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1.
《Forest Ecology and Management》1997,91(1):61-73
With increasing population pressure, the agricultural frontier in tropical countries is being expanded into previously untouched or little changed areas, frequently resulting in environmental degradation. At the same time, the use of agricultural lands is undergoing rapid changes in response to increasing environmental concerns and external market forces. In large areas of Central America, for example, the production systems for coffee have lost much of their biological diversity in the last couple of decades. Observations of apparently higher yields in high-input and low-diversity systems resulted in recommendations to eliminate trees. In recent years, however, as a result of low coffee prices and environmental concerns, calls to reverse this trend have been made in many countries and research and implementation initiatives are being developed to, once again, increase the diversity of the systems by incorporating trees.The necessary changes in the objectives and management of land-use systems must be gradual to assure high acceptability of the new practices. Under such conditions, which are typical for most traditional land-use systems, the development of practices which integrate trees into the agricultural land-use systems assumes special importance. Agroforestry practices can help to improve land-use systems towards higher sustainability and/or provide a stepping stone towards other, often tree-based, land-use systems of higher viability.Using examples from the research and extension experiences at CATIE, some silvopastoral and agrisilvicultural systems are discussed with their potentials and limitations. To help evaluate improved systems, promising methodologies for appropriate research and extension are outlined. New research has shifted the focus to on-farm experimentation, and economic and extension aspects of agroforestry. 相似文献
2.
《Southern Forests》2013,75(3):213-221
Globally, the intensification of land use for agriculture, timber and fuel is considered the leading threat to the diversity and biomass of forests and woodlands. To suggest management options, it is important to understand the patterns and drivers of diversity, structure, biomass and carbon stock of woodland vegetation. In this study we used data from three sites in the Miombo woodlands of western Zambia, which are subject to low, medium and high land-use intensity. We sampled 20 plots of 1 000 m² at each of these sites. Woody vegetation was sampled for richness and structure to provide an understanding of the impact of land-use intensity. Woody plant species richness was not affected by land-use intensity. However, an ANOVA revealed that stem diameter at breast height (DBH) was higher at the low land-use intensity (national park) than at medium and high land-use intensities (selective timber harvest, and non-selective harvest for crop fields and timber). We tested three different allometric equations (one global and two regionally adapted) to determine woody aboveground biomass (AGB) and carbon stock at the three sites. The estimated AGB using the regionally adapted allometric equation of Ryan et al. and the global tropical equation of Brown et al. revealed that the AGB for low and high land-use intensity sites were significantly different from each other with the medium land-use intensity site being intermediate. We concluded that DBH and AGB estimations were influenced by the land-use intensity in the Miombo woodlands as suggested by other studies in the tropical forest and woodlands. 相似文献
3.
In sub-Saharan Africa (SSA), the main goals behind the development of a biofuel industry are employment creation and income generation. Jatropha (Jatropha curcas L.) has emerged as a candidate for biodiesel production. It is a non-edible oil producing, drought-resistant plant that can be grown on marginal land with limited water and low soil fertility. However, these are also attributes that typify weedy and invasive plant species. Adding to these concerns are the general questioning of whether biofuel production will reduce Greenhouse gas (GHG) emissions globally. Currently, there is limited information on the potential invasiveness of many biofuel crops, and in particular, the potential risks of cultivating Jatropha. This paper aims to assess the benefits and risks, especially risks, of growing Jatropha for biodiesel production. Jatropha should be screened through a science-based risk-assessment procedure to predict the risk of becoming invasive before it is released for large-scale commercial cultivation. The net GHG savings can be achieved through the cultivation of Jatropha, considering two main factors: no land-use change and crop management without chemical fertilization. 相似文献
4.
