Detecting low fragmented sites surrounding European protected areas – Implications for expansion of the Natura 2000 network

EU member states have set an ambitious goal of establishing additional protected areas (PAs) preserving 30 % of terrestrial land by 2030, specifying that additions should be of high ecological quality. A targeted selection of existing PA expansions into surroundings marginally fragmented by human infrastructure, may be an efficacious strategy to secure high ecological quality by maximizing PA area, accommodating species movement, and boosting climate change resilience. We used high-resolution data on effective mesh density, a metric measuring landscape fragmentation, in the vicinity of Natura 2000 PAs (N2k) to assess their potential for expansion. Our results show that contrary to most of Central Europe, mountainous and remote territories exhibit the lowest degree of fragmentation in N2k surroundings. Fragmentation in N2k surroundings is highly correlated with national population density, while economic wealth, measured by GDP per capita, plays a minor role. To address the long-standing dilemma of where scarce economic resources in nature conservation do the most-good, we conducted a country-level comparison between fragmentation in N2k surroundings and national expenditures on nature conservation relative to N2k area. Our results show a vast incongruity in resource availability for nature conservation among EU countries. Eastern European states, especially Romania, host underfunded N2k PAs while holding the highest potential for expanding N2k PAs into low fragmented lands. If protecting low fragmented lands is accepted as an efficacious strategy to meet EU biodiversity targets our results could be used to formulate pragmatic conservation decisions, while also ensuring high ecological quality of PA additions under climate change.     

Predator-prey models with delay and prey harvesting

It is known that predator-prey systems with constant rate harvesting exhibit very rich dynamics. On the other hand, incorporating time delays into predator-prey models could induce instability and bifurcation. In this paper we are interested in studying the combined effects of the harvesting rate and the time delay on the dynamics of the generalized Gause-type predator-prey models and the Wangersky-Cunningham model. It is shown that in these models the time delay can cause a stable equilibrium to become unstable and even a switching of stabilities, while the harvesting rate has a stabilizing effect on the equilibrium if it is under the critical harvesting level. In particular, one of these models loses stability when the delay varies and then regains its stability when the harvesting rate is increased. Computer simulations are carried to explain the mathematical conclusions. Received: 1 March 2000 / Revised version: 7 September 2000 /?Published online: 21 August 2001