Estrategias fisiológicas de respuesta a ambientes adversos en orófitos de la Sierra de Guadarrama

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Biológicas, Departamento de Biodiversidad, Ecología y Evolución, leída el 12/12/2019The impending changes in climatic conditions (i.e. decrease in rainfall regimes and increasing temperatures) as an outcome of climate change, coupled to a greater incidence of human disturbance, underlines the challenges and vulnerability faced by Mediterranean high-mountain plant communities. Albeit increased research efforts have demonstrated the effects of environmental factors over plant physiology, along with the responses and adaptation capacity on high-mountain plant species; these primarily concern the vegetation from temperate mountains (i.e. alpine), while studies on Mediterranean high-mountain flora, including their Spanish elements, remain scarce. The latter exposes the urgent need to identify the specific responses and strategies to counteract the seasonal aggravation of summer stress in the remaining species comprising these Mediterranean high-mountain communities. This in view of the expected lengthening and increased intensity of the summer season in these mountains. In turn, these studies will enable discerning potential alterations in community structure and dynamics, fostering their conservation. OBJECTIVES: The main objective of the present PhD Thesis is to study the physiological mechanisms driving the response to adverse conditions in high-mountain specialists and narrowly-distributed species inhabiting the Sistema Central mountainous range, for instance Armeria caespitosa and Erysimum penyalarense. Specifically, we aimed to unveil the strategies in response to the main abiotic stressor driving plant life in Mediterranean high-mountains, i.e. summer stress. In turn, we assessed the involvement of well-known responses in lowland species. For instance, osmolyte accumulation (proline and non-structural carbohydrates, NSC) in response to drought and occasional freezing stress befalling the brief growing season. In addition, we evaluated the protective role of photosynthetic and “accessory” pigments in response to the seasonal aggravation of summer stress and diurnal climatic variations, respectively. Lastly, we assessed the adaptive capacity of a high-mountain hemicryptophyte using herbarium specimens from the past 71 years to the long-term climate exacerbation in these high-mountain areas, via morphological and micro-morphological leaf traits related to transpiration-mediated cooling and photosynthetic gain...La predicción de cambio en los parámetros climáticos (disminución de las precipitaciones, aumento de las temperaturas), aunado al aumento de la perturbación antrópica, resaltan la fragilidad y dificultad de supervivencia de la gran diversidad de especies vegetales colonizadoras de los ecosistemas de la alta montaña Mediterránea. La exigüidad de los estudios enfocados en las respuestas fisiológicas y la capacidad adaptativa de las especies que forman la vegetación de las cumbres Mediterráneas es muy alta, comparado con los crecientes estudios de esta índole en sistemas alpinos. Esto destaca la necesidad de identificar las respuestas específicas para contrarrestar los efectos de la sequía estival, incidente a lo largo de la corta temporada de actividad vegetal, en las especies que integran estas comunidades de alta montaña. Estos estudios ayudarán a discernir posibles alteraciones en la estructura de estas comunidades y, dado el esperado aumento en la intensidad de la sequía estival en estos ecosistemas, facilitar su conservación. OBJETIVOS: El objetivo principal de esta Memoria doctoral es el estudio de los mecanismos fisiológicos de respuesta al estrés estival en orófitos de las comunidades de la alta montaña Mediterránea; incluyendo especies endémicas y de limitada distribución, como es el caso de Armeria caespitosa, o Erysimum penyalarense. Para ello, se llevó a cabo la cuantificación estacional de metabolitos ampliamente estudiados en especies modelo y cultivadas, establecidos como indicadores de la respuesta al estrés por sequía y temperaturas extremas (osmolitos: prolina y carbohidratos no estructurales, NSC en inglés). Aunado a esto, se estudió el papel de pigmentos fotosintéticos y fotoprotectores en estos orófitos, esclareciendo sus oscilaciones en respuesta a la variación climática estacional y diaria, respectivamente. Finalmente, buscando evaluar la capacidad adaptativa de la estructura foliar en respuesta al agravamiento de las condiciones climáticas registrado en estas montañas, se evaluaron caracteres relacionados con la actividad fotosintética y termorregulación en pliegos de herbario de los últimos 71 años...Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEunpu

Changes in Foliar Functional Traits of S. pyrenaicus subsp. carpetanus under the Ongoing Climate Change: A Retrospective Survey

The sensitivity of stomatal behavior and patterning (i.e., distribution, density, size) to environmental stimuli, renders them crucial for defining the physiological performance of leaves. Thus, assessing long-term modifications in stomatal traits in conserved specimens arises as a valuable eco-physiological approach to predict how the rising trend of warmer, drier summers could a_ect plant fitness; particularly in mountain areas already experiencing climate aggravation and lacking the related monitoring schemes like Mediterranean high-mountains. Variations in foliar and stomatal traits were studied in conserved specimens of Senecio pyrenaicus subsp. carpetanus from Sierra de Guadarrama over the past 71 years. Our findings revealed decreasing trends in leaf width, stomatal size, and increasing tendency in stomatal density, all correlated with the recent 30-year climate exacerbation in these mountains. This evidenced a positive selection favoring traits that allow safeguarding plant performance under drier, hotter weather conditions. The significant relation between stomatal traits and climatic variables upholds the role of stomatal patterning in sensing environmental cues in this species, feasibly optimizing physiological responses involved in the growth–water loss trade-o_. The transition to smaller, densely packed stomata observed in recent decades could indicate local-adaptive plasticity in this species, enhancing stomatal response, as coarser environmental conditions take place in Sierra de Guadarrama

