Open Access
Relating the spatial distribution of a tall-grass to fertility islands in a temperate mountain grassland
(Elsevier, 2021) San Emeterio Garciandía, Leticia; Durán Lázaro, María; Múgica Azpilicueta, Leire; Jiménez, Juan José; Canals Tresserras, Rosa María; Agronomia, Bioteknologia eta Elikadura; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Agronomía, Biotecnología y Alimentación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Plant-soil feedback mechanisms influence the abundance and rarity of plant species and can favour invasive processes, including those of native species. To explore these mechanisms, we analysed correlations between spatial distributions of plant biomass and soil properties in two neighbouring grasslands at different phases of expansion of the native Eurasian tall-grass Brachypodium rupestre (Host) Roem & Schult (B. rupestre cover: >75 and 25–50%). For this, we applied spatially explicit sampling, geostatistical analysis and structural equation models (SEM) to probe causal relationships among measured variables involved in nutrient accumulation. We hypothesized that if litter accumulates as a result of reduced grazing, ‘fertility islands’ (spots of high SOM and nutrient contents) will form under B. rupestre clumps because the increase in resource inputs from litter will trigger SOM build-up and promote microbial growth. Our results show that ‘fertility islands’ of P and amino acids occurred under the patchy clumps of B. rupestre in the less invaded grassland. In addition, the SEMs indicated that nutrient accumulation was partially due to mineralization of the SOM and modulated by the soil microbial biomass. However, there was no correlation between spatial patterns of B. rupestre biomass, SOM and microbial biomass. Moreover, the SEMs explained small amounts of variance in them (SOM r2 = 0.22 and microbial biomass r2 = 0.08), suggesting that factors other than B. rupestre biomass were responsible for the high fertility below the patches. Our spatially explicit approach demonstrated that litter inputs in dense temperate grassland communities can generate ‘fertility islands’ that may favour the stability and expansion of a tall-grass invader and suggest that herbivory may enhance or inhibit this phenomenon.
Open Access
Land use change effects on carbon and nitrogen stocks in the Pyrenees during the last 150 years: a modelling approach
(Elsevier, 2015) Lo, Yueh-Hsin; Blanco Vaca, Juan Antonio; Canals Tresserras, Rosa María; González de Andrés, Ester; San Emeterio Garciandía, Leticia; Imbert Rodríguez, Bosco; Castillo Martínez, Federico; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
In the southern Pyrenees, human population and therefore land uses have changed from forests to pastures, then crops, and back to pastures and secondary forests during the last two centuries. To understand what such rapid land use changes have meant for carbon (C) and nitrogen (N) stocks, we used data from two forest sites in the western Pyrenees, combined with regional data on pastures and crop production (potato, cereal), to calibrate the ecosystem-level model FORECAST. Then, we simulated 150-year of land use for each site, emulating historical changes. Our estimates show that the conversion from forests into pastures and crops created C and N deficits (378-427 Mg C ha-1, 4.0-4.6 Mg N ha-1) from which these sites are still recovering. The main ecological process behind the creation of these deficits was the loss of the ecological legacy of soil organic matter (SOM) created by the forest, particularly during conversion to farming. Pastures were able to reverse, stop or at least slow down the loss of such legacy. In conclusion, our work shows the deep impact of historical land use in ecosystem attributes, both in magnitude of removed C and N stocks and in duration of such impact. Also, the usefulness of ecological modelling in absence of historical data to estimate such changes is showcased, providing a framework for potential C and N stocks to be reached by climate change mitigation measures such as forest restoration.
Open Access
Disruption of traditional land use regimes causes an economic loss of provisioning services in high-mountain grasslands
(Elsevier, 2020) Durán Lázaro, María; Canals Tresserras, Rosa María; Sáez Istilart, José Luis; Ferrer Lorés, V.; Lera López, Fernando; Ekonomia; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Institute for Advanced Research in Business and Economics - INARBE; Economía; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Mountain ecosystems face many challenges related to global change. Most high-altitude grasslands in the Pyrenees, despite representing valuable assets recognised in the European conservation heritage, are at risk due to the decline of traditional extensive ranging. This research intends to quantify economically the loss of the provisioning service of high-quality food for livestock of an upland area on the western side of the range. The area is experiencing degradation due to the expansion of the native tall-grass Brachypodium rupestre, favoured by disruption of traditional grazing and anthropogenic fire regimes. We implement the substitution economic approach and use floristic and husbandry data to determine that the loss of food rations for livestock results in an unitary cost of 107 (sic).ha(-1).year(-1), amounting to 21146 (sic) for the whole degraded area, according to the most conservative estimate. The study also finds evidence that the decline in grassland value is closely associated with the digestibility to herbivores of B. rupestre during the growing season. This approach may be an effective tool to raise awareness of the problem among local and regional stakeholders and encourage further environmental actions to prevent the degradation.
