This research extends upon land cover change studies by incorporating methodological approaches, which are compatible with heterogeneous ecosystems, are able to link landscape changes to system processes, such as climate change, and provide potential linkages to concepts of ecological resilience. The study region in southern Africa experienced a significant climatic shift in the 1970s, resulting in drier conditions. The state of these ecosystems and their response to such climatic shock is quantified in terms of vegetation amount and heterogeneity. We monitor these characteristics pre- and post-disturbance using a Landsat image series and examine the utility of continuous characterizations of land cover for measuring ecosystem resilience. Land cover change is evaluated using a mean-variance analysis in concert with a spatial persistence analysis. This investigation indicates that although the impact of the decreased precipitation is evident in the 1980s, recovery occurred by the 1990s and 2000s. We found the continuous methodological approach used holds potential for studying heterogeneous landscapes within a resilience framework.
References
[1]
Hill, M.J.; Hanan, N.P. Savannas: Biogeographical and Ecological Perspectives. In Ecosystem Function in Savannas: Measuring and Modeling at Landscape to Global Scales; CRC Press: Boca Raton, FL, USA, 2010; pp. 1–10.
[2]
Scholes, R.J.; Archer, S.R. Tree-grass interactions in savanna. Ann. Rev. Ecol. Systemat. 1997, 28, 517–544, doi:10.1146/annurev.ecolsys.28.1.517.
[3]
Peters, D.P.C.; Havstad, K.M. Nonlinear dynamics in arid and semi-arid systems: Interactions among drivers and processes across scales. J. Arid Environ. 2006, 65, 196–206, doi:10.1016/j.jaridenv.2005.05.010.
[4]
Scholes, R.J.; Walker, B.H. An African Savanna: Synthesis of the Nylsvley Study; Cambridge University Press: Cambridge, UK, 1993; pp. 264–267.
[5]
Reynolds, J.F.; Smith, D.M.S.; Lambin, E.F.; Turner, B.L., II; Mortimore, M.; Batterbury, S.P.; Downing, T.E.; Dowlatabadi, H.; Fernandez, R.J.; Herrick, J.E.; et al. Global desertification: building a science for dryland development. Science 2007, 316, 847–851, doi:10.1126/science.1131634.
[6]
Hüttich, C.; Herold, M.; Wegmann, M.; Cord, A.; Strohbach, B.; Schmullius, C.; Dech, S. Assessing effects of temporal compositing and varying observation periods for large-area land-cover mapping in semi-arid ecosystems: Implications for global monitoring. Remote Sens. Environ. 2011, 115, 2445–2459, doi:10.1016/j.rse.2011.05.005.
[7]
Herold, M.; Mayaux, P.; Woodcock, C.E.; Baccini, A.; Schmullius, C. Some challenges in global land cover mapping: An assessment of agreement and accuracy in existing 1 km datasets. Remote Sens. Environ. 2008, 112, 2538–2556, doi:10.1016/j.rse.2007.11.013.
[8]
Jung, M.; Henkel, K.; Herold, M.; Churkina, G. Exploiting synergies of global land cover products for carbon cycle modeling. Remote Sens. Environ. 2006, 101, 534–553, doi:10.1016/j.rse.2006.01.020.
[9]
Lambin, E.F.; Geist, H.J. Land Use and Land Cover Change: Local Processes and Global Impacts; Springer: New York, NY, USA, 2005.
[10]
Foody, G.M. Monitoring the magnitude of land-cover change around the southern limits of the Sahara. Photogramm. Eng. Remote Sensing 2001, 67, 841–847.
[11]
Chamaille-Jammes, S.; Fritz, H.; Murindagomo, F. Spatial patterns of the NDVI-rainfall relationship at the seasonal and interannual time scales in an African savanna. Int. J. Remote Sens. 2006, 27, 5185–5200, doi:10.1080/01431160600702392.
[12]
Vanacker, V.; Linderman, M.; Lupo, F.; Flasse, S.; Lambin, E. Impact of short term rainfall fluctuation on interannual land cover change in sub-Saharan Africa. Global Ecol. Biogeogr. 2005, 14, 123–135, doi:10.1111/j.1466-822X.2005.00136.x.
[13]
Richard, Y.; Poccard, I. A statistical study of NDVI sensitivity to seasonal and interannual rainfall variations in Southern Africa. Int. J. Remote Sens. 1998, 19, 2907–2920, doi:10.1080/014311698214343.
[14]
Fuller, D.O.; Prince, S.D. Rainfall and foliar dynamics in tropical southern Africa: Potential impacts of global climatic change on savanna vegetation. Clim. Change 1996, 33, 69–96, doi:10.1007/BF00140514.
[15]
Townshend, J.R.G.; Justice, C.O. Analysis of the dynamics of African vegetation using the normalized difference vegetation index. Int. J. Remote Sens. 1986, 7, 1435–1445, doi:10.1080/01431168608948946.
[16]
Chavez, F.; Ryan, J.; Lluch-Cota, S.; Niquen, M. From anchovies to sardines and back: Multidecadal change in the Pacific ocean. Science 2003, 299, 217–221, doi:10.1126/science.1075880.
