In the Mediterranean area, a special focus on cork oak forests (Quercus suber L.) is needed as they are an integral part of the most extensive agroforestry systems in Europe. Covering approximately 2.5 million hectares in Europe and North Africa, cork oak woodlands represent some of the most threatened European ecosystems [1]. Since they are often considered fragile ecosystems [2], protection measures are needed to maintain their integrity and to preserve biodiversity. Cork oak woodlands are also a vital part of the rural landscape, providing contact with wildlife and environmental services with additional socio-ecological benefits to the overall quality of life. Deforestation, fragmentation and over-exploitation are considered to be the main drivers of forest biodiversity loss at the global level. The role of ants as environmental indicators is becoming more important in assessing the ecological health of terrestrial ecosystems, mostly because of their high diversity and functional importance. Ants (Hymenoptera family) are well represented in almost all terrestrial habitats because of a wide range of thermal niches and their ability to cope in varying environmental conditions. Due to their taxonomical and ecological diversity, ubiquity and abundance in the field, beetles (Coleoptera family) can be considered as an indicator group in biomonitoring practices. In addition, the sampling of ants and beetles, and particularly of ground-dwelling species, can be easily carried out using pitfall traps, which are relatively inexpensive to collect arthropods. We evaluated the potential use of ants and beetles as a powerful tool for environmental monitoring in cork oak woodlands across the Mediterranean region and non-metric Multi Dimensional Scaling (NMDS) based on Bray-Curtis dissimilarity measures was performed on the insect data [3]. Ants were sampled along linear transects at 12 sites located in the main cork districts of Italy and Morocco (Gallura in Sardinia, and Maâmora, east of Rabat). A total of 13,501 specimens were collected, belonging to 38 species (five shared species). A distinct separation in the NMDS plots between Gallura and Maâmora ant assemblages was clearly visible. Ant species composition was widely different between the two districts and significant differences were detected within the Gallura district at the species level. Multi-scale ant diversity showed that the true turnover was higher in Sardinia than in Maâmora as a result of a higher environmental homogeneity in Moroccan woodlands. Twenty-two sampling sites were randomly selected throughout the main cork oak districts of Sardinia and categorized by the contrasting effects of livestock in grazed and ungrazed woodlands. Multivariate analyses performed on ground-dwelling beetle data showed a distinct separation in terms of assemblages between grazed and ungrazed sites. The pattern of land use resulted in the establishment of different beetle communities composition and diversity as a response to grazing. The average diameter of cork oak trees and the degree of shrub cover were significantly linked to the beetle assemblages. In addition, constrained multivariate analyses indicated the significance of grazing, by both large and small domestic herbivores, and altitude as variables determining the pattern of scarab beetle assemblages. The taxonomic family level might be a reliable predictor of environmental changes as it detected differences among beetle assemblages in Mediterranean cork oak forests. Although a higher taxa approach is highly recommended when rapid surveys are required, it can only be used when higher taxa richness and species richness are strongly correlated [4]. This approach could be further explored in monitoring programmes aimed at estimating the potential impact of different grazing intensities. Given the undoubted ecological complexity of cork oak woodlands, it is imperative to select bioindicators that are readily accessible and reliable in detecting early warning signs of habitat disturbance, but also in defining a useful management strategy to increase the resilience of agroforestry systems under future global change scenarios.
Biodiversity in cork oak woodlands: ants and beetles as indicators of land use
Marcello Verdinelli;
2018
Abstract
In the Mediterranean area, a special focus on cork oak forests (Quercus suber L.) is needed as they are an integral part of the most extensive agroforestry systems in Europe. Covering approximately 2.5 million hectares in Europe and North Africa, cork oak woodlands represent some of the most threatened European ecosystems [1]. Since they are often considered fragile ecosystems [2], protection measures are needed to maintain their integrity and to preserve biodiversity. Cork oak woodlands are also a vital part of the rural landscape, providing contact with wildlife and environmental services with additional socio-ecological benefits to the overall quality of life. Deforestation, fragmentation and over-exploitation are considered to be the main drivers of forest biodiversity loss at the global level. The role of ants as environmental indicators is becoming more important in assessing the ecological health of terrestrial ecosystems, mostly because of their high diversity and functional importance. Ants (Hymenoptera family) are well represented in almost all terrestrial habitats because of a wide range of thermal niches and their ability to cope in varying environmental conditions. Due to their taxonomical and ecological diversity, ubiquity and abundance in the field, beetles (Coleoptera family) can be considered as an indicator group in biomonitoring practices. In addition, the sampling of ants and beetles, and particularly of ground-dwelling species, can be easily carried out using pitfall traps, which are relatively inexpensive to collect arthropods. We evaluated the potential use of ants and beetles as a powerful tool for environmental monitoring in cork oak woodlands across the Mediterranean region and non-metric Multi Dimensional Scaling (NMDS) based on Bray-Curtis dissimilarity measures was performed on the insect data [3]. Ants were sampled along linear transects at 12 sites located in the main cork districts of Italy and Morocco (Gallura in Sardinia, and Maâmora, east of Rabat). A total of 13,501 specimens were collected, belonging to 38 species (five shared species). A distinct separation in the NMDS plots between Gallura and Maâmora ant assemblages was clearly visible. Ant species composition was widely different between the two districts and significant differences were detected within the Gallura district at the species level. Multi-scale ant diversity showed that the true turnover was higher in Sardinia than in Maâmora as a result of a higher environmental homogeneity in Moroccan woodlands. Twenty-two sampling sites were randomly selected throughout the main cork oak districts of Sardinia and categorized by the contrasting effects of livestock in grazed and ungrazed woodlands. Multivariate analyses performed on ground-dwelling beetle data showed a distinct separation in terms of assemblages between grazed and ungrazed sites. The pattern of land use resulted in the establishment of different beetle communities composition and diversity as a response to grazing. The average diameter of cork oak trees and the degree of shrub cover were significantly linked to the beetle assemblages. In addition, constrained multivariate analyses indicated the significance of grazing, by both large and small domestic herbivores, and altitude as variables determining the pattern of scarab beetle assemblages. The taxonomic family level might be a reliable predictor of environmental changes as it detected differences among beetle assemblages in Mediterranean cork oak forests. Although a higher taxa approach is highly recommended when rapid surveys are required, it can only be used when higher taxa richness and species richness are strongly correlated [4]. This approach could be further explored in monitoring programmes aimed at estimating the potential impact of different grazing intensities. Given the undoubted ecological complexity of cork oak woodlands, it is imperative to select bioindicators that are readily accessible and reliable in detecting early warning signs of habitat disturbance, but also in defining a useful management strategy to increase the resilience of agroforestry systems under future global change scenarios.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
