Impacts of Deforestation and Land Cover Change on Mountain Soils in Hrazdan,Armenia

The impacts of deforestation and land cover change upon underlying soils were examined on one hillside in central Armenia. Soil characteristics in three land cover areas—forest, coppice, and pasture—were recorded and soil samples were analyzed. Deforestation and land cover change were found to increase erosion rates. From soil horizon and structural characteristics, it can be estimated that 40 cm of soil have been lost in the pasture and 20 cm have been lost in the coppice compared to the forest. Soil organic carbon was also affected by deforestation and land cover change. Compared to the forest (4.7% organic carbon), both the coppice (3.7%) and the pasture (3.4%) had lower values. Phosphorus, potassium, and nitrogen content varied and may have been affected by erosion, animal deposition, differing amounts of vegetative residues present, differing organic matter decomposition rates, and differing hydrological processes. Deforestation was also found to change the species composition of seedlings and saplings in the coppice in comparison to the forest, reducing oak numbers and increasing hornbeam recruitment.     

Prospects and problems: considerations for smallholder cattle grazing in oil palm plantations in South Kalimantan,Indonesia

Current Indonesian beef production only meets 45% of local demand. Increasing local beef production through integration of cattle production in pre-existing oil palm plantations is a possible solution to meeting this shortfall. The oil palm understorey provides feed, alleviating the need to convert additional land to agriculture. Smallholders are important contributors to both Indonesian cattle and palm oil production. This case study research seeks to understand key aspects of smallholder cattle management in palm oil production areas, to highlight opportunities and barriers to cattle integration. Thirty-nine smallholder cattle farmers from four villages in South Kalimantan were individually interviewed. The lack of alternative feed sources was the major driver towards the adoption of cattle production using oil palm understorey as feed. Cattle grazing was uncontrolled due to labour shortages and occurred in individually owned and ‘plasma’ plantations, with cattle penned at night where possible to avoid theft. Arrangements on land access and use between stakeholders are needed for systematic cattle grazing and to control cattle theft.

     

Analysis of forest cover change at Khadimnagar National Park,Sylhet, Bangladesh,using Landsat TM and GIS data

We mapped the forest cover of Khadimnagar National Park （KNP） of Sylhet Forest Division and estimated forest change over a period of 22 years （1988-2010） using Landsat TM images and other GIS data. Supervised classification and Normalized Difference Vegetation Index （NDVI） image classification approaches were applied to the images to produce three cover classes, viz. dense forest, medium dense forest, and bare land. The change map was produced by differencing classified imageries of 1988 and 2010 as before image and after image, respectively, in ERDAS IMAGINE. Error matrix and kappa statistics were used to assess the accuracy of the produced maps. Overall map accuracies resulting from supervised classification of 1988 and 2010 imageries were 84.6% （Kappa 0.75） and 87.5% （Kappa 0.80）, respec- tively. Forest cover statistics resulting from supervised classification showed that dense forest and bare land declined from 526 ha （67%） to 417 ha （59%） and 105 ha （13%） to 8 ha （1%）, respectively, whereas medium dense forest increased from 155 ha （20%） to 317 ha （40%）. Forest cover change statistics derived from NDVI classification showed that dense forest declined from 525 ha （67%） to 421 ha （54%） while medium dense forest increased from 253 ha （32%） to 356 ha （45%）. Both supervised and NDVI classification approaches showed similar trends of forest change, i.e. decrease of dense forest and increase of medium dense forest, which indicates dense forest has been converted to medium dense forest. Area of bare land was unchanged. Illicit felling, encroachment, and settlement near forests caused the dense forest decline while short and long rotation plantations raised in various years caused the increase in area of medium dense forest. Protective measures should be undertaken to check further degradation of forest at KNP.     

