The restoration status of recovering degraded forests can be assessed by comparing their ecosystem characteristics with those of a reference system, most often what is considered the natural climax vegetation. However, comprehensive measurements needed for traditional vegetation description are often hard or impractical in complex ecosystems. Therefore, an alternative approach is the identification of simple indicators of ecosystem integrity. The use of such indicators can speed up availability of resource inventories and thus contribute to the accelerated implementation of successful rehabilitation practices. Thermal buffer capacity (TBC) of ecosystems has previously been proposed as an overall indicator of ecosystem integrity. In this paper, sequential surface temperature measurements are proposed as a method for TBC assessment of different land use types.
Surface temperatures of 7 land units in Central Tigray (Northern Ethiopia), each with uniform land use type (degraded and bushy grazing land, enriched (planted) and non-enriched restoration area and forest), were measured with a hand-held infrared-thermometer in the rainy and the dry season. Surface temperature models were derived by means of quadratic regression. Cross-correlation functions were calculated for all possible pairs of land unit time series data to compare protected and grazed lands. Instantaneous heat-up rates, average thermal buffer capacity and accumulated heat load were calculated.
Time lags between land unit surface temperatures are caused by differences in aspect rather than land use type. Protection status and aspect have a significant effect on the average thermal buffer capacity. Results clearly demonstrate a differentiation between protected (low heat-up rate) and grazed areas (high heat-up rate). Overall ranking suggests that the remnant forest has the highest TBC of all surveyed land use types, followed by the enriched protected area.
Results of this study show that thermal buffer capacity quickly responds to protection and can therefore be used to monitor the development of protected areas. It is strongly recommended that a detailed monitoring strategy for protected areas, based on this technology, be devised, validated and finally transferred to the local communities.