Lila Ferrat

Long-Term Forest Dynamics and Land-Use Abandonment in the Mediterranean Mountains, Corsica, France

Human practices have had an impact on Mediterranean ecosystems for millennia, particularly through agricultural and pastoral activities. Since the mid-19th century, land-use abandonment has led to the expansion of shrubland and forest, especially in the mountainous areas of the northern Mediterranean basin. Knowledge of these factors is vital to understanding present forest patterns and predicting future forest dynamics in the Mediterranean mountains. We aimed to analyze and understand how land-use abandonment affected spatial modifications of landscapes in two study areas, 44,000 ha and 60,000 ha, located on the island of Corsica, France, representing a typical Mediterranean environment with chestnut forests. Our approach used land-cover archive documents from 1774, 1913, 1975, and 2000, and human population history, 1770 to present day, to describe landscape patterns following land-use abandonment. This research showed that dramatic changes in landscape at the two study areas were caused by the suspension of human influence and the interruption of traditional farming practices. Over the study period, both study sites showed significant reforestation of shrubland and cultivated areas marked by the presence of Quercus ilex forests (+3.40% yr-1 between 1975 and 2000) and by Pinus pinaster (+3.00% yr-1 between 1975 and 2000) at one study site that had experienced heavy rural exodus. At the same time, areas containing chestnut forests decreased by 50% between 1774 and 2000 (-0.09% yr-1 between 1774 and 1975 and -1.42% yr-1 between 1975 and 2000). Shrubland expansion remained limited at both study sites. Our study highlights the value of small-scale approaches for understanding the ecological consequences of land-use abandonment and present and future land-management decisions. Discussion concludes on the importance of working with long-term series for studies on resilience in social-ecological systems and on the consequences in terms of provision of ecosystem services.

Mercury and non-protein thiol compounds in the seagrass Posidonia oceanica.

Mercury concentrations, non-protein thiol levels and the enzyme activities of glutathione-S-transferase (GST) were measured in the blades and sheaths of the marine phanerogam Posidonia oceanica. The seagrass was collected in January and June and at three sites: the Bay of Rosignano (Italy) known for its mercury contamination, the north of the Lérins islands (Bay of Cannes, France), the Bay of Tonnara (Corsica, France). The two latter sites are considered as free of any known industrial inputs. Mercury concentrations and GST activities in both tissues were always higher in samples from Rosignano, particularly in June. Non-protein thiol levels were significantly higher in the blades than in the sheaths of P. oceanica from Tonnara and Lérins. In contrast, at Rosignano, the sheaths presented a significantly higher non-protein thiol concentration than the blades, particularly in June. Levels in the sheaths appeared to increase with the degree of pollution. Western Blot performed on sheaths of P. oceanica collected in June at Rosignano and Lérins revealed a characteristic band of GSTs at 31 kDa, proving the presence of the GST enzyme in this tissue. Mercury seemed to exert an influence upon non-protein thiol metabolism, including GST induction, in P. oceanica collected from the NW Mediterranean.

Characterization of phenolic compounds in Pinus laricio needles and their responses to prescribed burnings.

Fire is a dominant ecological factor in Mediterranean-type ecosystems. Management strategies include prescribed (controlled) burning, which has been used in the management of several species, such as Pinus nigra ssp laricio var. Corsicana, a pine endemic to Corsica of great ecological and economic importance. The effects of prescribed burning on Pinus laricio have been little studied. The first aim of this study was to characterize total and simple phenolic compounds in Pinus laricio. The second aim was to understand: i) the short term (one to three months) and medium term (three years) effects of prescribed burning, and ii) the effects of periodic prescribed burning on the production of phenolic compounds in Pinus laricio. The first result of this study is the presence of total and simple phenolic compounds in the needles of Pinus laricio. 3-Vanillyl propanol is the major compound. After a prescribed burning, the synthesis of total phenolic compounds increases in Pinus laricio for a period of three months. Total phenolic compounds could be used as bioindicators for the short-term response of Pinus laricio needles to prescribed burning. Simple phenolic compounds do not seem to be good indicators of the impact of prescribed burning because prescribed burnings are low in intensity.

