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Evaluating the extinction risk of a perennial herb: demographic data versus historical records
Stockholm University, Faculty of Science, Department of Botany.
Stockholm University, Faculty of Science, Department of Botany.
2002 (English)In: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, Vol. 16, no 3, 683-690 p.Article in journal (Refereed) Published
Abstract [en]

Demographic information is frequently used to project the long-term extinction risk of endangered species, but the limitations of this approach have not been extensively discussed. We examined demographic data for the endangered perennial herb Primula farinosa with matrix models to assess population growth rates and extinction risks. The data came from six populations in contrasting habitats followed over a 4-year period. The results of these demographic models were compared to the results of experimental manipulations and to the actual change in occurrence of P. farinosa over a 70-year period in different habitat types. According to demographic models, all managed populations had a projected negative population growth rate and experienced a high extinction risk in 100 years, whereas unmanaged populations had increasing population sizes. In contrast, experiments and historical records suggested that continuous grazing is positively correlated with population persistence. Our results thus show that demographic studies done during a transient phase of population growth after management cessation may not capture the long-term changes. In such cases, projections of population growth rates may give misleading guidance for conservation. Short-term demographic studies are in many cases unlikely to correctly assess the survival probability of a species. We therefore argue that complementary information, such as long-term historical data or experimental manipulations of the environment, should be used whenever possible.

Place, publisher, year, edition, pages
2002. Vol. 16, no 3, 683-690 p.
Keyword [en]
primroses, endangered plants, plant populations, extinction (biology)
URN: urn:nbn:se:su:diva-22645DOI: 10.1046/j.1523-1739.2002.00509.xOAI: diva2:189210
Part of urn:nbn:se:su:diva-102Available from: 2004-04-15 Created: 2004-04-15 Last updated: 2010-07-27Bibliographically approved
In thesis
1. Land Use Change in Space and Time: implications for plant species conservation in semi-natural grasslands
Open this publication in new window or tab >>Land Use Change in Space and Time: implications for plant species conservation in semi-natural grasslands
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Land use change has during the last century altered the traditional rural landscape in Sweden, resulting in a major decline in species diversity. Traditional small-scale farming, with a remarkably high small-scale species richness, has changed in favour of rationalized agriculture, and many semi-natural grasslands, i.e. traditionally managed pastures and meadows, have become abandoned. In this thesis I examine how spatio-temporal processes affect plant species in Swedish semi-natural grasslands exposed to habitat degradation as well as recovery (restoration). I also discuss how to conserve plant species associated with semi-natural grasslands.

In general, species responded slowly to habitat degradation, but quickly to improvement of habitat quality. Population viability analysis (PVA) of the grazing favoured herb Primula farinosa suggested, in contrast to historical records, that populations in abandoned grasslands performed better than populations in traditionally managed grasslands, a result questioning the accuracy of PVAs. Restoration of grasslands counteracted species richness decline and the number of species increased within seven years after restoration. It was possible to recruit grassland species in grazed former arable fields by artificial seed-sowing. This may help to speed up the natural recruitment, which often is low due to dispersal limitations in modern fragmented landscapes.

Studies at larger regional scales showed century long time-lags in the response of plant species richness to land use change. Species richness was not related to present-day connectivity of grasslands, but positive effects appeared for grassland configuration in 1950s and 1900s. Thus, making conservation guidelines based solely on present-day data may be strongly misleading and under-estimate the actual risk of species loss. To secure long-term survival of species, it is important to focus on processes associated with larger spatial scales. This may benefit natural dynamics at longer time-scales, where abandoned and restored grasslands, together with species-rich semi-natural grasslands, could become natural parts of sustainable landscape management.

Place, publisher, year, edition, pages
Stockholm: Botaniska institutionen, 2004. 120 p.
diversity, management, restoration, landscape, history, Population viability analysis, seed-sowing, Primula farinosa, Campanula rotundifolia, grazing, fragmentation, extinction risk
National Category
Biological Sciences
urn:nbn:se:su:diva-102 (URN)91-7265-825-8 (ISBN)
Public defence
2004-05-07, föreläsningssalen, Botanicum, Lilla Frescativägen 5, Stockholm, 10:00
Available from: 2004-04-15 Created: 2004-04-15Bibliographically approved

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Lindborg, ReginaEhrlén, Johan
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