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1.
Information on forest structure is fundamentally important to track successional vegetation dynamics for efficient forest management.This study reports on vegetation characteristics,dominance patterns and species height growth in a northern mistbelt forest type in South Africa.Common alpha-diversity indices(species richness and Shannon-Weiner diversity),structural vegetation parameters(tree density and basal area),and species importance value index were used.Size class distribution and height-diameter allometry were further examined for the overall stand and most important species.Stem densities(472.0±43.5 and 605.3±28.1 trees ha^-1 for C 5 cm to\10 cm and C 10 cm dbh(diameter at breast height)classes,respectively)and basal area values(1.99±0.19 and 48.07±3.46 m^2 ha^-1,respectively)are comparable to other Afromontane forests in East Africa.The overall stand showed an inverted-J shaped distribution pattern which is a typical feature of stand size class distribution in most natural forests.Most ecologically important species also exhibited an inverted-J shaped distribution pattern,suggesting good regeneration and recruitment potential.There were significant differences in species on height,reflecting species-specific height growth patterns,possibly a result of intrinsic growth potential and competitive interactions.The present study suggests that conservation and management policies,including protection of surrounding land uses against fire,contribute to maintaining a successful recovery of these forests.However,it should be noted that these forests may be experiencing relatively slow dynamic flux as a result of the overmature state of some trees with several years under relatively strict protection.  相似文献   

2.
The scale of deforestation in sub-Saharan Africa underscores the need for forest restoration. Information is scarce for evidence-based restoration options. Sown Senna didymobotrya, planted Ficus thonningii cuttings, sown S. didymobotrya and planted F. thonningii combined, and previously occurring native non-browse shrubs (NNS) were compared for their effect on selected plant nutrients and occurrence of Olea europaea subsp. cuspidata in north-west Ethiopia. The treatments were applied to experimental units established on previous grazing land. At the end of the fourth year, 60% of planted F. thonningii stakes survived. The leaf biomass production was encouraging. Senna didymobotrya attained close to 1 m height and crown width. Natural regeneration of O. europaea was observed only under previously occurring shrubs. Six previously occurring NNS species were identified. Soils immediately under these shrubs were richer in nutrients than between shrubs in the open spaces. Our results suggest that vegetative stakes and NNS could be promising tools for ecological restoration of decimated ecosystems in the highlands of Ethiopia. Management interventions, which aim at steering succession close to pre-disturbance forest community structure by facilitation, should be selective of the shrub species.  相似文献   

3.
In a survey of the Bore–Anferara–Wadera forest to study the vegetation structure and regeneration status of woody plant species, 112 quadrats were systematically sampled along altitudinal transects to collect vegetation data. Nested sample plots of 30 m × 30 m and 5 m × 5 m were laid for collecting data on abundance and some variables of tree and shrub size. The regeneration status of woody species was assessed by counting all seedlings within the main sample plot. Woody plant species taller than or equal to 3 m were counted and their height and DBH measured. Density, frequency, basal area and importance value(IV) of woody plant species were computed. A total of 136 vascular plant species belonging to119 genera and 63 families were recorded. The overall Shannon—Wiener diversity value was 3.84 and evenness was 0.78. Total density of trees and shrubs with DBH >2 cm was 1047 ha-1. Size class distribution of woody species across different DBH and height classes indicated a relatively high proportion of individuals at lower classes,suggesting impacts of past anthropogenic disturbances.Analysis of population structure and regeneration status of the forest revealed various patterns of population dynamics where some species were represented by only a few mature plants, suggesting that they are on the verge of local extinction and that immediate conservation measures should be taken. The results highlight the need for joint management and conservation measures by the government, local people and other stakeholders to abate the rapid rate of deforestation and promote sustainable utilization of the forest resources in this forest in southern Ethiopia.  相似文献   

4.
This paper presents a total survey of the characteristics and changes over time (1990–2010) within the entire population of Swedish non-industrial private forest owners (NIPF owners). By charting the changed demographic, socio-economic and geographic profile of the NIPF owners, it also provides a baseline for a discussion and analysis of potential implications for forest management, policy and values. NIPF owners differ in important ways from the general population of Sweden. However, the gap has narrowed over time with regard to, e.g., educational level and sex composition. The ongoing urbanization process is evident in the growing share of non-residential NIPF owners who live at a distance from their forest property and who differ from their residential (rural) peers through, e.g., higher education, higher income and a higher prevalence of co-ownership of their forest holdings. Although these changes might translate into updated views on forest values among NIPF owners, there could be a delay before this impacts on forest management practices and output.  相似文献   

