Comparing direct image and wavelet transform-based approaches to analysing remote sensing imagery for predicting wildlife distribution

In this study we tested the ability to predict the probability of elephant (Loxodonta africana) presence in an agricultural landscape of Zimbabwe based on three methods of measuring the spatial heterogeneity in vegetation cover, where vegetation cover was measured using the Landsat Thematic Mapper (TM)-derived normalized difference vegetation index (NDVI). The three methods of measuring spatial heterogeneity were: one wavelet-derived spatial heterogeneity measure; and two direct image measures. The wavelet-derived spatial heterogeneity measure consists of the intensity, which measures the maximum contrast in the vegetation cover, and the dominant scale, which determines the scale at which this intensity occurs. The two direct image measures use the NDVI average and the NDVI coefficient of variation (NDVIcv). The results show that the wavelet-derived spatial heterogeneity significantly explains 80% of the variance in elephant presence compared with 60% and 48% variance explained by the NDVI average and NDVIcv, respectively. We conclude that the wavelet transform-based approach predicts elephant distribution better than the direct image measures of spatial heterogeneity.

[1]  D. Wardle,et al.  Spatial soil ecology , 2002 .

[2]  Jonathan Kingdon,et al.  The Kingdon field guide to African mammals , 1997 .

[3]  A. Sparrow,et al.  A heterogeneity of heterogeneities. , 1999, Trends in ecology & evolution.

[4]  J. Kerr,et al.  From space to species: ecological applications for remote sensing , 2003 .

[5]  M. Charlton,et al.  Quantitative geography : perspectives on spatial data analysis by , 2001 .

[6]  Piermaria Corona,et al.  Exploring forest structural complexity by multi-scale segmentation of VHR imagery , 2008 .

[7]  P. R. Guy,et al.  Diurnal activity patterns of elephant in the Sengwa Area, Rhodesia , 1976 .

[8]  K. M. Dunham.  Movements of elephant cows in the unflooded Middle Zambezi Valley, Zimbabwe Introduction , 1986 .

[9]  M. Fortin,et al.  Spatial pattern and ecological analysis , 1989, Vegetatio.

[10]  D. Cumming,et al.  THE MANAGEMENT OF ELEPHANT AND OTHER LARGE MAMMALS IN ZIMBABWE , 1981 .

[11]  Brian Everitt,et al.  An Introduction to S-PLUS , 2001 .

[12]  Karen C. Seto,et al.  Linking spatial patterns of bird and butterfly species richness with Landsat TM derived NDVI , 2004 .

[13]  A. Skidmore,et al.  The response of elephants to the spatial heterogeneity of vegetation in a Southern African agricultural landscape , 2005, Landscape Ecology.

[14]  David A. Norton,et al.  Estimation of Tree Size Diversity Using Object Oriented Texture Analysis and Aster Imagery , 2008, Sensors.

[15]  D. Rocchini.  Effects of spatial and spectral resolution in estimating ecosystem α-diversity by satellite imagery , 2007 .

[16]  Sujit K. Ghosh,et al.  Essential Wavelets for Statistical Applications and Data Analysis , 2001, Technometrics.

[17]  A. Skidmore,et al.  Monitoring change in the spatial heterogeneity of vegetation cover in an African savanna , 2006 .

[18]  A. Skidmore,et al.  Interannual variability of NDVI and species richness in Kenya , 2002 .

[19]  Mark E. Ritchie,et al.  Populations in a Landscape Context: Sources, Sinks, and Metapopulations , 1997 .

[20]  J. Ragle,et al.  IUCN Red List of Threatened Species , 2010 .

[21]  J. R. Timberlake,et al.  Vegetation survey of the communal lands north and west Zimbabwe. , 1993 .

[22]  R. Ogden,et al.  Essential Wavelets for Statistical Applications and Data Analysis , 1996 .

[23]  Stephen J. Walsh,et al.  Scale-Dependent Relationships between Population and Environment in Northeastern Thailand , 1999 .

[24]  Stéphane Mallat,et al.  A Theory for Multiresolution Signal Decomposition: The Wavelet Representation , 1989, IEEE Trans. Pattern Anal. Mach. Intell..

[25]  Hong-Ye Gao,et al.  Applied wavelet analysis with S-plus , 1996 .

[26]  Bruce T. Milne,et al.  Animal movements and population dynamics in heterogeneous landscapes , 1992, Landscape Ecology.

[27]  J. D. du Toit,et al.  Coexistence between People and Elephants in African Savannas , 1999 .

[28]  F. Tanser,et al.  The application of a remotely-sensed diversity index to monitor degradation patterns in a semi-arid, heterogeneous, South African landscape , 1999 .