[17]
Nicholson, S.E. The nature of rainfall variability over Africa on time scales of decades to millenia. Glob. Planet. Change 2000, 26, 137–158, doi:10.1016/S0921-8181(00)00040-0.
[18]
Hare, S.R.; Mantua, N.J. Empirical evidence for North Pacific regime shifts 1977 and 1989. Prog. Oceanogr. 2000, 47, 103–145, doi:10.1016/S0079-6611(00)00033-1.
[19]
Batisani, N.; Yarnal, B. Rainfall variability and trends in semi-arid Botswana: Implications for climate change adaptation policy. Appl. Geogr. 2010, 30, 483–486, doi:10.1016/j.apgeog.2009.10.007.
[20]
Nicholson, S.E.; Leposo, D.; Grist, J. The relationship between El Ni？o and drought over Botswana. J. Clim. 2001, 14, 323–335, doi:10.1175/1520-0442(2001)014<0323:TRBENO>2.0.CO;2.
[21]
Reason, C.J.C.; Mulenga, H.M. Relationships between South African rainfall and SST anomalies in the southwest Indian Ocean. Int. J. Climatol. 1999, 19, 1651–1673, doi:10.1002/(SICI)1097-0088(199912)19:15<1651::AID-JOC439>3.0.CO;2-U.
[22]
Shi, G.; Ribbe, J.; Cai, W.; Cowan, T. Multidecadal variability in the transmission of ENSO signals to the Indian Ocean. Geophys. Res. Lett. 2007, 34, L10610.
[23]
Mason, S. El Ni？o, climate change, and Southern African climate. Environmetrics 2001, 12, 327–345, doi:10.1002/env.476.
[24]
Chown, S. Temporal biodiversity change in transformed landscapes: A southern African perspective. Phil. Trans. R. Soc. 2010, 365, 3729–3742, doi:10.1098/rstb.2010.0274.
[25]
Magadza, C. Climate change: some likely multiple impacts in Southern Africa. Food Policy 1994, 19, 165–191, doi:10.1016/0306-9192(94)90068-X.
[26]
Washington-Allen, R.A.; Ramsey, R.; West, N.E. Spatiotemporal mapping of the dry season vegetation response of sagebrush steppe. Comm. Ecol. 2004, 5, 69–79, doi:10.1556/ComEc.5.2004.1.7.
[27]
Washington-Allen, R.A.; Ramsey, R.; West, N.E.; Norton, B.E. Quantification of the ecological resilience of drylands using digital remote sensing. Ecol. Soc. 2008, 13, 33.
[28]
Goheen, J.; Young, T.; Keesing, F.; Palmer, T. Consequences of herbivory by native ungulates for the reproduction of a savanna tree. J. Ecol. 2007, 95, 129–138.
[29]
Ringrose, S.; Matheson, W.; Tempest, F.; Boyle, T. The development and causes of range degradation features in southeast Botswana using multi-temporal Landsat MSS imagery. Photogramm. Eng. Remote Sensing 1990, 56, 1252–1262.
[30]
Adger, W.N.; Hughes, T.P.; Folke, C.; Carpenter, S.; Rockstrom, J. Social-ecological resilience to coastal disasters. Science 2005, 309, 1036–1039.
[31]
Carpenter, S.R.; Walker, B.H.; Anderies, J.M.; Abel, N. From metaphor to measurement: Resilience of what to what? Ecosystems 2001, 4, 765–781, doi:10.1007/s10021-001-0045-9.
[32]
Westman, W.E.; O’Leary, J. Measures of resilience: the response of coastal sage scrub to fire. Vegetatio 1986, 65, 179–189, doi:10.1007/BF00044818.
[33]
Simoniello, T.; Lanfredi, M.; Liberti, M.; Coppola, R.; Macchiato, M. Estimation of vegetation cover resilience from satellite timer series. Hydrol. Earth Syst. Sci. Discuss. 2008, 5, 511–546, doi:10.5194/hessd-5-511-2008.
[34]
Dougill, A.; Trodd, N. Monitoring and Modelling Open Savannas Using Multisource Information: Analyses of Kalahari Studies. Global Ecol. Biogeogr. 1999, 8, 211–221, doi:10.1046/j.1365-2699.1999.00132.x.
[35]
Frost, P.G.H.; Robertson, F. Fire: The Ecological Effects of Fire in Savannas. In Determinants of Tropical Savannas; Walker, T.S., Walker, B.H., Eds.; IRL Press: Oxford, UK, 1987; pp. 93–140.
[36]
Walker, B.H.; Noy-Meir, I. Aspects of the Stability and Resilience of Savanna Ecosystems. In Ecology of Tropical Savannas; Huntley, B.J., Walker, B.H., Eds.; Springer Verlag: Berlin, Germany/New York, NY, USA, 1982; pp. 577–590.
[37]
Martiny, N.; Camberlin, P.; Richard, Y.; Philippon, N. Compared regimes of NDVI and rainfall in semi-arid regions of Africa. Int. J. Remote Sens. 2006, 27, 5201–5223.
