Rajendra P. Shrestha

Influence of Coastal Land Use on Soil Heavy-Metal Contamination in Pattani Bay, Thailand

Abstract Expansion of land use in coastal areas results in natural resources being degraded, particularly by soil and water pollution. The objectives of this study were to assess land-use patterns and determine the influence of land-use types on soil heavy-metal contamination in Pattani Bay, Thailand. In studying land use, high-resolution SPOT satellite images were used and analyzed using ArcView GIS 3.2a and ENVI 3.5 software. Collections from 16 soil-sampling sites with topsoil and subsoil layers (0–20 and 21–50 cm in depth) from nine land-use types were carried out during March and April 2006. The heavy metals mercury, lead (Pb), cadmium, arsenic (As), and zinc were analyzed using a Perkin Elmer Optima 2100 DV. Results found that land uses in 2006 were mainly dominated by agricultural, residential, and mangrove-forest areas. In agricultural areas, paddy field were the main land use, followed by shrimp farms. In residential areas, most land was used for living, infrastructure, and industry. Land-use types affected soil pollution in different ways. Municipality areas, industrial zones, and dockyard areas had the highest potential for soil contamination by heavy metals, particularly Pb and As, while shrimp farming and traditional land uses such as salt flats, paddy fields, orchards, and mangrove forests showed low levels of metals. At the dockyard and Pattani River–mouth sampling sites, Pb was recorded in high concentrations of 385.77 and 557.15 mg/kg, respectively; the latter exceeds the soil quality standards of the United States Environmental Protection Agency soil screening levels for residential areas (400 mg/kg). A high concentration of As was found at the dockyard, Pattani River mouth, and industrial zone (4.46, 4.75, and 3.48 mg/kg, respectively), while the EPA standard is not to exceed 4.0 mg/kg. The results indicate that using coastal lands without planning and good management negatively influences soil resources degradation, especially in the area of soil pollution.

Soil-Quality Indicators for Predicting Sustainable Organic Rice Production

Soil physical, chemical, and biological properties in a rice field located at the Surin Rice Research Center, Thailand, were evaluated as indicators for predicting organic rice (Kao Dok Mali 105 variety) production and yield. Four treatments under different management practices were studied. They included (1) conventional farming (CF) receiving chemical fertilizer application; (2) organic plot receiving green manure (GM) addition; (3) organic plot receiving rice straw (RS) addition; and (4) control plot (CT) without any external plant nutrient source. Soil quality in the four treatments was assessed based upon selected physical, chemical, and biological parameters. Key findings are as follows: cation exchange capacity (CEC), electrical conductivity (EC), pH, soil organic matter (SOM), and essential macronutrients [nitrogen (N), phosphorus (P), and potassium (K)] were low in all plots. Soil biological properties including potential N mineralization (PMN), soil basal respiration (BR), microbial biomass carbon (MBC) and microbial biomass N (MBN) in all treatments were also low. Principal component analysis (PCA), using 15 soil properties, showed significant differences among farm management practices. Soil chemical and biological properties best related to soil quality included P, N, and SOM (for chemical properties) and MBC, MBN, and BR (for biological properties). Based on significant relationships between yield (r > 0.75) and the soil properties (r > 0.55), selected soil biological (MBC, MBN, and BR) and chemical (TOP [total organic phosphorus], TK [total potassium], TN [total nitrogen], SOC [soil organic carbon], and SOM) properties were determined to be suitable soil-quality indicators, respectively. A soil-quality indicator for predicting rice yield was computed using multiple regression analyses. The regression model (Y = −1.685 + 0.333 (MBN) + 0.640 (TK) − 0.282 (SOC), r2 adjusted = 0.962) was used for predicting yield. Grain yield of rice (RMSE = 0.046 t ha−1, D index = 0.45) was obtained using this regression model.

