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Joel Flores - One of the best experts on this subject based on the ideXlab platform.
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Effects of Nurse Plants and the granivore guild in the associational susceptibility of seeds from the columnar cactus Pilosocereus leucocephalus
Journal of Arid Environments, 2017Co-Authors: Antonio Miranda-jácome, Joel FloresAbstract:The Nurse-protege interaction involves benefits for the protected species by the reduction in the abiotic stress intensity. Nurse Plants, however, could affect other biotic interactions by reducing that natural benefit. Studies about plant-plant-animal interaction assume that Plants can recover from and/or avoid granivory when they grow under higher resources availability; nevertheless, in early stages they could be subject to different pressures. Thus, the resistance or susceptibility to granivores could occur because of differential responses of the Plants (Nurse and protected) to the environment (abiotic factors) or as results of differential responses of the Plants to granivores (biotic factors), altering the probability of the resistance or susceptibility of Plants to herbivores. We evaluated diurnal and nocturnal granivore activity on P. leucocephalus seeds, and we also evaluated if a Nurse species could determine the association type (i.e. associational resistance or susceptibility) from the intensity of the granivore in early stage (e.g. seeds) of the P. leucocephalus life cycle. We found higher granivory under Nurse Plants than in open spaces (the control group), indicating associational susceptibility. Furthermore, most of the granivory was performed by nocturnal animals (mice). These results suggest a cost/benefit of the Nurse-protege interaction, which can be modulated by the granivory.
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growth and ecophysiology of succulent seedlings under the protection of Nurse Plants in the southern chihuahuan desert
Ecosphere, 2015Co-Authors: Reyes Perezsanchez, Joel Flores, Enrique Jurado, Claudia GonzalezsalvatierraAbstract:In arid zones, light and water are two important factors that limit seedling development. The shade provided by Nurse Plants can reduce overheating, excessive transpiration, and photoinhibition in protege seedlings. The difference that a Nurse plant microenvironment may provide on the physiological performance of succulent desert seedlings could be tested by measuring plant growth and photosynthesis. Specifically, in this study we measured the variables related to chlorophyll fluorescence: Quantum yield of photosystem II photochemistry (ΦPSII) and electron transport rate (ETR), as well as relative growth rate (RGR) and its components (net assimilation rate, NAR, and leaf area rate, LAR), root to shoot (R/S) ratio, and relative water content (RWC) for seedlings transplanted under Nurse Plants and seedlings transplanted under direct sunlight. We tested whether ΦPSII, ETR, LAR, R/S ratio, and RWC, were lower, and RGR and NAR were higher for seedlings of seven succulent species common to the Southern Chihuahu...
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Effect of seed burial in different soils on the germination of three specially protected cactus species
Southwestern Naturalist, 2014Co-Authors: Gisela Muro-pérez, Joel Flores, Enrique Jurado, Jaime Sánchez-salasAbstract:Abstract Seedling establishment of many cactus species appears to be more frequent under canopies of Nurse Plants, which provide a less stressful microenvironment. Under these Nurse Plants, nutrient levels in the soil could be higher than in surrounding areas; these higher nutrient levels could promote higher seed germination. Seed burial under Nurse Plants may occur by seeds falling in the litter or in soil cracks; however, buried seeds are in the dark, which has been shown to inhibit seed germination for some cactus species. We measured germination percentage on nutrient-rich soil from under Nurse mesquites and in soil from open spaces, and the effect of seed burial (buried and unburied seeds) on seed germination of three cactus species (Coryphantha durangensis, Peniocereus greggii, and Echinocereus longisetus) that grow under Nurse Plants in the Chihuahuan Desert. Echinocereus longisetus had very low germination across substrates. Coryphantha durangensis had higher germination on mesquite soil than on ...
