Impacts of Climate Change and Land Use on Forest Degradation in Teknaf Peninsula

Impacts of Climate Change and Land Use on Forest Degradation in Teknaf Peninsula

Md. Abiar Rahman, Masakazu Tani, Kazuo Asahiro, Md. Zulfikar Rahman, and

Abu Zofar Md. Moslehuddin

ISSN: 2186-6872 (print) ISSN: 2186-0009 (online) http://www.BENJapan.org/IJE

ARTICLE HISTORY Received: 14 May 2014 Revised: 08 August 2014 Accepted: 1 September 2014

Published online: 10 Sept 2014

Abstract

Teknaf peninsula was very rich in natural resources, which is under threat due to climate change and human activities. Various land uses are degrading the forest resources. The aim of this study was to examine the impacts of climate change and land use on forest resources in Teknaf peninsula of Bangladesh. Long-term climatic data were used to understand the trend of climatic parameters. A survey was conducted to know the impacts of climate and land use changes on forest resources degradation. Climatic data showed that minimum temperature did not vary much over time, while maximum temperature has increased slightly in recent years compared to 30 years back. Rainfall was not well distributed over month, although it showed an increasing trend. The monsoon rainfall was increased by 66%, while dry season rainfall was decreased by 29%. Forest area and settlement showed reverse trend, particularly the period between 1972 and 1990, while agriculture was widely started after 1990. Currently, the area for betel leaf cultivation has increased tremendously and farmers mostly collect shading materials from forest area. Climate change along with improper land use has created huge pressure on forest resources. Appropriate adaptation, mitigation and conservation measures should be taken immediately to conserve the forest ecosystem in Teknaf peninsula.

Keywords: Climate change, land use, agriculture, forest resources, degradation.

 2014, International Journal of Environment. All rights reserved.

I.

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Teknaf upazila, under Cox`s Bazaar district, is located at the southeast corner of

AUTHORS INFO

Md. Abiar Rahman*

e-mail: abiarbd@yahoo.com

Faculty of Design, Kyushu University, Japan; Faculty of Agriculture, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Bangladesh

Masakazu Tani

e-mail: tani@design.kyushu-u.ac.jp

Kazuo Asahiro

e-mail: asahiro@design.kyushu-u.ac.jp Faculty of Design, Kyushu University, Japan

Md. Zulfikar Rahman

e-mail: abunazia@yahoo.com

Abu Zofar Md. Moslehuddin

e-mail: zulfikar64@yahoo.com

Faculty of Agriculture, Bangladesh Agricultural University, Bangladesh

*Corresponding author

for environmental degradation, which is a very big concern. Expansion of agricultural land has been eroding the natural environment; therefore the sustainability of agriculture itself is in a critical situation [10]. In the recent years, betel leaf (Piper betle) became one of the most important crops in Teknaf peninsula and the area coverage has been increased tremendously. Shading is a must for betel leaf cultivation, which ensures high production and quality. Farmers use to go forest to collect shading materials, which is one of the major causes of forest degradation. It is very urgent to address the problem and take necessary steps to conserve the forest as well as the environment. The aim of this study was to understand the trend of climate and land use changes; and their impacts on forest ecosystem degradation in Teknaf peninsula.

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A. Study area and climate

The study was conducted in Baharchara union under Teknaf upazila (Fig. 1), which has been declared as an ecologically critical area by Bangladesh Government because of reduction of biodiversity at an alarming rate. The study area is located along the west coast of the peninsula and about 30 km far from the upazila headquarter. The area is characterized by subtropical climate with 15 and 33°C minimum (January) and maximum (May) temperatures, respectively. Total annual rainfall is appreciable (around 5000 mm), but it is not well distributed. Significant amount of rainfall occurs during the months of June to August, and negligible rainfall occurs from December through March.

B. Dataset

The long-term monthly temperature and rainfall data series for the study area was collected from Bangladesh Meteorology Department (BMD). Data of monthly mean, maximum and minimum surface air temperatures were used in this study. The mean monthly maximum and minimum temperatures were derived by averaging the daily maximum and minimum temperatures. C. Survey

A survey on betel leaf cultivation was done during December 2012 to know the impact of betel leaf cultivation on forest resource degradation. A structured questionnaire was used to survey 50 farmers for data collection. Focus group discussion (FGD) was conducted to validate the information.

Fig. 1. Study area

D. Secondary information

Secondary information on forest resources and land use were collected from Department of Agricultural Extension (DAE), Bangladesh Space Research & Remote Sensing Organization(SPARRSO), Bangladesh Meteorological Department (BMD) and Forest Department (FD).

E. Data analyses

Climatic data were analysed by MS Excel, while survey data were analysed by the Statistical Package for the Social Science (SPSS) computer software.

III.

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A. Climate change

hot months; and it decreased in winter (February). In case of maximum temperature, it showed increasing trend throughout the year. The average maximum temperature was 30°C in 1977-86 decade, which was raised to 30.5 and 30.7°C in 1997-06 and recent year (2008), respectively. Rainfall showed an interesting trend of variation at different decades. The estimation showed that rainfall was increased by 66% during monsoon (June to August), while it was decreased by 29% during dry season (November to March) in recent year compared to base decade (1977-86).

