Jayakumar S, Ramachandran A, Bhaskaran G, Heo J
Department of Civil & Environmental Engineering, Yonsei University, Seoul 120-749, Korea.
Environ Manage. 2009 Feb;43(2):326-45. doi: 10.1007/s00267-008-9219-y. Epub 2008 Oct 25.
The primary deciduous forests in the Eastern Ghats (EG) of Tamil Nadu (TN) India have undergone many changes owing to various need-based forest managements, such as timber extraction for industry, railway sleepers, charcoal, and forest clearance for hydroelectric projects and agriculture, during preindependence and postindependence periods (i.e., from 1800 to 1980). The enactment of a forest conservation act during the 1980s changed the perception of forest managers from utilization to conservation. This study was taken up to assess the forests dynamics in the EG of TN spatially between 1990 and 2003 and nonspatially between 1900 and the 1980s. Landsat Thematic Mapper (TM) and Indian Remote Sensing satellite (IRS) 1D Linear Imaging and Self Scanning (LISS III) data were used to assess forests during 1990 and 2003, respectively. Field floristic survey and secondary data (such as published literature, floras, books, and forest working plans) were used to assess the forest dynamics in terms of forest type and species composition among the preindependence period, the postindependence period, and the present (i.e., before and after 1980). The satellite data analysis revealed a considerable amount of changes in all forest types during the 13 years. The comparison of species composition and forest types between the past and present revealed that need-based forest management along with anthropogenic activity have altered the primary deciduous forest in to secondary and postextraction secondary forests such as southern thorn and southern thorn scrub forests in the middle [400-900 m above mean sea level (MSL)] and lower slopes (<400 m MSL). However, the evergreen forests present at the upper slope (>900 m MSL) and plateau seemed not to be much affected by the forest management. The changes estimated by the satellite data processing in the major forest types such as evergreen, deciduous, southern thorn, and southern thorn scrub are really alarming because these changes have occurred after the implementation of a forest conservation act. The dependence of local people on forests for various purposes in this region is also considerably high, which might be a key factor for the changes in the forests. The results of this study not only provide an outlook on the present status of the forests and the change trends but also provide the basis for further studies on forests in the EG of TN.
印度泰米尔纳德邦东高止山脉的原始落叶林，在1800年至1980年的独立前和独立后时期，由于各种基于需求的森林管理措施，发生了许多变化，比如为工业、铁路枕木、木炭进行木材采伐，以及为水电项目和农业进行森林砍伐。20世纪80年代森林保护法的颁布，改变了森林管理者从利用到保护的观念。本研究旨在评估1990年至2003年期间泰米尔纳德邦东高止山脉森林的空间动态，以及1900年至20世纪80年代期间的非空间动态。分别使用陆地卫星专题制图仪（TM）和印度遥感卫星（IRS）1D线性成像自扫描传感器（LISS III）数据来评估1990年和2003年的森林状况。通过实地植物调查和二手数据（如已发表的文献、植物志、书籍和森林经营计划），从森林类型和物种组成方面评估独立前时期、独立后时期以及当前（即1980年前后）的森林动态。卫星数据分析显示，在这13年中所有森林类型都发生了相当大的变化。过去和现在的物种组成及森林类型比较表明，基于需求的森林管理以及人为活动，已将原始落叶林转变为次生林和采伐后次生林，如海拔中部[平均海平面（MSL）以上400 - 900米]和较低山坡（<400米MSL）的南部荆棘林和南部荆棘灌丛林。然而，上坡（>900米MSL）和高原地区的常绿林似乎受森林管理影响不大。通过卫星数据处理估算出的主要森林类型（如常绿林、落叶林、南部荆棘林和南部荆棘灌丛林）的变化令人担忧，因为这些变化是在森林保护法实施之后发生的。该地区当地居民出于各种目的对森林的依赖程度也相当高，这可能是森林发生变化的一个关键因素。本研究结果不仅提供了森林现状和变化趋势的展望，也为泰米尔纳德邦东高止山脉森林的进一步研究提供了依据。