The effect of cattle grazing on soil physical and chemical properties in a silvopastoral system in the Peruvian Amazon

In a six-year-old peach palm (Bactris gasipaes) plantation, centrosema (Centrosema macrocarpum), a leguminous forage plant, was established as a cover crop which was eventually grazed. This experiment was designed to monitor probable changes in soil physical and chemical properties and measure peach palm fruit production and live-weight gain of cattle grazing this silvopastoral system. The experiment was installed on land that was previously cleared by a D7 bulldozer having a straight blade that mixed the thin layer of topsoil with the acid subsoil (20–40 cm) and severely compacted the soil. The results demonstrated that the centrosema cover crop reduced soil bulk density, increased water infiltration rates and reduced mechanical resistance. In general soil physical properties were improved with the use of Centrosema as forage and cover crop. Soil acidity and aluminum saturation decreased considerably, while potassium concentrations increased. Calcium and magnesium concentrations decreased over time as these minerals were stored in the pasture biomass, translocated to fresh peach palm fruits and/or exported to animals. A strong competition for nutrients was observed between the peach palm plants and Centrosema. The low production of peach palm fruits was in response to mechanized land clearing during initial establishment of the plantation, and also probably due to deficits of N, P, K, Ca and Mg in the soil instead of being a consequence to the presence of cattle. The average increase in live-weight gains of the cattle was at a rate of 445 g/animal/day during the four-years of the study. Such an increase is substantially greater than those registered in the area under traditional grazing systems used in the region. This revised version was published online in August 2006 with corrections to the Cover Date.     

Formal Address

Summary

A combination of social, economic and physical factors contribute to a decision to migrate for a peasant farmer. Seventy percent of Panamanian land comprises steep topography with low soil fertility. Campesinos (peasant farmers) must perpetually migrate when the land they have settled in the forest loses fertility. This process of continual migration results in deforestation and conversion of forest land to pasture land, which then becomes degraded and subsequently abandoned. Also, government policy has not favored the activities of small land owners, but loans from national banks have financed the promotion of large-scale cattle ranches.

Migration patterns consist of moving to a forested area, clearing it for agriculture for one to three years, and thereafter sowing it for pasture. These conditions eventually result in low agricultural and cattle production. Campesinos therefore sell the land to cattle ranchers who can afford to invest in better management practices. Deforestation in the Canal Watershed, therefore, has left a pattern of land ownership comprising a matrix of a few large landowners, within which remain numerous but small peasant land holdings.

A program for small land owners in and around the Watershed region that promotes social, cultural, and economic stability of land use is needed. Supporting and promoting agroforestry with uses of native tree species associated with subsistence and market crops is an alternative for slowing deforestation and promoting sedentary land use.     

An analysis of a silvopastoral system for the marginal land in the Southeast United States

Almost 20 million acres of non-forest cropland in the South can be classified as marginal. Demand projections for forest products call for a 40 percent increase by year 2030. Recent regenerated tree acres lag behind harvested acres. Multiple land use practices combining trees and grazing adjust cash flows forward mitigating negative flow period associated with conventional forest production. Profit opportunities for private, non-industrial landowners can be increased by ranking inputs in order of changes to net present value(NPV). A sensitivity analysis of an agroforestry scenario, including trees, beef cattle, and pasture, allows producers to concentrate management efforts where returns are greatest. Model results show greatest returns to NPV was realized from improvement to Chip-N-Saw income. The least increase in NPV came when the cost of control burns was changed.     

A methodology for the description of border hedges and the analysis of variables influencing their distribution: a case study in western Kenya