A GIS-Based Multicriteria Evaluation for Aiding Risk Management Pinus pinaster Ait. Forests: A Case Study in Corsican Island, Western Mediterranean Region

Forest management can benefit from decision support tools, including GIS-based multicriteria decision-aiding approach. In the Mediterranean region, Pinus pinaster forests play a very important role in biodiversity conservation and offer many socioeconomic benefits. However, the conservation of this species is affected by the increase in forest fires and the expansion of Matsucoccus feytaudi. This paper proposes a methodology based on commonly available data for assessing the values and risks of P. pinaster forests and to generating maps to aid in decisions pertaining to fire and phytosanitary risk management. The criteria for assessing the values (land cover type, legislative tools for biodiversity conservation, environmental tourist sites and access routes, and timber yield) and the risks (fire and phytosanitation) of P. pinaster forests were obtained directly or by considering specific indicators, and they were subsequently aggregated by means of GIS-based multicriteria analysis. This approach was tested on the island of Corsica (France), and maps to aid in decisions pertaining to fire risk and phytosanitary risk (M. feytaudi) were obtained for P. pinaster forest management. Study results are used by the technical offices of the local administration—Corsican Agricultural and Rural Development Agency (ODARC)—for planning the conservation of P. pinaster forests with regard to fire prevention and safety and phytosanitary risks. The decision maker took part in the evaluation criteria study (weight, normalization, and classification of the values). Most suitable locations are given to target the public intervention. The methodology presented in this paper could be applied to other species and in other Mediterranean regions.

Variability of Ruppia cirrhosa in two coastal lagoons with differing anthropogenic stresses

Abstract The dynamics of Ruppia cirrhosa were studied over two years in two coastal lagoons on the Corsican coast (France, Mediterranean Sea). The lagoons differed in type of eutrophication: (1) Biguglia lagoon (urban and industrial effluent, agriculture, runoff from catchment area) and (2) Santa Giulia lagoon (tourist pressure in summer). Spatio-temporal variability of R. cirrhosa occurrence was monitored on permanent transects. We also monitored temporal changes in density, aboveground/belowground biomass and organic matter. Most of the parameters studied along the transects show variations with season and site. Density and aboveground biomass of R. cirrhosa in Biguglia lagoon were lower when Ulva species were present. This may be related to differences in nutrient availability. During the first year of the study, rainfall was greater with concomitantly higher nutrient inputs, which may account for the higher values of measured parameters in the first year. The results suggest that environmental parameter variations affect the functioning of R. cirrhosa meadows.

Phenolic compounds of Pinus laricio needles: a bioindicator of the effects of prescribed burning in function of season.

Fire is a dominant ecological factor in Mediterranean-type ecosystems. Forest management includes many preventive tools, in particular for fire prevention, such as mechanical treatments and prescribed burning. Prescribed burning is a commonly used method for treating fuel loads, but fuel reduction targets for reducing wildfire hazards must be balanced against fuel retention targets in order to maintain habitat and other forest functions. This approach was used on Pinus nigra ssp laricio var. Corsicana, a pine endemic to Corsica of great ecological and economic importance. Many studies of plant phenolic compounds have been carried out concerning responses to various stresses. The aim of this study was to understand i) the effects of prescribed burning 1 to 16 months later and ii) the effects of the seasonality of burning, spring or fall, on the production of phenolic compounds in Pinus laricio. After prescribed burning conducted in spring, Pinus laricio increases the synthesis of total phenolic compounds for a period of 7 months. The increase is greater after spring-burning than fall-burning. With regard to simple phenols, only dihydroferulic acid responds about 1 year after both types of prescribed burning. The causes of these increases are discussed in this paper. Total phenolic compounds could be used as a bioindicator for the short-term response of Pinus laricio needles to prescribed burning. Simple phenols may be useful for revealing the medium-term effects of prescribed burning. The results of this study include recommending forest managers to use prescribed burning in the fall rather than spring to reduce fuel loads and have less impact on the trees.

