Search results for "abundance dynamics"
showing 3 items of 3 documents
Detection of Allee effects in marine fishes: analytical biases generated by data availability and model selection
2017
The demographic Allee effect, or depensation, implies positive association between per capita population growth rate and population size at low abundances, thereby lowering growth ability of sparse populations. This can have far-reaching consequences on population recovery ability and colonization success. In the context of marine fishes, there is a widespread perception that Allee effects are rare or non-existent. However, studies that have failed to detect Allee effects in marine fishes have suffered from several fundamental methodological and data limitations. In the present study, we challenge the prevailing perception about the rarity of Allee effects by analysing nine populations of …
Allee effects and the Allee-effect zone in northwest Atlantic cod
2022
According to the theory of compensatory dynamics, depleted populations should recover when the threat responsible for their decline is removed because per capita population growth is assumed to be highest when populations are at their smallest viable sizes. Yet, many seriously depleted fish populations have failed to recover despite threat mitigation. Atlantic cod (Gadus morhua) stocks off Newfoundland, despite 30 years of dramatically reduced fishing mortality and numerous fishery closures, have not recovered, suggesting that drivers other than fishing can regulate the growth of collapsed fish populations, inhibiting or preventing their recovery. Here, using Bayesian inference, we show str…
Long-term changes in breeding bird community of a Primeval Temperate Forest: 45 years of Censuses in the Białowieża National Park (Poland)
2022
W pracy omówiono długoterminowe trendy zmian liczebności 30 leśnych, pospolitych ptaków lęgowych na 7 stałych powierzchniach próbnych w Białowieskim Parku Narodowym w latach 1975– 2019 (wschodnia Polska, dalej BPN, Fig. 1). Przeanalizowano zmiany w składzie ugrupowań ptaków lęgowych w trzech najważniejszych typach drzewostanów pierwotnych w BPN: łęgach (Fig. 2), grądach (Fig. 3) i borach (Fig. 4). Cenzusy kontynuowane w latach 2015–2019 z wykorzystaniem kombinowanej metody kartograficznej na siedmiu stałych powierzchniach próbnych w BPN, monitorowanych od 1975 r., w tym dwóch na skraju lasu i pięciu w jego wnętrzu wykazały gniazdowanie 69 gatunków ptaków. Najwięcej gatunków gniazdowało w łę…