Characterisation of Landscape with ForestFragmentation Dynamics

Abstract

Land cover (LC) and land use (LU) dynamics induced by human and natural processes play a major role in global as well as regional patterns of landscapes influencing biodiversity, hydrology, ecology and climate. Changes in LC features resulting in forest fragmentations have posed direct threats to biodiversity, endangering the sustainability of ecological goods and services. Habitat fragmentation is of added concern as the residual spatial patterns mitigate or exacerbate edge effects. LU dynamics are obtained by classifying temporal remotely sensed satellite imagery of different spatial and spectral resolutions. This paper reviews five different image classification algorithms using spatio-temporal data of a temperate watershed in Himachal Pradesh, India. Gaussian Maximum Likelihood classifier was found to be apt for analysing spatial pattern at regional scale based on accuracy assessment through error matrix and ROC (receiver operating characteristic) curves. The LU information thus derived was then used to assess spatial changes from temporal data using principal component analysis and correspondence analysis based image differencing. The forest area dynamics was further studied by analysing the different types of fragmentation through forest fragmentation models. The computed forest fragmentation and landscape metrics show a decline of interior intact forests with a substantial increase in patch forest during 1972-2007

Geospatial analysis of forest fragmentation in Uttara Kannada District, India

“…Land use patterns are the collective result of interactions among local geophysical indicators, such as elevation, slope and rainfall and agro-climatic indicators, demographic variation, market forces and related development policies (Munroe et al 2004;Ameztegui et al 2010). Numerous studies focusing on deforestation at the landscape level have explored the spatial patterns and interactions among the geophysical elements of the landscape and its dynamics (Nelson and Geoghegan 2002;Alix-Garcia et al 2005;Echeverria et al 2008;Ramachandra and Kumar 2011;Ramachandra et al 2013). These changes, measured at temporal scales, help in monitoring ecosystems and aid in the implementation of location specific mitigation measures.…”

“…Fragmentation of forests at the pixel level are estimated through the computation of P f (the ratio of the number of pixels that are forested to the total number of nonwater pixels in the window) and P ff (the proportion of all adjacent (in cardinal directions) pixel pairs that include at least one forest pixel, for which both pixels are forested) as given in equations 1 and 2 (Riitters et al 2002;Kuèas et al 2011;Ramachandra and Kumar 2011). …”

“…During the succession stage, edges will become more prominent with higher light availability and loss of soil moisture. This will directly affect seed dispersal, seed viability, species distribution and propagation of invasive species (Ramachandra and Kumar 2011). These cascading effects have the potential to disrupt seriously many basic ecological processes over large areas.…”

“…At a large-scale land use, more recent land cover changes (LULC) are altering the ecosystem structure, affecting the goods and services of the ecosystem. These disturbances have resulted in fragmentation of forests with a mosaic of natural patches surrounded by other land uses (Ramachandra and Kumar 2011). A host of anthropogenic activities, such as tree logging, conversion of forest land to agriculture, intense agricultural practices, forest fire and unplanned infrastructural development have contributed to the disruption of the contiguity of forests in predominantly natural landscapes (Buskirk et al 2000;Boogaert et al 2004).…”

“…An alteration in forest structure through fragmentation of forests has affected its functional abilities, as is evident from the decline in water yield, carbon sequestration potential and biodiversity. (Diaz et al 2006;Ramachandra and Kumar 2011).…”