Summary 1.Wood-decaying fungi are ubiquitous and functionally important organisms within forest ecosystems world-wide, but remarkably little is known of their population dynamics in relation to the dynamics of their host substrates. Living in transient environments, where local extinctions are caused by gradual substrate (patch) destruction or deterioration due to wood decomposition, the long-term persistence of these species requires successful colonization of new patches. 2. During a 6-year period, we examined the colonization-extinction dynamics of wood-decaying fungi ( Aphyllophorales : Polyporaceae and Corticiaceae ) in relation to the spatiotemporal distribution of host logs within a boreal old-growth Norway spruce ( Picea abies ) forest. 3. The dynamics of the species studied were strongly influenced by both local log characteristics (within patch) and connectivity (between patch). Several species (e.g. Asterodon ferruginosus , Phellinus ferrugineofuscus , P. viticola , Phlebia centrifuga ) showed a positive effect of connectivity, mainly colonizing logs in the vicinity of previously occupied logs. This implies that some wood-decaying fungi may be dispersal limited in terms of successful colonizations. The relative importance of patch conditions and connectivity was however, highly species specific. 4. Our results further illustrate the importance of life-strategies adopted by species that are present during different stages of wood decomposition. Early colonizers were primarily affected by the stage of decomposition; secondary colonizers were affected by a variety of within patch and/or between patch variables, maintaining high species coexistence within intermediate stages of decay. Phellinus nigrolimitatus was the dominant polyporous decayer at the final stages of decomposition, clearly gaining a competitive advantage from specializing on highly decomposed wood and having very low mean annual mortality rates. 5. Local extinction rates were higher on small diameter logs than large diameter logs, and generally increased as decay proceeded, illustrating the importance of deterministic patch destruction due to wood decomposition. 6. Synthesis . The fungi-log study system was highly dynamic, illustrating that both characteristics and spatiotemporal availability of logs are important in explaining the distribution patterns and population dynamics of wood-decaying fungal communities. The result implies that the dynamics of some wood-decaying fungi can be characterized as patch-tracking metapopulations, with connectivity-dependent colonizations and local extinctions caused by the turnover of the patches.

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Opportunistically collected species observations contributed by volunteer reporters are increasingly available for species and regions for which systematically collected data are not available. However, it is unclear if they are suitable to produce reliable habitat suitability models (HSMs), and hence if the species–habitat relationships found and habitat suitability maps produced can be used with confidence to advice conservation management and address basic and applied research questions. We evaluated HSMs with opportunistically collected observations against HSMs with systematically collected observations. We enhanced the opportunistically collected presence‐only data by adding inferred species absences. To obtain inferred absences, we asked individual reporters about their identification skills and if they reported certain species consistently and combined this information with their observations. We evaluated several HSM methods using a forest bird species, Siberian jay (Perisoreus infaustus), in Sweden: logistic regression with inferred absences, two versions of MaxEnt, a model combining presence–absence with presence‐only observations and a Bayesian site‐occupancy‐detection model. All HSM methods produced nationwide habitat suitability maps of Siberian jay that agreed well with systematically collected observations (AUC: 086–0.88) and were very similar to a habitat suitability map produced from the HSM with systematically collected observations (Spearman rho: 0.94–0.98). At finer geographical scales there were differences among methods. At finer scale, the resulting habitat suitability maps from logistic regression with inferred absences agreed better with results from systematically collected observations than other methods. The species–habitat relationships found with logistic regression also agreed well with those found from systematically collected data and with prior expectations based on the species ecology. Synthesis and application. For many regions and species, systematically collected data are not available. By using inferred absences from high‐quality, opportunistically collected contributions of few very active reporters in logistic regression we obtained HSMs that produced results similar to those from a systematic survey. Adding high‐quality inferred absences to opportunistically collected data is likely possible for many less common species across various organism groups. Well‐performing HSMs are important to facilitate applications such as spatial conservation planning and prioritization, monitoring of invasive species, understanding species habitat requirements or climate change studies.