Role of Moose and Deer Browsing in Harvested Forests of Southern New England since 2008

Sampling protocol Tree Seedlings. In each 20x20 m treatment, a 5 x 5 matrix of subplots was laid out in the center of the plot (4m from edges and 3m from each other). Each circular subplot was 2.25 m in diameter (100 m2 total sampling area per plot) (Risenhoover and Maas 1987). The center of each subplot was marked with a permanent stake. In each subplot all tree seedlings (at least 30cm DBH less than 2.5cm DBH) were tallied, identified, and given a height class (30-99cm, 1-2m, and greater than 2m. For sprout clumps, stems that shared a common base above the stump were characterized as a single stem, whereas stems that individually attached to the stump were counted as separate. Data from the subplots were summed. Each stem in the partial and control plot was assessed for evidence of past ungulate browsing (a torn, ragged stem). Woody stems 2019. In each of the treatment plots, a 16 x 16 m plot was established which was divided into four quadrants, each 8 x 8 m in size. In each quadrant, the diameter and species of all woody stems ≥ 2 cm in diameter are recorded. Each stem is noted as being either alive or dead and if it is intact or broken from browsing. Moose commonly pull larger saplings down to browse the leading shoots, which often breaks the stems (Faison et al. 2010). Coarse Woody Debris. Two diagonal transects were run from corner to corner and two transects and bisected the plot in a N-S direction and E-W direction. The diameter of every piece of wood that intersected the line-transect (greater than 7.5 cm in diameter) was recorded. Stumps. All stumps within the 20x20m plots were measured for diameter and identified. Browsing. Each woody stem at least 50 cm and no more than 3m is assessed for past browsing by estimating the percentage of twigs branching off the main stem that are browsed by moose or deer (torn, ragged, squared off bite). Stems are assigned to one of the following browsing classes: (0 = none, 1=1-33% twigs browsed, 2 = 34-66% twigs browsed, 3 = 67-100% twigs browsed). The leading shoot of each stem was also assessed for past browsing. Low Shrubs and Herbaceous Vegetation. In each of the 25 subplots in the three treatments, the percent cover of graminoids, Rubus, Fern, and Ericaceous shrubs are estimated using the following cover classes: 0 = absent, 1 = 1-24%, 2= 25-49%, 3 = 50-74%, 4 = 75-100% Pellet Groups. In each of the 25 subplots in the three treatments, the number of deer and moose pellet groups (at least 15 individual pellets = a group) were recorded. Total pellet groups for each species was pooled for each plot. Bird Nests. In each of the 20 x 20 m plots in the three treatments, the presence of bird nests were noted, and the height of the nest above ground was measured. Bird nests were generally not able to be identified. In 2013, we sampled all herbaceous and woody vegetation in 13, 1 m2 grid plots in a systematic grid in the center of each plot. Five rows were established with 3 subplots on the outer and middle rows and two subplots in the second and fourth rows. Subplots were positioned 6 m apart within the same row and 4.5 meters apart between rows. At each 1 x 1 m subplot, all vascular plants in the forest floor layer were recorded by a single observer (original field data collected by Glenn Motzkin archived at Harvard Forest). Percent cover was estimated for each species and for each plant group (i.e., woody plants, graminoids, and forbs), as well as rock cover and coarse woody debris, in one of 7 cover classes (1 = less than 1%, 2 = 1-5%, 3 = 6-15%; 4 = 16-25%, 5 = 26-50; 6 = 51-75%, 7 = 76-100%). We also estimated the percent cover of woody plants ≥ 2 m in height. In addition, we performed a 20 minute “meander” survey throughout the central 13 x 13 m of each plot and recorded the presence of all woody and herbaceous plant species that did not occur in the subplots. Our tree data were collected in July 2014, 6–7 years after plots were established. We established 13 4-m2 subplots along 5 successive parallel transect lines within each of the larger 20 x 20 m treatment plots, totaling a 52-m2 sampling area. Three subplots were positioned on the 2 outer and middle rows, and 2 subplots in the second and fourth rows. The center of each subplot was 6 m apart within the same row and 4.5 meters apart between rows. At each of the subplots, all tree and shrub species ≥2 m in height were recorded, and the diameter at breast height (DBH) of each stem was measured.