5.
Abstract

Tree response to climate trends is most likely to be observed in the forest–tundra ecotone, where mainly temperature limits tree growth. On-ground observation and multitemporal Landsat data were used in the analysis of forest–tundra ecotone dynamics (from 1976 to 2000) in the Western Sayan Mountains, Siberia. Observations showed an increase in forest stand crown closure, upward tree-line and regeneration shift and the transformation of Siberian pine and fir krummholz into arboreal forms. Closed stands were increasing in the area at a rate of 0.8% year?1 and advancing their upper boundary at an altitudinal rate of 0.6 m year?1; these changes were shown mainly by the transformation of sparse stands into closed stands. The altitudinal rate of regeneration propagation was estimated at 1.2 m year?1. It was also found that these changes correlated positively with temperature trends. The response of tree vegetation to air temperature increase was dependent on topographic relief features (azimuth and slope steepness).  相似文献   

6.
The paper came up with the basic principles, technology system, planning and forest governance system of close-to-nature and value-oriented forest management on the basis of discussions on its concept and theoretical foundation, and finally introduced initial effects of close-to-nature and value-oriented forest management implemented in Harbin.  相似文献   

7.
LandscapePatternsandDynamicsinShanhaiguanForestFarm,HebeiProvinceLiuXianyinChinaForestryPublishingHouse,BeijingXuHuachengZhen...  相似文献   

8.
Importance–performance (I-P) analysis is a common evaluative measure in forest recreation management. However, concerns with I-P analysis have been raised. In this study, the observance–influence (O-I) analysis technique modified from I-P analysis was adapted for analysing the observance of various use and resource impacts by on-site visitors, and the influence that these impact conditions have on forest recreation area visitor experiences. During the summer and autumn of 2000, 476 Worak-san Forest National Park visitors in Korea were surveyed. The O-I grid generated from the survey data indicated that managers are doing a good job. The grid revealed most impacts clustering in the low priority concern and no concern quadrants. Impacts shown to be of most concern related to utility poles and power lines, poor maintenance of buildings, dead and dying trees, and discourteous behaviour. The O-I grid analysis model has considerable utility for park managers in analysing visitors’ perceptions of park impacts.  相似文献   

9.
Dendroecological techniques were used to examine the disturbance history and patterns of species recruitment in an old-growth Quercus rubra L. (northern red oak)–Acer saccharum Marsh. (sugar maple)–Tilia americana L. (basswood) forest on a steep, talus slope in eastern West Virginia. The forest was uneven-aged as were the populations of red oak. Sugar maple dominated the sapling layer, which comprised little or no basswood and red oak. A compilation of major and moderate releases (indicative of disturbance) in 25 cores revealed single or multiple release events in every decade from 1870–1990. The high elevation of the forest coupled with a fertile sub-soil beneath the talus ameliorated the outwardly harsh conditions of the site, allowing for the domination of typically mesophytic, nutrient demanding tree species. We observed several fire scarred trees as well as extensive small-scale blow-down throughout the forest. Frequent disturbance events were probably crucial to the co-existence and continuous canopy recruitment of the relatively light demanding red oak with highly shade tolerant sugar maple and basswood. The strong successional replacement tendencies of red oak by northern hardwoods noted elsewhere in the eastern US may be less apparent on high elevation, rocky sites in the central Appalachians. Thus, this is a unique case study of long-term red oak domination with later successional species in an old-growth forest.  相似文献   

10.
11.
李伟林  肖波  李郁 《林业研究》2000,11(1):69-71
ForeSt is an jmPOhant. renewable resource which iscomPOrt Of all kinds of plantS. It has the charaCtersOf long grOWth P6riod and complex land distribution.So it has spotal rules of dynamic change. Forestcannot be subStituted by other resources in theeconomic conSbothen and environmentsl proteCtion.SO ti is imment tO eStablish a good pattern of forestresource management. In odder tO realize this goal,ffod the dynamic change Of forest resource must bemonitored and Predbe. then on this b…  相似文献   

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14.
From 1983 to 1985, a network of agroforestry research trials was established at six localities throughout Victoria. This paper describes experimental designs and establishment procedures used at the trial sites. The overall aim of the research program is to provide definitive information on the costs and benefits of a wide range of agroforestry combinations. Accordingly, trials were established at the following locations to test a total of 93 tree species grown in combination with specific types of agriculture:
  1. Carngham (near Ballarat) — sheep grazing andPinus radiata D. Don (radiata pine);
  2. Hamilton (several sites) — sheep grazing and mixed tree species;
  3. Kyabram — irrigated pastures andEucalyptus grandis W. Hill ex Maiden (flooded gum);
  4. Rutherglen — cereal cropping and shelterbelts;
  5. Myrtleford — irrigatedMentha spp. (mint) and two clones ofPopulus spp. (poplar); and
  6. Neerim South (near Warragul) — cattle grazing and mixed tree species.
Conventional and systematic experimental designs have been used in setting up these trials, which in total constitute the most comprehensive agroforestry research in Australia. This paper describes these trials in detail, and stresses the importance of their continued expert management, so that the full benefits of the work can be realised for rural Victoria.  相似文献   