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are Nurse Plants always necessary for succulent Plants observations in northeastern mexico including endangered and threatened species
Bradleya, 2013Co-Authors: Enrique Jurado, Joel Flores, Gisela Muro Perez, Humberto Gonzalez Rodriguez, Marisela Pando Moreno, Omar DoriaAbstract:In harsh environments some plant species grow under the shelter of other Plants. This spatial association known as Nurse-protege interaction is common in arid and semiarid environments. In here we studied the spatial association of six cacti (Ariocarpus retusus, Astrophytum asterias, Echinocactus texensis, Cylindropuntia leptocaulis, Sclerocactus scheeri and Mammillaria heyderi) and one Asparagaceae (Manfreda longiflora) to other plant species. We determined whether they occurred more often under other Plants, if they grew very near them or at an angle that provided shade. Manfreda longiflora always grew under the canopy of other Plants. Ariocarpus retusus, Astrophytum asterias, Cylindropuntia leptocaulis, and Mammillaria heyderi occurred equally under Nurse Plants and in open spaces. Echinocactus texensis and Sclerocactus scheeri occurred more often than expected in open areas, but Sclerocactus scheeri occurred shaded from the afternoon sun. We argue that Nurse-protege interactions are less common in our study site due to higher rainfall than that in other studied environments.
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emulating Nurse Plants to restore oak forests
Ecological Engineering, 2011Co-Authors: Ernesto I Badano, Omar R Samournieva, Joel FloresAbstract:Several forested areas of Mexico are dominated by oaks (Quercus spp.), but these forests have suffered strong changes in land use throughout the last century and need to be restored. Most of these areas, however, are within seasonally dry ecosystems and heavy losses of oak seedlings occur in the dry season. Nurse Plants that ameliorate extreme environmental conditions have been proved to enhance the success of reforestation practices in these ecosystems. Nevertheless, at several sites in Mexico the density of putative Nurse Plants is too low to consider this practice as a viable restoration strategy. This study explores the possibility of emulating the effects of Nurse Plants by means of artificial-shade structures. The study areas were located at the ecological park Flor del Bosque (State of Puebla, Mexico). At the beginning of the rainy season, seedlings of Quercus castanea and Quercus laurina were transplanted beneath and outside artificial-shade structures at two deforested areas of the park. We monitored seedling mortality during 22 weeks, until the middle of dry season; each week we recorded if individual seedlings were killed by abiotic stress or predation. We also measured chlorophyll fluorescence on seedlings to assess whether the shade structures improve their physiological performance. Comparisons of mortality rates indicated that, at both experimental sites, oak seedlings were less affected by drought and predation beneath the shade structures than outside them. Indeed, seedlings beneath these structures showed higher physiological performances. This suggests that artificial-shade structures can emulate the effects of Nurse Plants at deforested sites, and that this strategy could help to improve the recovery of oak forests.
Jose A Hodar - One of the best experts on this subject based on the ideXlab platform.
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facilitation of tree saplings by Nurse Plants microhabitat amelioration or protection against herbivores
Journal of Vegetation Science, 2008Co-Authors: Lorena Gomezaparicio, Jorge Castro, Regino Zamora, Jose A HodarAbstract:Abstract Question: Positive interactions are predicted to be common in communities developing under high physical stress or high herbivory pressure due to neighbour amelioration of limiting physical and consumer stresses, respectively. However, when both stress sources meet in the same community, the relative importance of the two facilitation mechanisms is poorly understood. We ask: What is the relative importance of abiotic vs. biotic mechanisms of facilitation of tree saplings by shrubs in Mediterranean mountain forests? Location: Sierra Nevada, SE Spain (1800–1850 m a.s.l.) Methods: Saplings of four tree taxa (Acer opalus ssp. granatense, Quercus ilex, Pinus nigra ssp. salzmanii and P. sylvestris var. nevadensis) were planted following a 2 × 2 factorial design: two levels of herbivory (control and ungulate exclusion) and two microhabitats (under shrubs and in open areas). Sapling survival and growth were monitored for five years. Results: Shrubs had positive effects on sapling survival both in control...
