Examinando por Autor "Luzuriaga, Arantzazu L."

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Climate change and biocrust disturbance synergistically decreased taxonomic, functional and phylogenetic diversity in annual communities on gypsiferous soils
(Wiley, 2021) Sánchez, Ana M.; Peralta, Ana M. L.; Luzuriaga, Arantzazu L.; Prieto, María; Escudero, Adrián
Rainfall and biocrusts are important sources of temporal and spatial environmental heterogeneity and niche differentiation for annual plants, a major component of diversity in drylands. Therefore, global change processes comprising shifts in rainfall timing and drought exacerbation, together with biocrust disturbance may affect species coexistence and result in disrupted diversity patterns. In this study, we experimentally evaluated the effects of the rainfall amount and timing as well as physical biocrust disturbance and their interaction on the taxonomic, phylogenetic and functional diversity of annual plant communities on gypsum soil drylands. All diversity estimates were determined at different times during community development in each experimental unit (α), as the contribution of each experimental unit to the total diversity in each treatment (β) and as the total diversity in each treatment (γ). Rainfall timings led to changes in all diversity dimensions, with higher diversity under the typical timing. The community was quite resilient to moderate reductions in rainfall, but extreme droughts decreased the alpha and beta taxonomic, functional and phylogenetic diversities. In addition, the simultaneous occurrence of biocrust disturbance and extreme drought led to consistent collapses in all diversity dimensions, probably because the effects of water shortage were exacerbated. Observations of the community at different times during its development highlighted the importance of regenerative strategies for niche differentiation and species coexistence, and their strong dependence on global change drivers. Indeed, our experimental study demonstrated that rainfall patterns and biocrusts are key factors related to the maintenance of diversity in semiarid annual plant communities. In particular, our results highlight the key role of biocrusts in modulating the effects of drought on plant diversity and the need for integrative approaches that consider both plants and biocrusts in order to elucidate the influence of climate change on the diversity of drylands.
Evidence of functional species sorting by rainfall and biotic interactions: A community monoliths experimental approach
(Wiley, 2019) Peralta, Ana M.L.; Sánchez, Ana M.; Luzuriaga, Arantzazu L.; de Bello, Francesco; Escudero, Adrián
1. Different abiotic and biotic sources of environmental heterogeneity have been proposed as determinants of community assembly, but few experimental studies have identified the processes and functional traits through which they operate. Thus, we aimed to experimentally determine the relationships between variations in functional structure according to spatiotemporal environmental heterogeneity to understand how biotic and abiotic drivers affect the highly dynamic nature of annual plant communities. 2. Entire annual plant communities were subjected to experimental manipulation of rain regimes (timing and amount) and perturbation of the biological soil crust (BSC; intact vs. perturbed) in a community common garden. We surveyed the experimental assemblages at different life stages (seedlings to reproductive adults) and characterized their functional structure (community weighted means and Rao) based on key functional traits. 3. We found an important filtering effect of rain timing and amount on the composition and functional structure. Drought conditions limited the community weighted means and diversity to better functionally equipped species in terms of stress resistance (high leaf dry matter content and low specific leaf area) and resource economy (short species with low reproductive ratios and higher root:shoot ratios), although the timing of drought could determine the intensity of the filtering effect. BSC acted as a filter on germination via seed mass and as a ‘biotic buffer’ in later stages by minimizing the stressful conditions during severe droughts decreasing evapotranspiration. 4. Synthesis. We found clear cause–effect relationships among abiotic and biotic factors and their interaction, and the experimental communities in terms of species composition and functional structure. We demonstrated the importance of rain regimes for shaping annual plant communities and identified germination as the main process determining the community assembly, suggesting phenotypic integration of a complete set of functional traits for resisting drought throughout the whole life cycle. The BSC–annual plant relationship shifted from negative by acting as a germination filter to positive by acting as a biotic buffer in later stages. We demonstrate the importance of evaluating these relationships at multiple 37 plant stages. The temporal and spatial heterogeneity related to the factors considered are key sources of niche differentiation that promote species coexistence.
Functional diversity of experimental annual plant assemblages drives plant responses to biological soil crusts in gypsum systems
(Wiley, 2022) Ortiz, Laura; Luzuriaga, Arantzazu L.; Ferrandis, Pablo
1. Biological soil crusts (BSC) are complex biotic aggregates comprised of lichens, cyanobacteria, algae and other micro-organism that are known to differently af-fect plant development along life cycle by selecting plant functional traits based on species-specific effects. In addition, functional differences between inter-acting species should modulate their response ability to other environmental factors. Thus, it should be expected that the effects of the BSC on plants will be significantly determined by the own functional diversity in the community.2. To understand the multiple effects of BSC and the extent to which the func-tional diversity of interacting plant species can modulate their effects on the development of coexisting species, we applied an experimental approach by manipulating the initial functional diversity of the entire annual plant commu-nity and BSC conditions in a common garden trial. We crossed three sorts of assemblages built on the basis of plant stature (combinations of only large, or only small, or diverse sized plant species in pots) with three lichen-dominated BSC disturbance scenarios (intact, or tiny mechanically disaggregated, or absent portions of BSC).3. BSC strongly affected the establishment and development of gypsophilous an-nual plants in a complex, multifaceted manner, which shifted throughout the plant life cycle. We demonstrated that lichen-dominated BSC could act as a major physical barrier to the establishment of annual plants at a heterogene-ous fine spatial scale. Such a restrictive effect was particularly marked in the presence of intact BSC. However, after annual plants overcame the restrictions imposed by BSC, the same biotic layer facilitated plant growth and fitness, re-gardless of its physical integrity, resulting in larger plants producing more fruits.4. Importantly, our results suggest that the functional diversity structure of the community may also drive growth and fitness of coexisting species by activat-ing alternative coexistence mechanisms such as niche partitioning or competi-tion symmetry. This study highlights the importance of plant neighbourhood features for the performance of interacting species, and confirms a novel, ex-perimental way to explore the effects of community diversity on plants for the interpretation of assembly mechanisms.
