Jose Ignacio Querejeta

Spanish National Research Council | CSIC · Department of Soil and Water Conservation and Organic Waste Management

Mistletoes are xylem-tapping hemiparasites that rely on their hosts for water and nutrient uptake. Thus, they impair tree performance in the face of environmental stress via altering the carbon and water relations and nutritional status of trees. To improve our understanding of physiological responses to mistletoe and ongoing climate change, we inv...

Exploring the diversity of above and belowground water-use traits among coexisting plant species can improve understanding of soil water partitioning in species-rich plant communities and provide insights into how dryland vegetation copes with drought stress. We assessed the diversity of plant water use strategies among coexisting woody species at...

In this 9-year manipulative field experiment, we examined the impacts of experimental warming (2 °C, W), rainfall reduction (30% decrease in annual rainfall, RR), and their combination (W+RR) on soil microbial communities and native vegetation in a semi-arid shrubland in southeastern Spain. Warming had strong negative effects on plant performance a...

Introduction: Climate change has increased the need for forest restoration, but low planting success and limited availability of planting materials hamper these efforts. Invasive plants and their soil legacies can further reduce restoration success. Thus, strategies that optimize restoration are crucial. Assisted migration and inoculation with nati...

N 2 ‐fixing legumes can strongly affect ecosystem functions by supplying nitrogen (N) and improving the carbon‐fixing capacity of vegetation. Still, the question of how their leaf‐level N status and carbon metabolism are coordinated along leaf ageing remains unexplored. Leaf tissue carbon isotopic composition (δ ¹³ C) provides a useful indicator of...

Intrinsic water use efficiency (WUEi) reflects the trade‐off between photosynthetic carbon gain and water loss through stomatal conductance and is key for understanding dryland plant responses to climate change. Stipa tenacissima is a perennial tussock C 3 grass with an opportunistic, drought‐avoiding water use strategy that dominates arid and semi...

During the United Nation's Decade on Ecosystem Restoration, planting material shortages are constraining restoration, while climate change exacerbates the need for restoration and reduces recruitment. Concurrently, research shows that native mycorrhizal fungi (symbiotic with plant roots) appropriate to plant provenance and site conditions significa...

The least‐cost economic theory of photosynthesis shows that water and nitrogen are mutually substitutable resources to achieve a given carbon gain. However, vegetation in the Sahel has to cope with the dual challenge imposed by drought and nutrient‐poor soils. We addressed how variation in leaf nitrogen per area (Narea) modulates leaf oxygen and ca...

Water is the most limiting resource for plant survival and growth in arid environments, but the diversity of water‐use strategies among coexisting species in dryland communities is not well understood. There is also growing interest in assessing whether a whole‐plant coordination exists between traits related to water‐use and the leaf economic spec...

Rear‐edge populations at the xeric distribution limit of tree species are particularly vulnerable to forest dieback triggered by drought. This is the case of silver fir (Abies alba) forests located in the southwestern of Europe. While silver fir drought‐induced dieback patterns have been previously explored, information on the role played by nutrit...

Predicted hotter and drier climatic conditions in the Mediterranean Basin will probably hamper current afforestations and reforestations by negatively influencing tree performance. Understanding how saplings can adjust their physiology to shortages in water availability is essential to predict early-stage success of forest ecological restoration. P...

The aboveground impacts of climate change receive extensive research attention, but climate change could also alter belowground processes such as the delicate balance between free-living fungal decomposers and nutrient-scavenging mycorrhizal fungi that can inhibit decomposition through a mechanism called the Gadgil effect. We investigated how clima...

Extensive research efforts are devoted to understand fine root trait variation and to confirm the existence of a belowground root economics spectrum (RES) from acquisitive to conservative root strategies that is analogous to the leaf economics spectrum (LES). The economics spectrum implies a trade-off between maximizing resource acquisition and pro...

We carried out a 4-year manipulative field experiment in a semiarid shrubland in southeastern Spain to assess the impacts of experimental warming (W), rainfall reduction (RR), and their combination (W + RR) on the composition and diversity of arbuscular mycorrhizal fungal (AMF) communities in rhizosphere soil of H. syriacum and G. struthium shrubs...