Ian Jeffreys 《Small-Scale Forestry》2004,3(1):99-117
Small-scale farm forestry has the potential to offer many benefits both to landholders and the wider community. As with all
changes in land-use practices, there are associated benefits and costs and these are not uniformly distributed. They have
varying impacts on the different values, aspirations, goals and objectives that exist within the community. Furthermore, the
community does not consider these values, aspirations, goals and objectives of equal importance. The degree of concern can
vary from minor to high and overriding all other considerations. When evaluating farm forestry options it is necessary to
address all of these concerns. This paper examines the combined use compensatory and non-compensatory multi-criteria analyses
to evaluate forestry options, in a case study for the Darling Downs region of Queensland, Australia. These aggregation techniques
are found to be highly complementary and together provide a comprehensive analysis. The compensatory technique provides a
sound measure of overall performance of a forestry system, whereas the non-compensatory technique alerts decision-makers to
presence of particularly poor performance with respect to individual criteria. The compensatory technique used is simple and
understandable even for those with non-mathematical backgrounds. This analysis can identify and aid communication of the relative
benefits and costs, and trade-offs, between economic, environmental and social considerations. 相似文献
5.
This study developed an integrated decision support system (DSS) to assist land managers in taking a long-term holistic approach to integrated land-use decisions. “MyLand” is a unique combination of existing methods and techniques: meta-modelling calibrated off-productivity surfaces for spatial application, a decision tree for selecting options, multiple land-use analysis, multiple outputs and a mapping interface deployed over the Web. The design provides visualisation of geospatial information and enables multiple stakeholders to contribute to a more collaborative land-use planning process. Techniques to solve forestry modelling challenges have been generalised and applied in modelling pastoral and forestry land-use types. Forestry yield modelling is accommodated by a two-stage approach of spatial modelling of a productivity index followed by meta-modelling output from forest stand growth models. Livestock farming is modelled using the property owner's estimates of livestock carrying capacity of land management units in a whole property stock reconciliation model. The environmental performance of the property is calculated from the land-use type and management regime. A case study is described to demonstrate the use of “MyLand” and results of user evaluation of the DSS are presented. 相似文献
6.
An integrated tree plantation approach combining indigenous livelihoods and industrial wood production is being implemented in West Kalimantan, Indonesia. In this study the economics of land-use was investigated in villages within the plantation scheme. The effect of three alternative land-use scenarios and costs and benefits of each land-use type were studied using linear programming. The scenarios were based 1) on the current land-use, 2) on the integrated tree plantation system with incentives and government regulations, and 3) on a financially optimal land-use distribution. Additionally, plant species richness in different land-use types was surveyed. The scenarios had different kinds of effects on villages varying in respect to their possibilities for land-use intensification. In villages with extensive land use, establishment of tree plantations without any land-use regulations increased the potential economic return on land, resulting in conversion of natural and man-made semi-natural forests into swidden fields. In villages with more sedentary agriculture, the plantation scheme did not create pressures towards remaining forests even in the case of financially optimal land-use distribution. Incorporation of land-use regulations prevented further deforestation but also decreased households' economic returns. The results also showed that conversion of Imperata grasslands to any other land-use increased species richness. Incentives, restrictions or regulations aiming at conserving natural and semi-natural forests are needed to ensure conservation of biodiversity and long-term improvements in local livelihoods. It can be concluded that tree plantations can be combined with other land-use practices: They can improve the economic return on land without further degradation of the environment.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
7.
Silvio Frosini de Barros Ferraz Carlos Alberto Vettorazzi David M. Theobald 《Forest Ecology and Management》2009
In Rondônia State, Brazil, settlement processes have cleared 68,000 km2 of tropical forests since the 1970s. The intensity of deforestation has differed by region depending on driving factors like roads and economic activities. Different histories of land-use activities and rates of change have resulted in mosaics of forest patches embedded in an agricultural matrix. Yet, most assessments of deforestation and its effects on vegetation, soil and water typically focus on landscape patterns of current conditions, yet historical deforestation dynamics can influence current conditions strongly. Here, we develop and describe the use of four land-use dynamic indicators to capture historical land-use changes of catchments and to measure the rate of deforestation (annual deforestation rate), forest regeneration level (secondary forest mean proportion), time since disturbance (mean time since deforestation) and deforestation profile (deforestation profile curvature). We used the proposed indices to analyze a watershed located in central Rondônia. Landsat TM and ETM+ images were used to produce historical land-use maps of the last 18 years, each even year from 1984 to 2002 for 20 catchments. We found that the land-use dynamics indicators are able to distinguish catchments with different land-use change profiles. Four categories of historical land-use were identified: old and dominant pasture cover on small properties, recent deforestation and dominance of secondary growth, old extensive pastures and large forest remnants and, recent deforestation, pasture and large forest remnants. Knowing historical deforestation processes is important to develop appropriate conservation strategies and define priorities and actions for conserving forests currently under deforestation. 相似文献
8.
