Sammanfattning

Habitat loss is a major cause of species decline and extinction. Immediately after habitat loss, species occurrences are not in equilibrium with the new landscape and more closely reflect the previous landscape structure. Species with slow colonisation-extinction dynamics may display long time-lags before reaching a new equilibrium. We investigated the importance of connectivity to current and historical dispersal sources with the aim of explaining the occurrence pattern of epiphytic lichens with different traits among 104 old oaks. We used oak survey data collected from 1830 and 2009 for a Swedish landscape where oak densities declined drastically shortly after 1830. We fitted a commonly used connectivity measure and estimated the confidence interval for the spatial scale parameter. Small differences in the spatial scale parameter resulted in large differences in model fit. Connectivity to trees in 1830 better explained the occurrence of three of the four species compared to the connectivity in 2009. The explanatory power of the historical landscape structure was highest for the species with traits that may result in a low colonisation rate-both a narrow niche (here few suitable trees) and large dispersal propagules. The results suggest that oak-dependent epiphytic lichens have not reached equilibrium with the spatial landscape structure 180 years after the drastic decline in habitat. For the long-term persistence of epiphytes associated with old trees, conservation efforts should focus on (1) protecting and restoring stands where specialised species with large dispersal propagules (i.e. with low colonisation rates) occur today and (2) promoting tree regeneration in their near vicinity.

Nyckelord

Colonisation rate; Extinction debt; Landscape history; Lichens; Southeastern Sweden

Publicerad i

Oecologia
2013, Volym: 172, nummer: 2, sidor: 607-615
Utgivare: SPRINGER

SLU författare

• Johansson, Victor

  • Institutionen för ekologi, Sveriges lantbruksuniversitet
    

• Snäll, Tord

  • Institutionen för ekologi, Sveriges lantbruksuniversitet
    

• Ranius, Thomas

  • Institutionen för ekologi, Sveriges lantbruksuniversitet
    

Globala målen

SDG15 Skydda, återställa och främja ett hållbart nyttjande av landbaserade ekosystem, hållbart bruka skogar, bekämpa ökenspridning, hejda och vrida tillbaka markförstöringen samt hejda förlusten av biologisk mångfald


UKÄ forskningsämne

Ekologi


Publikationens identifierare

DOI: https://doi.org/10.1007/s00442-012-2509-3

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/56040