Photoprotective Strategies in Mediterranean High-Mountain Grasslands

Albeit the remarkably high Ultraviolet B loads, high temperatures, and drought stress substantiate the need for efficient photoprotective strategies in Mediterranean high-mountain plants, these remain understudied. Considering the sensitivity of photosystems to extreme conditions, we evaluated an environmental gradient’s weight on the photoprotection of five high-mountain specialists from Central Spain. Diurnal and seasonal variations in chlorophyll, chlorophyll fluorescence, carotenoids, and xanthophylls in consecutive and climatically contrasting years were taken to evaluate the effect of the impending climate coarsening at the photosystem level. Our results revealed significant differences among species in the xanthophyll cycle functioning, acting either as a continuous photoprotective strategy enhancing photochemistry-steadiness; or prompted only to counteract the cumulative effects of atypically adverse conditions. The lutein cycle’s involvement is inferred from the high lutein content found in all species and elevations, acting as a sustained photoprotective strategy. These findings added to high de-epoxidation state (DEPS) and minor seasonal changes in the chlorophyll a/b ratio, infer the xanthophyll and Lutein cycles are crucial for upkeeping the photosystems’ optimal functioning in these plants heightening their photoprotective capacity during periods of more unfavorable conditions. Nevertheless, an atypically dry growing season’s detrimental effect infers the feasible surpassing of stress-thresholds and the precariousness of the communities’ functional diversity under climate change

<scp>ReSurveyEurope</scp>: A database of resurveyed vegetation plots in Europe

AbstractAimsWe introduce ReSurveyEurope — a new data source of resurveyed vegetation plots in Europe, compiled by a collaborative network of vegetation scientists. We describe the scope of this initiative, provide an overview of currently available data, governance, data contribution rules, and accessibility. In addition, we outline further steps, including potential research questions.ResultsReSurveyEurope includes resurveyed vegetation plots from all habitats. Version 1.0 of ReSurveyEurope contains 283,135 observations (i.e., individual surveys of each plot) from 79,190 plots sampled in 449 independent resurvey projects. Of these, 62,139 (78%) are permanent plots, that is, marked in situ, or located with GPS, which allow for high spatial accuracy in resurvey. The remaining 17,051 (22%) plots are from studies in which plots from the initial survey could not be exactly relocated. Four data sets, which together account for 28,470 (36%) plots, provide only presence/absence information on plant species, while the remaining 50,720 (64%) plots contain abundance information (e.g., percentage cover or cover–abundance classes such as variants of the Braun‐Blanquet scale). The oldest plots were sampled in 1911 in the Swiss Alps, while most plots were sampled between 1950 and 2020.ConclusionsReSurveyEurope is a new resource to address a wide range of research questions on fine‐scale changes in European vegetation. The initiative is devoted to an inclusive and transparent governance and data usage approach, based on slightly adapted rules of the well‐established European Vegetation Archive (EVA). ReSurveyEurope data are ready for use, and proposals for analyses of the data set can be submitted at any time to the coordinators. Still, further data contributions are highly welcome.</jats:sec

Quercus ilex germination

Germination data of sterilized and non-sterilized oak (Quercus ilex) seeds on sterilized and non-sterilized oak and pine soils, added with microbial extracts from oak and pine soils, plus a control of distilled water.Junta de Andalucía Regional Government (grant PY2020-0223), Spanish Research Agency (grant MCIN/AEI 10.13039/501100011033)Peer reviewe

Rooting depth and xylem vulnerability are independent woody plant traits jointly selected by aridity, seasonality, and water table depth

Evolutionary radiations of woody taxa within arid environments were made possible by multiple trait innovations including deep roots and embolism-resistant xylem, but little is known about how these traits have coevolved across the phylogeny of woody plants or how they jointly influence the distribution of species. We synthesized global trait and vegetation plot datasets to examine how rooting depth and xylem vulnerability across 188 woody plant species interact with aridity, precipitation seasonality, and water table depth to influence species occurrence probabilities across all biomes. Xylem resistance to embolism and rooting depth are independent woody plant traits that do not exhibit an interspecific trade-off. Resistant xylem and deep roots increase occurrence probabilities in arid, seasonal climates over deep water tables. Resistant xylem and shallow roots increase occurrence probabilities in arid, nonseasonal climates over deep water tables. Vulnerable xylem and deep roots increase occurrence probabilities in arid, nonseasonal climates over shallow water tables. Lastly, vulnerable xylem and shallow roots increase occurrence probabilities in humid climates. Each combination of trait values optimizes occurrence probabilities in unique environmental conditions. Responses of deeply rooted vegetation may be buffered if evaporative demand changes faster than water table depth under climate change