Birds and the Fire Cycle in a Resilient Mediterranean Forest: Is There Any Baseline?

This study investigates the effects of recurrent wildfires on the resilience of a typical Mediterranean ecosystem. It is based on uninterrupted monitoring over 42 years of the avifauna in a cork oak forest that burned three times during this time interval. The monitoring involved two line-transect counts in spring accompanied by the simultaneous and independent estimation of the vegetation cover profile. One of the two transects was initially designed to serve as an unburned control before it also burned during the second fire. Many forest bird species were already present from the first spring postfire due to the rapid regeneration of the canopy. Some open-habitat bird species colonized the burned area during the first 2–4 years after the fire, resulting in an initial phase of high diversity. The postfire bird succession was mainly driven by sedentary species that recolonized the burned area after the first winter, whereas most migratory species present before the fire resettled as early as the first postfire spring, probably because of site tenacity. It was found that the impact of the second fire on avifauna was lower than that of the first or third fire. The return to an avifauna and forest structure successionally equivalent to the prefire control was achieved in about 15 years, which can be considered as the recovery time. Afterwards, both vegetation and avifauna in the burned areas tended to take on more forest characteristics than in the prefire control. These findings suggest that: (i) the recurrence of fire does not necessarily result in the cumulative degradation of the ecosystem at each repetition; (ii) the asymptotic resilience model is not adapted to the case of disturbances in non-mature environments; (iii) the notion of returning to an original undisturbed baseline is illusive in an area that has been under continuous human influence since ancient times.

Towards optimizing acorn use as animal feed in Tunisia: evaluation and impact on natural regeneration

In Mediterranean forests, besides the conflict between forest managers and local populations who are often poor and dependent on livestock for survival, the cost of raw materials used in animal feed is increasingly a burden for farmers. There is growing recognition that wise use of acorns can reduce feed costs and enhance sustainable participatory governance of these woodlands. This paper aimed to carry out a quantitative, qualitative and economic evaluation of acorn potential in a cork oak forest in north-western Tunisia and to investigate the impact of their post-dispersal on natural regeneration. Quantities were estimated in November and February, respectively for acorns collected directly from trees and from the ground. Time-dependent monitoring of acorn quality and numbers of new seedlings was also conducted from autumn 2014 to spring 2015. The results show a significant decrease in acorn quantity from 5.28 ± 4.61 t/ha in November to 0.684 ± 0.1 t/ha in February. However, this loss did not put the early stages of natural cork oak regeneration at risk since the percentage of acorns not able to germinate was estimated at only 37% in late February. Furthermore, the average number of new seedlings was estimated in April at 40,000 seedlings/ha. A model was fitted to predict tree acorn production and to establish the best agroforestry system to optimize acorn use. Based on acorn quantity and quality data, earlier acorns should be directed to nursery and livestock production and the later acorns to wildlife and natural regeneration.

Characterization of Bradyrhizobium spp. Nodulating Lupinus cosentinii and L. luteus Microsymbionts in Morocco

In this work, we analyzed the diversity of the nodule-forming bacteria associated with Lupinus luteus and Lupinus cosentinii grown in the Maamora Cork oak forest acidic soils in Morocco. The phenotypic analysis showed the high diversity of the strains nodulating the two lupine's species. The strains were not tolerant to acidity or high alkalinity. They do not tolerate salinity or high temperatures either. The strains isolated from L. luteus were more tolerant to antibiotics and salinity than those isolated from L. cosentinii. The plant growth promoting (PGP) activities of our strains are modest, as among the 28 tested isolates, only six produced auxins, six produced siderophores, whereas three solubilized phosphates. Only two strains possess the three activities. The rrs gene sequences from eight representative strains selected following ARDRA and REP-PCR results revealed that they were members of the genus Bradyrhizobium. Six strains were then retained for further molecular analysis. The glnII, recA, gyrB, dnaK, and rpoB housekeeping gene sequence phylogeny showed that some strains were close to B. lupini LMG28514T whereas others may constitute new genospecies in the genus Bradyrhizobium. The strains were unable to nodulate Glycine max and Phaseolus vulgaris and effectively nodulated L. luteus, L. cosentinii, L. angustifolius, Chamaecytisus albidus, and Retama monosperma. The nodC and nodA symbiotic gene phylogenies showed that the strains are members of the genistearum symbiovar.

