Pinus Pinea Forests Research Articles

The Interplay of the Tree and Stand-Level Processes Mediate Drought-Induced Forest Dieback: Evidence from Complementary Remote Sensing and Tree-Ring Approaches

Drought-induced forest dieback can lead to a tipping point in community dominance, but the coupled response at the tree and stand-level response has not been properly addressed. New spatially and temporally integrated monitoring approaches that target different biological organization levels are needed. Here, we compared the temporal responses of dendrochronological and spectral indices from 1984 to 2020 at both tree and stand levels, respectively, of a drought-prone Mediterranean Pinus pinea forest currently suffering strong dieback. We test the influence of climate on temporal patterns of tree radial growth, greenness and wetness spectral indices; and we address the influence of major drought episodes on resilience metrics. Tree-ring data and spectral indices followed different spatio-temporal patterns over the study period (1984–2020). Combined information from tree growth and spectral trajectories suggests that a reduction in tree density during the mid-1990s could have promoted tree growth and reduced dieback risk. Additionally, over the last decade, extreme and recurrent droughts have resulted in crown defoliation greater than 40% in most plots since 2019. We found that tree growth and the greenness spectral index were positively related to annual precipitation, while the wetness index was positively related to mean annual temperature. The response to drought, however, was stronger for tree growth than for spectral indices. Our study demonstrates the value of long-term retrospective multiscale analyses including tree and stand-level scales to disentangle mechanisms triggering and driving forest dieback.

Measurement of the Threatened Biodiversity Existence Value Output: Application of the Refined System of Environmental-Economic Accounting in the Pinus pinea Forests of Andalusia, Spain

Are we able to determine the existence value output generated for society through the preservation of wild species threatened with extinction? In this article we defend the theory that the service of preserving threatened species with risk of extinction is an existence value output with a hidden transaction price if it can be established that there are consumer or state willingness to pay an additional tax above the government total cost to avoid an increase in one threatened species in relation to the number recorded at the opening of the accounting period. This output is estimated by adding the total cost and the additional consumer tax which the consumers state that they are willing to pay through a choice experiment survey. Our refined monetary System of Environmental-Economic Accounting (rSEEA) extends the existence value output concept and valuation principles recommended by the United Nations. In this paper, this rSEEA was applied to Pinus pinea forests in protected as well as non-protected areas of Andalusia, Spain in 2010. The results show that the net value added from protected areas is 40% higher than that from non-protected areas. It is incidental that the environmental benefits in both areas coincide.

Vegetation dynamics and regeneration of Pinus pinea forests in Mount Lebanon: Towards the progressive disappearance of pine

Pinus pinea is a species of great economic and ecological importance in Lebanon, but there is a lack of knowledge about the distribution of the pine forests, their vegetation dynamics and regeneration. Our study aims to produce the first classification of the pine stands according to their floristic composition and the abiotic factors of the Mount Lebanon region and to analyse natural pine recruitment. Floristic composition, environmental and soil factors as well as stand dendrometric characteristics and woody seedling regeneration were recorded on fifty plots distributed in the main stone pine stands of the study area. Using canonical correspondence and clustering analyses, we classified pine stands into five groups which were mainly influenced by physiographic factors (altitude, slope, temperature, rainfall), nature of the bedrock, and evidence of human interventions. Most stone pine stands in Mount Lebanon were dense (849 stems.ha−1), old (81 years) with a high basal area (49 m2.ha−1). Pine regeneration was particularly scant, and the understory was dominated by the oak species: Quercus calliprinos, mainly and Quercus infectoria, secondarily. Based on these results, we concluded that the presence of stone pine and its persistence are linked to human actions. In the absence of human intervention, the stone pine stands will progressively disappear and be replaced by oak formations. Thus, an urgent management plan is required to favour pine regeneration to allow for the renewal of the pine stands in the Mount-Lebanon region.

Restorative urban forests: Exploring the relationships between forest stand structure, perceived restorativeness and benefits gained by visitors to coastal Pinus pinea forests

Forests are widely recognized as important landscape elements which contribute to human health and well-being. They provide benefits derived from direct and indirect experiences of contact with nature by reducing psychological and physical stress, thus creating positive feelings and facilitating the recovery of psychological resources. In order to establish or manage forests for recreational purposes, it is essential to know which forest stand structure features and indicators are linked to actual or perceived psychological restoration. The aim of this study is to evaluate the association between individual factors, perceived restorativeness, stand structure attributes and self-reported physical-psychological benefits obtained when visiting woodlands in urban or peri-urban areas especially coastal Italian stone pine forests using a quantile regression approach. Perceived restorativeness components such as ‘being-away’, ‘fascination’ and ‘compatibility’ emerged as significant predictors of visitors’ perceived psychological benefits, showing a positive and significant association in all of the quantiles under study. Stand density, measured by basal area per hectare of understory trees and shrubs negatively influences the perception of the benefits obtained, holding constant the other covariates.

