Raquel Lobo-do-Vale

University of Lisbon | UL · Forest Research Center (CEF)

Understory woody plants are increasing in open Mediterranean oak open woodlands as a result of a number of factors, including land abandonment and/or less active management. This change in vegetation cover has many implications—such as increased fire hazard, changes in plant and animal biodiversity, reduced ability of oak trees to regenerate, and a...

Mediterranean ecosystems are threatened by climate change and shrub encroachment. An increase in shrub cover can intensify the competition for water, aggravating the impacts of drought on ecosystem functioning. The effects of shrubs can be positive or negative, depending on the shrub species and density. We used a Mediterranean cork oak (Quercus su...

Mediterranean ecosystems face threats from both climate change and shrub invasion. As shrub cover increases, competition for water intensifies, exacerbating the negative effects of drought on ecosystem functioning. However, research into the combined effects of drought and shrub invasion on tree carbon assimilation has been limited. We used a Medit...

Recent advances in plant hydraulics indicate that the hydraulic behaviour (i.e. the degree of isohydricity) of plants might be more flexible than previously thought. While there is now evidence that seasonal abiotic factors, such as vapour pressure deficit or photosynthetically active photon flux density, can modify the isohydricity in plants, less...

Understanding of plant hydraulic strategies (i.e. the degree of iso‐/anisohydricity) is crucial to predict the response of plants to changing environmental conditions such as climate‐change induced extreme drought. Several abiotic factors, including evaporative demand, have been shown to seasonally modify the isohydricity of plants. However, the im...

The impact of various environmental stressors, such as plant invasion and extreme drought is increasing in many ecosystems around the globe. Mediterranean ecosystems have especially been affected by both stressors in recent decades. Thus, we conducted a precipitation and shrub invasion manipulation experiment in a Mediterranean cork oak (Quercus su...

Interaction effects of different stressors, such as extreme drought and plant invasion, can have detrimental effects on ecosystem functioning and recovery after drought. With ongoing climate change and increasing plant invasion, there is an urgent need to predict the short‐ and long‐term interaction impacts of these stressors on ecosystems. We esta...

Knowledge of plant hydraulic strategies (isohydric vs anisohydric) is crucial to predict the response of plants to changing environmental conditions, such as climate-change induced extreme drought. Several abiotic factors, such as evaporative demand, have been shown to seasonally modify the isohydricity of plants, however, the impact of biotic fact...

The impact of interacting global change stressors on terrestrial ecosystems is hard to predict due to non-linear, amplifying, neutral or even buffering interaction effects. We investigated the effects of drought and plant invasion on Mediterranean cork oak (Quercus suber L.) ecosystem functioning and recovery with a combined rain exclusion (30-45 %...

Sap flow measurements are essential for estimating whole plant- and ecosystem water use. Yet, several challenges and pitfalls exist in the application and analysis of sap flow data, such as the determination of zero-flow (ΔTmax). Here, we used different methods to estimate ΔTmax and their effect on the determination of sap flow of Quercus suber L....

The impact of atmospheric reactive nitrogen (Nr) deposition on carbon (C) sequestration in soils and biomass of unfertilized, natural, semi-natural and forest ecosystems has been much debated. Many previous results of this dC/dN response were based on changes in carbon stocks from periodical soil and ecosystem inventories, associated with estimates...

Our knowledge on the biosynthesis of several biogenic volatile organic compounds (BVOCs) is still limited. In this regard, natural abundant stable carbon isotope ratios (δ13C) of BVOCs may provide a powerful tool to evaluate different metabolic pathways. In the present study, BVOC emissions, and their carbon isotope composition from two Mediterrane...

The impact of atmospheric reactive nitrogen (Nr) deposition on carbon (C) sequestration in soils and biomass of unfertilised, natural, semi-natural and forest ecosystems has been much debated. Many previous results of this dC / dN response were based on changes in carbon stocks from periodical soil and ecosystem inventories, associated with estimat...