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restoring quercus pyrenaica forests using pioneer shrubs as Nurse Plants
Applied Vegetation Science, 2006Co-Authors: Jorge Castro, Regino Zamora, Jose A HodarAbstract:Abstract Question: How to improve reforestation success of Quercus pyrenaica. Location: 1800 m a.s.l., southern Spain. Methods: One-year-old Quercus pyrenaica seedlings were planted using two treatments: (1) bare soil, using a 30-cm diameter augur bit (conventional technique) and (2) under the canopy of a pioneer shrub, Salvia lavandulifolia, using a 12-cm diameter augur bit. Survival and growth were monitored for six years. Our hypothesis is that the use of shrubs as Nurse Plants is an alternative technique of reforestation with higher success than traditional techniques, in which pre-existing vegetation is usually considered a source of competition. The rationale for the study was that for environments with a dry season, pre-existing vegetation buffers summer drought stress, ameliorates the water status of seedlings and thus usually increases seedling recruitment. Results: Quercus survival was 6.3 × higher when planted under individuals of the pioneer shrub as compared to open areas. Quercus seedlings u...
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benefits of using shrubs as Nurse Plants for reforestation in mediterranean mountains a 4 year study
Restoration Ecology, 2004Co-Authors: Jorge Castro, Regino Zamora, Jose A Hodar, Jose M Gomez, Lorena GomezaparicioAbstract:Shrubs are commonly considered competitors of planted seedlings in reforestation programs. However, shrubs can facilitate the establishment of understory seedlings in environments that, like Mediterranean-type ecosystems, are characterized by harsh environmental conditions. In 1997, an experiment was set up in the Sierra Nevada mountains (southeast Spain) to test the use of shrubs as Nurse Plants for an alternative reforestation technique. Two-year-old seedlings of Pinus sylvestris and Pinus nigra were planted in four microhabitats: (1) open interspaces without vegetation (which is the usual method employed in reforestation programs), (2) under individuals of the shrub Salvia lavandulifolia, (3) under the north side of spiny shrubs, and (4) under the south side of spiny shrubs. Seedlings were also distributed in plots with and without ungulates to test the effect of herbivore damage. We report here the results of survival and growth after four growing seasons, a time span long enough to draw robust conclusions concerning the suitability of this technique. Pine survival was remarkably higher when planted under individuals of S. lavandulifolia as compared with open areas (2.6 times for P. sylvestris and 1.8 for P. nigra). The survival of both pine species was also higher when planted on the north side of spiny shrubs, while mortality on the south side was similar to that found in open areas. The reduction of solar radiation by the canopy of shrubs was likely the main factor determining shrub facilitation. The growth of the pines differed among years. However, growth was not inhibited when planted with shrubs as compared with open areas in any of the years. Herbivore damage was low but was mostly concentrated in the leader shoot, exacerbating the deleterious effect of ungulate herbivores on pine growth. We conclude that the use of shrubs as Nurse Plants for reforestation is a viable technique to increase establishment success of reforestation in Mediterranean-type ecosystems and that it might be similarly useful in other water-stressed environments. In addition, this technique offers the advantage of following natural succession, thus minimizing the impact in the community.
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applying plant facilitation to forest restoration a meta analysis of the use of shrubs as Nurse Plants
Ecological Applications, 2004Co-Authors: Lorena Gomezaparicio, Jorge Castro, Regino Zamora, Jose A Hodar, Jose M Gomez, Elena BarazaAbstract:After a millenarian history of overexploitation, most forests in the Medi- terranean Basin have disappeared, leaving many degraded landscapes that have been re- colonized by early successional shrub-dominated communities. Common reforestation tech- niques treat these shrubs as competitors against newly planted tree seedlings; thus shrubs are cleared before tree plantation. However, empirical studies and theory governing plant- plant interactions suggest that, in stress-prone Mediterranean environments, shrubs can have a net positive effect on recruitment of other species. Between 1997 and 2001, we carried out experimental reforestations in the Sierra Nevada Protected Area (southeast Spain) with the aim of comparing the survival and growth of seedlings planted in open areas (the current reforestation technique) with seedlings planted under the canopy of preexisting shrub species. Over 18 000 seedlings of 11 woody species were planted under 16 different Nurse shrubs throughout a broad geographical area. We sought to explore variation in the sign and magnitude of interactions along spatial gradients defined by altitude and aspect. In the present work, we report the results of a meta-analysis conducted with seedling survival and growth data for the first summer following planting, the most critical period for reforestation success in Mediterranean areas. The facilitative effect was consistent in all environmental situations explored (grand mean effect size d 1 5 0.89 for survival and 0.27 for growth). However, there were differences in the magnitude of the interaction, depending on the seedling species planted as well as the Nurse shrub species involved. Additionally, Nurse shrubs had a stronger facilitative effect on seedling survival and growth at low altitudes and sunny, drier slopes than at high altitudes or shady, wetter slopes. Facilitation in the dry years proved higher than in the one wet year. Our results show that pioneer shrubs facilitate the establishment of woody, late-successional Mediterranean spe- cies and thus can positively affect reforestation success in many different ecological settings.