This paper presents results from a survey of border hedges on farmland in western Kenya. The survey covered 160000 ha of high potential land in eastern Siaya District and Vihiga District of western Kenya. The survey attempted to widen the knowledge of the typology, the biomass and the parameters influencing the spatial distribution of hedge types. Spatial analysis was used to delimit hedge type sub-regions (using cluster analysis) and to identify the variables influencing the spatial distribution of hedge types (using discriminant analysis). It is demonstrated that a complex association of variables is influencing the subdivision of the two districts in hedge type sub-regions in which ethnicity, population density, area in woodlots and ecological variables like elevation, rainfall and soil fertility are important variables. These variables are influencing each other and are responsible for the contrasting situation in Vihiga and Siaya District. Border hedges have similar functions in both districts (demarcation of land, to prevent cattle from entering), nevertheless species composition and dimensions differ remarkably in both districts. Border hedges in Siaya District are poorly managed or not managed at all. In Vihiga District people are used to manage their hedges. Agroforestry techniques, for example techniques based on frequent pruning of border hedges, have a high chance in being successful in this district because no additional investment in labour or time is required. The spatial distribution in the amount of biomass is strongly correlated with the distribution in the per cent area ground cover of border hedges. This means that secondary data on the area in hedges derived from aerial photographs can serve as a useful indicator of the biomass present. As a result, the most difficult part of the field survey, the destructive sampling for the determination of the biomass, can be eliminated, making general surveys considerably easier. This revised version was published online in June 2006 with corrections to the Cover Date.     

Regional Comparative Advantage,Location of Agriculture,and Deforestation in Brazil

ABSTRACT

This article highlights how deforestation is not only linked to economic processes within the Amazon, but also to economic forces in the rest of Brazil. In light of recent trends in Brazil's agricultural production inside and outside the Amazon, this article maintains that the growing importance of beef production in the Amazon relative to the rest of Brazil is likely to lead to further increases in deforestation. From 1991 to 2001 the Amazon's share of the Brazilian bovine herd increased from 15% to 25%—an average change of 1% per year. With the Brazilian herd size in 2003 estimated at 196 million head of cattle, the current rate of increase implies an increase of 1.96 million cattle per year in the Amazon. At Brazil's average stocking rate of 1.1 head of cattle per hectare, it means that an additional 18,000 km² of land are needed each year in the Amazon to account for this expansion. However, Brazil has abundant agricultural land outside the Amazon to meet increases in demand for beef. The difficulty lies in the comparative advantage of these other areas in producing soy and grains as opposed to livestock. I conclude that targeting resources toward specific agricultural development opportunities outside the Amazon—especially grain-fed beef— would be an effective way to reduce incentives to clear land in the Amazon.     

Pasture or permanent crops after slash-and-burn cultivation? Land-use choice in three Amazon colonies

Land use was examined in three settlements – Pedro Peixoto in Acre and Theobroma in Rondonia, Brazil, and Pucallpa, in Peru. Research aimed at characterizing the differences in land use after initial slash-and-burn, and presenting hypotheses to assess the feasibility of improved land uses. Settlers in the Amazon practice slash-and-burn agriculture in forest lands to produce annual crops. After cropping, lands are converted to pasture, or planted with perennial crops, or fallowed in anticipation of future annual crop production. Land use after slash-and-burn cultivation in forest lands differed among the colonies examined. Whereas colonists in Pedro Peixoto converted lands to pasture for cattle production, settlers in Theobroma adopted a strategy encompassing both dual-purpose (milk and meat) cattle and perennial crop production. The more heterogeneous settlers in Pucallpa, who included small-scale cattle ranchers and riverine and forest slash-and-burn farmers, gave more importance to perennial crops. Hypotheses are suggested regarding the described land use differences, and implications for the adoption of agroforestry are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