Mediterranean ecosystems are hotspots for climate change, as the highest impacts are forecasted for the Mediterranean region, mainly by more frequent and intense severe droughts. Plant phenology is a good indicator of species' responses to climate change. In this study, we compared the spring phenology of cork oak trees (Quercus suber), an evergree...

The objective of this study was to evaluate the litterfall deposition, the decomposition rate (KL) and the water holding capacity (WHC) of litter stored in the soil in two areas degraded by mining submitted to different methods of forest restoration: induction of natural regeneration (NR) and planting seedlings of native forest species (PS) with a...

Drought is a major environmental constrain affecting plant performance and survival, particularly in Mediterranean ecosystems. Terpenoids may play a protective role under these conditions, however, observations of drought effects on plant terpenoid emissions are controversial ranging from decreased emissions to unaffected or increased release of te...

Mediterranean vegetation emits a wide range of biogenic volatile organic compounds (BVOCs) among which isoprenoids present quantitatively the most important compound class. Here, we investigated the isoprenoid emission from two Mediterranean Cistaceae shrubs, Halimium halimifolium and Cistus ladanifer, under controlled and natural conditions, respe...

Many studies have reported that hydraulic properties vary considerably between tree species, but little is known about their intraspecific variation and, therefore, their capacity to adapt to a warmer and drier climate. Here, we quantify phenotypic divergence and clinal variation for embolism resistance, hydraulic conductivity and branch growth, in...

Species, studied populations and latitude and climate conditions per population. Coordinates are provided in decimal degrees. MAT: annual mean temperature (°C); MAP: annual sum of precipitation (mm); PET: annual sum of potential evapotranspiration (mm); AI: aridity index (calculated as MAP/PET); T_Sum: average temperature of June, July and August (...

P50 (MPa) versus xylem-specific hydraulic conductivity (Ks, kg m-1 MPa-1 s-1) measured for each tree, for the two species for which P50/Ks correlations were statistically significant (Picea abies and Pinus sylvestris). (DOCX)

Natural distribution areas of the studied species (dark grey) in Western Europe (www.euforgen.org). The triangles represent the populations and sites sampled for this study. CR: Czech Republic; PO: Portugal; NE: The Netherlands; FI-RU: Finland-Ruotsinkylä; FI-VA: Finland-Värriö; FI-HYY: Finland-Hyytiälä; IT: Italy; SW-LOE: Switzerland-Loetschental;...

Vulnerability curves of each individual and species. Black dot are the raw measure of percentage of loss of conductivity (PLC in %) along the negative pressure gradient (in MPa). The red line connects the PLC fitted by the Pammenter model to the measured xylem pressure. All adjustments were statistically significant. (DOCX)

Trees scale leaf ( A L ) and xylem ( A X ) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in A L : A X balance in response to climate conditions, but whether trees of different species acclimate in A L : A X in similar ways over their entire (continental) distributions is unknown....

Tree mortality is a key factor influencing forest functions and dynamics, but our understanding of the mechanisms leading to mortality and the associated changes in tree growth rates are still limited. We compiled a new pan-continental tree-ring width database from sites where both dead and living trees were sampled (2,970 dead and 4,224 living tre...

Phloem osmolality and its components are involved in basic cell metabolism, cell growth, and in various physiological processes including the ability of living cells to withstand drought and frost. Osmolality and sugar composition responses to environmental stresses have been extensively studied for leaves, but less for the secondary phloem of plan...

Cork oak woodlands (montado) are agroforestry systems distributed all over the Mediterranean basin with a very important social, economic and ecological value. A generalized cork oak decline has been occurring in the last decades jeopardizing its future sustainability. It is unknown how loss of tree cover affects microbial processes that are consum...

Determining climate change feedbacks from tropical rainforests requires an understanding of how carbon gain through photosynthesis and loss through respiration will be altered. One of the key changes that tropical rainforests may experience under future climate change scenarios is reduced soil moisture availability. In this study we examine if and...

