Showing papers in "Tropics in 2014"

Forest Use and Agriculture in Ucayali, Peruvian Amazon: Interactions Among Livelihood Strategies, Income and Environmental Outcomes

Abstract: Findings from a survey on sources of income and land allocation outcomes of 578 households from 26 communities with diverse ethnic composition at distinct environmental settings in Ucayali (Peruvian Amazon) are used to contrast livelihood strategies featuring high forest and high agriculture dependency, examining whether agricultural intensification can be linked to lower deforestation. A typology of households based on their land use allocation profile was used to assess current and cumulative cleared land. Recently cleared areas by households oriented to perennials, semi-perennials and pastures were similar to those focusing on annual crops. Multiple class comparisons provided evidence that land use intensification is not associated to land sparing. Near 40% of the households' annual income was derived from forests, followed by agriculture (25%), wages (17%) and livestock (11%). Income structure was used to determine high dependency on forests and on agriculture, featured by respectively 24% and 17% of the households, while 10% relied mostly on wages and/or businesses and half of them had a balanced income structure. Results indicate different expressions of the criticality of forest products, highlighting livelihood strategies based on the integration of income sources. Moreover, the study shows that despite the relevance of forest products, mestizo and indigenous livelihoods heavily depend on agriculture. Policy interventions aimed at environmental conservation and economic development will only be successful when strengthening the integration between agriculture and forest use featured by different social groups in the Amazon.

Occurrence and anatomical features of growth rings in tropical rainforest trees in Peninsular Malaysia: a preliminary study

Abstract: The occurrence and anatomical features of growth rings were investigated in tropical tree species in Peninsular Malaysia. The species studied included five species from two plantations, in a tropical monsoon and tropical rainforest climate, and 26 species from a natural forest in a tropical rainforest climate. Most of the trees were diffuse-porous species, with the exception of Peronema canescens, which was ring-porous. The growth rings were observed macroscopically and microscopically and were classified as having fiber zones, radially flattened fibers, marginal parenchyma, thick-walled fibers, or variations in vessel size and density. Whereas P. canescens from two plantations and Intsia palembanica from the natural forest showed well-defined growth rings, possibly formed annually following environmental stresses, 17 species showed indefinable growth rings and 10 species had no growth rings. Many of the samples presented intermittent growth rings, ambiguous growth rings, discontinuous growth rings, or resin canals and/or traumatic canals that made them difficult to classify. Bands of axial parenchyma were observed macroscopically in Sindora wallichii and Azadirachta excelsa, but microscopic analysis revealed that these bands were formed by concentric traumatic canals. Parenchyma bands with resin ducts or traumatic canals were likely not to be formed periodically. We concluded that some tree species that grow in a tropical rainforest climate do form growth rings and may be used in tree-ring analysis studies.

Migration patterns and land use by immigrants under a changing frontier society in the Peruvian Amazon

Abstract: One of main factors identified as explaining forest loss and degradation in the Selva (the Peruvian Amazon) is the migration of people from the Sierra (Andes highlands), where agricultural conditions are severe, to forest areas in the Selva in search of new land. This paper aims at clarifying the characteristics and process of migration based on interviews with local people near Pucallpa, Ucayali Department, where forest loss and degradation has advanced in recent decades. In the study area, forest loss and degradation progressed by commercial logging after construction of a road connecting between Lima and Pucallpa in 1943. After logging, stock-farming companies and immigrants entered the area, and land uses other than high forest have been expanding. Today, the study area is occupied by people who have immigrated since the 1960s. Many of them earned income by logging until the 1980s, while today almost of them make a livelihood by agriculture, stock farming, or tree planting. As a result of these economic activities, there are substantial areas of mixed shrubs and grass in the study area today. This paper clarifies two points. First, the majority of immigrants were born not in the Sierra, but in the Selva, for instance as part of the expanding population in the Departments of San Martin and Amazonas. The main stream of migration is from parts of the Selva where immigrants had started reclamation in earlier days to other parts of the Selva with still abundant forests (such as the study area). Second, most migrants were not born in a rural area, but in Pucallpa, a developing urban area in the Selva. Pucallpa is also an important place for step migrants who stayed there for a while and worked temporarily before immigrating to the study area. The urban area has gained an important role in migration to forests in the Selva as a place of birth of migrants and for its function in step migration.

