Interregional variation in the floristic recovery of post‐agricultural forests

Abstract

Summary1. Worldwide, the floristic composition of temperate forests bears the imprint of past land use for decades to centuries as forests regrow on agricultural land. Many species, however, display significant interregional variation in their ability to (re)colonize post-agricultural forests. This variation in colonization across regions and the underlying factors remain largely unexplored. 2. We compiled data on 90 species and 812 species · study combinations from 18 studies across Europe that determined species' distribution patterns in ancient (i.e. continuously forested since the first available land use maps) and post-agricultural forests. The recovery rate (RR) of species in each landscape was quantified as the log-response ratio of the percentage occurrence in post-agricultural over ancient forest and related to the species-specific life-history traits and local (soil characteristics and light availability) and regional factors (landscape properties as habitat availability, time available for colonization, and climate). 3. For the herb species, we demonstrate a strong (interactive) effect of species' life-history traits and forest habitat availability on the RR of post-agricultural forest. In graminoids, however, none of the investigated variables were significantly related to the RR. 4. The better colonizing species that mainly belonged to the short-lived herbs group showed the largest interregional variability. Their recovery significantly increased with the amount of forest habitat within the landscape, whereas, surprisingly, the time available for colonization, climate, soil characteristics and light availability had no effect. 5. Synthesis. By analysing 18 independent studies across Europe, we clearly showed for the first time on a continental scale that the recovery of short-lived forest herbs increased with the forest habitat availability in the landscape. Small perennial forest herbs, however, were generally unsuccessful in colonizing post-agricultural forest -even in relatively densely forested landscapes. Hence, our results stress the need to avoid ancient forest clearance to preserve the typical woodland flora.

Microclimate moderates plant responses to macroclimate warming

“…Higher relative humidity in dense forests can also protect forest herbs and tree seedlings from summer drought, decreasing mortality and thus buffering the impacts of large-scale climate change (15,29). Furthermore, many forest herbs are known to be slow-colonizing species (30). Given the high degree of habitat fragmentation in contemporary landscapes, microclimatic buffering in dense forests may be a critical mechanism to ensure the future conservation of temperate forest plant diversity.…”

Four decades of post-agricultural forest development have caused major redistributions of soil phosphorus fractions

“…Consequently, soil P concentrations are often still elevated hundreds to thousands years after agriculture has been abandoned (Wood et al 1984;Koerner et al 1997;Dupouey et al 2002;McLauchlan 2006;Dambrine et al 2007;Plue et al 2008), making them excellent indicators of previous agricultural activity. The elevated P concentrations may result in a paradox for the development of forest vegetation on agricultural land: higher P bioavailability can on the one hand stimulate stand productivity and tree growth (Fischer and Binkley 2000), but on the other, it can hamper the development of typical forest plant communities Baeten et al 2010a, b;De Frenne et al 2011).…”

L’ancienneté n’est pas un déterminant majeur de la biodiversité des forêts de montagne

“…Dans les forêts de montagne des Alpes du Nord,l 'antécé-dent cultural n'ad onc pas laissé de trace tangible dans l'écosystème. Ce résultat peut s'expliquer par le contexte écologique différent des forêts de montagne comparativement àl at rès grande majorité des études jusqu'ici publiées, conduites dans les forêts tempérées de plaine, incluses dans des paysages plutôt fragmentés, avec un taux de boisement faible àm oyen (5 à5 1%)e tu ne ( De Frenne et al, 2011). Parc omparaison, dans les Préalpes, le taux de boisement moyene st de 63 %, et le taux de forêts anciennes de 64 %.…”