scholarly journals Widespread holm oak dieback in Mediterranean forests: the roles of carbon stress and hydraulic failure under recurrent drought events

2020 ◽  
Author(s):  
Cecilia Brunetti ◽  
Antonella Gori ◽  
Francesca Alderotti ◽  
Raffaella Balestrini ◽  
Fabiano Sillo ◽  
...  
Keyword(s):  
Holm Oak ◽  
Mediterranean Forests ◽  
Hydraulic Failure ◽  
Carbon Stress

Root biomass of Quercusilex in a montane Mediterranean forest

1991 ◽  
Vol 21 (12) ◽  
pp. 1771-1778 ◽  
Author(s):  
Josep Canadell ◽  
Ferran Rodà
Keyword(s):  
Root Biomass ◽  
Temperate Forest ◽  
Light Availability ◽  
Belowground Biomass ◽  
Holm Oak ◽  
Oak Forests ◽  
Mediterranean Forests ◽  
Mesic Site ◽  
Shallow Soils ◽  
Root:Shoot Ratios

Biomass allocation to roots was studied in holm oak (Quercusilex L.), a dominant evergreen tree in broad-leaved sclerophyllous Mediterranean forests. The root systems of 32 single-stemmed holm oaks growing in shallow soils on largely unfissured bedrock were excavated in a mesic site and a xeric site in the Montseny Mountains (northeast Spain). Individual root:shoot biomass ratios (roots with diameter <1 cm not included) of single-stemmed trees were significantly higher in the xeric site (mean 0.45) than in the mesic site (mean 0.37), probably reflecting the lower water availability and higher light availability in the xeric site. It is concluded that single-stemmed holm oaks have higher root:shoot ratios than most temperate forest trees, particularly so when growing on a xeric site. Root:shoot ratios of single-stemmed trees were not linearly correlated with dbh. Allometric regressions of root biomass on dbh did significantly differ between sites. Roots <1 cm in diameter were sampled with soil cores in the mesic site. Holm oaks ≥5 cm dbh in a stand dominated by single-stemmed trees on the mesic site had an aboveground biomass of 160 t/ha and a belowground biomass of 63 t/ha. The belowground biomass was composed of 30 t/ha of root crowns plus roots >5 cm in diameter, 17 t/ha of roots 1–5 cm in diameter, and 16 t/ha of roots <1 cm in diameter. The xeric stand was dominated by multistemmed holm oaks with massive root crowns developed after repeated coppicing. Three multistemmed trees were excavated, yielding a mean root:shoot ratio of 1.2. Through resprouting from root crowns, managed or disturbed holm oak forests can accumulate a belowground biomass greater than that displayed aboveground: 91 t/ha (excluding roots <1 cm in diameter) and 79 t/ha, respectively, in our xeric stand.

scholarly journals Canopy recovery after drought dieback in holm-oak Mediterranean forests of Catalonia (NE Spain)

2004 ◽  
Vol 10 (12) ◽  
pp. 2092-2099 ◽  
Author(s):  
Francisco Lloret ◽  
Daniel Siscart ◽  
Carles Dalmases
Keyword(s):  
Holm Oak ◽  
Mediterranean Forests ◽  
Ne Spain

Three new species of Stibeutes and Gnotus (Hymenoptera: Ichneumonidae) from holm-oak and cork-oak Mediterranean forests

2004 ◽  
Vol 35 (1) ◽  
pp. 65-78
Author(s):  
Estefanía Hernández-Rodríguez ◽  
Santiago Bordera
Keyword(s):  
New Species ◽  
Species Group ◽  
Cork Oak ◽  
Holm Oak ◽  
Oak Forest ◽  
Mediterranean Forests ◽  
Three New Species ◽  
Cork Oak Forest ◽  
First Time

AbstractThe new species Stibeutes hirsutus, S. calderonae and Gnotus klausi from Spanish holm-oak and cork-oak woods are described and illustrated. Data on their habitat and the phenology of S. hirsutus are reported. The species S. breviareolatus collected in a cork-oak forest is recorded for the first time for Spain. New keys for the Gnotus tenuipes species group and for the Spanish species of Stibeutes are provided.

scholarly journals Holm oak fecundity does not acclimate to a drier world

2021 ◽  
Author(s):  
Iris Le Roncé ◽  
Jordane Gavinet ◽  
Jean‐Marc Ourcival ◽  
Florent Mouillot ◽  
Isabelle Chuine ◽  
...  
Keyword(s):  
Holm Oak

Hydraulic segmentation does not protect stems from acute water loss during fire

2021 ◽  
Author(s):  
William A Hoffmann ◽  
Amanda C Rodrigues ◽  
Nicholas Uncles ◽  
Lorenzo Rossi
Keyword(s):  
Water Uptake ◽  
Water Loss ◽  
High Water ◽  
Fire Plume ◽  
Magnolia Grandiflora ◽  
Hydraulic Failure ◽  
Factors Influencing ◽  
Wide Range ◽  
Transport Path ◽  
Measured Water

