Disentangling the roles of climate, propagule pressure and land use on the current and potential elevational distribution of the invasive weed Oxalis pes-caprae L. on Crete

Louise C Ross, Philip W Lambdon, Philip E. Hulme

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Abstract

Climatic warming and land use change are likely to facilitate range expansions in invasive plant species, although the ability to predict such changes requires a better mechanistic understanding of the biological limits of populations. The introduced weed Oxalis pes-caprae, a significant pest of cultivation in many Mediterranean-type ecosystems, presents a suitable case study. The species distribution in the Mediterranean Basin closely follows that of olive cultivation, limited to below 600 m; yet its potential to colonise vulnerable areas at higher elevations has yet to be adequately assessed. To investigate the possibility, plant performance was assessed by experimentally sowing O. pes-caprae bulbils along an altitudinal gradient in the Lefka Ori mountains, Crete. The survivorship and bulbil biomass of the resulting plants all declined significantly with elevation, irrespective of soil type, initial bulbil size or seasonal variation. Whilst plants survived vegetatively up to 1400 m, seasonal bulbil productivity, likely to be critical to population viability, exceeded that of the sown bulbil biomass only below 750 m. These data indicate that the current elevation of O. pes-caprae is close to, but not at, its current climatic limit, and that low propagule pressure and scarcity of suitable habitat probably also act to limit the altitudinal distribution. Plant performance was correlated strongly with the duration of spring snow cover. Despite a 2 °C difference in mean spring temperatures in the 2 years of study, the predicted elevational change was only 37 m higher in the milder conditions. Overall, our results suggest that while O. pes-caprae performance is strongly linked to climate and is currently close to its climatic limit on Crete, there is limited scope for further spread unless land use and/or propagule pressure change at higher elevations. For this species, these elements are likely to be more significant drivers of invasion risk than the predicted changes of future climates.
Original languageEnglish
Pages (from-to)251-258
Number of pages8
JournalPerspectives in plant ecology, evolution and systematics
Volume10
Issue number4
Early online date15 Aug 2008
DOIs
Publication statusPublished - 20 Oct 2008

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Oxalis pes-caprae
Crete
propagule
Capra
weed
land use
weeds
climate
range expansion
snowpack
biomass
survivorship
sowing
snow cover
land use change
global warming
soil type
soil types
viability
biogeography

Cite this

@article{54a4a94e7a2e4535b9b39f34b346f02f,
title = "Disentangling the roles of climate, propagule pressure and land use on the current and potential elevational distribution of the invasive weed Oxalis pes-caprae L. on Crete",
abstract = "Climatic warming and land use change are likely to facilitate range expansions in invasive plant species, although the ability to predict such changes requires a better mechanistic understanding of the biological limits of populations. The introduced weed Oxalis pes-caprae, a significant pest of cultivation in many Mediterranean-type ecosystems, presents a suitable case study. The species distribution in the Mediterranean Basin closely follows that of olive cultivation, limited to below 600 m; yet its potential to colonise vulnerable areas at higher elevations has yet to be adequately assessed. To investigate the possibility, plant performance was assessed by experimentally sowing O. pes-caprae bulbils along an altitudinal gradient in the Lefka Ori mountains, Crete. The survivorship and bulbil biomass of the resulting plants all declined significantly with elevation, irrespective of soil type, initial bulbil size or seasonal variation. Whilst plants survived vegetatively up to 1400 m, seasonal bulbil productivity, likely to be critical to population viability, exceeded that of the sown bulbil biomass only below 750 m. These data indicate that the current elevation of O. pes-caprae is close to, but not at, its current climatic limit, and that low propagule pressure and scarcity of suitable habitat probably also act to limit the altitudinal distribution. Plant performance was correlated strongly with the duration of spring snow cover. Despite a 2 °C difference in mean spring temperatures in the 2 years of study, the predicted elevational change was only 37 m higher in the milder conditions. Overall, our results suggest that while O. pes-caprae performance is strongly linked to climate and is currently close to its climatic limit on Crete, there is limited scope for further spread unless land use and/or propagule pressure change at higher elevations. For this species, these elements are likely to be more significant drivers of invasion risk than the predicted changes of future climates.",
author = "Ross, {Louise C} and Lambdon, {Philip W} and Hulme, {Philip E.}",
note = "Thanks to Laura Hayton, Louise Newell, Marie Pandolfo, Linda Turner and Laura Flegg for assistance with the fieldwork and data entry. We are grateful to Carsten Dormann, Ruth Mitchell, Antoine Guisan and two anonymous referees for their helpful comments on the manuscript. This study is part of the European Commission Fifth Framework Project EPIDEMIE (Exotic Plant Invasions: Deleterious Effects on Mediterranean Island Ecosystems), Contract number EVK2-CT-2000-00074.",
year = "2008",
month = "10",
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doi = "10.1016/j.ppees.2008.06.001",
language = "English",
volume = "10",
pages = "251--258",
journal = "Perspectives in plant ecology, evolution and systematics",
issn = "1433-8319",
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TY - JOUR

T1 - Disentangling the roles of climate, propagule pressure and land use on the current and potential elevational distribution of the invasive weed Oxalis pes-caprae L. on Crete

AU - Ross, Louise C

AU - Lambdon, Philip W

AU - Hulme, Philip E.

