TY - JOUR
T1 - Plant competition and facilitation after extreme drought episodes in Mediterranean shrubland: Does damage to vegetation cover trigger replacement by juniper woodland?
AU - Lloret, Francisco
AU - Granzow-de la Cerda, Iñigo
PY - 2013/11/1
Y1 - 2013/11/1
N2 - Question: We analyse the contribution of plant-plant interactions, particularly the outcome of plant competition and plant facilitation, on vegetation dynamics as a result of extreme drought episodes. These events will likely become more frequent under climate change, can induce vegetation die-off and alter community dynamics. We study succession in a shrubland that tends to be replaced by juniper (Juniperus phoenicea) woodland. Due to drought, shrubland die-off may result in competition release favouring J. phoenicea juveniles, and accelerating shrubland replacement. Alternatively, deleterious abiotic stress may increase after loss of vegetation cover protection. Location: Mediterranean coastal shrublands, South Spain (Doñana National Park). Methods: Field estimates of plant growth, production of needle-like leaves, water-use efficiency (WUE; leaf δ13C) and N leaf content of J. phoenicea juveniles in relation to plant size, drought-induced damage, cover and habit characteristics of surrounding vegetation, and drought-induced defoliation of the surrounding vegetation. Results: Juniperus phoenicea juveniles growing beneath a dense vegetation canopy, particularly trees and large shrubs, were less damaged during the extreme drought episode. Plant size correlated negatively with damage. Post-drought growth was higher in juveniles partially released from the vegetation canopy, supporting the existence of a balance between competition and facilitation. Cover of pines, large shrubs and spiny shrubs favoured growth of juveniles. Needle-like juvenile leaves were more abundant in plants covered by the surrounding vegetation or in moderately damaged plants, but less abundant in plants without damage. Higher leaf δ13C values - indicating water stress - were measured in plants more damaged by drought and in those without canopy protection, or under vegetation strongly affected by drought. Leaf N content was lower in undamaged plants and individuals covered by surrounding vegetation. Conclusion: We did not find evidence that gaps opened by drought promoted growth of the potential replacing J. phoenicea. Thus, drought-induced enhancement of successional replacement of shrublands with woodlands was not supported; instead, our findings foresee shrubland prevalence under future climate change conditions. Plant facilitation will play a relevant role in this process. Thus, we herein extend the relevance of plant-plant interactions to extreme drought episodes related to climate change, highlighting their role as drivers of community dynamics. © 2012 International Association for Vegetation Science.
AB - Question: We analyse the contribution of plant-plant interactions, particularly the outcome of plant competition and plant facilitation, on vegetation dynamics as a result of extreme drought episodes. These events will likely become more frequent under climate change, can induce vegetation die-off and alter community dynamics. We study succession in a shrubland that tends to be replaced by juniper (Juniperus phoenicea) woodland. Due to drought, shrubland die-off may result in competition release favouring J. phoenicea juveniles, and accelerating shrubland replacement. Alternatively, deleterious abiotic stress may increase after loss of vegetation cover protection. Location: Mediterranean coastal shrublands, South Spain (Doñana National Park). Methods: Field estimates of plant growth, production of needle-like leaves, water-use efficiency (WUE; leaf δ13C) and N leaf content of J. phoenicea juveniles in relation to plant size, drought-induced damage, cover and habit characteristics of surrounding vegetation, and drought-induced defoliation of the surrounding vegetation. Results: Juniperus phoenicea juveniles growing beneath a dense vegetation canopy, particularly trees and large shrubs, were less damaged during the extreme drought episode. Plant size correlated negatively with damage. Post-drought growth was higher in juveniles partially released from the vegetation canopy, supporting the existence of a balance between competition and facilitation. Cover of pines, large shrubs and spiny shrubs favoured growth of juveniles. Needle-like juvenile leaves were more abundant in plants covered by the surrounding vegetation or in moderately damaged plants, but less abundant in plants without damage. Higher leaf δ13C values - indicating water stress - were measured in plants more damaged by drought and in those without canopy protection, or under vegetation strongly affected by drought. Leaf N content was lower in undamaged plants and individuals covered by surrounding vegetation. Conclusion: We did not find evidence that gaps opened by drought promoted growth of the potential replacing J. phoenicea. Thus, drought-induced enhancement of successional replacement of shrublands with woodlands was not supported; instead, our findings foresee shrubland prevalence under future climate change conditions. Plant facilitation will play a relevant role in this process. Thus, we herein extend the relevance of plant-plant interactions to extreme drought episodes related to climate change, highlighting their role as drivers of community dynamics. © 2012 International Association for Vegetation Science.
KW - Climate change
KW - Competition
KW - Extreme climate episodes
KW - Juniperus phoenicea
KW - Mediterranean-type ecosystems
KW - Succession
KW - Vegetation dynamics
U2 - https://doi.org/10.1111/jvs.12030
DO - https://doi.org/10.1111/jvs.12030
M3 - Article
VL - 24
SP - 1020
EP - 1032
JO - Journal of Vegetation Science
JF - Journal of Vegetation Science
SN - 1100-9233
ER -