Long‐term colonization ecology of forest‐dwelling species in a fragmented rural landscape – dispersal versus establishment

Species colonization in a new habitat patch is an efficiency indicator of biodiversity conservation. Colonization is a two‐step process of dispersal and establishment, characterized by the compatibility of plant traits with landscape structure and habitat conditions. Therefore, ecological trait profiling of specialist species is initially required to estimate the relative importance of colonization filters. Old planted parks best satisfy the criteria of a newly created and structurally matured habitat for forest‐dwelling plant species. We sampled species in 230 ancient deciduous forests (source habitat), 74 closed‐canopy manor parks (target habitats), 151 linear wooded habitats (landscape corridors), and 97 open habitats (isolating matrix) in Estonia. We defined two species groups of interest: forest (107 species) and corridor specialists (53 species). An extra group of open habitat specialists was extracted for trait scaling. Differing from expectations, forest specialists have high plasticity in reproduction mechanisms: smaller seeds, larger dispersules, complementary selfing ability, and diversity of dispersal vectors. Forest specialists are shorter, less nutrient‐demanding and mycorrhizal‐dependent, stress‐tolerant disturbance‐sensitive competitors, while corridor specialists are large‐seeded disturbance‐tolerant competitors. About 40% of species from local species pools have immigrated into parks. The historic forest area, establishment‐related traits, and stand quality enhance the colonization of forest specialists. The openness of landscape and mowing in the park facilitate corridor specialists. Species traits in parks vary between a forest and corridor specialist, except for earlier flowering and larger propagules. Forest species are not dispersal limited, but they continue to be limited by habitat properties even in the long term. Therefore, the shady parts of historic parks should be appreciated as important forest biodiversity‐enhancing landscape structures. The habitat quality of secondary stands can be improved by nurturing a heterogeneous shrub and tree layer, and modest herb layer management.     

Seasonal habitat selection and space use by a semi‐free range herbivore in a heterogeneous savanna landscape

Understanding factors that influence habitat selection in heterogeneous landscapes is fundamental for establishing realistic models on animal distribution to inform rangeland management. In this study, we tested whether seasonal variation in habitat selection within the home range of a large herbivore was influenced by constraints such as, distances from water and central place using semi‐free range cattle (Bos taurus) as a case study. We also tested whether shifts in space use over time were dependent on spatial scale and on the overall abundance of resources. We predicted that distance from water significantly influenced dry season habitat selection while the influence of the central place on habitat selection was season‐independent. We also predicted that shifts in space use over time were spatial scale‐dependent, and that large herbivores would include more diverse habitats in their home ranges during the dry season, when water and food resources are less abundant. Multinomial logit models were used to construct habitat selection models with distances from water and central place as habitat‐specific constraints. Results showed significant variations in habitat selection between the dry and wet season. As predicted, the effect of distance from central place was season‐independent, while the effect of water was not included in the top dry season models contrary to expectation. A diverse range of habitats were also selected during the dry season including agricultural fields. Results also indicated that shifts in space use were spatial scale dependent, with core areas being more sensitive to changes than the home range. In addition, shifts in space use responded to temporal changes in habitat composition. Overall, our results suggest that semi‐free range herbivores adopt different foraging strategies in response to spatial‐temporal changes in habitat availability.     

The Net Landscape Carbon Balance—Integrating terrestrial and aquatic carbon fluxes in a managed boreal forest landscape in Sweden

The boreal biome exchanges large amounts of carbon (C) and greenhouse gases (GHGs) with the atmosphere and thus significantly affects the global climate. A managed boreal landscape consists of various sinks and sources of carbon dioxide (CO₂), methane (CH₄), and dissolved organic and inorganic carbon (DOC and DIC) across forests, mires, lakes, and streams. Due to the spatial heterogeneity, large uncertainties exist regarding the net landscape carbon balance (NLCB). In this study, we compiled terrestrial and aquatic fluxes of CO₂, CH₄, DOC, DIC, and harvested C obtained from tall‐tower eddy covariance measurements, stream monitoring, and remote sensing of biomass stocks for an entire boreal catchment (~68 km²) in Sweden to estimate the NLCB across the land–water–atmosphere continuum. Our results showed that this managed boreal forest landscape was a net C sink (NLCB = 39 g C m^?2 year^?1) with the landscape–atmosphere CO₂ exchange being the dominant component, followed by the C export via harvest and streams. Accounting for the global warming potential of CH₄, the landscape was a GHG sink of 237 g CO₂‐eq m^?2 year^?1, thus providing a climate‐cooling effect. The CH₄ flux contribution to the annual GHG budget increased from 0.6% during spring to 3.2% during winter. The aquatic C loss was most significant during spring contributing 8% to the annual NLCB. We further found that abiotic controls (e.g., air temperature and incoming radiation) regulated the temporal variability of the NLCB whereas land cover types (e.g., mire vs. forest) and management practices (e.g., clear‐cutting) determined their spatial variability. Our study advocates the need for integrating terrestrial and aquatic fluxes at the landscape scale based on tall‐tower eddy covariance measurements combined with biomass stock and stream monitoring to develop a holistic understanding of the NLCB of managed boreal forest landscapes and to better evaluate their potential for mitigating climate change.