Structure and conservation value of high-diversity hedgerows in southeastern Brazil

Abstract

We studied the tree component of hedgerows resulting from the natural colonization of land plot boundaries’ ditches. These three-meter wide ditches were dug during the European occupation of southeastern Brazil, and are a prominent feature of the landscape. The hedgerows are connected to forest fragments within a farmland matrix. In two systems of hedgerows, we sampled a total of 2.28 ha (114 plots of 200 m²), where we evaluated the structural and floristic similarity between fragments and hedgerows, the similarities between the hedgerows and the fragments’ edges and interior, and the relationships between distribution of tree species and soil variables. The systems presented similar richness and diversity; hedgerows had greater similarity to the fragments included in the same system than to hedgerows of the other system, indicating possible functional linkages between their components (fragments and hedgerows). Tree species composition in the hedgerows was not more similar to the fragment edges as we expected. The hedgerows exhibited greater density and basal area than the fragments. For either single system, species showed preferences for fragments or hedgerows or for sections of the ditch (edge, wall and bottom of the ditch), but for species common in both systems, those preferences were rarely held. The environmental conditions in the ditches seem to favor the establishment of species from the fragments, even those more common in fragment interior, suggesting that, in spite of their narrow widths, these hedgerows may play an important role in the conservation of flora without negatively impacting agriculturally productive rural areas.