Forest dieback and mortality episodes triggered by droughts are receiving increasing attention due to the projected increases in these extreme climate events. However, the role played by nutrient impairment in dieback is understudied, despite interactions among carbon-water balances and nutrition. Here, we followed a comparative analysis of long-te...

The aboveground impacts of climate change receive extensive research attention, but climate change could also alter belowground processes such as the delicate balance between free‐living fungal decomposers and nutrient‐scavenging mycorrhizal fungi that can inhibit decomposition through a mechanism called the Gadgil effect. We investigated how clima...

We carried out a 4-year manipulative field experiment in a semiarid shrubland in Southeastern Spain to assess the impacts of experimental warming (W), rainfall reduction (RR) and their combination (W+RR) on the composition and diversity of arbuscular mycorrhizal fungal (AMF) communities in rhizosphere soil using singlemolecule real-time (SMRT) DNA...

Aims Harsh edaphic environments harbor species with different soil affinities. Plant’s responses to specific edaphic constraints may be compromised against responses to prevalent stresses shared with other semi-arid environments. We expect that species with high edaphic affinity may show traits to overcome harsh soil properties, while species with...

Warming‐induced desiccation of the fertile topsoil layer could lead to decreased nutrient diffusion, mobility, mineralization and uptake by roots. Increased vertical decoupling between nutrients in topsoil and water availability in subsoil/bedrock layers under warming could thereby reduce cumulative nutrient uptake over the growing season. We used...

Water is the most limiting factor in dryland ecosystems, and plants are adapted to cope with this constraint. Particularly vulnerable are phreatophytic plants from groundwater-dependent ecosystems (GDEs) in regions that have to face water regime alterations due to the impacts of climate and land-use changes. We investigated two aspects related to t...

Root access to bedrock water storage or groundwater is an important trait allowing plant survival in seasonally dry environments. However, the degree of coordination between water uptake depth, leaf‐level water‐use efficiency (WUEi) and water potential in drought‐prone plant communities is not well understood. We conducted a 135‐d rainfall exclusio...

The Popocatépetl volcano resumed its eruptive activity in 1994 and is still active. The largest eruption recorded during this new stage of activity occurred in December 2000. We traced the volcanic activity signal in tree-rings from Pinus hartwegii trees located in the north slope of the volcano, located at ∼3 km from the volcanic cone. Annually re...

Nutrient resorption is the process whereby plants recover nutrients from senescing leaves and reallocate them to storage structures or newer tissues. Elemental resorption of foliar N and P has been shown to respond to temperature and precipitation but we know remarkably little about the influence of warming and drought on the resorption of these an...

Climate change will increase heat and drought stress in many dryland areas, which could reduce soil nutrient availability for plants and aggravate nutrient limitation of primary productivity. Any negative impacts of climate change on foliar nutrient contents would be expected to negatively affect the photosynthetic capacity, water use efficiency an...

The role of soil fertility in modulating plant water utilization from rainfall pulses under dryland conditions is poorly understood. Moreover, the effectiveness of soil fertilization in drylands is difficult to ensure due to immobilization of nutrients such as phosphorus and micronutrients. The use of foliar fertilization could overcome these diffi...

Drought-induced forest dieback is causing reductions in productivity, increasing tree mortality and impairing terrestrial carbon uptake worldwide. However, the role played by long-term nutrient imbalances during drought-induced dieback is still unknown. To improve our knowledge on the relationships between dieback and nutrient imbalances, we analys...

Leaf litter decomposition is a key component of global biogeochemical cycles that influence soil carbon storage, nutrient availability and plant productivity. Ongoing climate change will lead to warmer and drier conditions in many dryland regions, potentially affecting litter decomposition and nutrient dynamics. Climate change effects can be direct...

The suitable phytomanaging of mine tailings not only requires an improvement of soil fertility but also the assessment of the biotic interactions between the selected plant species. This study aimed to evaluate the effect of an organic amendment on the response of two plant species of contrasting habit, a tree, Pinus halepensis and a grass, Piptath...

Resource availability for plants in dry ecosystems is largely controlled by the occurrence of irregular rainfall pulses, which means that they must be able to rapidly take up water and nutrients during the narrow windows of opportunity following rainfall when resources become available. Epiphytic plant communities in Mediterranean climates provide...