Temporal evolution of C stock in soils from the cork oak forest in a post-fire scenario

<p>Forest fires are increasing their recurrence, intensity and scale in Portugal, increasing also the vulnerability of this region of Southwestern Europe to the impacts of the climate change. In Portugal, several studies have been focusing the dynamic of cork oak forest after fires from tree level to landscape level. However few information is available about the impact of wildfires in the soil quality, namely C stock, and its evolution. This component of the ecosystem and the evolution of its characteristics can be related with the dynamics of the landscape in the post-fire period and its knowledge can help in the management and rehabilitation of plant-soil system.</p><p>Serra do Caldeirão is located in Algarve region (S of Portugal). The soils are classified as Leptosols with low fertility. The landscape is characterized by cork oak forests with shrub cover which is dominated by Cistus species. To assess the distribution of total organic C in the study area, several soil sampling were intersected, on two sampling dates (2012 and 2013), with the vector information of the burned area in 2004. This information was intended to assess the temporal evolution of C concentration, depending on its location in a burnt or non-burnt area.</p><p>In general, the burnt areas showed greater variability of C concentrations in soils collected in both the years, with maximum values ​​of 33.0 g/kg for 2012 and 36.5 g/kg for 2013. These maximum values ​​exceed those obtained for soils in non-burnt areas. Despite of this scenario, and independently of the year, no statistically significant differences were found in the C concentrations of the burnt plots and the control plots. For other chemical characteristics (e.g. nutrients), the variations depended on the area. Implementation of post-fire recovery measures and forest management of the areas can justify this variation.</p><p>Acknowledgment: This work is co-financed by project REMAS (SOE3/P4/E0954) from Interreg SUDOE 2014-2020 program and is also financed by the FEDER Funds through the Operational Competitiveness Factors Program - COMPETE and by National Funds through FCT - Foundation for Science and Technology within the scope of the project  UID/AGR/04129/2020 (LEAF) and  the project UID/BIA/50027/2019 (CEABN/InBIO).</p>

Evolution of Mediterranean Forest Ecosystems and Impact of Natural and Anthropogenic Disturbances: Case of the Cork Oak Forest- Tlemcen- Algeria

Background: Forest cover change continues to be one of the most important topics in global environment discussions and negotiations. In North Africa, there is a broad consensus on forest decline but available information on the extent and rate of degradation has been far lower than needed. The present study uses the example of the cork oak forest of Tlemcen (Hafir-Zariffet forest), North West Algeria, to provide spatially explicit and up-to-date information on forest cover changes. The goal was to fill a knowledge gap in a poorly studied area by determining the extent of changes in forest cover. Methods: Land use land cover maps of 1989, 1999, 2009 and 2019 were classified using Random Forest Algorithm in R software and change assessed via intensity analysis. Results: The results revealed that sparse vegetation was the dominant land cover at the end of the study period, although it decreased from 71.25% in 1989 to 65.24% in 2019. The lowest coverage was water body from 0.47% in 1989 to 0.18% in 2019. Sparse vegetation and dense forest experienced a major decline of 6.01% and 3.22% respectively. On the other hand, open forest (+6.96%), bare areas (+0.37%), settlements (+1.99%) and agricultural (+0.21%) increased. In the LULC transitions analysis, dense forest recorded loss for two consecutive periods (1989-1999 and 1999-2009). The path of conversion was mainly from dense forest to open forest, an evidence of anthropogenic activities. Conclusion: The findings show that the cork oak forest of Hafir-Zariffet suffered multiple pressures, which cause degradation of this natural heritage. These pressures continue to increase the fragility of forest ecosystem and can affect the rehabilitation or even its resilience. In order to conserve the dwindling cork oak forest, a sustainable and effective management which ensures ecological, economic and social balance should be adopted.

Incorporating Landscape Character in Cork Oak Forest Expansion in Sardinia: Constraint or Opportunity?

Cork oak (Quercus suber) is a declining woodland species across the island of Sardinia, despite its former economic importance for wine production and its significance for biodiversity. In particular, cork oak forests (COFs) on the island have seen a 29% decrease in the past 45 years. A spatial GIS model was developed to determine suitability for the expansion of cork oak forests on the island. The model uses a set of simple spatial decision rules based on principles of landscape ecology and expert opinion to assign a suitability score for pure cork oak forests to every land use parcel in Sardinia. These rules include the type of existing land parcel, its size, distance to existing cork oak forest, and the area of seminatural habitats in its neighborhood. This was coupled with a map of landscape types to assist with the development of policy for the protection of cork oak forests across Sardinia. The results show that there is an area of 116,785 ha potentially suitable for cork oak forest expansion in Sardinia, with the largest area of potential habitat on granitic mountains. There is a substantial overall agreement (Cohen’s kappa = 0.61) between the suitability map produced and the historical reference map. The model is flexible and can be rerun to reflect changes in policy relating to agri-environmental targets for habitats and species.