Functional and ecosystem service differences between tree species: implications for tree species replacement

Key message Tree species differ in their functioning at the scale of an individual tree which will result in differences in ecosystem service provision. Replacement trees for diseased trees should take account of functional differences. Globally tree species composition is changing due to species loss from pests and pathogens. The impact of this change on ecological functioning is rarely tested. Using six sites across the UK, with multiple tree species at each site, we test for functional differences between three species threatened by disease in the UK:Quercus petraea,Q. roburandFraxinus excelsiorand six other species:Acer pseudoplatanus,Castanea sativa,Fagus sylvatica,Quercus cerris,Quercus rubra,andTilia x europaea, which have previously been suggested as ecological replacements. Differences between species were detected for all the variables measured: nitrogen mineralization, decomposition rate, total soil carbon and nitrogen, soil pH, soil temperature, and bark water holding capacity. Non-nativeQuercusspecies were only suitable replacements for nativeQuercus for some of the functions measured but replicating nativeQuercus functioning using a mixture of other species may be possible. The functioning ofF. excelsiorwas different from most other tree species, suggesting that replicating its functioning with replacement tree species is difficult. The work highlighted that which species replaces diseased trees, even at the scale of single trees, will impact on the functions and ecosystem services provided.

Automated summary

Tree species differ in their functioning at the scale of an individual tree, and the global tree species composition is changing due to species loss from pests and pathogens. The replacement of diseased trees should consider functional differences, as shown in the study with differences detected in nitrogen mineralization, decomposition rate, total soil carbon and nitrogen, soil pH, soil temperature, and bark water holding capacity between different species. Non-native replacement species may only be suitable for some functions of native trees, and replicating native tree functioning with a mix of other species is possible. The study also found that replicating the functioning of certain tree species may be difficult with replacement species.