[38]
Farrar, T.J.; Nicholson, S.E.; Lare, A.R. The influence of soil type on the relationships between NDVI, rainfall, and soil moisture in semiarid Botswan. II. NDVI response to soil moisture. Remote Sens. Environ. 1994, 50, 121–133, doi:10.1016/0034-4257(94)90039-6.
[39]
Scanlon, T.M.; Caylor, K.K.; Manfreda, S.; Levin, S.A.; Rodriguez-Iturbe, I. Dynamic response of grass cover to rainfall variability: implications for the function and persistence of savanna ecosystems. Adv. Water Resour. 2005, 28, 291–302, doi:10.1016/j.advwatres.2004.10.014.
[40]
Stige, L.; Stave, J.; Chan, K.; Ciannelli, L.; Pettorelli, N.; Glantz, M.; Herren, H. The effect of climate variation on agro-pastoral production in Africa. Proc. Natl. Acad. Sci. USA 2006, 103, 3049–3053.
[41]
Area, Kavango-Zambezi Transfrontier Conservation. Mitigation of Human-Elephant Conflict in the Kavango-Zambezi Transfrontier Conservation Area through Community Based Problem Animal Control, with Particular Reference to the Use of Chilli Peppers, 2006. Available online: http://www.dlist-benguela.org/sites/default/files/doclib/human%20elephant%20conflict%20TFCA.pdf (Accessed on 3 August 2013).
[42]
Gaughan, A.E.; Waylen, P.R. Spatial and temporal precipitation variability in the Okavango-Kwando-Zambezi catchment, southern Africa. J. Arid Environ. 2012, 82, 19–30, doi:10.1016/j.jaridenv.2012.02.007.
[43]
Archibald, S.; Scholes, R.J. Leaf green-up in a semi-arid African savanna—Separating tree and grass responses to environmental cues. J. Veg. Sci. 2007, 181, 583–594.
[44]
Jensen, J.R. Introductory Digital Image Processing: A Remote Sensing Perspective, 3rd ed.; Prentice-Hall: New York, NY, USA, 2005.
[45]
Green, G.M.; Schweik, C.M.; Randolf, J.C. Retrieving Land-Cover Change Information from Landsat Satellite Images by Minimizing Other Sources of Reflectance Variability. In Seeing the Forest and the Trees: Human–Environment Interactions in Forest Ecosystems; Moran, E.F., Ostrom, E., Eds.; MIT Press: Cambridge, MA, USA, 2005.
Guerschman, J.P.; Hill, M.J.; Renzullo, L.J.; Barrett, D.J.; Marks, A.S.; Botha, E.J. Estimating fractional cover of photosynthetic vegetation, non-photosynthetic vegetation and bare soil in the Australian tropical savanna region upscaling the EO-1 Hyperion and MODIS sensors. Remote Sens. Environ. 2009, 113, 928–945, doi:10.1016/j.rse.2009.01.006.
[48]
Schmidt, H.; Karnieli, A. Remote Sensing of the seasonal variability of vegetation in a semi-arid environment. J. Arid Environ. 2000, 45, 43–59, doi:10.1006/jare.1999.0607.
[49]
Running, S.W.; Loveland, T.L.; Pierce, L. A vegetation classification logic based on remote sensing for use in global biogeochemical models. Ambio 1994, 23, 77–81.
[50]
Sedano, F.; Gong, P.; Ferrao, M. Land cover assessment with MODIS imagery in southern African Miombo ecosystems. Remote Sens. Environ. 2005, 98, 429–441, doi:10.1016/j.rse.2005.08.009.
[51]
Adler, R.F.; Huffman, G.J.; Change, A.; Ferraro, R.; Xie, P.-P.; Janowiak, J.; Rudolf, B.; Schneider, U.; Curtis, S.; Bolvin, D.; et al. The version-2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979–present). J. Hydrometeorol. 2003, 4, 1147–1167, doi:10.1175/1525-7541(2003)004<1147:TVGPCP>2.0.CO;2.
[52]
Curtis, S.; Adler, R.F. ENSO indices based on patterns of satellite-derived precipitation. J. Clim. 2000, 13, 2786–2793, doi:10.1175/1520-0442(2000)013<2786:EIBOPO>2.0.CO;2.
[53]
Pickup, G.; Foran, B.D. The use of spectral and spatial variability to monitor cover change on inert landscapes. Remote Sens. Environ. 1987, 23, 361–363.
[54]
Lanfredi, M.; Simoniello, T.; Macchiato, M. Temporal persistence in vegetation cover changes observed from satellite: Development of an estimation procedure in the test site of the Mediterranean Italy. Remote Sens. Environ. 2004, 93, 565–576, doi:10.1016/j.rse.2004.08.012.
[55]
Swanson, K.L.; Tsonis, A.A. Has the climate recently shifted? Geophys. Res. Lett. 2009, 36, L06711, doi:10.1029/2008GL037022.
[56]
Meyer, K.; Wiegand, K.; Wards, D.; Moustakas, A. The rhythm of savanna patch dynamics. J. Ecol. 2007, 95, 1306–1315, doi:10.1111/j.1365-2745.2007.01289.x.
