The seed bank of subtropical grasslands with contrasting land-use history in southern Brazil

Mariana De Souza Vieira,Ilsi Iob Boldrini,Camila Leal Bonilha,Gerhard Ernst Overbeck

doi:10.1590/0102-33062015abb0026

Mariana De Souza Vieira, Ilsi Iob Boldrini + Show 2 more

Open Access

https://doi.org/10.1590/0102-33062015abb0026

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Abstract

The expansion of land use for agriculture is among the main reasons for the reduction of natural grasslands around the world, and little is known about the recovery potential of original native grassland vegetation from seed banks. The aim of this study was to assess the seed bank potential of grassland areas with or without history of cultivation in southern Brazil. Specifically, we aimed at evaluating if agricultural use allowed for the persistence of species typical of natural grasslands in soil seed banks. We analyzed seed banks in two areas with a history of cultivation and in two natural grasslands. Samples were collected in spring and autumn in order to assess transient and persistent components, and were characterized by density, richness, presence of exotic species and relationship between seed bank and established vegetation. Both richness and density were high; we found a total of 114 species and a mean density of 61,796 seedlings/m2 for all four areas in the spring sampling. In the natural grasslands, the dominant species of established vegetation were mostly absent from the soil seed bank. Our study indicates that the seed bank is of little relevance for the recovery of typical grassland vegetation after disturbance.

Highlights

With rising impacts of land use changes on biodiversity, understanding recovery processes of vegetation after severe disturbance has become increasingly important
Land use affects a wide range of ecosystem services and functions (White et al 2000; Bullock et al 2011), many of which are closely related to biodiversity (Millennium Ecosystem Assessment 2005; Perrings et al 2010)
The soil seed bank represents the main regenerative potential of vegetation in areas that have suffered severe disturbance, and at the same time can be considered the memory of past environmental conditions and vegetation established previously (Bakker et al 1996; Thompson 2000)

Summary

Introduction

With rising impacts of land use changes on biodiversity, understanding recovery processes of vegetation after severe disturbance has become increasingly important. Land use changes have been considered to be the most important factor affecting biodiversity in this century, and grassland ecosystems are among the most impacted by land conversion (Sala et al 2000). A better understanding of the regeneration potential of natural vegetation after intensive land use becomes important as a basis for conservation or restoration policy and for a better integration of these with agricultural policy (Mattison & Norris 2005). The soil seed bank represents the main regenerative potential of vegetation in areas that have suffered severe disturbance, and at the same time can be considered the memory of past environmental conditions and vegetation established previously (Bakker et al 1996; Thompson 2000). Seed bank data may help to evaluate whether restoration of degraded ecosystems requires the addition of seeds of target species with low seed numbers (e.g. Kiehl et al 2010)

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