While early efforts to establish protected areas often excluded local people, modern approaches in many countries now seek to involve local communities in ways that are appropriate to the objectives for the protected area. In the Lao People's Democratic Republic (Lao PDR), a protected area management system was established in 1993. In many cases, the new protected areas had land-use conflicts with inhabitants who depended on the areas for their living. This study was undertaken in a protected area in the northwest of the Lao PDR. The primary objective was to identify and gain experiences from a feasible approach for improvement and implementation of protected area management with a positive interaction between people and the natural environment. An integrated land-use planning approach was adopted. It included participatory methods for data capture and analysis, including the use of a simple simulation model, the ‘Area Production Model’ (APM) aiming at evaluating different options for land use and primary production. The outcome of the study was positive in the sense that this integrated land-use planning approach was found to be well adapted to the needs of the protected area management system. 相似文献
9.
Environmental factors and land-use are likely interacting to drive forest structure and species diversity, making it difficult
to disentangle their separate impacts. Both components influence the resilience and stability of mountain forests in the Mediterranean
Basin, since secular land-use has shaped stands structure and forests dynamics are constrained to the environment. Approaches
covering environmental factors and contrasting land-uses are still needed to understand their implications on forest dynamics.
We investigated patterns of environmental variables, stand structure and biodiversity in forest dominated by Abies pinsapo for 61 stands over their whole range. In addition, since land-use by local inhabitant could be a key factor, logging intensity
was quantified by stumps basal area and recent land-use history was investigated. Partial redundancy analysis (pRDA) was conducted
to assess to which degree the structural attributes are related to environmental characteristics and/or the land-use in the
main A. pinsapo forests. Environmental characteristics accounted for 13% of the total variance, while the contrasting land-use (Spain vs.
Morocco) and the stumps basal area, as indicator of human logging, accounted for 23% of the total variance. Trees species
diversity was near 5 times higher in Moroccan stands than in stands from south Spain. According to recent human logging, Spanish
stands have been strictly protected, but Moroccan stands showed widespread axe-logging by local inhabitant over the smaller
tree sizes. Our results suggest that the preservation of a minor perturbation regimen by local populations enhance and help
to preserve the whole biodiversity of this relict habitat. 相似文献
10.
Land-use changes and land cover strongly influence carbon stock and distribution within ecosystems. Changing the land-use from natural forest to other land-uses has been more rapid in the past few decades than at any time in Iran’s history. In this study, we investigated the effects of changing the land-use from natural forest to other land-uses on carbon stocks in northern Iran. We selected five sites for this study: (I) a natural forest, (II) an agricultural field and (III) plantations of three different species (Alnus subcordata. L, Acer velutinum.Boiss and Cupressus sempervirens). We examined the effects of land-use changes on: (I) soil carbon stock (0–50 cm depth), (II) biomass and carbon content of grassy vegetation and litter and (III) above- and below-ground biomass C in trees. Soil C stock was higher under A. velutinum and C. sempervirens whereas it was lower under A. subcordata and agricultural sites. Biomass and C content of grassy vegetation were significantly higher at A. velutinum and C. sempervirens plantations. However, litter biomass and C content were significantly higher at the natural forest site. Natural forest had the highest amount of C content in above- and below-ground biomass. Total ecosystem C stocks declined following land-use changes. 相似文献
11.