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applying plant facilitation to forest restoration in mediterranean ecosystems a meta analysis of the use of shrubs as Nurse Plants
2004Co-Authors: Lorena Gomez Aparicio, Jose A Hodar, Regino Zamora Rodriguez, Jose Gomez M Reyes, Jorge Castro Gutierrez, Elena Baraza RuizAbstract:11 pages, 4 figures, 1 table, 75 references. We thank the Consejeria de Medio Ambiente, Junta de Andalucia, and the Direction of the National Park of Sierra Nevada for permission to field work, constant support and facilities. We are also especially grateful to Empresa de Transformacion Agraria S.A. (TRAGSA) for carrying out the experimental reforestation. We thank Sergio de Haro and several students for field assistance. David Nesbitt looked over the English version of the manuscript.
Taly Dawn Drezner - One of the best experts on this subject based on the ideXlab platform.
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Dominant Plants alter the microclimate along a fog gradient in the Atacama Desert
Plant Ecology, 2019Co-Authors: Diego A. Sotomayor, Taly Dawn DreznerAbstract:We assessed the impact of fog on microclimate in a poorly understood fog desert under two common Nurse plant species, at three sites: (1) foggy coast, (2) intermediate, and (3) above the main fog belt in the Atacama Desert (Peru). We quantify Nurse plant modification of their understory that creates favorable microsites for other species. Dataloggers collected temperature, relative humidity (RH) and dew point temperature under Randia armata , Caesalpinia spinosa and in the open at the three sites. The Relative Interaction Index (RII), Friedman’s two-way ANOVA, and correlation were used to compare conditions across microsites and field sites. At noon, the understory was cooler and RH was higher than in the open, consistent with non-fog deserts. Early morning temperatures were warmer in the open at the more fog-influenced sites, unlike non-fog deserts. The temperature gap (cooler in the understory) is smallest at the coast and largest in the interior. Temperature and moisture generally fluctuate less at the most fog-influenced sites, while understory conditions at the interior (least-fog influenced) site was most similar to those found in non-fog deserts. Because fog reduces weather extremes, amelioration by vegetation becomes less on foggy days as extremes are already dampened by the fog, and facilitation by Nurse Plants is greatest when conditions are most like traditional deserts (e.g., clear skies, hot). These results provide mechanistic support for the effects of Nurse Plants through stress amelioration in fog deserts.
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The keystone saguaro (Carnegiea gigantea, Cactaceae): a review of its ecology, associations, reproduction, limits, and demographics
Plant Ecology, 2014Co-Authors: Taly Dawn DreznerAbstract:This paper reviews the basics of a Sonoran Desert keystone cactus species, including the ecology of its establishment and high mortality, its association with Nurse Plants to provide ameliorated conditions for survival, and variability in longevity and reproduction over its range such as delayed reproduction in hotter and more arid populations where this delay is met with longer lifespans. The production of flowers, branches, and spines from areoles is reviewed, as well as current methods for estimating individual age despite great variability in growth rates, most notably linked to summer rainfall. Possible implications of anthropogenic influences that impact populations as well as global climate change are discussed as are implications for potential range shifts in the future. This paper also provides a table listing of over 100 birds, mammals, insects, reptiles, and other animal species that use Carnegiea and highlighting its keystone status.
