Wednesday, 11 July 2012

F1000 July review: Invasion and phenology

This month we chose to review a Nature paper, which presents data that perhaps poses more intriguing questions than it actually answers.

Extended leaf phenology and the autumn niche in deciduous forest invasions. Fridley JD. Nature. 2012; 485(7398):359-62

Our review:
Parry H, Lonsdale M: 2012.

Invasion ecologists have invoked phenology as one explanation of the apparent success of non-indigenous forest species compared to native species. This paper shows that the invasion of forest species with canopies that persist later into autumn is resulting in a seasonal change in primary productivity that may rival climate change in size and extent. 

This paper shows a clear difference in autumn leaf fall timing for these two groups of species, where non-native invasives maintain their leaves for longer. In spring there is also more rapid bud/leaf formation by non-native invasives before canopy shading. This paper discusses whether this would constitute a competitive advantage (increased annual tree growth) or, in fact, a disadvantage (lack of nutrient resorption in autumn due to frost damage of leaves and subsequent nutrient loss). It would be interesting to compare the data from this study to the behaviour of these same non-native trees in their native range. They do not necessarily behave the same way – there may have been a selection process, or phenotypic plasticity, at play here. The role of phenotypic plasticity in invasion ecology had been suggested a long time ago {1} and has been the subject of recent literature {2}, with some novel suggestions on how it may operate geographically (e.g. see ref {3}).