Open Access
Comparison of culturing and metabarcoding methods to describe the fungal endophytic assemblage of brachypodium rupestre growing in a range of anthropized disturbance regimes
(MDPI, 2021) Durán Lázaro, María; San Emeterio Garciandía, Leticia; Canals Tresserras, Rosa María; Agronomia, Bioteknologia eta Elikadura; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Agronomía, Biotecnología y Alimentación; Gobierno de Navarra / Nafarroako Gobernua, CENEDUCA18; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Fungal endophytes develop inside plants without visible external signs, and they may confer adaptive advantages to their hosts. Culturing methods have been traditionally used to recognize the fungal endophytic assemblage, but novel metabarcoding techniques are being increasingly applied. This study aims to characterize the fungal endophytic assemblage in shoots, rhizomes and roots of the tall grass Brachypodium rupestre growing in a large area of natural grasslands with a continuum of anthropized disturbance regimes. Seven out of 88 taxa identified via metabarcoding accounted for 81.2% of the reads (Helotiaceae, Lachnum sp. A, Albotricha sp. A, Helotiales A, Agaricales A, Mycena sp. and Mollisiaceae C), revealing a small group of abundant endophytes and a large group of rare species. Although both methods detected the same trends in richness and fungal diversity among the tissues (root > rhizome > shoot) and grasslands (low-diversity >high-diversity grasslands), the metabarcoding tool identified 5.8 times more taxa than the traditional culturing method (15 taxa) but, surprisingly, failed to sequence the most isolated endophyte on plates, Omnidemptus graminis. Since both methods are still subject to important constraints, both are required to obtain a complete characterization of the fungal endophytic assemblage of the plant species.
Open Access
Soil bacterial functional diversity mirrors the loss of plant diversity by the expansion of a native tall-grass in high mountain grasslands
(Springer, 2019) Canals Tresserras, Rosa María; Múgica Azpilicueta, Leire; Durán Lázaro, María; San Emeterio Garciandía, Leticia; Agronomia, Bioteknologia eta Elikadura; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Agronomía, Biotecnología y Alimentación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Background and Aims: In highland ecosystems, global change processes are intense and foster vegetation shifts that may have an impact on soil functioning. Soil bacterial communities may be particularly sensitive to these changing scenarios. The aim of this research is to determine whether the loss of floristic diversity caused by the unusual dominance of a native component -the perennial grass Brachypodium rupestre (L.) Beauv., which is expanding aggressively in natural grasslands of the Western Pyrenees-, parallels a decrease of the soil bacterial functional diversity and their potential for nutrient transformations. Methods: We conducted the study in eight grasslands exposed to different degrees of B. rupestre spreading. Soil community physiological profiles of the heterotrophic bacteria, enzymatic activities related to C, P and N cycles, C and N microbial biomasses, N components and soil physical and chemical properties were determined. Results: Soils below low-diversity grasslands had lower bacterial functional richness and diversity but greater urease activity, pH and nitrate than soils in diverse grasslands. Ammonium pools, C and N microbial biomasses and enzymatic activities related to C and P did not differ between grasslands. Conclusions: The expansion of B. rupestre and the decrease of plant diversity coincided with a significant decline of bacterial functional diversity and an alteration of the N cycle. Not only plant composition but the prevailing disturbance regime may account for the results. Results also suggest that B. rupestre may rely on its capability to use N efficiently rather than on a soil bacteria-mediated N availability.
Open Access
Calibración y evaluación de dos métodos no destructivos de estimación de la producción en praderas polífitas con Lolium sp.
(Sociedad Española para el Estudio de los Pastos, 2012) Sáez Istilart, José Luis; Vergara Hernández, Iosu; Canals Tresserras, Rosa María; Producción Agraria; Nekazaritza Ekoizpena
En esta comunicación se expone el trabajo realizado para calibrar y evaluar dos métodos de estimación indirecta de la materia seca presente en praderas polífitas de Lolium sp. La comparativa metodológica se realizó entre un herbómetro por capacitancia y un medidor de altura de la cubierta vegetal por señal láser. Los mejores modelos de predicción se obtuvieron con el herbómetro de capacitancia, con R2 que oscilaron entre 0,579 y 0,798, dependiendo de las variables ambientales incluidas en el modelo, del número de muestras, y del criterio de inclusión de variables en el modelo. La altura de la vegetación medida con la señal láser no intervino como variable independiente en ninguno de los mejores modelos de predicción obtenidos.