Functional traits explain both seedling and adult plant spatial patterns in gypsum annual species
(Wiley, 2023) Peralta, Ana L.; Escudero, Adrián; Cruz, Marcelino de la; Sánchez, Ana M.; Luzuriaga, Arantzazu L.
Ecological processes such as seed dispersal or plant–plant interactions and environmental constraints such as climate or soil heterogeneity are known to influence establishment, and thus the spatial patterns of plant communities and populations. In this study, we hypothesized that key functional traits such as the specific leaf area (SLA), reproductive ratio (reproductive/vegetative biomass), seed mass and maximum plant height would influence the spatial patterns of individual species in annual, gypsophilous plant communities, and that these effects would be modulated by both the soil surface structure (biocrust) and climate (precipitation) conditions.We mapped the spatial patterns of all plants found in six 1 × 1 m plots (more than 1000 individuals per plot) in both the seedling (autumn) and adult stages (spring) under two biocrust experimental conditions (intact vs. disturbed biocrust) during two consecutive years which were contrasted in term of precipitation (dry year and wet year). To assess the spatial patterns of seedlings and adults, we fitted four different spatial point pattern models (i.e. Poisson, inhomogeneous Poisson, Poisson cluster and inhomogeneous Poisson cluster processes) to each of the 242 populations of the 26 most abundant species that had more than 15 individuals per plot.Most seedling populations exhibited clustered spatial patterns that persisted in the adult stage, which suggests that short-distance dispersal is an adaptive trait for soil specialists such as gypsophilous plants. One-third of the populations fitted an inhomogeneous model best but the physical structure of the biocrust was not related to them. More importantly, we found a connection between the functional strategies of species and the spatial distribution of plants. In particular, during the dry year, irrespective of the biocrust conditions, species with a high SLA and high Rep/Veg mainly exhibited clustered spatial patterns, whereas low SLA and low Rep/Veg were associated with random distributions. Species with heavy and light seed masses had random and clustered patterns, respectively. In both the dry and wet years, species with lower maximum heights had clustered patterns, whereas taller species exhibited random patterns. In addition, species with heavier seeds and greater maximum heights had the largest cluster sizes.Our results confirm that the spatial patterns of seedlings and adult plants are significantly determined by the functional strategy of each species.Read the free Plain Language Summary for this article on the Journal blog.
Winter is coming: plant freezing resistance as a key functional trait for the assembly of annual Mediterranean communities
(2018-01-23) Pescador, David S.; Sánchez, Ana M.; Luzuriaga, Arantzazu L.; Sierra-Almeida, Ángela; Escudero, Adrián
Background and Aims In Mediterranean annual plants, germination mainly occurs during the autumn and only those seedlings that survive winter freezing can flower and produce seedlings in spring. Surprisingly, the effect of freezing events as an abiotic determinant of these communities remains unexplored. The present study aimed to investigate how freezing events affect annual Mediterranean communities and whether their functional structure as related to freezing resistance is linked to the main biotic and abiotic determinants of these communities. Methods In 120 plots located on a semi-arid Mediterranean steppe (Spain), the community functional structure related to the lethal temperature causing 50 % frost damage (LT50 trait) in seedlings was estimated and summarized as the community-weighted mean (CWM-LT50) and its functional diversity (FD-LT50). Plots were stratified according to distance to rabbit shelters and latrines as a proxy for rabbit density, proximity to Stipa tenacissima and spring water availability, where annual species abundance was recorded in all plots over three consecutive years. Key Results Annual species were able to resist a threshold temperature of –4 °C and most had LT50 values around the absolute minimum temperature (–9.5 °C) in the three years. Higher rabbit densities led to lower CWM-LT50 and higher FD-LT50 values. Plots close to Stipa tussocks had higher CWM-LT50 values whereas water availability had no effects. Conclusions High freezing resistance was extended among winter annual species, suggesting the presence of an association between historical environmental filtering and low winter temperatures. However, the community functional structure related to freezing resistance remained variable among scenarios with differences in herbivory pressure and distance to perennial vegetation. The trends observed indicate that traits that allow plants to deal with herbivory may also promote freezing resistance, and that tussocks can act as nurses via microclimatic amelioration of harsher winter conditions.