European agroecosystems host a variety of farm woodlands that act as primary determinants of biodiversity and ecosystem services. While woodland areas have been in decline worldwide, they have regionally increased, for example, in Eastern Germany. This study performs a quantitative and spatially explicit assessment of differences in species richness, diversity, and evenness as well as forest physiognomy and structure among Eastern German farm woodlands established during (1) the presocialist era (until 1945), (2) the socialist era (1945–1990), and (3) the postsocialist era (after 1990). Aerial imagery was used to allocate woodlands to one of the three eras, after which a forest inventory of 120 woodlands was performed. The results show substantial differences in forest composition and structure. Presocialist-era woodlands are composed of native (mean 96 %), deciduous (mean 94 %) tree species. Mean diameters and species richness values are high. Typical socialist woodland species are nonnative (mean 35 %) and/or coniferous (mean 51 %). Stands have a uniform, even-aged stand structure. Species richness/diversity indices are generally low. Postsocialist woodlands exhibit a high degree of variability. Percentages of nonnative (7 %) and coniferous (10 %) individuals are low. The findings suggest that socialist and postsocialist farmland and forest policies translated into distinct land-use legacies in the newly established farm woodlands, which differ considerably from the composition and structure of presocialist woodlands. We argue that forest conservation planning should actively consider land-use legacies, which are of particular relevance in the landscapes of Central and Eastern Europe, as these have undergone multiple, abrupt, and severe land-use transitions. 相似文献
12.
Shibu Jose 《Agroforestry Systems》2009,76(1):1-10
Agroforestry systems are believed to provide a number of ecosystem services; however, until recently evidence in the agroforestry
literature supporting these perceived benefits has been lacking. This special issue brings together a series of papers from
around the globe to address recent findings on the ecosystem services and environmental benefits provided by agroforestry.
As prelude to the special issue, this paper examines four major ecosystem services and environmental benefits of agroforestry:
(1) carbon sequestration, (2) biodiversity conservation, (3) soil enrichment and (4) air and water quality. Past and present
evidence clearly indicates that agroforestry, as part of a multifunctional working landscape, can be a viable land-use option
that, in addition to alleviating poverty, offers a number of ecosystem services and environmental benefits. This realization
should help promote agroforestry and its role as an integral part of a multifunctional working landscape the world over. 相似文献
13.
Economic policies that boost profits from agroforesty, thereby creating financial incentives for land managers to favor these
systems over less environmentally friendly land uses, could, in theory, have ancillary environmental benefits. This paper
analyses primary and secondary data to determine whether a voluntary price support program for Mexican coffee—mostly grown
in shaded systems that supply important ecosystem services—has had such “win-win” benefits by stemming land-use change in
the coffee sector. We find that although the program attracted the types of growers associated with land-use change, it attracted
only a relatively small number of them, did not target growing areas hardest hit by conversion to other land uses, and provided
subsidies that were probably too small to affect land-use decisions. These results raise serious questions about the ability
of an agroforestry price support program with a modest price floor to have a significant conservation impact. 相似文献
14.
The threshold wind velocity of a number of variables was studied in four different land-use types: farm land, forestland,
wild grassland and a flood plain in the Yongding River sandy land in Beijing. The variables studied were transport of sand,
underlying surface roughness, windblown sediment, wind-sand flow structure, soil mechanical composition and amount of wind
erosion. The following conclusions were drawn: 1) The order of decreasing threshold of wind speed for sand displacement and
surface roughness were forestland, wild grassland, farm land, sparse wild grassland and flood plain. 2) There were significant
differences in sand flux among different ground covers. At a height of 0–20 cm, the height increased while the sediment discharge
percent of sand flux decreased; there were significant differences in the sand flow formation under different land-use types.
3) The mechanical composition of sand particles consisted mainly of silver sand in the flood plain and sparse wild grassland,
and of silver sand, particle silver sand and floury sand in other land-use types. 4) The amounts of wind erosion and sand
sediment were different among different land-use types. Increased vegetation cover and change in farming techniques were suggested
to prevent and control wind erosion of sand and soil.
__________
Translated from Scientia Silvae Sinicae, 2005, 41(4) [译自: 林业科学, 2005, 41(4)] 相似文献
15.