Abstract The heat plume associated with fire has been hypothesized to cause sufficient water loss from trees to induce embolism and hydraulic failure. However, it is unclear whether the water transport path remains sufficiently intact during scorching or burning of foliage to sustain high water loss. We measured water uptake by branches of Magnolia grandiflora while exposing them to a range of fire intensities, and examined factors influencing continued water uptake after fire. Burning caused a 22-fold mean increase in water uptake, with greatest rates of water loss observed at burn intensities that caused complete consumption of leaves. Such rapid uptake is possible only with steep gradients in water potential, which would likely result in substantial cavitation of xylem and loss of conductivity in intact stems. Water uptake continued after burning was complete, and was greatest following burn intensities that killed leaves but did not consume them. This post-fire uptake was mostly driven by rehydration of the remaining tissues, rather than evaporation from the tissues. Our results indicate that the fire-plume hypothesis can be expanded to include a wide range of burning conditions experienced by plants. High rates of water loss are sustained during burning, even when leaves are killed or completely consumed.

scholarly journals Canopy Height Estimation in Mediterranean Forests of Spain with TanDEM-X Data

2021 ◽  
pp. 1-1
Author(s):  
Cristina Gomez ◽  
Juan M Lopez-Sanchez ◽  
Noelia Romero-Puig ◽  
Jianjun Zhu ◽  
Haiqiang Fu ◽  
...  
Keyword(s):  
Canopy Height ◽  
Mediterranean Forests ◽  
Height Estimation

scholarly journals Comparison of Satellite and Drone-Based Images at Two Spatial Scales to Evaluate Vegetation Regeneration after Post-Fire Treatments in a Mediterranean Forest

2021 ◽  
Vol 11 (12) ◽  
pp. 5423
Author(s):  
Jose Luis Martinez ◽  
Manuel Esteban Lucas-Borja ◽  
Pedro Antonio Plaza-Alvarez ◽  
Pietro Denisi ◽  
Miguel Angel Moreno ◽  
...  
Keyword(s):  
Vegetation Cover ◽  
Spatial Scales ◽  
Soil Surface ◽  
Plant Biodiversity ◽  
Mediterranean Forests ◽  
Experimental Conditions ◽  
Vegetation Growth ◽  
Surface Conditions ◽  
Vegetation Regeneration ◽  
Forest Managers

The evaluation of vegetation cover after post-fire treatments of burned lands is important for forest managers to restore soil quality and plant biodiversity in burned ecosystems. Unfortunately, this evaluation may be time consuming and expensive, requiring much fieldwork for surveys. The use of remote sensing, which makes these evaluation activities quicker and easier, have rarely been carried out in the Mediterranean forests, subjected to wildfire and post-fire stabilization techniques. To fill this gap, this study evaluates the feasibility of satellite (using LANDSAT8 images) and drone surveys to evaluate changes in vegetation cover and composition after wildfire and two hillslope stabilization treatments (log erosion barriers, LEBs, and contour-felled log debris, CFDs) in a forest of Central Eastern Spain. Surveys by drone were able to detect the variability of vegetation cover among burned and unburned areas through the Visible Atmospherically Resistant Index (VARI), but gave unrealistic results when the effectiveness of a post-fire treatment must be evaluated. LANDSAT8 images may be instead misleading to evaluate the changes in land cover after wildfire and post-fire treatments, due to the lack of correlation between VARI and vegetation cover. The spatial analysis has shown that: (i) the post-fire restoration strategy of landscape managers that have prioritized steeper slopes for treatments was successful; (ii) vegetation growth, at least in the experimental conditions, played a limited influence on soil surface conditions, since no significant increases in terrain roughness were detected in treated areas.

scholarly journals Effects of Windthrows on Forest Cover, Tree Growth and Soil Characteristics in Drought-Prone Pine Plantations

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 817
Author(s):  
Jesús Julio Camarero ◽  
Michele Colangelo ◽  
Antonio Gazol ◽  
Manuel Pizarro ◽  
Cristina Valeriano ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Forest Cover ◽  
Normalized Difference Vegetation Index ◽  
Pinus Halepensis ◽  
Soil Characteristics ◽  
Tree Cover ◽  
Mediterranean Forests ◽  
Soil Microbial Community Structure ◽  
Soil Features ◽  
Disturbance Intensity

Windstorms are forest disturbances which generate canopy gaps. However, their effects on Mediterranean forests are understudied. To fill that research gap, changes in tree, cover, growth and soil features in Pinus halepensis and Pinus sylvestris plantations affected by windthrows were quantified. In each plantation, trees and soils in closed-canopy stands and gaps created by the windthrow were sampled. Changes in tree cover and radial growth were assessed by using the Normalized Difference Vegetation Index (NDVI) and dendrochronology, respectively. Soil features including texture, nutrients concentration and soil microbial community structure were also analyzed. Windthrows reduced tree cover and enhanced growth, particularly in the P. halepensis site, which was probably more severely impacted. Soil characteristics were also more altered by the windthrow in this site: the clay percentage increased in gaps, whereas K and Mg concentrations decreased. The biomass of Gram positive bacteria and actinomycetes increased in gaps, but the biomass of Gram negative bacteria and fungi decreased. Soil gaps became less fertile and dominated by bacteria after the windthrow in the P. halepensis site. We emphasize the relevance of considering post-disturbance time recovery and disturbance intensity to assess forest resilience within a multi-scale approach.

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