Increased grazing drives homogenisation but reduced grazing increases turnover in upland habitat mosaics

Many ecosystems are grazed by livestock or large, wild herbivores and exist as mosaics of different vegetation communities. Changing grazing could have an impact on heterogeneity as well as on composition. A long-term, large-scale grazing experiment that maintained existing low-intensity sheep grazing, tripled it, removed it and partially substituted sheep grazing by cattle grazing was set up on a mosaic of upland vegetation types. The impact of changing grazing regimes was assessed in terms of changes in temporal and spatial species and functional beta diversity. Removal of grazing had the highest impact on species replacement, whilst increased grazing was closest to maintaining the original species complement. Wet heath and Molina mire had the lowest turnover, but wet heath showed the highest changes in unidirectional abundance as it contained species capable of increasing in abundance in response to changing grazing intensity. Agrostis-Festuca and Nardus grasslands displayed the highest level of balanced species replacement reflecting their more dynamic vegetation. In functional terms, there was no clear separation of communities based on their grazing preference, all were relatively resistant to change but Nardus grassland was the most resistant to the removal of grazing. The increased offtake associated with increased grazing led to a degree of homogenisation as grazing tolerant species associated with preferred communities increased in the unpreferred ones. Decisions about grazing management of the uplands involve many trade-offs, and this study identified potential trade-offs between stability and homogenisation to add to existing ones on the biodiversity of different groups of species and on ecosystem services.

Threatened salmon rely on a rare life history strategy in a modified and warming landscape

Rare phenotypes and behaviors adopted by only few individuals in a population are often overlooked, yet they may serve a heightened role for many organisms coping with warming climates. In threatened spring-run Chinook salmon spawning at the edge of the species range (Central Valley, CA USA), late-migrating juveniles were critical to cohort success in years characterized by multi-year droughts and ocean heatwaves. Late migrants rely on cool over-summer river temperatures, and are thus increasingly rare due to the combined effects of warming and dam construction. Yet our results suggest, the further loss of this within-population diversity could have critical impacts to their persistence in a warming climate. Our modeling predicts that thermally appropriate river conditions to support this phenotype will shrink rapidly in the future, and will primarily occur above impassable dams. Importantly, while late migrants dominated returns in some years, interannual variability in individual growth rates and migratory strategies suggests the importance of portfolio effects for these at-risk populations. Reconnecting and maintaining diverse habitat mosaics to support phenotypic and phenological diversity will be integral to the long term persistence of this species.

Progress on Research Regarding Ecology and Biodiversity of Coastal Fisheries and Nektonic Species and Their Habitats within Coastal Landscapes

This Special Issue aims to highlight the new research and significant advances in our understanding of links between coastal habitat quality/quantity/diversity and the diversity of fisheries species and other mobile aquatic species (hereafter nekton) that use them within coastal landscapes. This topic is quite diverse owing to the myriad of habitat types found in coastal marine waters and the variety of life history strategies fisheries species and nekton use in these environments. Thus, we focus our mini-review on five selective but relevant topics, habitat templates, essential fish habitat, habitat mosaics/habitat connectivity, transitory/ephemeral habitat, and the emerging/maturing approaches to the study of fish-habitat systems as a roadmap to its development. We have highlighted selected important contributions in the progress made on each topic to better identify and quantify landscape scale interactions between living biota and structured habitats set within a dynamic landscape.

Basic characteristics of microhabitats of snake-eyed skink (Ablepharus kitaibelii) in Western Hungary

Following the rediscovery after 200 years of Ablepharus kitaibelii fitzingeri in 2017, we carried out data collection its habitats regarding vegetation, microclimate, and soil on two prominent dolomite hills of the Eastern Bakony. Data collections were carried out in habitat mosaics (xerothermic forest edges on the plateaus, karst shrub forests in south-facing exposure, dry grasslands among forest patches on the plateaus, rocky grasslands in south-facing exposure) of three sampling blocks. Vegetation was examined by phytosociological relevés, microclimate from April to November continuously by TMS-2 dataloggers, and soil by laboratory analyses focused mainly on percentage of different fractions. According to our results a) shrub forests with a south-facing exposure provide a cooler microclimate with temperated fluctuation in the spring–early summer and late summer–early autumn periods; b) plateau grasslands and shrubs are characterised by looser soil structure. Based on our results, heterogeneous habitat character of forest–grassland mosaics of the Pannonicum can mitigate the expected negative effects of climate change on reptiles.

Late Miocene origin and recent population collapse of the Malagasy savanna olive tree (Noronhia lowryi)

Debates regarding the origin of tropical savannas have attempted to disentangle the role of human, biotic and abiotic factors. Understanding the origins of savanna remains essential to identifying processes that gave rise to habitat mosaics, particularly those found in the Central Plateau of Madagascar. Documenting the evolutionary history and demography of native trees occurring in open habitats may reveal footprints left by past and recent environmental changes. We conducted a population genetic analysis of an endangered Malagasy shrub (Noronhia lowryi, Oleaceae) of the Central Plateau. Seventy-seven individuals were sampled from three sites and genotyped at 14 nuclear and 24 chloroplast microsatellites. We found a highly contrasting nuclear and plastid genetic structure, suggesting that pollen-mediated gene flow allows panmixia, while seed-based dispersal may rarely exceed tens of metres. From a phylogeny based on full plastomes, we dated the surprisingly old crown age of maternal lineages back to ~6.2 Mya, perhaps co-occurring with the global expansion of savanna. In contrast, recent demographic history inferred from nuclear data shows a bottleneck signature ~350 generations ago, probably reflecting an environmental shift during the Late Pleistocene or the Holocene. Ancient in situ adaptation and recent demographic collapse of an endangered woody plant highlight the unique value and vulnerability of the Malagasy savannas.

Land Use Guidelines to Maintain Habitat Diversity of Wood- Pastures in the Southern Carpathians Under Projected Climate Change

The biodiversity of wood-pastures depends on a balance between human interference and natural vegetation succession, which however is undergoing changes driven by socio-economic factors and climate change. Widely spread throughout Europe, wood-pastures were subject to either intensification or abandonment, leading to habitat segregation and loss. This is currently the fate of large Romanian remnant woodpastures and climate warming further complicates management adaptation.In a series of simulation experiments, we compared the long-term effects of different land use and climate change scenarios on the habitat diversity of a wood-pasture in the Southern Carpathians (Fundata village, Romania). We tested livestock densities according to management guidelines, complemented with shrub-cutting in order to maintain a structurally-diverse landscape with high habitat values in the light of climate change. We found that significant losses of open pastureland and inclusion into forest, as well as landscape structural simplification and loss of complex habitats can be expected from climate warming, with more severe consequences in a hotter climate perspective. We arguefor the re-establishment of the traditional multi-use of wood-pastures at optimum livestock densities in combination with low-intensity shrubcutting, because our study demonstrated that traditional practices offer a balanced compromise between agricultural use and maintaining habitat mosaics that are robust to climate change.