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branch direction in carnegiea gigantea cactaceae regional patterns and the effect of Nurse Plants
Journal of Vegetation Science, 2003Co-Authors: Taly Dawn DreznerAbstract:Abstract Branch direction in Carnegiea gigantea (saguaro) cacti affects PAR interception and CO2 uptake, and may influence reception of photomorphogenic cues. Branch direction data were collected in 29 saguaro populations over Arizona to determine if the southerly bias observed in previous studies at two locales can be generalized to the American range of the saguaro, and to determine the effect of shading by Nurse Plants on branch direction. Locally observed S bias from previous studies can be extended and generalized to include the American saguaro range. Branches were statistically uniform across environmental variability regarding temperature and precipitation. The S bias was not found in saguaros shaded by large Nurse Plants, supporting the assertion that branch direction occurs, in part, to maximize receipt of insolation. Abbreviations: OPCNM = Organ Pipe Cactus National Monument; SNP = Saguaro National Park.
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saguaro distribution under Nurse Plants in arizona s sonoran desert directional and microclimate influences
The Professional Geographer, 2003Co-Authors: Taly Dawn Drezner, Colleen M GarrityAbstract:Abstract The saguaro cactus, an icon of the American southwestern desert, defines the extent of the Sonoran Desert through portions of its range. Saguaros rely upon Nurse Plants for establishment and survival in the harsh temperature and moisture regime of the desert. Freezing temperatures limit the range of the saguaro to the north in Arizona. However, Nurse Plants extend the range of saguaros by providing more moderate conditions beneath their canopies. This study focuses on precisely these small, highly localized temperature variations, which, we suggest, are linked to regional-scale patterns of distribution of the species, particularly in marginal, cold-limited locales. We sampled 291 saguaros over thirty populations in Arizona, in the northern portion of their range. Saguaros establish under the south side of their Nurse's canopy in the coldest parts of their range more often than expected, while a significant distributional bias is not observed in those in warmer, more moderate plots. To further inv...
Jorge Castro - One of the best experts on this subject based on the ideXlab platform.
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facilitation of tree saplings by Nurse Plants microhabitat amelioration or protection against herbivores
Journal of Vegetation Science, 2008Co-Authors: Lorena Gomezaparicio, Jorge Castro, Regino Zamora, Jose A HodarAbstract:Abstract Question: Positive interactions are predicted to be common in communities developing under high physical stress or high herbivory pressure due to neighbour amelioration of limiting physical and consumer stresses, respectively. However, when both stress sources meet in the same community, the relative importance of the two facilitation mechanisms is poorly understood. We ask: What is the relative importance of abiotic vs. biotic mechanisms of facilitation of tree saplings by shrubs in Mediterranean mountain forests? Location: Sierra Nevada, SE Spain (1800–1850 m a.s.l.) Methods: Saplings of four tree taxa (Acer opalus ssp. granatense, Quercus ilex, Pinus nigra ssp. salzmanii and P. sylvestris var. nevadensis) were planted following a 2 × 2 factorial design: two levels of herbivory (control and ungulate exclusion) and two microhabitats (under shrubs and in open areas). Sapling survival and growth were monitored for five years. Results: Shrubs had positive effects on sapling survival both in control...
