Recovery of the Bird Community after a Mine Spill and Landscape Restoration of a Mediterranean River

In Mediterranean areas, river systems are key for maintaining regional biodiversity by providing a high diversity of habitats. We studied bird community recovery for 9 years (2001–2009) during landscape restoration and Guadiamar Green Corridor establishment in the area affected by the Aznalcóllar mine spill (SW Spain, 1998). One year following plant restoration (3 years after the spill), values for α‐ and β‐bird species diversity were high, sooner than reported for similar restoration processes elsewhere. Species richness, ecological diversity, and abundance increased only slightly in the following 8 years. Overlap between communities in sequential years, measured by similarity indexes, increased throughout the study period to about 70% during final survey years, and most breeding bird species present before the accident again inhabit the area. Only 5 years after the mine accident, bird communities in the restored site were similar in species richness, abundance, and diversity to an unaffected reference site; redundancy analysis demonstrated that bird communities were also similar between the reference river and the Guadiamar. Despite the severity of the mine accident, our results suggest a swift recovery of the bird community. We attribute this success to the rapid restoration of habitat availability and the resilience of the birds. This long‐term study contributes to our limited knowledge of bird species response to habitat restoration following toxic spills in Mediterranean habitats.     

Italian Peninsula preserves an evolutionary lineage of the fat dormouse Glis glis L. (Rodentia: Gliridae)

The present study examines the population genetic structure of fifty‐nine specimens of Glis glis (Linneaus, 1766) from thirteen localities in central Europe, sequencing a 400‐bp segment of the mitochondrial cytochrome b (cyt b) gene and a 673‐bp segment of the cytochrome c oxidase subunit I (COI) gene. The consensus tree obtained from Bayesian analysis revealed a robust dichotomy, showing two sister groups: one clade includes samples from a wide geographical area, extending from north‐central Europe to northern Italy (major branch sensu Bilton), and the other comprises samples collected in central and southern Italy and in Sicily (Italian branch). According to the Tajima–Nei model, the two phylogroups were separated by a sequence divergence of 0.8% (cyt b) – 2.6% (COI), showing the COI gene to be more informative than cyt b. On a smaller geographical scale, the Italian clade was further substructured, displaying geographical differentiation along the Peninsula. The gene pool in this area was patchy; whereas populations from Sicily Island demonstrated fixed cyt b and COI haplotypes, assuming processes of isolation and selection. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 11–21.     

Influence of climate on Bonelli's eagle's (Hieraaetus fasciatus V. 1822) breeding success through the Western Mediterranean

Aim To assess the impact of certain climatic variables on the breeding success of some populations of Bonelli's eagle (Hieraaetus fasciatus V. 1822) throughout its latitudinal distribution range, in order to account for recent and differential declines in populations. Location Western Mediterranean, from southern Morocco to southern France. Methods Seven populations were considered for the latitudinal distribution range of the species. Data from 1052 breeding attempts were taken from the literature and, for each population, breeding success was measured as the mean number of fledglings per pair per year. Breeding success, as a dependent variable, was related to five geographical and climatic variables (latitude, mean annual temperature, mean minimum temperature of the coldest month, mean maximum temperature of the hottest month and mean annual precipitation) as independent variables, through some regression models, which take into account the multicolinearity of the variables. Results All the analyses agreed that average annual temperature was an important factor associated with the breeding success of the species in each region, and accounted for up to 97% of the variance of the breeding success throughout a latitudinal gradient in the study area. Main conclusions The low breeding success of the northern populations (probably because of climatic constraints) and the tendency of juveniles to disperse southwards, diminishes recruitment in those populations. Therefore, as human pressure and habitat destruction causes high adult and pre‐adult mortality of the species throughout its entire latitudinal range, disturbances in the northern populations have more profound effects, thereby explaining observed population declines.     

Geographical variation in macrohabitat use and preferences of the Lesser Spotted Eagle Aquila pomarina

Geographical variation in wildlife–habitat relationships has seldom been studied. We explored macrohabitat use and geographically distinct responses to habitat availability in the Lesser Spotted Eagle Aquila pomarina near the centre (Lithuania) and on the edge (Estonia) of its European distribution range, and in different zones within Estonia. Land cover types and distances to landscape elements, as well as landscape diversity, were measured around 198 Eagle nests and random forest points. Out of six macrohabitat characteristics, two (landscape diversity, area of optimal foraging habitat) showed no geographical variation in use, or preferences by the Eagle. Whereas variation in the use of suboptimal foraging habitats and forests could be attributed to regional differences in their availability, there were geographically distinct preferences for distances between nests and landscape elements. The species avoided anthropogenic edges in Lithuania but tended even to prefer their proximity in Estonia; Eagles selected nest-sites near remote waterbodies throughout Estonia but there was no such preference in Lithuania. The results did not support the hypothesis that latitudinal or range centre-to-periphery gradients existed in habitat relationships of the species; the main factor behind the geographical variation was probably land-use history. In general, the diversity of geographical effects indicated that extrapolating local habitat relationships to other areas may give erroneous results, and large-scale conservation planning regarding species' habitat may be ineffective.     

Acclimation of isoprene emission and photosynthesis to growth temperature in hybrid aspen: resolving structural and physiological controls

Acclimation of foliage to growth temperature involves both structural and physiological modifications, but the relative importance of these two mechanisms of acclimation is poorly known, especially for isoprene emission responses. We grew hybrid aspen (Populus tremula x P. tremuloides) under control (day/night temperature of 25/20 °C) and high temperature conditions (35/27 °C) to gain insight into the structural and physiological acclimation controls. Growth at high temperature resulted in larger and thinner leaves with smaller and more densely packed chloroplasts and with lower leaf dry mass per area (M_A). High growth temperature also led to lower photosynthetic and respiration rates, isoprene emission rate and leaf pigment content and isoprene substrate dimethylallyl diphosphate pool size per unit area, but to greater stomatal conductance. However, all physiological characteristics were similar when expressed per unit dry mass, indicating that the area‐based differences were primarily driven by M_A. Acclimation to high temperature further increased heat stability of photosynthesis and increased activation energies for isoprene emission and isoprene synthase rate constant. This study demonstrates that temperature acclimation of photosynthetic and isoprene emission characteristics per unit leaf area were primarily driven by structural modifications, and we argue that future studies investigating acclimation to growth temperature must consider structural modifications.     

Leaf anatomical properties in relation to differences in mesophyll conductance to CO2 and photosynthesis in two related Mediterranean Abies species

Abies alba and Abies pinsapo are closely related species with the same ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco) large subunit (rbcL) but contrasting hydraulic traits and mesophyll structure occurring in the Iberian Peninsula under contrasting conditions. As photosynthesis and hydraulic capacities often co‐scale, we hypothesize that these species differ in mesophyll conductance to CO₂ (g_m). g_m and key anatomical traits were measured in both species. Drought‐adapted population of A. pinsapo has higher photosynthesis than the more mesic population of A. alba, in agreement with its higher hydraulic capacity. However, A. alba exhibits the largest stomatal conductance (g_s), and so water use efficiency (WUE) is much higher in A. pinsapo. The differences in photosynthesis were explained by differences in g_m, indicating a correlation between hydraulic capacity and g_m. We report a case where g_m is the main factor limiting photosynthesis in one species (A. alba) when compared with the other one (A. pinsapo). The results also highlight the discrepancy between g_m estimates based on anatomical measurements and those based on gas exchange methods, probably due to the very large resistance exerted by cell walls and the stroma in both species. Thus, the cell wall and chloroplast properties in relation to CO₂ diffusion constitute a near‐future research priority.