Posidonia oceanica and Zostera marina as Potential Biomarkers of Heavy Metal Contamination in Coastal Systems

In the early 1960s recognition of the adverse effects of environmental contamination due to industrial, pesticide, and agricultural pollution led to the emergence of the field of ecotoxicology (Ramade, 1992). Today, marine estuary and inshore ecosystems continue to be negatively impacted by environmental contamination (Short & Wyllie-Echeverria 1996; Orth et al., 2006; Osborn & Datta, 2006). In order to reduce these negative impacts, biosurveillance programs are needed to monitor environmental conditions so that changes in ecosystem processes, structure, and the physiological condition of species can be assessed (Blandin, 1986; Tett et al., 2007). An important characteristic of these programs is that indicator species must be capable of rapidly detecting significant changes in the ecosystem so that the cause of deterioration can be addressed early (e.g. Hemminga & Duarte, 2000).

Morphological responses of Pinus laricio in Corsican island to prescribed burning

The effect of prescribed burning on morphological parameters of Pinus laricio in Corsica was examined over a 3-year period. Morphological responses measured included height and diameter of the trees and shoot length and morphological characteristics of the needles. Variations on Pinus laricio growth between the years are influenced by climate factors, in particular by the rainfall during June, July, August and September and the mean temperature in August. The year following the prescribed burning, an increase of morphological parameters (e.g. shoot and needle length, number of needles) is observed. These observations could be linked with the soil nutriment, in particular with nitrogen (N) and phosphorous (P). After two years, there are no differences in the measured parameters. These parameters can be considered as good indicators in the management of the prescribed burning.

Sap flow and photosynthetic response to climate and drought of Pinus nigra in a Mediterranean natural forest

Key messageDrought caused a decrease of water flux and photosynthesis due to stomata closure, typical of drought-avoiding strategy. No photoinhibitory stress was observed.AbstractDrought represents an important source of disturbance in Mediterranean ecosystems. For long-term forest management, knowledge of tree responses to climate is essential. To investigate the seasonal functioning of Pinus laricio and its tolerance to summer drought in a Mediterranean climate, we carried out a field study in a natural mountainous pine forest over a 2-year period. For the first time for this species, sap flow, chlorophyll fluorescence, and gas exchange were used as indicators of tree vitality. Mild winter did not alter photosynthetic performance while sap flow declined. In spring, increase of sap flow was observed, revealing the end of tree dormancy and the beginning of the growth season. In response to summer drought, stomatal closure caused a reduction of gas exchange and sap flow. At the same time, pines increased their water use efficiency and reduced the limitation of mesophyll conductance. The reduction in CO2 assimilation was associated with photochemical stability, which might cause an imbalance between light energy input and energy used in photochemistry. The stability of chlorophyll fluorescence parameters indicated the absence of photoinhibitory stress, probably because of the use of photorespiration. The reduction of sap flow and stomatal conductance during drought confirmed the water-saver status of P. laricio species.

Seasonal variations of water status and SPOT NDVI in Mediterranean woody plants

Facing the problem of fire risks, it is useful to test accurate tools to prevent this flail. Remote sensing and vegetation indices are suitable to estimate fire risks. The aim of the study was to follow the evolution of water status of various Mediterranean vegetal communities and of Normalised Difference of Vegetation Index (NDVI) calculated from SPOT images. The water status was studied using the water content and the water potential. Annual variations of the water status and NDVI show both the influence of the season and the type of vegetation community. At the end of the summer, the hierarchy of vegetal communities found for NDVI and water status are similar. At this period, sites composed with arborescent species have higher water content, water potential, and NDVI than sites composed with arbustive species. For the other seasons or for a precise site, there is no correlation between NDVI and water status.