Land-use history and forest herb diversity in Tompkins County, New York, USA.

Abstract

A legacy of past agriculture continues to shape many current forests in north-eastern North America and Europe, where the understorey flora of postagricultural stands shows reduced diversity and altered composition for hundreds of years. Effective management of forests recovering from human disturbance requires an understanding of the mechanisms that produce these patterns. Here we discuss forest regeneration on abandoned agricultural land in Tompkins County, New York. USA, in comparison with other regions that share a broadly similar history. Using data from vegetation surveys of primary and secondary forests, we assessed the relationship between land-use history and forest herb diversity; the effects of time since abandonment, distance from primary forest and type of agricultural use, whether cultivation or pasture, on the species-richness of secondary stands; and the influence of dispersal mechanism on individual species' distributions. Secondary forests 70-100 years old contained, on average, 65% the number of forest herb species in primary forests. Among all secondary stands, forest herb species-richness increased with time since abandonment, and decreased with distance from primary forest; type of agricultural use did not affect species-richness directly, but the relationship with distance was weaker for former pastures. Dispersal mechanism did not influence species' relative frequency in the two forest types. While landscape-level patterns indicate that the process of dispersal largely controls forest herb diversity in postagricultural stands, unexplained variation among species with similar dispersal mechanisms suggests that other processes, such as recruitment, may also affect the distributions of some species.

Understory succession in post-agricultural oak forests: Habitat fragmentation affects forest specialists and generalists differently

“…In the proximate plantations of this study, a minimum of approximately 60 years was needed to accumulate forest species numbers to a level comparable to core forests, a pattern that is consistent with earlier findings from floristic surveys in our study area (Brunet, 2004(Brunet, , 2007b and from similar studies carried out elsewhere (Bossuyt and Hermy, 2000;Honnay et al, 2002;Flinn and Marks, 2004).…”

Revisiting the Deciduous Forests of Eastern North America

“…It should be noted that although she considered the herbaceous understory important in distinguishing the regions, the present classification (as well as those using Braun's published stand data) does not consider it. (However, several studies have documented dramatic changes in the herbaceous understory in second-growth forests, compared with old-growth forests; see Duffy and Meier 1992, Matlack 1994, Bellemare et al 2002, Flinn and Marks 2004.) It is likely, though, that the lack of distinctiveness revealed by the data reflects changes in the abundance of woody species in secondary forests compared with the old-growth forests on which Braun focused.…”

Seed dispersal by white-tailed deer: implications for long-distance dispersal, invasion, and migration of plants in eastern North America

“…However, several observations suggest that long-distance movement is achieved in ways other than the presumed dispersal mode. Forest herb species considered to lack long-distance dispersal have colonized successional stands isolated from potential seed sources (Matlack 1994;GrashofBokdam and Geertsema 1998), and variation among species in colonization rate into successional forests is often not directly related to diaspore type (Singleton et al 2001;Verheyen et al 2003;Flinn and Marks 2004). Given the advantages of dispersal, another apparent anomaly is the large number of species considered to have no special seed dispersal morphology, accounting for 20-50% of the plant species in some regions (Willson et al 1990;Willson 1993).…”