Sustainable land-use options for enhancing carbon sequestration, plant diversity and productivity : a case of Khlong Yai Subwatershed, Thailand | |
| Author | Gnanavelrajah, Nalina |
| Call Number | AIT Diss. no.NR-07-05 |
| Subject(s) | Land use--Thailand Plant diversity--Thailand Carbon sequestration--Thailand |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Natural Resources Management, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. NR-07-05 |
| Abstract | Inappropriate agricultural land-use practices have resulted in key environmental degradation problems such as land degradation, loss of biodiversity, increased CO2 emission and reduced soil fertility. However, if properly planned agricultural land-uses can be part of the solution rather than a problem. Thus identifying agricultural land-uses that enhance carbon sequestration and biodiversity on one hand and reduce soil erosion and fertility loss on the other will contribute to the land-use sustainability. As the land-use decisions are affected by socioeconomic factors, land-use sustainability depends upon such factors as well. The study of agricultural land-use sustainability is of particular interest in Thailand where more than 40% of the country's area is occupied by agriculture. This study aimed to identify site-specific viable agricultural land-use options for agricultural sustainability in Khlong Yai sub-watershed of Thailand, integrating biophysical and socioeconomic factors. A step by step approach of estimating current level of carbon sequestration, plant diversity, soil erosion, land suitability and productivity was adopted and based on which sustainability of present land-uses was studied. A quadrate sampling technique was used to estimate the biomass and plant diversity of different land-uses. A household survey of the farmers managing the respective fields used for quadrate sampling was also conducted in order to collect household information including land management practices. The secondary data, such as the soil map, land-use map, climate and crop data were also used. Land suitability classification was performed following FAO framework of land evaluation. Viable land-use options were proposed under two different scenarios to improve agricultural sustainability depending on the sets of criteria. Among a potential set of biophysical and socioeconomic indicators, key factors were identified through the principal component analysis and finally sustainability models were built. The total biomass C, soil C, and total C stock of the agricultural land-uses in the study area were 8.5 million tons, 12.0 million tons and 20.5 million tons, respectively. Land-uses para rubber and mixed orchard had higher biomass/ha than coconut, coconut-cassava and eucalyptus which in turn had higher biomass/ha than the shrub crop land-uses, such as sugarcane, cassava and pineapple. In terms of plant diversity, the land- use orchard had the highest plant diversity and paddy had the lowest. Moreover, shrub crops, such as cassava under mono-cropping had lower plant diversity compared to tree crops, such as coconut under mono-cropping. The average potential annual soil loss of each land-use was ranged between 0.002 to 5.15 tons/ha/yr. Only 3% of agricultural land-uses have potential erosion rate higher than maximum permissible soil limit. With regard to the current land-uses and their biophysical suitability, 47% of the present land-uses are highly suitable, 46% moderately, 5% marginally and 2% are non-suitable. The land-use under coconut was found to have the highest economic return as shown by benefit cost analysis and sugarcane the least. About 7.6% of the present agricultural land-uses have long-term sustainability, 75.39% have medium-term, and 16.6% have short-term sustainability whereas less than 0.5% land area are either slightly or moderately unstable. Altogether 6 different models were generated that could be used to assess the sustainability. Alternative Land-use options are suggested for two different scenarios with different levels of constraints |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. NR-07-05 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Development and Sustainability (DDS) |
| Academic Program/FoS | Natural Resources Management (NRM) |
| Chairperson(s) | Shrestha, Rajendra Prasad; |
| Examination Committee(s) | Schmidt-Vogt, Dietrich ;Lal Samarakoon; |
| Scholarship Donor(s) | Asian Institute of Technology, Thailand; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2007 |