Causes of vegetation synanthropisation in Central Spain

Abstract

Context Human action has a direct impact on vegetation. Numerous studies use different indicators to evaluate this human influence in different regions. However, there are fewer studies that analyse in detail anthropisation causes, and the degree of protection that is being given to the best-preserved patches of vegetation.

Objectives This study firstly determines human alteration of vegetation through a synanthropisation index. Then, it responds to two questions: What contribution do different human activities have on vegetation synanthropisation? Do protected areas adequately preserve vegetation with reduced synanthropisation?

Methods The study area included six provinces of Central Spain. A global synanthropisation index (ISG) including flora and vegetation, and six anthropisation indicators (population, agriculture, forestry, livestock, mining and reservoirs) were established, conducting a statistical treatment. Areas with the lowest ISG were overlaid with protected areas to determine their degree of inclusion. The proposed methodology can be applied in other geographical regions, and is integrative, allowing the incorporation of other similar indices and indicators.

Results Average ISG value was 0.673; 58% of the area had high synanthropisation, 26% medium and 16% low. Multiple regression of ISG with anthropisation indicators was extremely significant. Agriculture would explain 63.7% of synathropisation, population 11.2%, forestry 8.8%, livestock 7.6%, dams 4.6% and mining 4.4%. Environmental protected areas included only 46.7% of vegetation plots with reduced synathropisation.

Conclusions The main cause of vegetation synanthropisation was agriculture. Vegetation with low synathropisation should be preserved, but almost half of the detected plots were outside protected areas. The synanthropisation of vegetation should be considered in decision-making on territorial planning and environmental assessment.