The Government of the Lao PDR's policy is to eliminate the cultivation of upland rice by means of 'slash-and-burn' cultivation and to replace it with more ecologically stable systems based on sustainable land use at the village and household level. The objectives of this policy are to alleviate poverty and to introduce more sustainable management of agricultural resources. In order to achieve these objectives, the government has initiated a program of relocation to upland 'focal areas' from which marketing, distribution and other services can be supplied, these being essential preconditions for effective agricultural development in these regions.This diagnostic study has examined communal and household strategies for addressing food security issues, and has highlighted the main problems encountered in the pursuit of food security on the local level. The specific objective was to conduct a broadly focused participatory problem diagnosis of the study areas in two districts Phonsay and Namo, in order to understand farmers' problems, livelihood goals and how their perspectives on food security have changed, and to investigate food security in shifting cultivation systems in Luang Prabang and Oudomxay provinces. Within these two provinces Phonsay and Namo districts were selected as the research areas. The two districts are the poorest districts in the Luang Prabang and Oudomxay provinces and two of ten priority poorest districts in the whole country. Semi-structured interviews were conducted for the study. The results of this study were reviewed against the sustainable land use systems strategy formulated from the Lao PDR policy. The study highlights both the benefits and stresses on household welfare, food insecurity conditions in the study areas, and interrelated problems of insufficient rice for household consumption. Finally based on these results the authors propose recommendations and future research indications.

Climate change is viewed as a cause in accelerating the rate of invasion by alien species in addition to the globalization of anthropogenic activities. Ecological niche modeling has become an instrument in predicting invasion from natural or invaded ranges to uninvaded ranges based on the presence records of organisms and environmental parameters. This study explored the changes in the distributions of globally noxious alien species (Aegratina adenophora, Ageratum conyzoides, Chromolaena odorata, Lantana camara, Mikania micrantha, and Parthenium hysterophorus) in Bhutan, to provide evidence that even a mountain environment is under the threat of invasion given the change in climatic conditions. With fairly high accuracy, the model results suggest that there will be a potential increase in the areas of invasion among most of the species, except Parthenium hysterophorus, which will experience a northerly shift and decline in distribution. The results also indicate changes in patterns of invasion, some becoming more concentrated toward a given direction, while others become more dispersed over time. This study provides a framework that can be used in the strategic control of the species, future detection surveys, and further research.Agronomy 2019, 9, 442 2 of 16 recreational amenities for ecotourism, deforestation, and upland agriculture adoption [19], compounded by climatic change, have exposed vulnerable mountains to disturbance [20][21][22][23][24]. The warming climate has resulted in an altitudinal upward shifting of cold-temperate species (e.g., Fagus sylvatica) and Mediterranean species (Quercus ilex) in Catalina, Spain [25]. In Bhutan, farmers have reported that due to climate change, invasive plants have started to colonize highland pasture, preventing the regeneration of fodder grasses [26]. Given a change in climatic conditions, adjacent lowland flora heavily influence species composition in mountain communities [27]. Mountain environments are rated as highly sensitive to climate change due to a short growing season and limited niches for resident species [28][29][30][31][32]. Human activities and climate change has led to invasions in mountainous areas in Europe, Australia, South Africa, Kashmir, Hawaii, the United States Pacific Northwest, and Chile [20]. Furthermore, alien invasive weeds are habitat generalists, with high plasticity to adapt to wide ranges of climatic conditions [33][34][35][36][37]. Species tolerant of wider environmental conditions are frequently associated with the following physiological traits: an efficient use of nutrients in low nutrient soils, higher root-shoot ratio in arid systems and a lower root-shoot ratio in light-limited systems for resource acquisition, lower leaf construction costs and higher photosynthetic energy use efficiency as well as early phenology in arid systems [38,39].With its inhospitable terrain and strong conservation strategies (maintaining 60% or more forest cover, with more than 51% designated as protected areas and with a rigid forest management rule...

Soil salinity is a major environmental constraint in Northeast Thailand. Sustainable land use and management in this region require careful mapping of the salinity status. This study was conducted to investigate performances of some digital classification techniques for soil salinity mapping in the Northeast. The techniques investigated were based on the use of LANDSAT-7 ETM+ with different combinations of three kinds of ancillary data (i.e., topography, geology, and underground water quality). In this study, the Maximum Likelihood classification method was employed. Statistics including KAPPA analysis and Z-statistic, overall accuracy, producer's accuracy, and user's accuracy, were used as the bases for assessments of mapping accuracies and, in turn, performances of the classification techniques. Results have shown that the use of ETM+ data bands 4,5 and 7, with the combination of all three kinds of the ancillary data yielded the most accurate soil salinity map with 83.6 % overall accuracy. The same subset of ETM+ data when used with any combination of two kinds of the ancillary data could serve as well. Other classification techniques yielded significantly less accurate results. It was, therefore, concluded that techniques based on the use of the selected ETM+ data subset with combinations of two or three kinds of the ancillary data were promising.