15.
Management of downed woody fuels and snags (standing dead trees) is receiving increasing attention because of their ecosystem values and effects on potential fire behavior. Research has correlated the abundance of many wildlife species with snags and downed woody material but very little information exists of the abundance and arrangement of these forest structures, particularly in unmanaged forests. Conifer forests in northwestern Mexico have not experienced systematic fire suppression or harvesting making them unique in western North America. In 1998, average snag density in Jeffrey pine–mixed conifer forests in the Sierra San Pedro Martir (SSPM) National Park was 3.95 snags/ha but 35% of inventoried plots had no snags. In 2002, average snag density significantly increased to 5.10 snags/ha after a multiple-year drought. Average surface and ground fuel loads were 15.8 and 8.7 t/ha, respectively. High variability characterized all snag and fuel attributes measured in this forest. This high amount of variation is probably the result of the relatively intact frequent surface fire regime and because no harvesting has occurred in the sampled area. The patchy distribution of snags observed argues against the application of uniform targets for snag retention across similar forested landscapes. An improvement in management guidelines would be to manage for snag density and large fuels over moderate spatial scales (hundreds of hectares) instead of on a per hectare basis. Forest fragmentation and diverse ownerships in many western United States forests complicates this recommendation. Conservation of the forests in the SSPM is critical because it is the last landscape-scale, old-growth mixed conifer forest in western North America with a relatively intact frequent fire regime.  相似文献   

16.
From 1983 to 1985, a network of agroforestry research trials was established at six localities throughout Victoria. This paper describes experimental designs and establishment procedures used at the trial sites. The overall aim of the research program is to provide definitive information on the costs and benefits of a wide range of agroforestry combinations. Accordingly, trials were established at the following locations to test a total of 93 tree species grown in combination with specific types of agriculture:
  1. Carngham (near Ballarat) — sheep grazing andPinus radiata D. Don (radiata pine);
  2. Hamilton (several sites) — sheep grazing and mixed tree species;
  3. Kyabram — irrigated pastures andEucalyptus grandis W. Hill ex Maiden (flooded gum);
  4. Rutherglen — cereal cropping and shelterbelts;
  5. Myrtleford — irrigatedMentha spp. (mint) and two clones ofPopulus spp. (poplar); and
  6. Neerim South (near Warragul) — cattle grazing and mixed tree species.
Conventional and systematic experimental designs have been used in setting up these trials, which in total constitute the most comprehensive agroforestry research in Australia. This paper describes these trials in detail, and stresses the importance of their continued expert management, so that the full benefits of the work can be realised for rural Victoria.  相似文献   

17.
Abstract

Although recreational pressure correlates to population size which in turn influences city growth, there is little evidence of how such processes of urban growth have affected the availability of urban fringe forests (forests with good recreational qualities located completely outside and up to 3 km from the city borders). Hence, the aim of this study was to examine consequences of urban growth on urban fringe forest availability in Sweden for the period 2000–2010. An overlay analysis was conducted in a GIS to identify urban fringe forests with good recreational qualities. A selection of Swedish cities with >2000 inhabitants (n = 428) was used along with a regional division to identify trends of cities in forest regions and in other regions. Results showed that the median availability of urban fringe forests had increased in all regions, both in absolute amounts and per 1000 inhabitants. A majority of the cities individually showed increased levels of urban fringe forests, despite contemporary urban growth. Availability had also decreased in about a third of the cities, most notably among those with greater population growth. Increasing populations and a future demand for recreation in proximate forests make further studies relevant, as other processes than urban growth have affected the availability of urban fringe forests.  相似文献   

18.
1ThisStudyisoneoftheprojectssuportedbyNaturalScienceFundationofHeilongjiangProvinceIntroductionSitoindexisaconvcnientstcptoxtardtl1eultin1ategoaiofpredictingtheproductioncapability'offorcstlwt;anditisausefuldircctmeasuresforapotentialexpetionparadigmintcn…  相似文献   

19.
Agroforestry Systems - Farmer Managed Natural Regeneration (FMNR) is a rapid, low cost and easily replicated approach to restore and improve degraded agricultural, forest and pasture lands. The...  相似文献   

20.
This study compares the performance of three fire risk indices for accuracy in predicting fires in semideciduous forest fragments,creates a fire risk map by integrating historical fire occurrences in a probabilistic density surface using the Kernel density estimator(KDE)in the municipality of Sorocaba,Sao Paulo state,Brazil.The logarithmic Telicyn index,Monte Alegre formula(MAF)and enhanced Monte Alegre formula(MAF+)were employed using data for the period 1 January 2005 to 31 December 2016.Meteorological data and numbers of fire occurrences were obtained from the National Institute of Meteorology(INMET)and the Institute for Space Research(INPE),respectively.Two performance measures were calculated:Heidke skill score(SS)and success rate(SR).The MAF+index was the most accurate,with values of SS and SR of 0.611%and 62.8%,respectively.The fire risk map revealed two most susceptible areas with high(63 km^2)and very high(47 km^2)risk of fires in the municipality.Identification of the best risk index and the generation of fire risk maps can contribute to better planning and cost reduction in preventing and fighting forest fires.  相似文献   

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