No abstract

Fine-scale topographic complexity creates important microclimates that can facilitate species to grow outside their main distributional range and increase biodiversity locally. Enclosed depressions in karst landscapes (‘dolines’) are topographically complex environments which produce microclimates that are drier and warmer (equator-facing slopes) and cooler and moister (pole-facing slopes and depression bottoms) than the surrounding climate. We show that the distribution patterns of functional groups for organisms in two different phyla, Arthropoda (ants) and Tracheophyta (vascular plants), mirror this variation of microclimate. We found that north-facing slopes and bottoms of solution dolines in northern Hungary provided key habitats for ant and plant species associated with cooler and/or moister conditions. Contrarily, south-facing slopes of dolines provided key habitats for species associated with warmer and/or drier conditions. Species occurring on the surrounding plateau were associated with intermediate conditions. We conclude that karst dolines provide a diversity of microclimatic habitats that may facilitate the persistence of taxa with diverse environmental preferences, indicating these dolines to be potential safe havens for multiple phyla under local and global climate oscillations.

The Pannonian region is situated in the Carpathian basin where forests have been used intensively for centuries. The article shows a map and a tabular overview of the forest reserves featured as forests ''left for free development'' of the region, and presents the most important stand structural characteristics of beech, mesophytic and thermophilous deciduous forests surveyed recently. The sampling points of six sites were selected to provide preliminary descriptive statistics according to the main types and abandonment status groups (recently managed, long abandoned and old-growth or primary stands) of these forests. In oldgrowth and primary stands the composition (list and mixture ratio of tree species) and stand structure characteristics [gap class distribution, stem density, distribution of relative crown classes and broad diameter at breast height (at 130 cm) classes, density of thick snags, and the amount of lying dead wood] proved to be similar to other European deciduous natural forests, while the abandoned and recently managed stands indicate that these forests are in a transitional stage towards natural ones.

The heat stress modification capacity of urban trees is widely acknowledged and makes these natural landscape elements very important in the field of climate conscious urban planning. Many studies proved that shading, i.e. the reduction of direct solar radiation is the most effective way to moderate summer heat stress under Central European climatic conditions. The investigation aims at determining the transmissivity of four tree species that occur frequently in Hungarian cities: Sophora japonica, Tilia cordata, Celtis occidentalis and Aesculus hippocastanum. In order to accomplish that, a systematic radiation measurement campaign was carried out in the South-Hungarian city of Szeged, from early summer (foliated condition of trees) to late autumn (nearly leafless condition). Short-wave radiation from the upper hemisphere was measured with Kipp & Zonen pyranometers under carefully selected tree specimens (transmitted radiation), as well as on a roof station free from sky obstruction (actual value of global radiation). The calculated transmissivity values varied greatly with the seasonal status of the canopy (the median value of transmissivity increased from 0.03 to 0.47 in case of A. hippocastanum), and we found considerable inter-species differences too, evidencing that solar permeability depends on the amount of leaves, leaf density and other tree crown-related characteristics.

To preserve the natural genetic pattern of species and to avoid the introduction of nonadapted ecotypes during restoration, seed transfer should be spatially restricted. Instead of applying administrative borders in the absence of species‐specific empirical data, biogeographical knowledge can be used as a proxy. Hungary was used as a suitable test region for this approach. The aims of the study were (1) to produce an evidence‐based seed transfer zone (STZ) map applying the Multiple Potential Natural Vegetation model; (2) to assess the uncertainty of the resulting STZ map; and (3) to compare the present seed transfer regulation based on administrative regions with the evidence‐based STZ map. The analysis was based on a floristic map, a vegetation map, and a landscape map of Hungary. Intersected polygons of the three maps were filled with Multiple Potential Natural Vegetation data and clustered to produce seven contiguous units that can serve as STZs. The uncertainty analyses provided a numerical comparison between the two approaches and demonstrated the inadequacy of defining administrative regions as STZs. The practical result of the study is the production of an evidence‐based STZ map that could replace the administrative map currently used for regulation in Hungary. Moreover, this map helps to develop native seed propagation and to enhance ecological restoration. We conclude that field‐based potential vegetation models, similar to the Multiple Potential Natural Vegetation, are suitable for STZ development in countries lacking an evidence‐based system for seed transfer.