Regeneration response to treatment
Prior to final overstory removal in 1999, there were 800 stems per acre of red oak seedlings that had an average height of 41 inches (3.4 ft). Key findings include:
- Natural red oak seedlings had slightly greater density than planted red oak seedlings 10 year after planting but the planted seedlings were almost 3 times taller (Figures 2 & 3)
- There were fewer sugar maple, aspen, ironwood, and miscellaneous species seedlings than red oak seedlings (seedling origin combined), but the non-oak seedlings were taller than the planted red oak and seed-origin red oak seedlings, 10 years after initial harvest and planting (Figures 2 & 3)
- Not surprising, the red oak stump sprouts were on average just as tall as aspen seedlings, and were the tallest seedlings on site
- Regeneration notes from 1996 state that the red oak seedling condition “overall was excellent; caliper 5/16” to 1/2” and most red oak is at or above competition from brush”; also, it was noted that there was heavy raspberry and blackberry cover
In July 2016, staff re-measured tree regeneration density, tree basal area, and species diversity. We measured tree regeneration in 4 size classes (Table 1): regenerants (less than 1 inch DBH and less than 1 foot tall), seedlings (less than 1 inch DBH and greater than 1 foot tall), saplings (1-3 inch DBH) and small trees (3-5 inch DBH). Key findings include:
- 17 years after final harvest, sugar maple dominates the regenerant, seedling, and sapling layers. However, the density of sugar maples in the small tree layer (3-5 inch DBH) is the same as that of red oak and aspen (Table 1)
- In terms of tree basal area, red oak is most dominant (28% of the BA), with aspen and sugar maple as the next most dominant trees (23% and 19%, respectively; Table 2)
Table 1. Tree regeneration density (avg. stems/acre) 17 years post final overstory removal. [regenerants = less than 1 inch DBH and less than 1 foot tall; seedlings = less than 1 inch DBH and greater than 1 foot tall; saplings = 1-3 inch DBH and small trees = 3-5 inch DBH]
| Species |
Regenerants
(<1" DBH and <1' tall) |
Seedlings
(< 1" DBH and > 1' tall) |
Saplings
(1 - 3" DBH)
|
Small trees
(3 - 5" DBH) |
| Red oak |
23 |
0 |
62 |
85 |
| Sugar maple |
46 |
131 |
123 |
85 |
| Aspen |
0 |
0 |
8 |
77 |
| Basswood |
0 |
15 |
15 |
8 |
| Black cherry |
15 |
15 |
0 |
15 |
| Ironwood |
8 |
23 |
92 |
0 |
| Ash spp. |
0 |
46 |
8 |
0 |
| Elm spp. |
8 |
46 |
31 |
46 |
| Red maple |
0 |
8 |
15 |
8 |
| Total |
100 |
285 |
354 |
323 |
Table 2. Tree basal area (feet^2/acre) and relative dominance (% of total basal area) 17 years after final overstory removal.
| Species |
Basal Area
(ft^2/acre) |
Dominance
(% of total basal area) |
| Red oak |
31.5 |
28.3 |
| Aspen |
25.4 |
22.8 |
| Sugar maple |
21.5 |
19.3 |
| Elm spp. |
13.8 |
12.4 |
| Ironwood |
5.4 |
4.8 |
| Basswood |
3.8 |
3.4 |
| Bur oak |
2.3 |
2.1 |
| Black cherry |
2.3 |
2.1 |
| Red maple |
1.5 |
1.3 |
| Butternut |
1.5 |
1.3 |
| Paper birch |
0.8 |
0.7 |
| Ash spp. |
0.8 |
0.7 |
| Boxelder |
0.8 |
0.7 |
| Total |
111.4 |
- |
Understory plant response to treatment using a species-area plot
We observed 65 plant species in a ~0.25 acre plot and only 4 of these species were introduced species. This tracks well with other MHc36 communities. Based on other species-area plots in MHc36, we have found anywhere from about 30 to 80 species in ~0.25 acre plot. In general, managed MHc36 stands that have been harvested and/or burned tend to result in greater species richness whereas the unmanaged, mature stands with heavy deer and worm presence result in lower species richness.
We found 4 introduced species, including common burdock (Arctium minus), tatarian honeysuckle (Lonicera tatarica), dandelion (Taraxacum officinale), and common mullien (Verbascum thapsus). All were minor components of the site and all were noted to be present pre-treatment as well.
There are similar numbers of observations for shade tolerant plants (21 plants with low synecological light scores, values of 1 or 2) and shade intolerant plants (18 plants with high synecological light scores, values of 4 or 5). We observed light loving plants hanging on under the closed canopy 17 years after the final harvest.