Ground cover in old-growth forests of the central hardwood regionThis article is part of a larger document. View the larger document here.
Differences in ground cover (percent cover of litter, percent cover of vegetation and litter weight) in old-growth forests across this region are not well understood. We initiated a long-term study in a three-state region to enhance knowledge in this area. We present baseline results for ground cover and compare these data across productivity regions. Thirty 0.25-ac (0.1-ha) main plots and 120 subplots 27 ft² (2.5 m²) in size were established in each old-growth forest and used to inventory ground cover. We estimated percent cover of: bare ground, boles of woody vegetation, dead leaves, downed woody material, exposed rock, and herbaceous cover. In addition, 240 subplots 1.35 ft² (0.125 m²) in size were used to estimate dry weight of litter down to the mineral soil horizon. Trends among sites were compared to a regional productivity gradient. Across all sites, mean values for percent ground cover were: bare ground, 6% (SD 10%); boles of woody vegetation ≥3.3 ft tall, 2% (SD 1%); dead leaves and dead herbaceous vegetation, 85% (SD 10%); downed woody material, 5% (SD 1%); exposed rock, 1% (SD 2%); other, 1% (SD 2%). Mean litter weight across all sites was 6.8 tons/ac (SD 3.1 tons/ac) [15.3 metric tons/ha (SD 7 metric tons/ha)]. Differences in litter weight were not significant between northeast and southwest slopes. The inverse relationship of percent cover of exposed rock to regional productivity class was highly significant (R² = 0.88 for negative exponential model, p-value < 0.01). The positive linear relationship between litter weight and productivity class was also significant (R² = 0.55, p-value = 0.01).