Epsilon Archive for Student Projects

Abstract

Climate change is expected to influence the phenophases of plants. For deciduous temperate and boreal understorey vegetation, the spring season is quite relevant as the majority of carbon assimilation is performed during this season. Lately, early and false springs have caused the overstorey species to leaf out at an earlier time than expected. This has direct and indirect impacts on the understorey vegetation due to changes in light conditions. Phenological mismatch within asymmetrical plant competition is expected to be intensified, as overstorey plants experience a prolonged growth season while the understorey vegetation experiences a decreased light window. This thesis explores, through a literature review of published papers, the influence of light conditions on the understorey vegetation of deciduous temperate and boreal forests within North America, Asia and Europe.
This thesis analysed 28 papers, of which temperate forest species were mentioned in 25 papers, 2 investigated boreal forests and 1 paper investigated a transition zone between a mixed-deciduous forest and a boreal forest. The results indicate that some species like Acer saccharum seedlings, Quercus rubra seedlings, Viola pubescens and Tiarella cordifolia may be able to adapt to future shadier conditions while other species like Aesculus glabra and Allium tricoccum may be unable to adapt in time. Some studies have already observed that light conditions have an impact beyond phenological response in understorey vegetation species. Carbon gain and resource allocation seemed to be impacted by the decrease in light window for tree seedlings and herbaceous species. This could potentially impact the species´ fitness to the environment. Management measures such as gap cutting and thinning the stand could increase the brightness to the understorey layer, promoting shade-intolerant species.