Reforestation of Bottomland Hardwoods and the Issue of Woody Species Diversity

Abstract

Bottomland hardwood forests in the southcentral United States have been cleared extensively for agriculture, and many of the remaining forests are fragmented and degraded. During the last decade, however, approximately 75,000 ha of land—mainly agricultural fields—have been replanted or contracted for replanting, with many more acres likely to be reforested in the near future. The approach used in most reforestation projects to date has been to plant one to three overstory tree species, usually Quercus spp. (oaks), and to rely on natural dispersal for the establishment of other woody species. I critique this practice by two means. First, a brief literature review demonstrates that moderately high woody species diversity occurs in natural bottomland hardwood forests in the region. This review, which relates diversity to site characteristics, serves as a basis for comparison with stands established by means of current reforestation practices. Second, I reevaluate data on the invasion of woody species from an earlier study of 10 reforestation projects in Mississippi, with the goal of assessing the likelihood that stands with high woody species diversity will develop. I show that natural invasion cannot always be counted on to produce a diverse stand, particularly on sites more than about 60 m from an existing forest edge. I then make several recommendations for altering current reforestation practices in order to establish stands with greater woody species diversity, a more natural appearance, and a more positive environmental impact at scales larger than individual sites.

Development of restoration trajectory metrics in reforested bottomland hardwood forests applying a rapid assessment approach

“…in the LMV (Twedt and Portwood, 1997;Allen et al, 2001;Williams et al, 1997). Following the closure of the canopy, the onset of ground shading initiates the observed decreases in shrub-sapling density and percent ground vegetation cover via light limitation (Allen, 1997). Results support the application of shrub-sapling density and ground vegetation cover as useful indicators of restoration trajectory and performance in the early years following reforestation.…”

“…Recent work suggests measures of performance focus on vegetation composition, ecosystem processes, species diversity, and structural benchmarks (Gardiner et al, 2004;Wilkins et al, 2003;Hamel, 2003;Allen, 1997). However, calibration of appropriate methods for determining restoration performance continues to lack clarity, specifically within the first few years following restoration (Steyer et al, 2003).…”

Arrival order among native plant functional groups does not affect invasibility of constructed dune communities

“…An example of priority effects and arrested immigration is in restored floodplain forests of the southcentral United States where replanted tree species (usually Quercus spp.) have largely excluded other immigrating species (Allen 1997). In addition, arrival order has been shown to affect experimental plant assembly (Kardol et al 2012).…”

Development of alder carr after the abandonment of wet grasslands during the last 70 years

“…However, knowledge about the mechanisms of succession from wet grasslands to alder carr, as well as the factors driving this process, remain largely unexplored. Similarly, secondary succession to wetland forests throughout the world has not been sufficiently investigated (but, Allen, 1997;Battaglia et al, 2002;DeSteven and Sharitz, 1997;Warren et al, 2004).…”