The response of forest plant regeneration to temperature variation along a latitudinal gradient
De Frenne, Pieter × Graae, Bente J. Brunet, Jörg Shevtsova, Anna De Schrijver, An Chabrerie, Olivier Cousins, Sara A.O. Decocq, Guillaume Diekmann, Martin Hermy, Martin Heinken, Thilo Kolb, Annette Nilsson, Christer Stanton, Sharon Verheyen, Kris #
Published for the Annals of Botany Co. by Academic Press
Annals of Botany vol:109 issue:5 pages:1037-1046
Background and Aims
The response of forest herb regeneration from seed to temperature variations across latitudes was experimentally assessed in order to forecast the likely response of understorey community dynamics to climate warming.
Seeds of two characteristic forest plants (Anemone nemorosa and Milium effusum) were collected in natural populations along a latitudinal gradient from northern France to northern Sweden and exposed to three temperature regimes in growth chambers (ﬁrst experiment). To test the importance of local adaptation, reciprocal transplants were also made of adult individuals that originated from the same populations in three common gardens located in southern, central and northern sites along the same gradient, and the resulting seeds were germinated (second experiment). Seedling establishment was quantiﬁed by measuring the timing and percentage of seedling emergence, and seedling biomass in both experiments.
Spring warming increased emergence rates and seedling growth in the early-ﬂowering forb A. nemorosa. Seedlings of the summer-ﬂowering grass M. effusum originating from northern populations responded more strongly in terms of biomass growth to temperature than southern populations. The aboveground biomass of the seedlings of both species decreased with increasing latitude of origin, irrespective of whether seeds were collected from natural populations or from the common gardens. The emergence percentage decreased with increasing home-away distance in seeds from the transplant experiment, suggesting that the maternal plants were locally adapted.
Decreasing seedling emergence and growth were found from the centre to the northern edge of the distribution range for both species. Stronger responses to temperature variation in seedling growth of the grass M. effusum in the north may offer a way to cope with environmental change. The results further suggest that climate warming might differentially affect seedling establishment of understorey plants across their distribution range and thus alter future understorey plant dynamics.