Latin America is mostly associated with tropical and sub-tropical climates but about a quarter of its surface actually belongs to the drylands, having hyper-arid, arid, semi-arid, and dry sub-humid climates. Over the whole continent, land use changes have intensified the use of natural resources and exacerbated land degradation processes in these already vulnerable areas.
During the last decennia, the Latin American drylands of which an estimated 28% is already degraded have seen a paramount increase of agricultural activities in response to commercial demands. Intensification of agricultural production poses considerable pressures on the land resource and invokes competition for its use.
The IPCC reports that the soybean cropping boom provoked critical Land use changes that will enhance aridity as well as land degradation in already water stressed regions in e.g. Argentina, Bolivia, Brazil and Paraguay. Land degradation results from such complex interactions of geo-physical, socio-economic and political aspects leading to trade-offs in which all too often environmental sustainability gets little consideration. Recent studies estimate at around 7 percent the loss in economic productivity of the land due to degradation in agricultural areas.
Extreme events, such as severe droughts, worsen this situation. Not adapted land use combined with increased drought recurrence resulting from climate change can affect the resilience of ecosystems tipping them into a less productive state. Land degradation is possible aggravating poverty in vulnerable areas. Hence, adapted land management is essential in combating those adverse conditions. To identify priorities and to monitor the consequences of actions, further knowledge on the trend of degradation processes and their spatial inventory can certainly contribute to this process.
Within Latin America substantial progress has been reached on the definition and implementation of land degradation indicators, building on the early work of IADIZA/CONICET on integrated assessment in Argentina dating back to 1989. Data and information is casually available for quite some indicators, hence the desertification related activities under the EUROCLIMA programme aim at inventorying these data sets and compiling adapted products to be freely accessible through a dedicated web site.
Furthermore, the project develops and produces relevant and spatial continuous baseline information layers for addressing land degradation issues based on innovative satellite remote sensing approaches. Using satellite based time-series imagery, vegetation phenology and productivity metrics for the whole continent are compiled. The monitoring of change in land surface phenology and productivity is an important and widely used approach to quantify degradation of ecosystems due to climatic or human influences.
Land use transitions as well as long term trends of the dynamics of e.g. agricultural and rangeland ecosystems can be understood by combining satellite based phenology and productivity variables. Within the EUROCLIMA programme such variables have been calculated from the NOAA satellite vegetation index time series extending from 1982 until now. The dynamics of the ecosystems is reflected by a change index: the steadiness index which addresses both the long-term trend and the net change of e.g. primary production as calculated from satellite time series.
Map “A” presents examples for the Latin American continent of the assessed dynamics of the ecosystem respective to its total net production capacity (NPP) in which the brown coloured areas suggest regions where the 1982-2010 dynamics have resulted in an observable loss of total productivity.
Map “B” illustrates the dynamics specific to only the permanent fraction of the observable vegetation, i.e. the part of the vegetative cover that remains on the soil from year to year; while the map “C” illustrates the long term trends of the yearly dynamic production. Combination of these variables can be indicative for land use changes that are crucial to land degradation: e.g. in central Argentina a decrease of permanent fraction and increase of annual dynamism can be related to change of semi-natural vegetation into agricultural land use. A long term negative dynamics in both permanent and cyclic vegetation fractions can indicate an overall loss of productive capacity of a system, as can be observed over some part of NE Brazil.
The EUROCLIMA programme is now in the phase of improving the calculation of these variables and developing more understanding in their combined meaning. Other ancillary data layers as compiled and collected by the EUROCLIMA partners are needed to accomplish the complex endeavour of understanding land degradation trends in the region required to outline adapted strategies.