Current situation of freshwater aquaculture in the lower Amazon River and the potentiality of development

Abstract: Aquaculture is regarded as a promising sector with its high feed efficiency and land productivity. However, capture fishery is still dominant in the northern states containing the Amazon River, where relatively late start of infrastructure development and insufficient administrative services are pointed out as the constraints. We applied snow-ball sampling in the northeast coast of Pará state and conducted interviews to nurseries and hatcheries to find current situation and the obstacles. The results of 21 privately-owned nurseries and hatcheries revealed that fishponds were constructed inside farms utilizing natural water sources; tilapia, an invasive alien species, and Serrasalmid and Pimelodid hybrids were commonly cultured; no respondents were or had been engaged in capture fishery; and aquaculture was rather regarded as a second job by farmers and stockbreeders. Distance from administrative supports favorably functioned in a sense because the aquaculturists were free from the government control. It can be expected that the water system of fishponds provides an incentive to preserve forests surrounding water sources and reservoirs.

A review of studies on swidden agriculture in Japan: cropping system and disappearing process

Abstract: This paper reviewed some of the major study results published mainly in Japanese on swidden agriculture which was once practiced in Japan. In this review, a focus was placed on the natural environment in which swidden agriculture was practiced, cropping systems, crop cultivation in swidden fields, the transition of swidden agriculture at the end of the disappearing stage, and the utilization of millet cultivated in swidden agriculture. Swidden agriculture of temperate Japan featured cultivation primarily of millet, and was characterized by highly sophisticated and complex cropping systems according to the natural environment, which varied from one region to another. In the 1970s, however, swidden agriculture which had been continuously practiced as a primary means of subsistence in mountainous areas of Japan ceased to exist. Accordingly, the review will primarily focus on studies from the 1950s to 1970s, the post-war period in which a large number of research findings were produced from the perspectives of the humanities and natural sciences. The methodologies and perspectives adopted in the studies on Japanese swidden agriculture are definitely applicable to currently conducted studies of swidden agriculture in tropical regions.

Aboveground net primary production and stand dynamics of mangroves along a river on Iriomote Island, southwestern Japan

Abstract: In this study, we examined the standing aboveground biomass, biomass growth, litterfall and tree species population dynamics of mangrove forest along the Nakara River, Iriomote Island, southwestern Japan, to explain the spatial patterns of stand structure and aboveground net primary production in reference to the stand dynamics of mangrove tree species along the river. The entire aboveground biomass of the mangrove forest did not vary with topographic position at the stand level, while three mangrove species showed different distributional patterns along the river. Although Bruguiera gymnorrhiza was generally dominant, Rhizophora stylosa codominated in the downstream areas. Kandelia obovata occurred only at the river's edge in the downstream area. The observed spatial patterns of aboveground productivity of each species depended mostly on their biomass. The distribution patterns of the mangrove tree species were based on parameters of their population dynamics, such as growth, recruitment and mortality. The effects of disturbance, especially the effects of typhoons, on the forest dynamics were prominent in this study period. The results of the study suggest that the spatial pattern of species distribution and productivity could be largely affected by the typhoon disturbances.

Water storages in plants and soils in two community forests of Karen tribe, northern Thailand

Abstract: This study aims to evaluate the roles of community forests managed for different purposes on water storages in plants and soils as the basic information for watershed management. Community forests of Karen people in Chiang Mai province, northern Thailand, were divided to conservation (CF) and utilization (UF) forests. These community forests were classified as pinemontane and montane forests. The number of tree species in the CF and the UF was 256 and 132, respectively. Shannon-Wiener Index in the CF (4.5±0.6) was higher than in the UF (3.4±1.0). Forest biomass was higher in the CF (252.4±72.5 Mg ha) than in the UF (139.7±36.3 Mg ha). Water amounts contained in biomass of CF in rainy season (on August 17, 2012), winter (on December 29, 2012) and dry season (on April 20, 2013) were 208.2±68.9, 228.5±71.4 and 231.2±70.7 m ha, respectively while those in the UF were 107.1±29.7, 129.0±33.3 and 124.3±33.0 m ha, respectively. More than 90 % of water was stored in soil. The maximum capacities of water storage within 2 m soil depths of the CF and the UF were 9584 ±934 and 9463 ±233 m ha, respectively. The water storage amounts in soils in rainy season were 73.8 % and 79.2 % of maximum capacities in the CF and the UF, respectively. In winter, the storages changed to 80.5 % and 74.6 %, and in dry season they decreased to be 39.5 % and 23.7 %. Timber harvest in the UF was the main cause of forest degradation and decrease in biomass water storage. The water storage by these community forests can reduce flash flooding and water supply from them is greatly beneficial to the villagers' livelihood and also to the lower land communities.