Open Access
Restorative pyric herbivory practices in shrub-encroached grasslands enhance nutrient resource availability and spatial heterogeneity
(Elsevier, 2024-05-31) Canals Tresserras, Rosa María; Múgica Azpilicueta, Leire; Durán Lázaro, María; San Emeterio Garciandía, Leticia; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
Pyric herbivory (PH), the combination of prescribed burnings and targeted herbivory, is a promising tool for landscape restoration that emulates historical disturbance regimes. Nitrogen (N) and phosphorus (P) are crucial nutrients for plant growth and although several studies have analysed the single effects of fire or grazers in their availability, the combined effect of both disturbances in the soil nutrient budgets have been rarely considered. This research was planned to analyse the 2-year impact of PH restoration practices on the availability of N and P in two Ulex gallii-encroached grasslands in the Pyrenees. We monitored available forms of N and P for two years using periodic replacements of ion exchange resins to test the hypothesis that mid-term effect of targeted grazing was more relevant than short-term effect of burning. Additionally, we investigated the role of temperature and precipitation on nutrients accumulation and compared its significance to management factors. Burning transformed vegetation and litter into a spatially heterogeneous layer of ash and charred material, which resulted in a variable availability of N and P at the rhizosphere level. After two periods of PH, nutrient availability was higher in soils from grazed plots compared to ungrazed, and the impacts of early burns were scarcely discernible. Nitrate was found to be the most rainfall-dependent nutrient, and grazing also affected its spatial distribution. Our results suggest that the heterogeneous nutrient enrichment enhanced by PH is important for promoting the establishment of a diverse pool of plant species, including both N2-fixing and non-fixing species. In these rainy areas, the use of burnings alone, without grazing, may perpetuate the dynamics of N2-fixing shrub encroachment.
Open Access
Las facerías internacionales en el Pirineo: historia, actualidad y futuro
(Sociedad Española para el Estudio de los Pastos, 2012) Razquin Lizarraga, Martín; Aranguren Ibáñez, E.; Taull Taull, M.; Fernández Otal, J.A.; Ferrer Lorés, V.; Gascouat, P.; Canals Tresserras, Rosa María; Derecho Público; Zuzenbide Publikoa; Producción Agraria; Nekazaritza Ekoizpena
La ponencia define el concepto de facería internacional pirenaica y realiza en sus primeros apartados una síntesis histórica de sus orígenes y de su evolución a lo largo de sus ocho siglos de existencia. Se realiza posteriormente una recopilación de las facerías existentes en el Pirineo y de su estado actual de vigencia y se comentan los aspectos más peculiares y particulares de las mismas. En la segunda parte de la ponencia se describe el nuevo marco político-jurídico de las facerías internacionales pirenaicas, se detalla un ejemplo de evolución de una facería actual, plenamente vigente y acorde a los tiempos actuales, la facería de Aezkoa-Cize, y se reflexiona sobre los retos y posibilidades a futuro de estos acuerdos internacionales de origen ancestral.
Open Access
Landscape in motion: revisiting the role of key disturbances in the preservation of mountain ecosystems
(Universidad de la Rioja, 2019) Canals Tresserras, Rosa María; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
La historia del planeta es una historia dinámica, de continuo cambio. Los responsables de la gestión del medio natural se enfrentan actualmente ante un paisaje muy cambiante debido a las condiciones de cambio global (cambio climático y de usos del suelo) provocadas por la acción humana en los últimos siglos. La dimensión temporal es un aspecto clave en la gestión del medio natural, y conocer la historia de los agentes que han esculpido el paisaje permite entender los nuevos escenarios impulsados por el cambio global. Este artículo discute el concepto tradicional de conservación del medio natural, analiza el papel de determinadas perturbaciones en el funcionamiento y la dinámica de los ecosistemas y ofrece un nuevo enfoque de gestión derivado de este conocimiento. Las prácticas combinadas de fuego controlado y pastoreo guiado (herbivorismo pírico) emergen como valiosas herramientas de conservación de los ecosistemas de montaña, que deben consolidarse aunando experiencia y conocimiento científico-técnico para maximizar sus efectos positivos y minimizar los potenciales impactos negativos.
Open Access
Soil C/N ratios cause opposing effects in forests compared to grasslands on decomposition rates and stabilization factors in southern European ecosystems
(Elsevier, 2023) Blanco Vaca, Juan Antonio; Durán Lázaro, María; Luquin, Josu; San Emeterio Garciandía, Leticia; Yeste Yeste, Antonio; Canals Tresserras, Rosa María; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Ciencias; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Soils store an important amount of carbon (C), mostly in the form of organic matter in different decomposing stages. Hence, understanding the factors that rule the rates at which decomposed organic matter is incorporated into the soil is paramount to better understand how C stocks will vary under changing atmospheric and land use conditions. We studied the interactions between vegetation cover, climate and soil factors using the Tea Bag Index in 16 different ecosystems (eight forests, eight grasslands) along two contrasting gradients in the Spanish province of Navarre (SW Europe). Such arrangement encompassed a range of four climate types, elevations from 80 to 1420 m.a.s.l., and precipitation (P) from 427 to 1881 mm year–1. After incubating tea bags during the spring of 2017, we identified strong interactions between vegetation cover type, soil C/N and precipitation affecting decomposition rates and stabilization factors. In both forests and grasslands, increasing precipitation increased decomposition rates (k) but also the litter stabilization factor (S). In forests, however, increasing the soil C/N ratio raised decomposition rates and the litter stabilization factor, while in grasslands higher C/N ratios caused the opposite effects. In addition, soil pH and N also affected decomposition rates positively, but for these factors no differences between ecosystem types were found. Our results demonstrate that soil C flows are altered by complex site-dependent and site-independent environmental factors, and that increased ecosystem lignification will significantly change C flows, likely increasing decomposition rates in the short term but also increasing the inhibiting factors that stabilize labile litter compounds.