Soil fauna can sensitively respond to alterations in soil environment induced by land-use changes.However,little is known about the impact of urban land-use changes on earthworm communities.In this study,three land-use types(i.e.,forest,nursery and abandoned lands)were chosen to identify differences in diversity,abundance and biomass of earthworm community in Kunming City.Urban land-use had a pronounced difference in species composition,evenness and diversity of earthworm communities.Forest land had the highest density,biomass and diversity of the earthworm communities.Total abundance was dominated by endogeic species in nursery land(70%)and abandoned land(80%),whereas in the forest land,the earthworm community comprised epigeic,endogeic and anecic species.Temporal changes in earthworm density and biomass were also significantly affected by land-use change.Total density and biomass of earthworms in the forest and nursery lands were highest in September,but highest in the abandoned land in October.The influence of soil physicochemical properties on the earthworm density and biomass also varied with land-use types.Soil temperature significantly affected earthworm density and biomass in the three land-use types.Soil pH was positively correlated with earthworm biomass in the forest land,but negatively associated with earthworm density in the abandoned land.Soil organic matter was positively correlated only with density and biomass of earthworms in the nursery and abandoned lands.Our results suggest that the species composition,abundance and biomass of earthworm communities can be determined by the modification of soil properties associated with urban land-use type. 相似文献
16.
Luisa Neumann-Cosel Beate Zimmermann Jefferson S. HallMichiel van Breugel Helmut Elsenbeer 《Forest Ecology and Management》2011,261(10):1625-1633
Secondary forests are gaining increased importance in tropical landscapes and have recently been reported to act as potential belowground carbon sinks. While economic interest in the management of secondary forests to mitigate carbon emissions is rising, the dynamics of soil carbon stocks under these ecosystems remain poorly understood. Recent studies report conflicting results concerning soil carbon trends as well as multiple confounding factors (e.g. soil type, topography and land-use history) affecting these trends. In this study, organic carbon stocks were measured in the mineral soil up to 20 cm depth of at 24 active pastures, 5-8-year-old, and 12-15-year-old secondary forest sites on former pastures. Additionally, we estimated carbon stocks under a 100-year-old secondary forest and compared them to those of nearby mature forests. Abiotic conditions in the study area were homogenous, enabling us to isolate the effect of land-use change on soil organic carbon stocks. Contrary to our expectations, soil carbon stocks in the top 10 cm did not change with young secondary forest development. Pasture soils stored 24.8 ± 2.9 Mg ha−1 carbon (mean ± standard error) in the top 10 cm, and no accumulation of soil carbon was apparent during the first 15 years of secondary succession. Soil carbon stocks under 100-year-old secondary forests, averaging 43.0 ± 7.9 Mg ha−1 (mean ± standard error), were clearly higher than those recorded at younger sites and approached levels of soil carbon stocks under mature forests. These data indicate that soil carbon stocks in this region of Panama are not affected by the land-use transition from pasture to young secondary regrowth. However, an increase of soil carbon storage might be possible over a longer period of time. Our results support trends observed in other tropical areas and highlight the importance of environmental conditions such as soil properties rather than land-use transitions on soil carbon dynamics. While our understanding of organic carbon dynamics in tropical soils remains limited, these results underscore the challenges of undertaking short-term reforestation projects with the expectation of increasing soil carbon sequestration. 相似文献
17.
Luz Maria Castro Baltazar Calvas Patrick Hildebrandt Thomas Knoke 《Agroforestry Systems》2013,87(2):331-347
We usually have only limited knowledge about the economic consequences of land-use decisions, thus they are uncertain. We analyze the implications of this uncertainty on conservation payments (CP) to preserve wildlife-friendly shade coffee production in southwest Ecuador, when conversion to maize is the most profitable alternative. Our objective is twofold: First, we analyze the consequences of applying Stochastic Dominance (SD) to derive CP, an approach making only minimal assumptions about the preferences of farmers. Second, we investigate the effects of land-use diversification to reduce CP by allowing for shade coffee on part of a landholding, and maize production on what remains. CP derived by SD turned out to be at least twice the amount calculated by an alternative method which maximizes a concave utility function—US$ 166 to US$ 294 ha?1 year?1 instead of US$ 86 ha?1 year?1. Given this result, we doubt that the assumptions underlying SD are reasonable for farmers, who are known to be risk-averse. Allowing for land-use diversification has a significant impact on CP. The optimal portfolio share of shade coffee is 27 % and for maize 73 % for moderately risk-averse farmers—without any CP. A larger share of shade coffee is preferable for strongly risk-averse farmers—51 and 49 % maize. The amount of CP necessary to encourage the expansion of shade coffee to 75 % is US$ 40 ha?1 year?1 (for moderately risk-averse) and US$ 19 ha?1 year?1 (for strongly risk-averse farmers). Stimulating diversification may thus help to significantly reduce CP necessary to preserve less profitable agroforestry options. 相似文献
18.