Differentiation in architectural properties and functional traits of forest- floor saplings among heath, peat swamp, and mixed dipterocarp forests

Abstract: There are physiognomically distinctive forest types in lowland tropics reflecting variation in edaphic conditions. Tree saplings that contribute to forest regeneration are expected to show morphological properties in response to forest environment. However, it remains unknown how sapling properties are similar or different across forest types. We examined architectural and functional traits of forest floor saplings across heath, peat swamp, and mixed dipterocarp forests that characterize lowland forests in Kalimantan, Indonesia. Saplings (150-310 cm tall) of 41 species, which represent each forest type, were selected under the canopy of developed forest stands. Among these, we chose one species found in all forest types and two species in heath and peat swamp forests. Significant differences in crown allometries were found across forest types and across species. Saplings in mixed dipterocarp forest had thicker trunk and wider crown at the same sapling height compared to other forests and they had higher specific leaf area, higher mass-based leaf nitrogen content and lower wood density. Heath forest saplings showed lowest leaf nitrogen content and highest wood density. Species with across forest-type distribution showed intra-specific variation in sapling traits, and which was similar to the difference among forest types. We conclude that saplings show morphological response to nutritional and water conditions that characterize forest types.

Secondary succession of mixed plantations established to rehabilitate abandoned pasture in the Peruvian Amazon

Abstract: Secondary succession or facilitation processes carried out at sites established for rehabilitating abandoned pastures and degraded forests (prurmas) are instrumental in their return to original forest status. An understanding of these secondary succession processes contributes to the rehabilitation of degraded forest ecosystems and to the livelihoods of local communities, and aids in conserving biodiversity. We studied secondary succession in mixed species plantations that were established to rehabilitate abandoned land. The initial vegetation in these abandoned pastures and croplands was grassland composed of three dominant species: Rottboellia exaltata, Imperata brasiliensis, and Brachyaria decumbens. After tree planting and weeding had been carried out, the site was first invaded by R. exaltata and Baccharis floribunda. These two species, which depend solely on sexual and not vegetative reproduction, facilitated secondary succession and elevated species diversity by enabling subsequent invasion by several species. By contrast, B. decumbens, I. brasiliensis, and Hyparrhenia rufa depend mainly on vegetative reproduction involving rhizomes and tillers, and subsequent invasion by other species was relatively less in stand types dominated by these three species. We found that further adequate rehabilitation techniques were necessary for the respective vegetation types.

An essay on the Boserupian model with particular emphasis on labour input and productivity in upland rice swiddens in Southeast Asia

Abstract: This study examined several aspects of Ester Boserup＇s model (1965), which has been highly influential in human ecological discussions on the dynamics of agricultural systems. The starting point of her model is that population pressure is the engine for changes in agricultural systems. For the cultivation stages prior to annual cropping, the result of the mathematical formulation devised in the present study is expressed by a simple equation whose independent variable is the population density in the territory of a community and dependent variable is the duration of fallow period of the fields in the territory. This equation can be graphically depicted as an equilateral hyperbola, although a few other factors may somewhat modify this basic pattern. This suggests that the fallow periods of the agricultural system of a community should be drastically shortened in the early phase of its population growth. At the next step, using a reasonably selected collection of available quantitative data originally obtained from upland rice swiddens in Southeast Asia, the assertion of the model that the labour productivity of a cultivation system with a longer fallow period is superior to that of a cultivation system with a shorter fallow period is tested. On the whole, the results do not confirm this assertion, most likely because such a test is strongly affected by local factors than by the common factor of the fallow period. Still, when the whole data of labour productivity are divided into those of the eight and the nine cases in the equatorial and the monsoonal zones, respectively, the results do roughly show the expected trend that labour productivity decreases with a shortened fallow period. Furthermore, if the two outliers of the nine values of the latter zone are excluded, this trend becomes highly noticeable and statistically significant.