N1 - Thanks to Laura Hayton, Louise Newell, Marie Pandolfo, Linda Turner and Laura Flegg for assistance with the fieldwork and data entry. We are grateful to Carsten Dormann, Ruth Mitchell, Antoine Guisan and two anonymous referees for their helpful comments on the manuscript. This study is part of the European Commission Fifth Framework Project EPIDEMIE (Exotic Plant Invasions: Deleterious Effects on Mediterranean Island Ecosystems), Contract number EVK2-CT-2000-00074.

PY - 2008/10/20

Y1 - 2008/10/20

N2 - Climatic warming and land use change are likely to facilitate range expansions in invasive plant species, although the ability to predict such changes requires a better mechanistic understanding of the biological limits of populations. The introduced weed Oxalis pes-caprae, a significant pest of cultivation in many Mediterranean-type ecosystems, presents a suitable case study. The species distribution in the Mediterranean Basin closely follows that of olive cultivation, limited to below 600 m; yet its potential to colonise vulnerable areas at higher elevations has yet to be adequately assessed. To investigate the possibility, plant performance was assessed by experimentally sowing O. pes-caprae bulbils along an altitudinal gradient in the Lefka Ori mountains, Crete. The survivorship and bulbil biomass of the resulting plants all declined significantly with elevation, irrespective of soil type, initial bulbil size or seasonal variation. Whilst plants survived vegetatively up to 1400 m, seasonal bulbil productivity, likely to be critical to population viability, exceeded that of the sown bulbil biomass only below 750 m. These data indicate that the current elevation of O. pes-caprae is close to, but not at, its current climatic limit, and that low propagule pressure and scarcity of suitable habitat probably also act to limit the altitudinal distribution. Plant performance was correlated strongly with the duration of spring snow cover. Despite a 2 °C difference in mean spring temperatures in the 2 years of study, the predicted elevational change was only 37 m higher in the milder conditions. Overall, our results suggest that while O. pes-caprae performance is strongly linked to climate and is currently close to its climatic limit on Crete, there is limited scope for further spread unless land use and/or propagule pressure change at higher elevations. For this species, these elements are likely to be more significant drivers of invasion risk than the predicted changes of future climates.

AB - Climatic warming and land use change are likely to facilitate range expansions in invasive plant species, although the ability to predict such changes requires a better mechanistic understanding of the biological limits of populations. The introduced weed Oxalis pes-caprae, a significant pest of cultivation in many Mediterranean-type ecosystems, presents a suitable case study. The species distribution in the Mediterranean Basin closely follows that of olive cultivation, limited to below 600 m; yet its potential to colonise vulnerable areas at higher elevations has yet to be adequately assessed. To investigate the possibility, plant performance was assessed by experimentally sowing O. pes-caprae bulbils along an altitudinal gradient in the Lefka Ori mountains, Crete. The survivorship and bulbil biomass of the resulting plants all declined significantly with elevation, irrespective of soil type, initial bulbil size or seasonal variation. Whilst plants survived vegetatively up to 1400 m, seasonal bulbil productivity, likely to be critical to population viability, exceeded that of the sown bulbil biomass only below 750 m. These data indicate that the current elevation of O. pes-caprae is close to, but not at, its current climatic limit, and that low propagule pressure and scarcity of suitable habitat probably also act to limit the altitudinal distribution. Plant performance was correlated strongly with the duration of spring snow cover. Despite a 2 °C difference in mean spring temperatures in the 2 years of study, the predicted elevational change was only 37 m higher in the milder conditions. Overall, our results suggest that while O. pes-caprae performance is strongly linked to climate and is currently close to its climatic limit on Crete, there is limited scope for further spread unless land use and/or propagule pressure change at higher elevations. For this species, these elements are likely to be more significant drivers of invasion risk than the predicted changes of future climates.

U2 - 10.1016/j.ppees.2008.06.001

DO - 10.1016/j.ppees.2008.06.001

M3 - Article

VL - 10

SP - 251

EP - 258

JO - Perspectives in plant ecology, evolution and systematics

JF - Perspectives in plant ecology, evolution and systematics

SN - 1433-8319

IS - 4

ER -