA. nilotica ont le mieux poussé parmi les différentes provenances testées. Lensemble de ces résultats suggèrent: (1) il devrait être possible daméliorer la croissance et la production dA. senegal et dA. nilotica par une sélection des deux partenaires symbiotiques; (2) Les jeunes plantules dA. senegal et dA. nilotica produites en pépinière devraient être inoculées juste après le semis avec des billes dalginate dissoutes contenant un cocktail de souches sélectionnées.  相似文献   

17.
Fallow utilization schemes are becoming increasingly popular in agroforestry designs. However little attention has been given to the fate of valuable fallow plants after the end of the initial fallow cycle, and over successive fallow cycles on a regional or inter-fallow level. Evidence is presented here for the spontaneous long-term community enrichment of an area with valuable plants in a cyclic or iterative fashion, in the context of an existing fallow utilization scheme in the Amazon. Review of the ecological processes which operate at microsite, field and community levels indicate that:
a.  Due to valuable plants left uncut in the swidden, seeds from valuable species are better able to survive the burn, and may experience a favored germination and establishment because of reduced competition, enhanced fertility of the young swidden, nutrient input from litterfall, and reduced soil temperatures and soil moisture evaporation.
b.  The much greater frequency of suitable germination and establishment sites in and around canopy gaps created by management practices during the fallow cycle interacts with a spatial and temporal distribution of fruit trees which may encourage a specific optimal foraging strategy among large numbers of frugivores. The net effect of this interaction would be to decrease competition for, and increase efficiency of, seed dispersal into the large number of available establishment sites.
c.  A greater opportunity for frugivore generated seed shadows exist in managed fallows due to the larger number of trails in and around these sites, which are used as flyways.
d.  A presence of the more efficient specialist fruit tree seed dispersal strategy in managed fallows — as opposed to the opportunist strategy — which produces patterns of seed dispersal more beneficial to the plant, and may have a longer more evenly spread fruiting season; which, along with relatively large numbers of trees would encourage frugivores to camp out on the resource, depositing seeds nearby.
e.  The existence of relict plant species that reflect pre-historic forest management which has led to long term and persistent effects on forest tree species composition.
  相似文献   

18.
The case of an agroforestry farm in the coastal mountain area of the federal state of Bahia, Brazil, is used to highlight benefits of the integration of traditional knowledge into a scientifically based farming system. Special attention is given to the selection, combination and management of the crops cultivated. Working hypotheses on the rationale of some major measures are suggested and discussed from a synecological point of view. The results show that under the site conditions the forest garden provides cocoa yields without external inputs at a level which, in the surrounding cocoa plantations, can only be attained by the use of considerable amounts of fertilizer and pesticides.  相似文献   

19.
The success of the green revolution in the fertile and agriculturally surplus plains of western U.P. in north India led to labour shortages, and increased opportunities for off-farm investments by landowners, requiring their time and energies away from farming. These changes impelled landowners to adopt strategies which saved family labour and supervision time in cultivation. Many off-site farmers, and such on-site farmers who had a high ratio of owned land to male members in the family, resorted to tree farming, mainly eucalyptus. On the other hand, farmers in eastern U.P., with small holdings, subsistence orientation and cheap labour, showed little enthusiasm for planting eucalyptus. Based on field investigation in six villages, this paper argues that woodlot planting of eucalyptus emerged as an attractive option for landowners facing management and labour problems in western U.P., as tree farming allowed saving in family labour time and permitted greater flexibility in the timing of operations. About 60% of the total trees planted were by this category of management-constrained farmers.  相似文献   

20.
An agroforestry project was funded by the US Agency for International Development and implemented by the Pan American Development Foundation in Haiti from 1981 to 1991. This project is considered by many to be one of the most successful projects of its kind in Haiti, and in the tropics as a whole. Over the ten years of its implementation, the project, referred to in Haitian Creole as Pwoje Pyebwa (Tree Project), evolved from a tree production and planting project to a much broader soil-conservation-based program involving trees. This paper summarizes the training and extension systems that developed during that period. The socioeconomic background studies that were done before the project began, and the flexible, consultative mode of field-team implementation, incorporating elements of the learning process approach, were important to the success of the project. During the implementation of the project, however, concern for farmer input and participation should have been incorporated more systematically into the field operations of the regional teams.  相似文献   

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