J. R. Bray

Data on the net production of oven-dry organic matter from 28 temperate angiosperm herbaceous species and 4 temperate arboreal species were analyzed to determine the relationship between below-ground and above-ground yearly increment. Mean yearly net herbaceous production (t/ha) was 3.9 for below-ground parts, 5.9 for above-ground parts, and 9.8 total. Mean yearly net arboreal production (t/ha) was 1.9 for below-ground parts, 8.9 for above-ground parts, and 10.8 total.The mean below-ground/above-ground ratio and mean below-ground production was significantly higher for herbaceous species. Mean above-ground production was significantly higher for arboreal species. There was no significant difference between total herbaceous and total arboreal production. Productivity comparisons based only upon above-ground parts are likely to be biased in favor of arboreal species.In herbaceous species, root production decreased with age and increased from fruit crops to root and tuber crops and the below-ground/above-ground ratio increased from moist to mesic to xeric species. Arboreal species were uniform in below-ground/above-ground ratios.

Trees, shrubs, and herbs were sampled inside and outside an exclosure in a 230—year—old Pinus resinosa forest in north—central Minnesota from 1946 to 1969. Prior to the building of the exclosure in 1937, white—tailed deer had existed at or above starvation population densities for 10 or more years. Overbrowsing continued outside the exclosure until 1945 when the deer were virtually eliminated by hunting. Since then deer numbers have gradually increased. Before 1937, severe browsing had apparently removed all tree reproduction greater than 1—2 years old. Since 1937, inside the exclosure the occurrence of seedlings and samplings has increased greatly and has followed a normal successional sequence dominated by Pinus strobus with lesser amounts of Betula papyrifera, Acer rubrum, Quercus borealis, and Abies balsamea. Outside, tree reproduction was scarce until after 1945; then Pinus resinosa, P. strobus, and Betula papyrifera saplings increased substantially. Only P. resinosa and B. papyrifera have grown above the sapling class in appreciable numbers, probably because B. papyrifera is of low preference as deer browse compared with the other intermediate species, Pinus strobus, Acer rubrum, and Quercus borealis. Thus, moderate—to—high browsing has continued to inhibit successional development.