Specific leaf area variations drive acclimation of Cistus salvifolius in different light environments

Cistus salvifolius L. is the most widely spread Cistus species around the Mediterranean basin. It colonizes a wide range of habitats growing from sea level to 1,800 m a.s.l., on silicolous and calcicolous soils, in sun areas as well as in the understory of wooded areas. Nevertheless, this species has been mainly investigated in term of its responsiveness to drought. Our aim was to understand which leaf traits allow C. salvifolius to cope with low-light environments. We questioned if biochemical and physiological leaf trait variations in response to a reduced photosynthetic photon flux density were related to leaf morphological plasticity, expressed by variations of specific leaf area (SLA) and its anatomical components (leaf tissue density and thickness). C. salvifolius shrubs growing along the Latium coast (41°43'N,12°18'E, 14 m a.s.l., Italy) in the open and in the understory of a Pinus pinea forest, were selected and the relationships between anatomical, gas exchange, chlorophyll (Chl) fluorescence, and biochemical parameters with SLA and PPFD variations were tested. The obtained results suggested long-term acclimation of the selected shrubs to contrasting light environments. In high-light conditions, leaf nitrogen and Chl contents per leaf area unit, leaf thickness, and Chl a/b ratio increased, thus maximizing net photosynthesis, while in shade photosynthesis, it was downregulated by a significant reduction in the electron transport rate. Nevertheless, the increased pigment-protein complexes and the decreased Chl a/b in shade drove to an increased light-harvesting capacity (i.e. higher actual quantum efficiency of PSII). Moreover, the measured vitality index highlighted the photosynthetic acclimation of C. salvifolius to contrasting light environments. Overall, our results demonstrated the morphological, anatomical, and physiological acclimation of C. salvifolius to a reduced light environment.

A model-based analysis of climate change vulnerability of Pinus pinea stands under multiobjective management in the Northern Plateau of Spain

Climate change is likely to heavily affect the provision of goods and services of Mediterranean forests. Our results strongly point out the need to develop adaptive strategies to mitigate the impact of climate change in order to assure the maintenance of the stands aiming their multifunctionality, more than their monetary revenues. Climate change in the Mediterranean region may heavily affect the provision of forest goods and services. Thus, options for adaptive forest management should be proposed. The aims of this study are to analyze the climate-related sensitivity of Pinus pinea forests in the Northern Plateau in Spain and to assess the vulnerability of multiobjective forest management to climate change by means of a simulation study, focusing on timber and cone production. The forest model PICUS v1.41, integrating a module for P. pinea cone and nut production, was used to simulate P. pinea stands at six site types under three forest management regimes (focus on timber, cones, and combined objectives) and five climate scenarios (current climate, four climate scenarios combining increases in temperature by +1 and +4 °C and decreases in precipitation by −10 and −30 %). Combined timber + cones management generated always the highest incomes from timber and cones. With the exception of the most productive site types, the combined timber + cone management produced also more timber volume than the cone and timber managements. Provisioning of ecosystem services decreased at all sites under all climate change scenarios. At very dry sites simulated, forests suffered from dieback events. Provisioning of ecosystem services decreased at all sites under all climate change scenarios analyzed and will be extremely limited on poor sites. Benefits and weaknesses of the assessment approach are discussed.

Modelling silviculture alternatives for managing Pinus pinea L.

A yield model was developed to simulate silviculture alternatives for Pinus pinea L. in north-east Spain (Catalonia). The model uses several functions to estimate the main silvicultural parameters at stand level and a disaggregation system to predict diameter distributions. From a network of 75 temporary plots a system of equations to predict stand variables was simultaneously fitted for two stand density types, namely low and high density stands, using the threestage least-squares method (3SLS). The diameter distributions were estimated by the Weibull distribution function using the parameter recovery method (PRM) and the method of moments. Based on this yield model, two silviculture alternatives were simulated for each stand density type and site class, resulting in 16 silviculture scenarios. The yield model and silviculture alternatives offer a management tool and a guide for the sustainable forest management of evenaged Pinus pinea forests in this region.

Structural characterization of charcoal size-fractions from a burnt Pinus pinea forest by FT-IR, Raman and surface-enhanced Raman spectroscopies

Charcoal is mainly composed by aromatic C but is characterized by several degrees of aromaticity, which complicate its identification and quantification in natural environments by conventional analyses. Charcoal is an almost ubiquitous component of soil, although often occurring in minor amounts. Hence, there is a great interest in studying the charcoal structure and understanding the behavior of charcoal in soils. In soil, it has been demonstrated that the chemical structure of charcoal is also dependant on its particle-size. In this paper we have applied infrared, normal Raman, SERS and SEF spectroscopies to study four size-fractions of charcoal (>2 mm, 2–1 mm, 1–0.5 mm and <0.5 mm) and their alkaline extracts from a burnt Pinus pinea forest. Second derivative FT-IR in agreement with the normal Raman spectroscopy have given information about the size of aromatic rings and the nature of substituted groups in size-fractions of charcoal. Carbon cluster size progressively decreased in the smallest fractions suggesting that higher graphitization and crystallization occurred in the coarsest fraction (>2 mm). The presence of organic N was well evidenced by the vibration of iso-cyanate and cyanamide groups in the fractions. This result is of great environmental importance because N may be immobilized in form of stable molecules like N-heterocyclic poliaromatic structures, and so persists in soils. The soluble organic C (SOC) extracted from charcoal size-fractions did not differ from the bulk charcoal in terms of IR and Raman spectra. Instead SERS and SEF provided further information regarding the ratio between the aromatic component and the aliphatic cross-linking one in studied fractions.

