Legacies of the agricultural past in the forested present: an assessment of historical land‐use effects on rich mesic forests

Abstract

Aim and location The research investigated the long-term effects of human disturbance, namely nineteenth century agricultural land-use, on the modern species composition, structure and distribution of Rich Mesic Forests (RMF) in western Massachusetts, USA. RMF are a species-rich north-eastern variant of the Mixed Mesophytic Forest Type of eastern North America.Methods Land-use history patterns were reconstructed for two towns (c. 16,000 ha) from the onset of widespread European settlement and agricultural land-use in the late eighteenth century until present. Vegetation and a range of environmental variables were sampled in sixty-one 10 · 10 m plots in thirty-four forest stands with varying histories of human disturbance. Vegetation data were ordinated (DCA) to identify patterns of variation and related environmental and historical factors. The distribution patterns of individual taxa in relation to historical land-use and environmental factors were analysed using G-tests of independence and logistic regression. Associations between species secondary forest colonization ability and life history characteristics (e.g. diaspore dispersal mode, degree of vegetative spread) were assessed.Results Persistent compositional differences were documented between the vegetation of primary forests and post-agricultural, secondary forests indicating that distribution patterns for many plant species still reflect the open, agricultural environment of the nineteenth century, despite the current predominance of forest cover in the study area. A major factor driving modern vegetation patterns in RMF is the ability and rate of colonization by forest herbs. In particular, species with seeds lacking morphological adaptations for dispersal (barochores) and those which produce seeds with elaiosomes to encourage ant dispersal (myrmecochores) are less frequent in secondary forests. Environmental differences between primary and secondary forests, although present, appear to be less important in influencing species distribution patterns.Main conclusions Widespread agricultural land-use represents a novel disturbance in the naturally forested ecosystems of eastern North America with long-term impacts on plant community composition and structure. Many secondary forest sites that are environmentally suitable for RMF vegetation do not support the suite of plant species typical of this community type, apparently because of the dispersal limitations of certain forest herbs. These poorly dispersed herb taxa are well adapted for growth in stable forest ecosystems characterized by local, small-scale disturbance (e.g. gap-phase dynamics), yet are maladapted for rapid population recovery and recolonization following severe disturbance (e.g. agricultural land-use).

Emerging forests on abandoned land: Puerto Rico’s new forests

“…The aliens that invade New England new forests include pests, pathogens, and herbaceous plants (Bellemare et al, 2002;Orwig, 2002). Alien species in New England have not invaded the canopy of its forests.…”

Impacts of land-use history on the recovery of ecosystems after agricultural abandonment

“…Differences between (near) pristine and post-agricultural forests or grasslands have been reported to persist for decades or centuries after agricultural abandonment for various variables, including soil pH (Falkengren-Grerup et al, 2006); microbial communities (Fichtner et al, 2014); soil C, N and phosphorus (Compton and Boone, 2000); and other nutrients (Wall and Hytonen, 2005). Furthermore, aboveground (ag) biomass (Wandelli and Fearnside, 2015), percentage vegetation cover (Lesschen et al, 2008), biodiversity (Vellend, 2004), species composition (Aide et al, 2000) and structure (Bellemare et al, 2002) remained affected for years to decades, or even longer. These effects have consequences, not only for the C sink capacity of the ecosystem but also for water and energy exchange between the land and the atmosphere (Foley et al, 2003), which also has important, albeit still highly uncertain, implications for regional climate change (e.g., Arora and Montenegro, 2011;Brovkin et al, 2013;de NobletDucoudre et al, 2012).…”

Role of plant functional traits in determining vegetation composition of abandoned grazing land in north‐eastern Victoria, Australia

“…In Europe and North America, past land use generally has a long-term impact on the composition of vegetation of post-agricultural, secondary forest due to the time it takes species with dispersal limitations to re-colonise (Matlack 1994;Brunet & von Oheimb 1998;Bossuyt et al 1999;Graae & Sunde 2000;Bellemare et al 2002). These species are typically herbaceous perennials with myrmecochorous or barochorous dispersal and large seeds (Bossuyt et al 1999;Hermy et al 1999;Verheyen et al 2003).…”