Climatic dryness imposes limitations on vascular plant growth by reducing stomatal conductance, thereby decreasing CO2 uptake and transpiration. Given that transpiration-driven water flow is required for nutrient uptake, climatic stress-induced nutrient deficit could be a key mechanism for decreased plant performance under prolonged drought. We pro...

The leaf economics spectrum (LES) describes covariation of traits relevant to carbon and nutrient economics across plant species, but much less is known about the relationship between the LES and leaf water economy. We propose an approach combining the measurement of two leaf traits related to water use economy, leaf carbon (δ13C) and oxygen (δ18O)...

Warmer and drier conditions associated with ongoing climate change will increase abiotic stress for plants and mycorrhizal fungi in drylands world‐wide, thereby potentially reducing vegetation cover and productivity and increasing the risk of land degradation and desertification. Rhizosphere–microbial interactions and feedbacks are critical process...

The objective of this work was to evaluate the effects of plant interactions (intra- and interspecific) on the growth and metal(loid) uptake of the tree species Pinus halepensis to determine its suitability for the phytomanagement of semiarid mine tailings. The pioneer tailings colonizer grass Piptatherum miliaceum was selected for assessing inters...

This chapter sets out the approach and research methods used to assess the plant types and species that grow in different parts of the targeted Mediterranean landscape and that could potentially be used in restoration strategies and mitigation of desertified and degraded land. Species occurring in the various land units in the study catchment in so...

Warmer and drier conditions associated with climate change could reduce vegetation productivity and cover in Mediterranean-type drylands, thus increasing the risk of land degradation and desertification. We conducted a four-year manipulative study in a semiarid shrubland to assess the effects of experimental warming and rainfall reduction on the pe...

Plant facilitative interactions enhance co-occurrence between distant relatives, partly due to limited overlap in resource requirements. We propose a different mechanism for the coexistence of distant relatives based on positive interactions of nutrient sharing. Nutrients move between plants following source-sink gradients driven by plant traits th...

Soil water retention capacity, hydraulic conductivity, and permeability are primarily determined by texture (sand, silt, clay contents), structure (bulk density and porosity), and organic matter content. Mycorrhizal fungi play a subtle but important role in shaping the hydraulic properties of soils through multiple direct and indirect mechanisms re...

Soil water retention capacity, hydraulic conductivity and permeability are primarily determined by texture (sand: silt: clay contents), structure (bulk density and porosity) and organic matter content. Mycorrhizal fungi play a subtle but important role in shaping the hydraulic properties of soils through multiple direct and indirect mechanisms rela...

Background and aims Interplant transfer of hydraulically redistributed water (HRW) can take place via mycorrhizal hyphal networks linking the roots of neighboring plants. We conducted a mesocosm experiment to evaluate the influence of reduced extraradical hyphal lengths on interplant HRW transfer. Methods Ectomycorrhizal Pinus halepensis saplings a...

We investigated the magnitude and drivers of spatial variability in soil and plant δ ¹⁵ N across the landscape in a topographically complex semiarid ecosystem. We hypothesized that large spatial heterogeneity in water availability, soil fertility and vegetation cover would be positively linked to high local‐scale variability in δ ¹⁵ N. We measured...

Whereas warming enhances plant nutrient status and photosynthesis in most terrestrial ecosystems, dryland vegetation is vulnerable to the likely increases in evapotranspiration and reductions in soil moisture caused by elevated temperatures. Any warming-induced declines in plant primary production and cover in drylands would increase erosion, land...

Appendix S1. Supporting information figures and tables.

Reforestation is common to restore degraded ecosystems, but tree-species choice often neglects ongoing environmental changes. We evaluated the performance of planted seedlings of two oak species at two sites in a Mediterranean mountain (Sierra Nevada, SE Spain): one located within the current altitudinal forest range (1,600–1,760 m), and one above...

Background and aims Aleppo pine (Pinus halepensis Mill.) is a widely used species for restoring degraded semiarid areas, but its use for the revegetation of metal(loid) polluted soils has not been thoroughly investigated. The main goal of this research was to study the ecophysiological status and elemental composition of spontaneous populations of...