A financial analysis of a silvopasture system in southern Mississippi

Silvopasture is reemerging as a land use in the southern US. Alternate land use treatments based on field trials for timber and pasture for beef cattle production were financially evaluated. Multiple-use management aspects of these systems were further illustrated by the addition of fee hunting. Land Expectation Values (LEVs) were lower when silvopasture treatments were compared to steer grazing only. However, silvopasture treatments compared favorably to some grazing treatments. LEVs were higher when silvopasture treatments were compared to commercial forest plantation applications on similar sites. Silvopasture systems promote multiple-use management of the land under an environmentally friendly cropping system whereby certain types of wildlife can thrive. This is particularly relevant in light of recent increases in fee hunting in the South. LEVs were reduced by $289, $200, and $151 ha⁻¹ at discount rates of 5%, 7%, and 9% respectively, when fee hunting was excluded in the recommended silvopasture treatment. The monetary value of a wildlife component in this system can be interpreted as the expected value gained per hectare per rotation in perpetuity when fee hunting is part of the management plan. On average, it represented an 8.6% gain in LEVs for this treatment. Results from this study support the potential for silvopasture applications in the South for private landowners. Cattle grazing of improved forage in commercially productive loblolly pine (Pinus taeda) stands can relieve annual cash flow problems inherent in tree production. This revised version was published online in June 2006 with corrections to the Cover Date.     

Use of goats as biological agents for the renovation of pastures in the Appalachian region of the United States

Much of hill-land pasture in the Appalachian region of the United States is dominated by herbaceous weeds and brush. Low cost, low input and environmentally acceptable reclamation procedures are needed to maintain the productivity of these pastures. This experiment evaluated the effectiveness of using goats (Capra hircus hircus) alone (30 mature, brush does/ha) or cattle (Bos taurus) with goats (17 mature, brush does/ha + two to three steers/ha -- 225 kg average live weight) to reclaim a pasture from an abandoned, overgrown 5.9 ha orchard left untouched for 15 years. Over four grazing seasons, managed defoliation resulted in a substantial increase in herbaceous vegetative cover in plots grazed by goats alone (65 to 86%) and by goats with cattle (65 to 80%) while vegetative cover decreased from 70 to 22% in the control plot. Similarly, the cover by grass species increased in the grazed plots (goats: 16 to 63%; goats + cattle: 13 to 54%) while averaging 10% in the control plot. Multiflora rose (Rosa multiflora Thumb.) bushes were practically eliminated after four grazing seasons as quantified by an average reduction in height from 2.1 m to 0.6 m, and by the number of dead canes (stems) in both the goat (100%) or goat + cattle (92%) treatments. Results indicated that the foraging habits of goats resulted in the elimination of multiflora rose bushes and in a significant increase in desirable forage species. This revised version was published online in June 2006 with corrections to the Cover Date.     

乡村土地利用与景观格局动态变化研究

依据景观生态学理论和研究方法,运用遥感和地理信息系统技术,对粤西南华农场３个时期土地利用与景观格局进行了分析与评价。结果表明,不同时期生产性用地中,斑块类型、块块数目与面积变化较大。７０年代,景观优势度较高,多样性和均匀性较低;８０年代,随斑块类型和斑块数量的增加,景观多样性、均匀性显著增加,破碎化指数增大,景观格局发生较大变化;９０年代,一些斑块类型逐渐消失,景观优势、多样性和均匀性较８０年代有     

Land use/land cover change dynamics and drivers in a low-grade marginal coffee growing region of Veracruz,Mexico

In the state of Veracruz, Mexico, lowland and marginal coffee growing regions have been particularly vulnerable since the 1989 coffee crisis. Government programs have promoted production diversification as a strategy to improve local incomes and conserve environmentally beneficial shade-tree coffee agroforests. We present results on land use/land cover dynamics in the municipality of Zozocolco de Hidalgo from 1973 to 2006. The municipality is recognized for its indigenous population and poverty, and currently, diversification efforts are being implemented. Our study combines remote sensing and GIS analyses, binary logistic regression and econometric modeling, as well as socioeconomic surveys to evaluate land use/land cover change (LULCC) dynamics and explore potential environmental and socioeconomic drivers. Results show that tree cover and coffee agroforests had largely been conserved during the first decade after the coffee crisis. But, recent trends indicate loss of tree cover in coffee agroforests and their conversion mostly to pasture. Land use/land cover drivers are largely explained by spatially explicit environmental variables such as slope and elevation. Relevant socioeconomic variables such as distance to markets and land use profitability were not significantly related to land use changes in Zozocolco. Surveys revealed that many households had converted coffee agroforests to pasture or agriculture in the past decade and others intended on renting or selling their agroforest plots, mostly for conversion to pasture. Diversification programs may not be sufficient to stem deforestation in lowland and marginal coffee growing regions. Moreover, information about locally varying socioeconomic and cultural contexts needs to be strongly considered in order to formulate effective strategies.     

