Colonization-extinction dynamics of epixylic lichens along a decay gradient in a dynamic landscape

Abstract

Metapopulation models are often used for understanding and predicting species dynamics in fragmented landscapes. Several models have been proposed depending on e.g. the relative importance of patch dynamics on the metapopulation dynamics. Dead wood is a dynamic substrate patch, and species that are confined to such patches have experienced a high degree of habitat loss in managed forests. Little is, however, known about how the population dynamics of epixylic species are affected by the fast dynamics of their substrate patches. We quantified the effect of local patch conditions and metapopulation processes on colonizations and extinctions of epixylic lichen species in a managed boreal forest landscape. This was done by twice surveying seven lichen metapopulations on 293 stumps in 30 stands of ages covering the duration of the dynamic patches (stumps). We also investigated the relative importance of local stochastic extinctions from stumps that remained available, and deterministic extinctions due to stump surface disappearance. We found importance of a decay gradient, surrounding metapopulation size, and local population sizes, in driving the colonization–extinction dynamics of epixylic lichens. The species were sorted along the stump decay gradient. Increasing surrounding metapopulation size was associated with increased colonization rates, and increasing local population size decreased lichen extinction rates. Finally, both local stochastic extinctions and deterministic extinctions due to patch disappearance occur, confirming that the long‐term persistence of epixylic lichens depends on colonization rates that compensate for stochastic population extinctions as well as deterministic extinctions.

Metapopulation Dynamics of the Mistletoe and Its Host in Savanna Areas with Different Fire Occurrence

“…The model was originally based on studies with epiphytic bryophytes, but can be applied to other groups [30], [46], [47]. In this system, the characteristics of host trees, as well as the environmental conditions and connectivity, were important for explaining the distribution patterns of bryophytes in forest environments [21], [22].…”

“…Thus, agreeing with Overton [9], we opted to approach our studied mistletoe populations using the metapopulation framework. A similar approach was used in several studies with species of epiphytic bryophytes in boreal forests modeled the metapopulation dynamics in habitat patches [18], [22], [23], [28], [29], [30], [31].…”

Local Competition and Metapopulation Processes Drive Long-Term Seagrass-Epiphyte Population Dynamics

“…Where studies of forest epiphyte distributions do include local factors relating to habitat condition, these typically take the form of environmental gradients (such as microclimate and edge effects) rather than explicitly modelling feedback between host and epiphyte populations [20]–[23]. Whilst including independent variation in habitat structure adds considerably to a homogeneous metapopulation approach [19], [24], such models fail to capture important non-linearities inherent in many other, higher-turnover ecosystems.…”

Drivers of lichen species richness at multiple spatial scales in temperate forests

“…The landscape context influences large-scale regional processes of lichen metapopulations especially in fragmented and dynamic landscapes, such as managed forests (Caruso et al 2010). In fragmented habitats, local species persistence is the result of extinction-colonisation dynamics which are influenced by the availability of propagules in the surrounding landscape and by habitat connectivity (Scheidegger and Werth 2009).…”