Facilitation of Conspecific Seedling Recruitment and Shifts in Temperate Savanna Ecotones

McPherson, Guy R.

doi:10.2307/2657229

Cited by 37 publications

(53 citation statements)

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“…For example, nurse plants are important to the establishment of some aridland perennials. This requirement could result in spatiotemporal dynamics of cyclic succession (Wiegand et al 1995;Weltzin and McPherson 1999), fostering coexistence through successional mosaics (Chesson and Huntly 1997) in which facilitation by nurse plants has an important role. Unfortunately, few studies of perennials in arid environments go beyond germination and early survival to allow robust evaluation of this mechanism.…”

Section: Regeneration and Pulse Usementioning

confidence: 99%

Resource pulses, species interactions, and diversity maintenance in arid and semi-arid environments

et al. 2004

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Arid environments are characterized by limited and variable rainfall that supplies resources in pulses. Resource pulsing is a special form of environmental variation, and the general theory of coexistence in variable environments suggests specific mechanisms by which rainfall variability might contribute to the maintenance of high species diversity in arid ecosystems. In this review, we discuss physiological, morphological, and life-history traits that facilitate plant survival and growth in strongly water-limited variable environments, outlining how species differences in these traits may promote diversity. Our analysis emphasizes that the variability of pulsed environments does not reduce the importance of species interactions in structuring communities, but instead provides axes of ecological differentiation between species that facilitate their coexistence. Pulses of rainfall also influence higher trophic levels and entire food webs. Better understanding of how rainfall affects the diversity, species composition, and dynamics of arid environments can contribute to solving environmental problems stemming from land use and global climate change.

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Section: Regeneration and Pulse Usementioning

confidence: 99%

Resource pulses, species interactions, and diversity maintenance in arid and semi-arid environments

et al. 2004

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“…Although potentially competitors of establishing seedlings, woody plants can facilitate recruitment beneath their crowns by ameliorating abiotic and biotic stresses (Jordan and Nobel 1981;Fuentes et al 1984;Franco and Nobel 1988;Hunter and Aarssen 1988;Valiente-Banuet and Ezcurra 1991;Bertness and Callaway 1994;Berkowitz et al 1995;Callaway 1995;Callaway and Walker 1997;Holmgren et al 1997;Callaway and Pugnaire 1998;Weltzin and McPherson 1999;Rousset and Lepart 2000). Facilitation may be due to a variety of influences, such as reduced evapotranspiration and temperature (Callaway 1995), improved soil conditions and moisture retention (Joffre and Rambal 1988), increased nutrient availability (Jackson and Caldwell 1993;Stark 1994), and physical protection from herbivory, especially from larger mammals (Jaksič and Fuentes 1980;Bullock 1991).…”

Section: Introductionmentioning

confidence: 98%

Positive and negative interactions between environmental conditions affecting Cercocarpus ledifolius seedling survival

Ibáñez

Schupp

2001

Oecologia

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We evaluated the balance between positive and negative effects of environmental conditions on first-year seedling survival of the tree Cercocarpus ledifolius during two summers, 1996 and 1997. The experimental design was fully crossed with two levels of water, with and without supplementation, two levels of herbivory, with and without protection, and three major microhabitats, open interspaces, under the canopy of Artemisia tridentata shrubs, and under the canopy of mature C. ledifolius trees. Effects of drought and herbivory on seedling survival depended on the year. Water supplementation and herbivory protection during the dry summer of 1996 (27.7 mm) generally increased seedling survival. Additionally, survival tended to be greatest beneath C. ledifolius canopies. More important ecologically were the significant interactions. In 1996, water supplementation increased survival more with than without herbivory protection. The three-way interaction, treatment-microhabitat combination, was most important; by far the greatest survival was in the water supplementation and herbivory protection in the tree microhabitat. During the wet summer of 1997 (158.5 mm), neither water supplementation, herbivory protection, nor microhabitat were significant as main effects. The water-supplemented and herbivory-protected treatment again combined to yield highest survival, but this time in open interspaces rather than beneath trees. Our study shows how the importance of individual limiting factors and the relative favorableness of particular microhabitats appear to change across years depending on environmental conditions.

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“…We expected climate to severely constrain sapling survival in abandoned fields, because the main limitation for successful establishment is survival to the first summer after emergence or transplant (Weltzin and McPherson 1999;Villar-Salvador and others 2004;Sá nchez-Gó mez and others 2006). Our results were not an exception, with mortality peaking after the first summer in all ecosystems.…”

Section: Discussionmentioning

confidence: 98%

“…This land-use change, woodland expansion into abandoned croplands and pastures, usually occurs spontaneously (Jessup and others 2003;Van Auken 2009). In contrast, in water-limited environments, woodland expansion can be severely constrained (Weltzin and McPherson 1999;Bonet 2004;Dickie and others 2007). This is the case in the Mediterranean region, where successful tree recruitment is primarily limited by water availability (Villar-Salvador and others 2004; Sá nchez-Gó mez and others 2006), a limitation that will be exacerbated under oncoming climatic conditions (Christensen and others 2007).…”

Section: Introductionmentioning

confidence: 89%

Previous Land Use Alters the Effect of Climate Change and Facilitation on Expanding Woodlands of Spanish Juniper

et al. 2012

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In Mediterranean-continental regions, changes in land use are leading to the expansion of valuable habitats like endemic Juniperus thurifera woodlands, but the impact of reduced rainfall, due to climate change, on this expansion remains uncertain. We assessed the early performance of J. thurifera in different global change scenarios with and without facilitation. Saplings were transplanted in three ecosystems types with different previous land use (woodlands, former agricultural fields, and former livestock pastures), microhabitats (open vs. understory of adult trees) and were subjected to two watering regimens. We characterized the abiotic environment and measured survival, growth and two ecophysiological parameters. Former livestock pastures were the least favorable ecosystem, where the nursing effect was greatest. Former agricultural fields had the highest survival, but were more sensitive than woodlands to water scarcity. Reduced rainfall decreased photochemical efficiency, particularly in the least favorable scenarios, but did not affect survival. Water use efficiency enhanced growth under the canopy, but not in the open, whereas photochemical efficiency enhanced growth and survival more in the open. Facilitation was critical for effective recruitment in the harshest scenarios: former livestock pastures and reduced rainfall. Comparison with previous studies suggests that establishment depends on infrequent wet episodes. In Mediterranean ecosystems, changes in land use and climate change are leading to woodland expansion due to the modulating effect of facilitation of the oncoming adverse drier conditions. Nevertheless, the positive effect of facilitation and the negative impact of aridity on tree recruitment are strongly influenced by previous land-use history.

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Facilitation of Conspecific Seedling Recruitment and Shifts in Temperate Savanna Ecotones

Cited by 37 publications

References 0 publications

Resource pulses, species interactions, and diversity maintenance in arid and semi-arid environments

Resource pulses, species interactions, and diversity maintenance in arid and semi-arid environments

Positive and negative interactions between environmental conditions affecting Cercocarpus ledifolius seedling survival

Previous Land Use Alters the Effect of Climate Change and Facilitation on Expanding Woodlands of Spanish Juniper

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