Scale‐dependent effects of isolation on seasonal patch colonisation by two Neotropical freshwater fishes

The metapopulation paradigm has been central to improve the conservation and management of natural populations. However, despite the large number of studies on metapopulation dynamics, the overall support for the relationships on which the paradigm is based has not been strong. Here, we studied the occupancy dynamics of two Neotropical fishes (i.e., Pimelodella gracilis and Leporinus friderici) to investigate two fundamental premises of the metapopulation paradigm, that is, that isolation and area/habitat quality affect colonisation and extinction probabilities in predictable ways. In order to do this, we used a modification of occupancy models that allows modelling the probability of a site's occupancy as a function of the occupancy of its neighbourhood. We found a weak positive effect of neighbourhood occupancy on P. gracilis colonisation, which is consistent with the propagule rain metapopulation, that is, colonists arriving from outside the studied system. However, we found a strong negative neighbourhood effect on extinction probability, suggesting that declining populations from stream sections are rescued from extinction by neighbouring patches. In contrast, the effect of neighbourhood occupancy on the metapopulation dynamics of L. friderici was in the opposite direction, affecting positively colonisation but not affecting extinction rates, which is consistent with the classical metapopulation model. In addition, the occupancy dynamics of both species were affected by water velocity. To our knowledge, this is the first study to link directly dispersal to local population dynamics in Neotropical fishes, and one of the few studies doing inferences on spatial population dynamics based on direct estimates of neighbourhood occupancy.     

Analysis of carbon in sediments using fast neutron activation analysis (FNAA)

Journal of Soils and Sediments -     

Investment Potential of Private Forests in Croatia

This paper presents a comprehensive financial analysis of the investment potential of seven private forest categories in the Republic of Croatia (total study area of 268,072 ha). It covers the period from 2018 to 2048 and includes forest purchase costs, management simulation, timber transport to mills, timber processing and veneer production, and finally the selling of sawmill, veneer and forest products. Data from the Croatian National Forest Inventory and forest habitats map were used as a basis for analyses. Spatial data on private forests, roads and timber process plants at the national level were also integrated into the analyses. For the forest management simulation, the MOSES 3.0 simulator was used, and the QGis 3.4 software was used for spatial analyses of forests, roads and mils. Based on data from several world stock exchanges that cover companies of the forestry sector, a real (inflation-free) discount rates were used. The financial analyses showed which forest categories have positive investment potential and under which conditions. Results pointed out that multi-aged European beech forests have the highest internal rate of return (8.45%) and are the only one which would meet the expectations of a financially rational investor using criteria of a risk-adjusted inflation-free discount rate of 8%.