Deforestation and loss of bushland and grassland primarily due to expansion of cultivation in mainland Tanzania (1995–2010)

Information on land use and cover changes (LUCC) is important for planning of conservation and development and thus ensure forest sustainability. The current paper assesses LUCC for the whole of the mainland Tanzania. The analyses were done using land use and cover maps covering the whole of mainland Tanzania for 1995 and 2010. For 1995, forest, bushland, grassland, cultivation and other land use and cover (built up areas, bare land, etc.) covered 43.5%, 19.8%, 23.5%, 11.2%, and 2.0% of the study area, respectively. For 2010, the same land use and cover classes covered 38.0%, 14.5%, 6.9%, 36.5%, and 4.1% of the study area, respectively. The annual rate of deforestation was 320,067 ha, which is equivalent to 0.9%. Bushland and grassland were lost at 313,745 and 969,982 ha/year, respectively. Most forest was converted to cultivation and least to other land use and cover. In conclusion, the net changes were deforestation and loss of bushland and grassland primarily due to expansion of cultivation. Further research on how to reduce or halt expansion of cultivation may shed light on improving sustainability of forest, bushland, and grassland in mainland Tanzania.     

南水北调中线水源区2000—2015年森林动态变化遥感监测

【目的】监测南水北调中线水源区2000—2015年森林空间分布格局,研究森林动态变化过程及其机制,为水源区森林生态系统保护和水质安全提供理论依据。【方法】基于2000、2010和2015年3期30 m分辨率国产环境灾害卫星HJ-1 A/B CCD以及Landsat TM影像数据,采用面向对象决策树分类方法,监测南水北调中线水源区的土地覆被,并运用像元二分模型和归一化植被指数估算植被覆盖度。【结果】3期土地覆被数据精度(K)分别为89. 4%、86. 9%和84. 4%,2000年用户精度为98%,2010年用户精度为96%,2015年用户精度为94%。土地覆被监测结果表明,受退耕还林和封山育林等生态工程项目实施影响,2000—2015年,南水北调中线水源区森林面积持续增加,增幅达9. 5%,增加面积主要来自草地、耕地和建设用地;然而,随着水源区大规模移民和区域经济不断发展,也使得约4 547 km^2的森林转化为耕地、草地和建设用地。分市统计分析表明,十堰市和安康市森林面积增量最大,均超过1 300 km^2,生态修复工程效果显著。2000—2015年,水源区植被覆盖度也呈增加趋势,其中森林植被覆盖度增幅达25. 4%,且植被覆盖度在0. 6以上的森林面积比例3期均超过70%。【结论】近15年来,南水北调中线水源区森林面积和森林植被覆盖度增加显著,森林密度得到提升,高密度的森林植被能够在地表形成植被保护层,降低水源区发生水力侵蚀和沟渠侵蚀的风险,从而提高水源区水土保持能力。     

梁山慈竹在退耕还林中的水土保持效应研究

利用小型径流观测场对比观测降雨时间集中的梁山慈竹林和未退耕种植红薯的耕地的17次降雨、10次水土流失过程进行效益对比,分析侵蚀量、径流量与降雨因子的关系。结果表明,退耕还梁山慈竹林的穿透降水率为89.14%,茎流率平均为1.57%,林冠截持降水率为9.29%;凋落物层的最大持水量约为27.54 t.hm-2,相当于水深2.4～3.3 mm,占降水量的14.46%～19.88%;与未退耕地相比,梁山慈竹林的平均径流量比耕地减少24.6%,而耕地侵蚀量约是林地的4.7倍,林地降水的泥沙侵蚀平均减少量达到78.56%。梁山慈竹有较好的水土保持作用,能够明显地减少地表径流和泥沙侵蚀。     

