Within the framework of the Project: Innovating and intensifying livestock farming to adapt and grow: Increasing the adaptive capacity and resilience of soils. Marcos Easdale gave us his second talk
Climate change confronts extensive livestock farming with adverse situations, such as changes in vegetation cover, which reduce the availability of forage for livestock. Among the technological innovations for adapting to climate change proposed by the FONTAGRO Project "Adaptation to climate change in extensive family livestock farming" are forage evaluation and adjustment of stocking rates. We understand that the stocking rate is linked to pasture productivity, so understanding its dynamics and having a prospective of its behavior will allow us to improve its use and conservation.
In this context, we invited Dr. Marcos Easdale to give a series of 5 talks entitled: Dynamics and satellite prospective of the productivity of arid and semi-arid rangelands.
Talk 2. Dynamics and satellite prospective of the productivity of arid and semi-arid rangelands. NDVI Trends Study.
Dr. Marcos H. Easdale talked about the NDVI Trends study for land degradation assessment and monitoring.
Land degradation and desertification are among the most relevant environmental problems in most arid and semi-arid regions of the world. Monitoring systems are in demand to support decision making and to assess the impact of intervention programs, such as the United Nations programs to combat desertification. Current methodologies to assess land degradation are under permanent debate and efforts are oriented to the development of precise operational tools aimed at large regions, such as Patagonia, Monte or Puna in Argentina. However, rigorous and systematic approaches to address the complex dynamics of arid and semi-arid rangeland productivity are still lacking.
Satellite information offers opportunities to go back in time to study ecological processes for which ground data were not recorded or were costly to obtain. Land degradation is generally defined as a long-term decline in ecosystem functioning and loss of productivity caused by the interaction of human and environmental disturbances. While it is a complex process, which must involve the assessment of different biophysical dimensions, productivity loss can be addressed by analyzing trends in spectral indices such as the Normalized Difference Vegetation Index (NDVI), a good estimator of photosynthetic activity of vegetation. However, most studies to date use monotonic or linear trends to assess land degradation. The point is that long-term trends in vegetation productivity can exhibit unidirectional (monotonic), but also cyclic (non-monotonic) dynamics, including oscillations that can last for several years, which cannot be captured by linear trends.
The talk discusses the study of NDVI trends using linear (estimated by linear regression) and non-linear (estimated by the wavelet autoregressive method, WARM) approaches. The talk discusses the results published in the following article:
Easdale, M.H., Bruzzone, O., Mapfumo, P., Tittonell, P. (2018). Phases or regimes? Revisiting NDVI trends as proxies for land degradation. Land Degradation & Development 29, 433-445. DOI:10.1002/ldr.2871.