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restoring quercus pyrenaica forests using pioneer shrubs as Nurse Plants
Applied Vegetation Science, 2006Co-Authors: Jorge Castro, Regino Zamora, Jose A HodarAbstract:Abstract Question: How to improve reforestation success of Quercus pyrenaica. Location: 1800 m a.s.l., southern Spain. Methods: One-year-old Quercus pyrenaica seedlings were planted using two treatments: (1) bare soil, using a 30-cm diameter augur bit (conventional technique) and (2) under the canopy of a pioneer shrub, Salvia lavandulifolia, using a 12-cm diameter augur bit. Survival and growth were monitored for six years. Our hypothesis is that the use of shrubs as Nurse Plants is an alternative technique of reforestation with higher success than traditional techniques, in which pre-existing vegetation is usually considered a source of competition. The rationale for the study was that for environments with a dry season, pre-existing vegetation buffers summer drought stress, ameliorates the water status of seedlings and thus usually increases seedling recruitment. Results: Quercus survival was 6.3 × higher when planted under individuals of the pioneer shrub as compared to open areas. Quercus seedlings u...
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benefits of using shrubs as Nurse Plants for reforestation in mediterranean mountains a 4 year study
Restoration Ecology, 2004Co-Authors: Jorge Castro, Regino Zamora, Jose A Hodar, Jose M Gomez, Lorena GomezaparicioAbstract:Shrubs are commonly considered competitors of planted seedlings in reforestation programs. However, shrubs can facilitate the establishment of understory seedlings in environments that, like Mediterranean-type ecosystems, are characterized by harsh environmental conditions. In 1997, an experiment was set up in the Sierra Nevada mountains (southeast Spain) to test the use of shrubs as Nurse Plants for an alternative reforestation technique. Two-year-old seedlings of Pinus sylvestris and Pinus nigra were planted in four microhabitats: (1) open interspaces without vegetation (which is the usual method employed in reforestation programs), (2) under individuals of the shrub Salvia lavandulifolia, (3) under the north side of spiny shrubs, and (4) under the south side of spiny shrubs. Seedlings were also distributed in plots with and without ungulates to test the effect of herbivore damage. We report here the results of survival and growth after four growing seasons, a time span long enough to draw robust conclusions concerning the suitability of this technique. Pine survival was remarkably higher when planted under individuals of S. lavandulifolia as compared with open areas (2.6 times for P. sylvestris and 1.8 for P. nigra). The survival of both pine species was also higher when planted on the north side of spiny shrubs, while mortality on the south side was similar to that found in open areas. The reduction of solar radiation by the canopy of shrubs was likely the main factor determining shrub facilitation. The growth of the pines differed among years. However, growth was not inhibited when planted with shrubs as compared with open areas in any of the years. Herbivore damage was low but was mostly concentrated in the leader shoot, exacerbating the deleterious effect of ungulate herbivores on pine growth. We conclude that the use of shrubs as Nurse Plants for reforestation is a viable technique to increase establishment success of reforestation in Mediterranean-type ecosystems and that it might be similarly useful in other water-stressed environments. In addition, this technique offers the advantage of following natural succession, thus minimizing the impact in the community.
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applying plant facilitation to forest restoration a meta analysis of the use of shrubs as Nurse Plants
Ecological Applications, 2004Co-Authors: Lorena Gomezaparicio, Jorge Castro, Regino Zamora, Jose A Hodar, Jose M Gomez, Elena BarazaAbstract:After a millenarian history of overexploitation, most forests in the Medi- terranean Basin have disappeared, leaving many degraded landscapes that have been re- colonized by early successional shrub-dominated communities. Common reforestation tech- niques treat these shrubs as competitors against newly planted tree seedlings; thus shrubs are cleared before tree plantation. However, empirical studies and theory governing plant- plant interactions suggest that, in stress-prone Mediterranean environments, shrubs can have a net positive effect on recruitment of other species. Between 1997 and 2001, we carried out experimental reforestations in the Sierra Nevada Protected Area (southeast Spain) with the aim of comparing the survival and growth of seedlings planted in open areas (the current reforestation technique) with seedlings planted under the canopy of preexisting shrub species. Over 18 000 seedlings of 11 woody species were planted under 16 different Nurse shrubs throughout a broad geographical area. We sought to explore variation in the sign and magnitude of interactions along spatial gradients defined by altitude and aspect. In the present work, we report the results of a meta-analysis conducted with seedling survival and growth data for the first summer following planting, the most critical period for reforestation success in Mediterranean areas. The facilitative effect was consistent in all environmental situations explored (grand mean effect size d 1 5 0.89 for survival and 0.27 for growth). However, there were differences in the magnitude of the interaction, depending on the seedling species planted as well as the Nurse shrub species involved. Additionally, Nurse shrubs had a stronger facilitative effect on seedling survival and growth at low altitudes and sunny, drier slopes than at high altitudes or shady, wetter slopes. Facilitation in the dry years proved higher than in the one wet year. Our results show that pioneer shrubs facilitate the establishment of woody, late-successional Mediterranean spe- cies and thus can positively affect reforestation success in many different ecological settings.
