Agroforestry in the management of sloping lands in Asia and the Pacific

Steeply sloping lands are widespread in the tropics. An estimated 500 million people practice subsistence agriculture in these marginal areas. Continued population growth has led to the intensified cultivation of large areas of the sloping lands, exacerbating the problem of soil erosion. Although research shows that alley cropping and other contour agroforestry systems can stabilize the sloping lands, these systems have not been widely adopted by farmers. The Framework for Evaluating Sustainable Land Management (FESLM) has been tested in sloping land areas in the Philippines. Sustainable land management must be productive, stable, viable, and acceptable to farmers, while protecting soil and water resources. Farms on which contour hedgerow intercropping has been adopted meet the multifaceted requirements of FESLM, whereas the farmers' current practice does not. Appropriate land management measures for particular locations depend on a complex suite of social, economic, and biophysical factors, and need to be developed in participation with farmers. The role of agroforestry in sustainable management of sloping lands is the subject of networks coordinated by the International Board for Soil Research and Management (IBSRAM) in seven countries in Asia (ASIALAND) and four countries in the Pacific (PACIFICLAND). We review selected outcomes from a wealth of network data. From these results the following conclusions about the sustainability of various agroforestry systems for sloping lands can be drawn: • In the Pacific, soil loss from sloping lands due to water erosion under farmers' current practices is episodic, unpredictable, and possibly not severe; • Agroforestry systems that utilize legume shrubs, fruit trees, coffee (Coffea spp.) or rubber (Hevea brasiliensis) provide useful economic returns, but are not an essential component in terms of soil protection because grass or pineapple (Ananas comosus) planted on the contour are equally effective in reducing erosion; • Agricultural intensification will lead to nutrient mining, reduction of aboveground biomass, declining yields, and less soil protection unless external sources of nutrients are used; • nitrogen can be effectively supplied using legumes; • Cash derived from hedgerow trees and/or shrubs may providean incentive for their adoption by farmers, as well as funds to purchase external inputs such as fertilizers; • Labor may be a major constraint to the adoption of complex agroforestry systems. We also discuss the information management systems required to effectively manage and utilize the extensive sets of experimental and indigenous data being accumulated. We believe such information systems can facilitate technology transfer across and between regions, and improve the efficiency of research into agroforestry and other land-management approaches. This revised version was published online in June 2006 with corrections to the Cover Date.     

The structure of four home gardens in the Petén,Guatemala

Forest-covered home gardens around the tropical world vary in their structure, but serve to supply food and other products for direct family consumption or marketing. Little quantitative data exist defining home garden structure. Thus, this study was undertaken to examine the variation in home garden structures in response to market or household needs and the subsequent variation in light interception and productivity.Four home gardens were studied in the Department of the Petén, in northern Guatemala. Areal extent and height of canopies were mapped in transects through four gardens representing a range of site water regimes and market orientation. Light intensities incident on the ground were measured along each transect to assess light use. Results showed structural complexity, with full canopy closure in the one or more layers within the canopy for most gardens. The garden architectures made efficient use of light and space, with intersive management for food and fuel production. Farmers grew the crops for both cash and family subsistence. One home garden on a comparatively dry site with shallow soil seemed less structured, with only a single broken canopy layer, but with diverse species of plants.The results indicate that development of gardens in this area utilized existing trees, thinning them to leave the most useful, and inserting other desirable trees and shrubs in the understory and in open spaces. This strategy seemed to maximize light use, regardless of market orientation.This look at the structure and composition of four home gardens, in a forested area of current immigration, demonstrated (1) variety of organization and plant components, (2) different architecture for different soil/site conditions and market orientations, and (3) efficient use of available light through the arrangement of plants.     

Tropical Tree Growth and Longevity: Validation of Growth Simulation,a Bootstrapping Model

ABSTRACT

Growth Simulation, an analytical modeling technique, has been increasingly used in ecological studies and practical forestry applications where dendrochronology is not applicable. The technique uses randomly sampled diameter increments from tagged trees over a known time interval to assemble a statistical sample of lifetime growth trajectories. We carried out a validation of Growth Simulation using a temperate species in order to compare indirect model outputs with direct tree ring analysis. Rings were measured on sample disks cut from 55 pine branches ranging in age from 8–36 years. Assessments included lifetime growth rates, growth rate with respect to diameter and age, periodic annual increment (PAI), cross-referencing of rings by date, and autocorrelation of growth over successive periods. Tree ring analysis and Growth Simulation showed close correspondence for all parameters tested (maximum, median, and minimum growth rates; longevity estimates). Growth Simulation is found to be a robust and informative technique for studies of tropical tree growth, and is especially useful where analysis of tree rings is not feasible or when bootstrapping analysis of ring data is of interest.     