Abstract. The MACROS crop model was evaluated for its utility to generate information on land suitability for dry season peanut cropping based on water availability at the regional scale in Khon Kaen Province, Northeast Thailand. The model was specific for the condition where crop growth is limited by water stress, and evaluated using both calibration and validation phases in sequence. In the model calibration, data sets from one peanut field experiment were used to calibrate some parameters to obtain the best agreement between experimental and simulated results. The model validation, in this study, consisted of a ‘validation A’, with emphasis on the accuracy and a ‘validation B’, with emphasis on the usefulness and relevance of the model. In the model validation A, data sets from peanut field experiments were used to validate the model under different conditions. Satisfactory agreements were found between the dynamics of observed and corresponding simulated values of shoot dry weight in every condition involved in this validation study. Also the simulated pod yields agree well with the field data. For the validation R, the model was further validated using data from 36 farm trials conducted at 5 different test sites. A high positive correlation (r= 0.91) existed between observed and simulated pod yields. Because of these satisfactory agreements between observed and corresponding simulated values, it was concluded that the model is valid and can be applied to Khon Kaen Province.

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This article is an attempt to assess the invasion risk from the most noxious alien plant species using the GPS recorded locations and environmental variables. The invasion risk was modelled by combining the three ecological niche modelling algorithms- DesktopGARP, Openmodeller DesktopGARP and Maxent after validating their accuracies. The accuracies ranged from moderate to good in all the algorithms, for all six species. The result showed Ageratina adenophora and Ageratum conyzoides as highly invasive species both in terms of area coverage and the ecological tolerance range of the study site. It was also indicative that, irrespective of the species, agricultural lands are most susceptible to invasion among all other types of land uses in the study area.

Salt-affected soil maps for Northeast Thailand focus on the percentage of salt crusts. Investigation was done to find the field-scale spatial variability of the electrical conductivity of saturation extract (ECe) in salt-affected areas (percentage salt crusts: very severely = class 1; severely = class 2, and moderately = class 3). Two study sites were selected for each class (n = 6). Soil samples (n = 100) were collected at each site using stratified, systematic, unaligned sampling, and analyzed for ECe. Variations in ECe were assessed using basic statistics and geostatistics. At the field-scale, in every class, the best-fit semivariogram model generated was satisfactory (R2 > 0.8). Interpretation from the relevant model parameters (i.e., nugget, sill, and effective range), together with the interpolated (kriged) maps, demonstrated that the characteristics of spatial variability of soil ECe were inconsistent, even between different sites of the same salt-affected soil class. In general, various degrees of small-scale variation were observed, very high variation of ECe was common, spatial dependence was strong to moderate, while the spatial distribution pattern was in distinctive patches. The size of patches depended on the effective range at each site. This study also revealed that the class 1 areas were entirely, very strongly saline (ECes range, 56.70 and 433.00 dS·m-1), whereas the areas of class 3 were non-saline to moderately saline (range, 0.11 - 5.26 dS·m-1). Class 2 areas were much more complex; the soils varied from non-saline to very strongly saline (range, 0.16 - 49.00 dS·m-1). Information on the nature and characteristics in the spatial variability of soil ECe is useful for developing strategies for management of salt-affected soils in precision agriculture in this region.

One possible management option for farmers to improve the soil nitrogen (N) supply for rice production is the cultivation of a prior legume. The objective of this study was to investigate the value of such an option in the lowland of the north-east of Thailand. Two experiments were established in 2 typical locations in a split-plot design with 4 replicates. The main plots included 3 nitrogen levels (0, 30, and 60 kg N/ha) and the subplots, 4 pre-rice managements: (i) fallow with weeds removed (FW–); (ii) with weeds incorporated before the rice crop (FW+); (iii) mungbean incorporated at flowering as green manure (MGM); or (iv) incorporated after grains harvest (MR+). In both experiments the difference in rice yield between MGM and MR+ was not significant. In Expt 1, in contrast to Expt 2, the rice yield increase due to MR+ was significant and significantly higher than that due to application of 60 kg N/ha. Moreover, significantly higher apparent recovery of N (ANRm, kg N uptake increase/kg N supplied by residues), probably due to the continuous flooding of the soil surface, was achieved in this experiment. The low values of internal efficiency of N (IEN, kg total grains/kg total N uptake), ANRf (Δ kg N uptake/kg N supplied by fertiliser), and of ANUEf (Δ kg grains/kg applied N fertiliser) recorded in the MR+ treatment of Expt 1, suggest that no application of N fertiliser is needed where the soil water conditions allow high recovery of the N supplied by a preceding mungbean crop.