Background and aims During the recent decades, cork oak (Q. suber) mortality has been increasing in Mediterranean oak woodland endangering the economical and environmental sustainability of the “montado” ecosystem. This fact in combination with climate change and conversion of forestland to pasture may significantly affect the soil-atmosphere green...

Forests in Europe are changing due to interactions between climate change, nitrogen (N) deposition and new forest management practices. The concurrent impact on the forest greenhouse gas (GHG) balance is at present difficult to predict due to a lack of knowledge on controlling factors of GHG fluxes and response to changes in these factors. To impro...

Climate change and air pollution, interact with altering forest management and land-use change to produce short and long-term changes to forest in Europe. The impact of these changes on the forest greenhouse gas (GHG) balance is currently difficult to predict. To improve the mechanistic understanding of the ongoing changes, we studied the response...

A 10–20% decrease in annual precipitation is predicted in the Mediterranean basin, and in particular to the Ibe- rian Peninsula, with foreseen effects on the exchange of soil-atmosphere greenhouse gases (GHGs; CO2, CH4, and N2O). To simulate this scenario, we setup an experimental design in the particularly dry period of 2008–2009 us- ing rainfall...

Understanding the responses of cork oak (Quercus suber L.) to actual and predicted summer conditions is essential to determine the future sustainability of cork oak woodlands in Iberia. Thermal imaging may provide a rapid method for monitoring the extent of stress. The ecophysiology of cork trees was studied over three years. Three treatments were...

*The effects of drought on the Amazon rainforest are potentially large but remain poorly understood. Here, carbon (C) cycling after 5 yr of a large-scale through-fall exclusion (TFE) experiment excluding about 50% of incident rainfall from an eastern Amazon rainforest was compared with a nearby control plot. *Principal C stocks and fluxes were inte...

1. The Amazon region may experience increasing moisture limitation over this century. Leaf dark respiration (R) is a key component of the Amazon rain forest carbon (C) cycle, but relatively little is known about its sensitivity to drought. 2. Here, we present measurements of R standardized to 25 °C and leaf morphology from different canopy heights...

The flux (R(s)) and carbon isotopic composition (delta(13)C (Rs)) of soil respired CO (2) was measured every 2 h over the course of three diel cycles in a Mediterranean oak woodland, together with measurements of the delta(13)C composition of leaf, root and soil organic matter (delta(13)C (SOM)) and metabolites. Simulations of R(s) and delta(13)C (...

Sap flux density in branches, leaf transpiration, stomatal conductance and leaf water potentials were measured in 16-year-old Quercus suber L. trees growing in a plantation in southern Portugal to understand how evergreen Mediterranean trees regulate water loss during summer drought. Leaf specific hydraulic conductance and leaf gas exchange were mo...

Studies were conducted to examine changes in soil (Ψs) and plant water status during summer in a 16-year old Quercus suber plantation in southern Portugal. Continuous measurements were conducted between May 2003 and August 2004, while discontinuous measurements were conducted on a monthly basis between May and September 2003 and repeated between Ma...

The aim of this study was to identify the sources and depth of water uptake by 15-years old Quercus suber L. trees in southern Portugal under a Mediterranean climate, measuring δ18O and δD in the soil–plant-atmosphere continuum. Evidence for hydraulic lift was substantiated by the daily fluctuations observed in Ψs at 0.4 and 1m depth and supported...

Climate modelling studies predict that the rain forests of the Eastern Amazon basin are likely to experience reductions in rainfall of up to 50% over the next 50-100 years. Efforts to predict the effects of changing climate, especially drought stress, on forest gas exchange are currently limited by uncertainty about the mechanism that controls stom...

Estudámos os efeitos da disponibilidade hídrica em parâmetros fisiológicos relacionados com o estado hídrico foliar e a assimilação de carbono em sobreiros de 15 anos de idade, na Herdade da Mitra, Évora. A disponibilidade hídrica foi experimentalmente manipulada, consistindo em 3 tratamentos: Wet (adição de 20% da precipitação anual), Dry (exclusã...