Upland agriculture,the land frontier and forest decline in the Philippines

Population pressure, expansion of small-scale agriculture and shifting cultivation are commonly cited as the causes of tropical deforestation. A close examination of deforestation and agriculture in the Philippine uplands reveals, however, that the vast majority of agriculturists must be sedentary farmers. In addition, the importance of population pressure as a cause of deforestation in the Philippines cannot be supported by the available evidence. Lastly, the concept of arable land is shown to be of limited value in discussing upland agriculture in the Philippines.     

几种热带果树在闽东南园林应用探讨

大多数木本常绿热带果树在闽东南适应性良好,有较高的经济开发价值和园林应用前景。针对目前闽东南水果品种不丰富和应用于园林绿化材料单调、配置单一的现状。在介绍几种新、优热带果树资源的基础上,探讨热带果树的开发前景和提出把热带果树应用于城市园林绿化建设的新思路,以丰富植物多样性和园林景观。     

当代中国热带庭园与传统岭南庭园的历史情结

文章分析传统岭南庭园的造园艺术在当代热带庭园设计中的运用和发展,重点对空间渗透交流、视线与空间序列、花木营造等方面进行分析,找寻其中的历史情结,以期为中国当代热带庭园的传承与创新提供一些参考。     

Blood oxygen transport and hemoglobin function in three tropical fish species from northern Australian freshwater billabongs

The oxygen binding properties of whole blood and hemoglobin were studied in three phylogenetically distant tropical teleosts inhabiting freshwater billabongs that exhibit marked seasonal oxygen stratification. The water breathing saratoga (Scleropages jardinii, Family Osteoglossidae), derived from an ancient divergence of the stem line leading to all other extant teleosts, has a low blood oxygen carrying capacity, Bohr and Root effect, and a high blood oxygen affinity. Erythrocytes contain a single major hemoglobin component, and equimolar concentrations of ATP and GTP. The tarpon (Megalops cyprinoides, Family Megalopidae), a facultative air-breather, has the highest blood oxygen carrying capacity and Bohr effect, and a low blood oxygen affinity and Root effect. Erythrocytes contain a single major hemoglobin and ATP as a putative regulator of hemoglobin oxygen affinity. Barramundi (Lates calcarifer, Family Centropomidae), is an obligate water-breather with intermediate blood oxygen binding properties, and the smallest Root effect. Erythrocytes contain at least 7 hemoglobins, and equimolar concentrations of ATP and GTP. Functional properties of these three blood oxygen transport systems are considered in terms of the respiratory environment and demand for oxygen. Our interpretation supports the hypothesis that the process of speciation can lead to divergence in physiological mechanisms, irrespective of past or present selection pressures.     

Visualisation of standardized life-history patterns

The life‐history patterns of fish and invertebrate species are complex. But much of this complexity can be captured in simple diagrams of coastal transects, where juveniles usually occur in larger numbers in shallow waters, while adults generally inhabit deeper, offshore waters. Iconographic representations of generalized life‐history patterns and depth profiles, with specific key life‐history parameters can capture much of these standardized patterns, including spawning areas, nursery/juvenile distributions, adult distributions and spawning migrations. Several examples presented here from a wide range of habitats and ecosystems (temperate and tropical waters, demersal, deep water, pelagic and coral reefs), including an example of different stocks of the same species, illustrate some general patterns with regard to water depth and distance from shore. The present approach should be viewed as a first step towards obtaining standardized patterns about key life‐history parameters, and will hopefully lead to incorporation into management of life‐history interconnectivity between different fishery sectors or gears. This may contribute to sustainable, ecosystem‐based approaches to management by informing policy options when faced with decisions to rationalize overcapitalized fisheries.     

Hypoxia-based habitat compression of tropical pelagic fishes

Large areas of cold hypoxic water occur as distinct strata in the eastern tropical Pacific (ETP) and Atlantic oceans as a result of high productivity initiated by intense nutrient upwelling. We show that this stratum restricts the depth distribution of tropical pelagic marlins, sailfish, and tunas by compressing the acceptable physical habitat into a narrow surface layer. This layer extends downward to a variable boundary defined by a shallow thermocline, often at 25 m, above a barrier of cold hypoxic water. The depth distributions of marlin and sailfish monitored with electronic tags and average dissolved oxygen (DO) and temperature profiles show that this cold hypoxic environment constitutes a lower habitat boundary in the ETP, but not in the western North Atlantic (WNA), where DO is not limiting. Eastern Pacific and eastern Atlantic sailfish are larger than those in WNA, where the hypoxic zone is much deeper or absent. Larger sizes may reflect enhanced foraging opportunities afforded by the closer proximity of predator and prey in compressed habitat, as well as by the higher productivity. The shallow band of acceptable habitat restricts these fishes to a very narrow surface layer and makes them more vulnerable to over‐exploitation by surface gears. Predictably, the long‐term landings of tropical pelagic tunas from areas of habitat compression have been far greater than in surrounding areas. Many tropical pelagic species in the Atlantic Ocean are currently either fully exploited or overfished and their future status could be quite sensitive to increased fishing pressures, particularly in areas of habitat compression.