Light and warming drive forest understorey community development in different environments

• Published in: Global change biology Vol. 26; no. 3; pp. 1681 - 1696
• Main Authors: Blondeel, Haben, Perring, Michael P., Depauw, Leen, De Lombaerde, Emiel, Landuyt, Dries, De Frenne, Pieter, Verheyen, Kris
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-03-2020
• Subjects: Availability; Climate Change; Community composition; Community development; community weighted mean; Deciduous forests; Design of experiments; Dispersal; Ecosystem; Ecosystem management; Environmental changes; Europe; Experimental design; Forest communities; Forest management; Forests; global change; Growing season; Height; herbaceous communities; Herbs; Land use; land‐use legacies; Leaf area; Leaves; Light; mesocosm; Mesocosms; Morphology; multifactor experiment; Nitrogen; nitrogen deposition; Nitrogen enrichment; Nutrient enrichment; Plant communities; Plants; Resource management; Restoration; Soil; Species; Temperate forests; Europe; land-use legacies; multifactor experiment; community weighted mean; global change; mesocosm; nitrogen deposition; herbaceous communities; forest management; climate change
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.14955

Plant community composition and functional traits respond to chronic drivers such as climate change and nitrogen (N) deposition. In contrast, pulse disturbances from ecosystem management can additionally change resources and conditions. Community responses to combined environmental changes may further depend on land‐use legacies. Disentangling the relative importance of these global change drivers is necessary to improve predictions of future plant communities. We performed a multifactor global change experiment to disentangle drivers of herbaceous plant community trajectories in a temperate deciduous forest. Communities of five species, assembled from a pool of 15 forest herb species with varying ecological strategies, were grown in 384 mesocosms on soils from ancient forest (forested at least since 1850) and postagricultural forest (forested since 1950) collected across Europe. Mesocosms were exposed to two‐level full‐factorial treatments of warming, light addition (representing changing forest management) and N enrichment. We measured plant height, specific leaf area (SLA) and species cover over the course of three growing seasons. Increasing light availability followed by warming reordered the species towards a taller herb community, with limited effects of N enrichment or the forest land‐use history. Two‐way interactions between treatments and incorporating intraspecific trait variation (ITV) did not yield additional inference on community height change. Contrastingly, community SLA differed when considering ITV along with species reordering, which highlights ITV’s importance for understanding leaf morphology responses to nutrient enrichment in dark conditions. Contrary to our expectations, we found limited evidence of land‐use legacies affecting community responses to environmental changes, perhaps because dispersal limitation was removed in the experimental design. These findings can improve predictions of community functional trait responses to global changes by acknowledging ITV, and subtle changes in light availability. Adaptive forest management to impending global change could benefit the restoration and conservation of understorey plant communities by reducing the light availability.
Light and warming reorder plant species towards taller forest understorey communities (a). Spring‐flowering species persist in dark ambient conditions, regardless whether soils originate from ancient forest or nutrient enriched postagricultural forest (b). These findings can improve predictions of the community distribution of key functional traits to global changes by acknowledging intraspecific trait variation, and subtle changes in light availability. Adaptive forest management to impending global change could benefit the restoration and conservation of typical understorey plant communities by reducing the light availability