Farmers' perception of and adaptation to climate-change impacts in the Dry Zone of Myanmar

In Myanmar, impacts of climate change have been apparent since 1977. Myanmars economy, which exclusively depends on agriculture, is increasingly at risk due to climate change. Since farmers are often the first to confront climate change, they must adapt to new climatic conditions. Local adaptation practices, the possible starting points in developing new adaptation strategies, are currently occurring at a local scale, particularly based on the traditional knowledge. We used household survey, participatory histogram mapping and key-informant interviews to explore the farmers’ perception and adaptation practices to climate change in the Myanmar Dry Zone. Ninety per cent of respondents perceived the changing climatic patterns in the Dry Zone, while increasing temperature and the erratic rainfall patterns were perceived as the predominant changes by 85% of the people. The farmers also perceived that there have already been several impacts of climate changes on agriculture. The common sesame/groundnut cropping pattern has been abandoned by the Dry Zone farmers in recent decades due to climate-change-driven agricultural production barriers. Farmers have been dealing with those barriers using their conventional agricultural practices, e.g. rainwater-collection, tube wells and water-harvesting techniques. They have also been using the traditional weather forecasting techniques to predict weather. Consequently, the study underlines the need to document existing agricultural practices that can prove to be successful adaptation measures, and it points out the crucial role of the extension strategy in disseminating agricultural techniques and weather information to support farmers to further adapt to climate-change impacts.

Land use change and its effect on biodiversity in Chiang Rai province of Thailand

Abstract The Chiang Rai province of Thailand has experienced rapid deforestation and consequent land use change in recent years. This research carried out in Chiang Rai province simulated future land uses under three management scenarios and assessed their effect on biodiversity. The Dyna-CLUE model was used to simulate land uses of 2029 according to the management scenarios, and their effect on biodiversity was analyzed by the GLOBIO3 model. About 4% of total area of the province was deforested within 2002–2009 and has a possibility to lose more, that is, 7% by 2029. If this rate of deforestation continues, then biodiversity will be affected as shown by reduced ‘mean species abundance’ of 0.45 at present to 0.38 by 2029, whereby highly threatened area can be increased up to 15% of the total land area. Hence, protecting locations with higher biodiversity value can be efficient in conserving biodiversity.

Developing indicators for assessing land-use sustainability in a tropical agro-ecosystem: The case of Sakaekrang watershed, Thailand

SUMMARY While the concept of sustainable land management is now widely accepted, there remains considerable scope for developing location-specific land-use indicators for sustainability evaluation. A study was conducted to investigate the indicators of land-use sustainability in the context of tropical agro-ecosystems using the case of Sakaekrang watershed, Thailand. The biophysical data were generated from Geographic Information Systems (GIs) and the socioeconomic data were collected through a field survey. In the light of sustainable land management objectives, a total of 32 criteria were considered in the analysis to determine land-use sustainability and identify indicators that best explain the sustainability level. About one quarter of the agricultural area in the watershed meets the sustainability threshold, indicating a substantial unstable area in the watershed. Among 11 indicators that showed a significant relationship with the computed land-use sustainability, land quality, source of farm income, and evapo transpiration were the most important.

Monitoring farmland loss and projecting the future land use of an urbanized watershed in Yogyakarta, Indonesia

This study analyzes land use changes in Yogyakarta, Indonesia, specifically farmland loss, which has occurred as a result of rapid urbanization by employing remote sensing, GIS, and land use modeling techniques. Landsat images from 1992 and 2004 and ASTER Terralook images from 2009 were classified using a supervised classification to generate land use maps. Land use change was detected using a post-classification method. During 1992–2009, high-density built-up areas increased by a factor of 3.7, and 80.47 km2 of farmland was lost due to land conversion to built-up areas during the same period. Based on these findings, land uses for the year 2029 were spatially simulated using Dyna-CLUE model for three scenarios: business as usual, farmland protection, and minimum required farmland. The results reveal that the ongoing trend of land use conversion combined with the lack of implementation of proper spatial policies will lead to a large loss of farmland and that it is desirable to protect prime farmland from urban sprawl.