Plant–plant interactions shape the structure and composition of plant communities, but shifts in interaction outcomes might occur in the face of ongoing climate change. We assessed the influence of P inus halepensis plantations on the long‐term ecophysiological performance of understorey vegetation, by conducting a retrospective comparison (1989–20...

Mycorrhizae ('fungus roots') are an almost universal terrestrial mutualism between plant roots and certain soil fungi, the oldest fossil evidence of which is in the rhizomes of early vascular plants from approximately 400. My ago. It is widely accepted that most mycorrhizae are mutualistic and provide soil resources that are otherwise unavailable t...

In semiarid Mediterranean ecosystems epiphytic plant species are practically absent and only some species of palm-trees can support epiphytes growing in their lower crown area, such as Phoenix dactylifera L. (date palm). In this study we focused in Sonchus tenerrimus L. plants growing as facultative epiphytes in P. dactylifera and its terrestrial f...

Sustainable farming practices can be beneficial or detrimental to crop production in the short-term, which will strongly determine their appeal to farmers. We evaluated the effects of several sustainable practices on soil properties, plant nutrition and ecophysiology and crop yield in a semiarid agroecosystem. A three-year randomised experiment was...

Drought-induced events of massive tree mortality appear to be increasing worldwide. Species-specific vulnerability to drought mortality may alter patterns of species diversity and affect future forest composition. We have explored the consequences of the extreme drought of 2005, which caused high sapling mortality (approx. 50 %) among 10-year-old s...

Unraveling belowground processes, especially root-soil interactions whereby plants acquire water and nutrients, remains one of the greatest challenges in plant ecology. Stable isotopic composition of xylem water and leaf tissues coupled with soil and different water sources provide valuable insights on fundamental plant processes such as plant wate...

Purpose Soil respiration (R s) is controlled by abiotic soil parameters interacting with characteristics of the vegetation and the soil microbial community. Few studies have attempted a comprehensive approach that simultaneously addresses the roles of all the major factors known to influence R s. Our goal was to explore the links between heterogene...

Variation in the stable carbon and oxygen isotope composition (δ ¹³ C, Δ ¹⁸ O) of co‐occurring plant species may reflect the functional diversity of water use strategies present in natural plant communities. We investigated the patterns of water use among 10 coexisting plant species representing diverse taxonomic groups and life forms in semiarid s...

Background and aims We conducted a mesocosm study to investigate the extent to which the process of hydraulic redistribution of soil water by plant roots is affected by mycorrhizosphere disturbance. Methods We used deuterium-labeled water to track the transfer of hydraulically lifted water (HLW) from well-hydrated donor oaks (Quercus agrifolia Nee....

Background and aims Plant productivity in drylands is frequently co-limited by water and nutrient availability, and thus is expected to be influenced by ongoing changes in rainfall regime and atmospheric nutrient deposition. Roadside grasslands are widespread worldwide, represent ecologically meaningful examples of highly dynamic anthropogenic ecos...

We investigated whether stand structure modulates the long-term physiological performance and growth of Pinus halepensis Mill. in a semiarid Mediterranean ecosystem. Tree radial growth and carbon and oxygen stable isotope composition of latewood (δ13CLW and δ18OLW, respectively) from 1967 to 2007 were measured in P. halepensis trees from two sharpl...

Background/Question/Methods Soil moisture availability is a major driver of mycorrhizal root colonization. Studies have shown that ectomycorrhizal (EMF) colonization of plant roots can be negatively affected by drought, whereas arbuscular mycorrhizal fungi (AMF) may be capable of enduring more negative soil water potentials. What is less well kno...

Silvicultural thinning usually improves the water status of remaining trees in water-limited forests. We evaluated the usefulness of a dual stable isotope approach (δ¹³C, δ¹⁸O) for comparing the physiological performance of remaining trees between forest stands subjected to two different thinning intensities (moderate versus heavy) in a 60-year-old...

Conservation tillage promotes the accretion of soil organic matter and often leads to improved soil fertility and moisture availability. However, few studies have looked at the physiological response of crop plants to different tillage practices. It was therefore hypothesised that measuring the nutrient concentrations and stable isotope composition...