Recovery of saturated hydraulic conductivity under secondary succession on former pasture in the humid tropics

Landscapes in the humid tropics are undergoing a continuous change in land use. Deforestation is still taking its toll on forested areas, but at the same time more and more secondary forests emerge where formerly agricultural lands and pastures are being abandoned. Regarding soil hydrology, the extent to which secondary succession can recover soil hydrological properties disturbed by antecedent deforestation and pasture use is yet poorly understood. We investigated the effect of secondary succession on saturated hydraulic conductivity (Ks) at two soil depths (0-6 and 6-12 cm) using a space-for-time approach in a landscape mosaic in central Panama. The following four land-use classes were studied: pasture (P), secondary forest of 5-8 years of age (SF5), secondary forest of 12-15 years of age (SF12) and secondary forest of more than 100 years of age (SF100), each replicated altogether four times in different micro-catchments across the study region. The hydrological implications of differences in Ks in response to land-use change with land use, especially regarding overland flow generation, were assessed via comparisons with rainfall intensities.Recovery of Ks could be detected in the 0-6 cm depth after 12 years of secondary succession: P and SF5 held similar Ks values, but differed significantly (α = 0.05) from SF12 and SF100 which in turn were indistinguishable. Variability within the land cover classes was large but, due to sufficient replication in the study, Ks recovery could be detected nonetheless. Ks in the 6-12 cm depth did not show any differences between the land cover classes; only Ks of the uppermost soil layer was affected by land-use changes. Overland flow - as inferred from comparisons of Ks with rainfall intensities - is more likely on P and SF5 sites compared to SF12 and SF100 for the upper sample depth; however, generally low values at the 6-12 cm depth are likely to impede vertical percolation during high rainfall intensities regardless of land use.We conclude that Ks can recover from pasture use under secondary succession up to pre-pasture levels, but the process may take more than 8 years. In order to gain comprehensive understanding of Ks change with land use and its hydrological implications, more studies with detailed land-use histories and combined measurements of Ks, overland flow, precipitation and throughfall are essential.     

李子口径流小区不同植被条件下降雨对土壤侵蚀的影响研究

采用径流小区实验的方法,在李子口小流域设立了6个不同植被类型的径流小区,研究径流小区不同植被条件下降雨对土壤侵蚀的影响,结果如下:(1)不同植被条件下,降雨对土壤侵蚀的影响可表现为撂荒地小区>农耕地小区>林地小区,降雨对林地的土壤侵蚀弱,林地对当地水土的保持能力强,最适合作为当地水土保持的植物措施。(2)总体上,6个径流小区的降雨量、降雨侵蚀力与地表径流量、径流深、土壤流失量之间的相关性均表现为显著正相关的关系,表明降雨对当地土壤侵蚀作用强,需重点防护。研究揭示了研究区降雨与土壤侵蚀的相关性,比较了不同植被条件下降雨对土壤侵蚀的影响,为水土保持的相关研究提供参考与借鉴。     

Impacts of different forest management scenarios on forestry and reindeer husbandry

In northern Sweden, the forests are used simultaneously for both timber production and reindeer husbandry. During the winter months, lichen is the most important fodder for reindeer. Forest management operations are generally considered having a negative impact on reindeer husbandry as harvesting and dense stands remove or obscure the ground lichen cover. In this study, we simulate three different scenarios for forest management, differing in the intensity and types of harvest operations. The resulting 100-year scenarios are analyzed with respect to their estimated suitability for providing reindeer pasture areas. Suitability is determined by vegetation type, stand density and stand height. The results indicate that the current trend of a decrease in lichen area will continue if existing forestry practice prevails. Implementing continuous cover forestry as a management alternative and carrying out precommercial thinning could halt the decrease in reindeer pasture area and even lead to a future increase in pasture area, with losses of approximately 5% in the net present value of forestry.