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use of shrubs as Nurse Plants a new technique for reforestation in mediterranean mountains
Restoration Ecology, 2002Co-Authors: Jorge Castro, Regino Zamora, Jose A Hodar, Jose M GomezAbstract:Common techniques currently used for afforestation in the Mediterranean basin consider the pre-existing vegetation (mainly shrubs) as a source of competition for trees, and consequently it is generally eliminated before planting. Nevertheless, it has been demonstrated that woody Plants can facilitate the establishment of understory seedlings in environments that, like the Mediterranean area, are characterized by a pronounced dry season. In this study, we experimentally analyze the usefulness of shrubs as Nurse Plants for afforestation of two native conifers, Pinus sylvestris L. (Scots pine) and Pinus nigra Arnold (black pine). Two-year-old seedlings were planted in four microhabitats: (1) open interspaces without vegetation (which is the usual method used in afforestation programs), (2) under individuals of Salvia lavandulifolia, (3) under the north side of spiny shrubs, and (4) under the south side of spiny shrubs. Pine survival was remarkably higher when planted under individuals of the shrub S. lavandulifolia (54.8% for Scots pine, 81.9% for black pine) compared with open areas (21.5% for Scots pine, 56.8% for black pine; chi square, p < 0.05). The survival of both pines was also higher when planted on the north side of spiny shrubs, although the survival on the south side was similar to that found in open areas. In addition, pine growth was not inhibited when planted in association with shrubs. This pattern appears to result from the combination of abiotic conditions imposed by the presence of a Nurse shrub, which leads to improvement in seedling water status and therefore reduced summer mortality by drought. The results show that the use of shrubs as Nurse Plants is a technique that offers both economic and ecological advantages, in terms of savings in labor and plant material and reduced and even negligible impact on the pre-existing vegetation.
Florencia Cuassolo - One of the best experts on this subject based on the ideXlab platform.
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when do Nurse Plants stop nursing temporal changes in water stress levels in austrocedrus chilensis growing within and outside shrubs
Journal of Vegetation Science, 2009Co-Authors: Cecilia I Nunez, Estela Raffaele, Martin A Nunez, Florencia CuassoloAbstract:Question: Does the proximity of shrubs affect seasonal water stress of young Austrocedrus chilensis trees (a native conifer of the Austral Temperate Forest of South America) in xeric sites? Location: A. chilensis xeric forest in northwest Patagonia, Argentina. Methods: We examined the dependence of predawn twig water potential on tree development (seedling to adult) and proximity to Nurse shrubs during spring and summer. We analysed spatial associations of seedlings, saplings and adult trees with Nurse shrubs, and also evaluated if trees affected shrub canopy vitality. Results: Water stress in Austrocedrus trees was affected by shrub presence. Small trees (i.e. 2 m in height) were not affected by shrub presence. Austrocedrus trees were spatially associated with shrubs in all height classes; however, the percentage of living shrub canopy decreased with tree height. Conclusions: In xeric areas of northwest Patagonia, the strength and direction of interactions between A. chilensis and shrubs, in terms of tree water stress, are dynamic and modulated by tree size and environmental conditions. Overall, positive effects of shrubs on early developmental stages appear to be more important than subsequent negative interactions, since nursing effects could generate a spatial association of shrubs and Austrocedrus trees that persists through later successional stages. These findings shed light on mechanisms behind successional changes, and have important conservation and management implications.
