Landscape Ecology

, Volume 31, Issue 9, pp 2133–2150 | Cite as

Landscape history, time lags and drivers of change: urban natural grassland remnants in Potchefstroom, South Africa

  • Marié J. du Toit
  • D. Johan Kotze
  • Sarel S. Cilliers
Research Article

Abstract

Context

The history of the landscape directly affects biotic assemblages, resulting in time lags in species response to disturbances. In highly fragmented environments, this phenomenon often causes extinction debts. However, few studies have been carried out in urban settings.

Objectives

To determine if there are time lags in the response of temperate natural grasslands to urbanization. Does it differ for indigenous species and for species indicative of disturbance and between woody and open grasslands? Do these time lags change over time? What are the potential landscape factors driving these changes? What are the corresponding vegetation changes?

Methods

In 1995 and 2012 vegetation sampling was carried out in 43 urban grassland sites. We calculated six urbanization and landscape measures in a 500 m buffer area surrounding each site for 1938, 1961, 1970, 1994, 1999, 2006, and 2010. We used generalized linear models and model selection to determine which time period best predicted the contemporary species richness patterns.

Results

Woody grasslands showed time lags of 20–40 years. Contemporary open grassland communities were, generally, associated with more contemporary landscapes. Altitude and road network density of natural areas were the most frequent predictors of species richness. The importance of the predictors changed between the different models. Species richness, specifically, indigenous herbaceous species, declined from 1995 to 2012.

Conclusions

The history of urbanization affects contemporary urban vegetation assemblages. This indicates potential extinction debts, which have important consequences for biodiversity conservation planning and sustainable future scenarios.

Keywords

Urban ecology Urban landscape measures Temperate grasslands Indigenous species Exotic species Disturbance indicator species Extinction debt 

Notes

Acknowledgments

We would like to thank the South African Weather Service for long-term climate data of Potchefstroom and the National Research Foundation (NRF) for financial assistance towards the studies of MJDT and incentive funding for SSC.

Supplementary material

10980_2016_386_MOESM1_ESM.docx (1.8 mb)
Supplementary material 1 (DOCX 1892 kb)
10980_2016_386_MOESM2_ESM.docx (50 kb)
Supplementary material 2 (DOCX 49 kb)

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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • Marié J. du Toit
    • 1
  • D. Johan Kotze
    • 2
  • Sarel S. Cilliers
    • 1
  1. 1.Unit of Environmental Sciences and ManagementNorth-West UniversityPotchefstroomSouth Africa
  2. 2.Department of Environmental SciencesUniversity of HelsinkiLahtiFinland

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