Veikko Hiltunen Mikko Kurttila Pekka Leskinen Karri Pasanen Jouni Pykäläinen 《Forest Policy and Economics》2009,11(1):1-9
We tested the Mesta Internet-based decision-support application in connection with a natural resources planning (NRP) process in Eastern and Western Lapland, Finland. The aim in this process was to define the land-use allocation and the corresponding forest management operations for state-owned forests within these planning regions. Mesta was used in examining and evaluating the strategy alternatives from the viewpoint of the stakeholders' objectives. The basic idea in using Mesta is to define the acceptance thresholds that divide the alternatives into ‘acceptable’ and ‘not acceptable’ alternatives with respect to each decision criterion. The thresholds are adjusted holistically, i.e. so that all decision criteria and criteria values of all decision alternatives are simultaneously visible from the user interface. The holistic adjustment process is continued until an acceptable solution compliant with the production possibilities of the planning area is found. In the NRP process, the members of the stakeholder group first used Mesta individually to set their own thresholds. Next, the participants' acceptance thresholds were combined and a negotiation process was launched to find the group's common acceptance thresholds. This negotiation was also supported by Mesta. The result of the negotiation was that the participants were able to collaboratively decide on their recommendation for the future land-use allocation and the forest management principles to be applied in the two planning regions. The main benefit of Mesta as a decision-support tool during the negotiation process of the group was that the participants were forced to merge their preferences with the realistic production possibilities of the planning regions. 相似文献
19.
QuickBird影像目视判读在土地利用类型调查中的应用研究 总被引：6，自引：0，他引：6
利用Q u ickB ird影像数据进行土地利用类型调查过程中采用人工目视判读或人机交互式判读方法能获取相对准确的土地利用类型信息。目视判读的难点是对易混淆地类和森林类型的判读,包括草地与农田、灌木林与果园地、经济林与用材林、陡坡地与常年旱地等。通过适当的前期图像处理,以建立解译标志为基础,采取综合的判读方法可将上述类型大部分判读出来。 相似文献
20.
《Forest Ecology and Management》2005,204(1):69-85
Central Rondônia is one of the most deforested regions in the Brazilian Amazon and contains areas at different stages of degradation forming a gradient from mature forest to highly urbanized and built-up areas. Regional data from satellite imagery are available from the 1980s, but apart from studies that quantify deforestation, the broad-scale landscape dynamics of Rondônia have not been examined well. This paper assesses the landscape changes between 1984 and 2002 in a watershed located in the central region of the state of Rondônia, Brazil, which has undergone systematic and rapid deforestation due to introduction of pasture that began in the 1970s. Bi-annual Landsat TM/ETM+ images from 1984 to 2002 were classified into three broad land cover types: mature forest, secondary forest, and pasture, resulting in a time series of land-use/land-cover maps. Landscape changes were evaluated by computing a cross tabulation between years, transition rates, and landscape metrics related to size, density, connectivity, configuration, and deforested patches distribution related to patch size and spatial proximity to roads and old pastures. Transition probability functions were fitted to the temporal series to predict land-use changes for the next 10 years, for three different scenarios: (1) continued land-use change; (2) eliminating clear-cutting and selective logging; and (3) eliminating clear-cutting, selective logging, and secondary vegetation clearing. Current land-use transitions cannot be sustained beyond the next 10–15 years. A more sustainable scenario for the region requires a major reduction of deforestation activities, implementing the “permanent preservation area” policy along riversides, and controlling land-use transitions at balanced levels. We recommend that forest managers in regions facing similar deforestation pressures should strive to maintain at least 35% mature or primary forest, because landscape fragmentation proceeds rapidly below this critical threshold. 相似文献