Long-term trends showed an increasing trend of maximum temperature, minimum temperature and rainfall (Fig. 3). The regression equations indicated that increasing trend of maximum temperature (R2 _{= 0.31)} was rapid than minimum temperature (R2 ₌ 0.22). The annual increment rates of maximum and minimum temperatures were 0.022 and 0.019°C, respectively. The increment rate, however, for rainfall was higher than temperature (R2 _{= 0.30). The} rainfall was increased annually by 42.08 mm, which was quite appreciable (Fig. 3). However, although the annual rainfall showed increasing trend but it was not well distributed over months.

Fig. 2. Monthwise decadal change of maximum temperature, minimum temperature and rainfall in the study area based on long-term data (1977 to 2008).

Fig. 3. Long-term (1977 to 2008) trends of maximum temperature, minimum temperature and rainfall in the study area. B. Land use change

Land use change over time in the study area has been presented in Fig. 4 and Table 1. It was observed that forest area decreased sharply between 1972 and 1990, while human settlement was increased dramatically during the same period. Forest area was decreased by 39% and settlement was increased by 50% during 2006 compared to 1972. Before 1990, people were not interested in agriculture as other resources (forest and marine) were abundant. Agricultural practice, however, was increased tremendously after 1990 [1].

Bangladesh,might be due to climate change and improper management. On the other hand, expansion of agriculture was creating tremendous pressure on forest as the expansion was mainly occurring in forest area due to encroachment.

Fig. 4. Changes of land use classes over time in the study area.

Table 1.Changes of area coverage of major crops in 2012 compared to five year back

Crop % Area change

Rice 12

Betel leaf 56

Corn 8

Tomato 13

Brinjal 22

Chili 25

C. Betel leaf cultivation and resource use

Nowadays, betel leaf is the most valuable cash crop in Teknaf. The cutting of betel leaf is usually planted after rain (August-October). It is a shade loving crop and the production and quality are largely dependent on the shade imposition. On the other hand, rainfall is scarce during its vegetative growth stage (November through March); therefore irrigation is indispensable for better production. Most of the farmers (36%) used to apply irrigation once a week followed by 3-day interval (28%), while few farmers (8%) also applied irrigation every alternative day (Fig. 5).

Fig. 5. Frequency of irrigation for betel leaf cultivation.

Farmers usally use various materails to provide shade for betel leaf cultivation. Farmers mostly used bamboo, sungrass, forest pole (different species) and grassess as shading materials and structure (Fig. 6).Among the shading materials, bamboo was mostly used (46%) by the betel leaf farmers followed by sungrass (32%), forest herb/vine (28%) and forest pole (24%). Farmers used to collected shading materilas from different sources. Forest was the prime source of materails (46%) followed by market (22%), own (18%) and market+forest (14%) (Fig. 7).

Fig. 6. Different shading materials used for betel leaf cultivation.

IV.

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Bangladesh is one of the most vulnerable countries in the world. The long-term data showed an increasing trend of both maximum and minimum temperatures although the maximum was more distinctly increased than minimum temperature. As a result, the diurnal temperature range (DTR) is increasing, which is not good for plant survival and production. Similarly, the total annual rainfall showed increasing trend, but the seasonal distribution was significantly different. In general, more than 70% rainfall occurs during the month June to August and most of times of dry season remain rainless. The long-term data indicated that monsoon season rainfall increased by 66%, while it decreased by 29% during dry season. Large year-to-year variation in monthly distribution of rainfall in Indo-Gangetic Region has been observed [8]. In the recent year, it was observed prolong drought during dry season and high rainfall during monsoon [5]. Therefore, this patchy rainfall is not good for resource conservation and agriculture production. Fluctuation of rainfall is associated with increasing temperatures [9].Rainfall anomalies and high fluctuation of temperature were observed in coastal area which was responsible for reducing crop productivity (19%) despite the technological development [6]. A warmer climate scenario with uncertainty of rainfall is likely to affect crop production, irrigation system and other resources of the ecosystem [3].

It was observed that source of irrigation water was scarce in the study area. In general, water table goes down during dry season and people cannot lift ground water as well. Many farmers carry water from canal or water catchment near by the hill, while in some cases they use pipe for applying irrigation. However, due to prolonged drought, most of the canals and catchments contain no water during dry season. On the other hand, because of over utilization of water for betel leaf and other crop cultivation, most of the canals and water catchments remain waterless in most of the months of the year, which ultimately affects biodiversity and resources of forests. Farmers are cultivating betel leaf intensively for higher income without considering the resource conservation. Climate change along with improper betel leaf cultivation is making the ecosystem more vulnerable in terms of availability of resources.

Many villagers got hilly area from forest department for their subsistance and livelihood activities. They are also committed

to conserve forest area. Surprisingly, most of the villagers were cultivating bettele leaf and sungrass in those lands. They were interested in sungrass cultivation as it was used as materials for shading and house making. Along with sungrass other shading materials come from forests. It inidicates that farmers largely depend on forest for shading materials. Over exploitation of resources is responsible for hamparing the forest growth and biodiversity loss. Moreover, cultivation activities in the hillay area also accelarating the soil erosion and eventually degrading the forest ecosystem.

Suitable conservation strategies should be undertaken to restore the forest resources. Sustainable production technique particularly for betel leaf should be introduced so that farmers may reduce their dependency on forest for materials collection. Development of well managed homestead production system, participation of local people in forest conservation, establishment of multistoried agroforestry system, introduction of trees and high value crops inside the betel leaf fieldmay be some good options.Various income generation activities need to introduce in the study area to build to capacity of the local people.

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This study was supported by the Japan Society for the Promotion of Science (JSPS) grant for scientific research (Grant # 24401040), Japan.

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