Ecological Features of the Pinus pinea Forests in the North-West Region of Turkey (Yalova)

In this study, the phytosociological structure and ecological features of the Pinus pinea forests in the Fýstýklý village of Yalova province in the north-west region of Turkey was investigated. From the phytogeographical point of view, it is situated in the Europe-Siberian floristic region. The vegetation of the study area was analyzed according to the Braun-Blanquet approach, and the plant associations were classified by considering the characteristic species. In this study, we will describe one plant association belonging to the forest vegetation types. Association and its higher units are as follows: Class: Quercetea ilicis Br.-Bl. 1947 Order: Quercetalia ilicis Br.-Bl. 1947 Alliance: Quercion ilicis Br.-Bl.(1931) 1936 Association: Lavandulo cariensis-Pinetum pineae ass. nova

Uso sperimentale di un isolato autoctono di Phlebiopsis gigantea: efficacia ed ecosostenibilità

Abstract: Heterobasidion annosum is an important pathogen, causing conifer root and butt rot. In Italy it attacks Pinus species both in mountain and in coastal plantations. Its diffusion is greatly enhanced during thinning, as its aerial inoculum germinates on new wounds or freshly cut butts. During thinning in the Castel Fusano Pinus pinea forest (Rome, Italy), in 2002-2005, a biological control trial was carried out for preventing new disease centres of a North American population of H. annosum, whose airborne spores were abundantly present. In particular, in February 2003 a suspension prepared with a native isolate of Phlebiopsis gigantea, previously studied in controlled environment, was applied on 23 butts. Observations on efficacy and persistence of the isolate in the treated stumps were carried out thirty months later. The pathogen was never detected in the stumps treated. Moreover, it was impossible to re-isolate from the upper part of the butts the P. gigantea individual isolate which had been profusely applied. These results confirm that the used isolate is an efficient biological control agent on P. pinea against the exotic isolates of H. annosum, and it is safe from an ecological point of view, as it does not trouble the natural succession of micro-organisms in butts.

Persistence of some pine pathogens in coarse woody debris and cones in a Pinus pinea forest

The persistence of Sphaeropsis sapinea, Leptographium serpens and Heterobasidion annosum s.s. in artificially inoculated pine branch pieces ( S. sapinea and L. serpens) and wood blocks ( L. serpens and H. annosum s.s.) was investigated in order to discuss the alternative of leaving coarse woody debris in stands of Italian stone pine ( Pinus pinea). Also, natural colonization by S. sapinea of pine cones of different ages was assessed. Methods used for inoculating branch pieces and wood blocks were highly effective for all fungi. Type of a forest stand in which branch pieces and wood blocks have been incubated did not affect the persistence of the pathogens in the inoculated samples. For branch pieces, the success of re-isolation of L. serpens dropped as the sample incubation time increased, while S. sapinea was always successfully (100%) re-isolated (even 12 months after the inoculation). L. serpens and H. annosum s.s. were re-isolated from most of the buried wood blocks (from more than 95% samples) up to 3 months following the inoculation. Of the observed P. pinea cones (in most cases, more than 2 years old), 74% were naturally infected by S. sapinea. All three investigated pathogens were able to survive in dead plant tissues for long periods of time (at least for several (3–12) months). The persistence of these pine-pathogenic species in dead plant material questions the feasibility of leaving coarse woody debris in managed Italian stone pine forests meant for landscape conservation and leisure activities.

The North American P group of Heterobasidion annosum s.l. is widely distributed in Pinus pinea forests of the western coast of central Italy

SummaryThe distribution of the North American P group of Heterobasidion annosum s.l., recently reported from a Pinus pinea forest in the surroundings of Rome, was studied using mating tests and DNA fingerprinting (mitochondrial DNA, random amplified microsatellite technique and two group‐specific markers). This fungus is present in several forests and small plantations along the Tyrrhenian coast of the Italian peninsula, within an area approximately 100 km long, extending from Fregene in the north to the National Park of Circeo in the south, and 27 km wide including the city of Rome. In pine forests of Castelporziano, Castel Fusano and Anzio, where US troops resided during the Second World War, the North American P group is more frequent than the European P group. The low number of mating alleles in the Italian population of the North American P group supports the hypothesis of its origin from a small number of introductions. The near 100% sexual compatibility between the North American and European P groups, together with inconsistencies in results obtained with different identification methods of these groups, suggests that hybridization between the North American and European P populations occurs occasionally.