Assessing livelihood for improvement: Samanalawewa reservoir environs, Sri Lanka

This paper explores household (HH)-level livelihood dynamics and determinants since construction of the Samanalawewa Hydroelectricity Reservoir (SHER) in the Samanalawewa watershed, Sri Lanka. The research is based on data from a structured questionnaire survey of 201 randomly selected households (HHs) in upstream and downstream areas. Livelihood dynamics at two separate points in time (1988 and 2008) were assessed based on a sustainable livelihood framework (SLF). Impact of livelihood determinants on livelihood was analysed using factor and regression analysis techniques, followed by an optimisation procedure to suggest requirements in selected significant determinants to improve the livelihood of various categories of farm HH. In both upstream and downstream areas, livelihood assets, viz. physical, social and human capital, increased significantly, while access to natural and financial capital decreased significantly and slightly, respectively, during last two decades. The factor analysis extracted six factors in the upstream area and seven in the downstream area. The derived regression models show that nine variables in the upstream area and ten in the downstream area are major determinants of HH livelihood. Based on optimisation results, policy implications are discussed in relation to needed improvements in livelihood determinants to improve overall livelihood of HHs.

Development of a land suitability model for saffron (Crocus sativus L.) cultivation in Khost Province of Afghanistan using GIS and AHP techniques

ABSTRACT In this study, we have attempted to develop a land suitability model for saffron, an agronomic crop, which is economically viable, environmentally bearable and socially equitable at Khost Province of Afghanistan. The objective was to determine different land suitability classes for saffron cultivation using Analytical Hierarchy Process (AHP) and Geographic Information System (GIS). A decision tree was developed encompassing the physical, economic and social criteria. We used the secondary data (meteorological, remote sensing) from available sources and also substantial primary data generated from soil survey, interviews and experts’ opinion. A total of 30 physical and socio-economic factors were included in the analysis. The final land suitability result showed that out of the total land area of Khost Province, 1.5, 4.5, 8.6 and 85.4% areas were highly suitable, moderately suitable, marginally suitable and not suitable, respectively. This modelling approach can be applied to determine the suitability of land for other crops covering a wider geographical region of Afghanistan.

Assessment of land degradation and its impact on crop production in the Dry Zone of Myanmar

Land degradation in terms of soil degradation is a major environmental issue posing threat to sustainable livelihood in the semi-arid region of Central Myanmar. However, the studies on soil degradation status and its impacts in this region are very scanty. The objective of this study was to determine the impact of land degradation on crop production both in terms of area and yield in the Dry Zone of Myanmar. Remote sensing and geographic information system-based modelling was utilized to assess and map soil erosion rates. Household survey was conducted to understand the causes of land degradation and its impacts on crop productivity and livelihoods. It has been found out that the current rate of soil erosion ranged from 0 to 114 t ha–1 yr–1, and that the average rate of soil erosion increased from 14.2 to 54.6 t ha–1 yr–1 over a period from 2000 to 2012. The major types of land degradation were physical and chemical soil degradation. Farmers identified topographic condition, soil types, improper crop management practices and climatic factors as the main causes of soil erosion. The observed crop yields of monsoon rice, groundnut, sesame and cotton in the highly degraded area were 3–12 times lower compared with the yields of these crops grown in less degraded area. Livelihoods of the farmers in the high-degraded area were affected by crop yield reduction, increased cultivation cost and increased uncultivable land area. The impact of land degradation on crop production was dependent on the severity of degradation. This suggests that advanced conservation measures are immediately required and the supportive policy strategies need to be implemented to educate farmers and to strengthen extension services for sustainable land management in the Dry Zone of Myanmar.

Climate Change Trends and Its Impact on Tourism Resources in Mu Ko Surin Marine National Park, Thailand

The objective of this paper is to investigate the current and potential future impacts of climate change on tourism resources and tourism activities in Mu Ko Surin National Park. The research method for this paper involved the collection of information from interviews with key informants, non-participant observation, and secondary data. The results found that the park has experienced changes in climate, including increasing temperatures, changes in precipitation, rising sea surface temperature, and sea-level rise. The impact of increasing temperature can lead to mass coral bleaching. The beach was shown to have eroded at a rate of about 0.38 m per year. However, water resources are still sufficient for tourism activities. The impacts of climate change have led to coral reefs and fish being less attractive and reduced in quantity, some snorkeling and diving sites being closed. Therefore, for sustainable tourism management, adaptation action should take place in this area.