Stand Selection
Stands were selected based on data provided by the United States Forest Service insect and disease aerial survey maps. The following criteria was used for stand selection: 1. At least 50% of pre-2000 species composition comprised of the same host tree; 2. No forest treatments within previous 20 years; and 3. Similar slope, aspect, vegetation association and elevation. Stands ranged from west-central New Mexico to north-central New Mexico. Sampling was completed in the summers of 2012 and 2013 in the Mount Taylor stands and the summer of 2013 for the remainder of the stands.
Plots
A randomized, systematic grid of ten clusters of two 0.02 ha plots were established using GIS software and exported to a handheld GPS. One plot of each cluster was located on the intersection of the grid (‘grid plots’) and the second located 50m at a random azimuth from the established grid plot (‘cluster plots’). This methodology was shown to improve sampling efficiency for stand characteristics pertaining to western spruce budworm within a set allowable error (Lynch 2003). Five 0.001 ha nested regeneration plots were also established (described below).
Plot Characteristics
Vegetation association was assessed using the Plant Associations of Arizona and New Mexico habitat typing guide. Canopy cover was recorded using a GRS densiometer in 1m increments on two 15.96 m transects bisecting plot center running north to south and east to west. Measurements will begin at 1m and extend to 15m totaling 15 measurements on the north to south transect. The east to west transect will exclude the measurement at 8m to avoid repeated measurements. Canopy cover was calculated by the number of canopy “hits” divided by the total number of measurements taken
Overstory Measurements
Species and diameter at breast height (DBH) was measured for all trees greater than 12.7 cm in diameter occurring in plot. DBH was considered to be 1.37 meters above ground. The height and canopy base height of each tree was recorded using a sonic hypsometer (Vertex III, Hagloff). Condition of tree (live or dead) along with cause of mortality should be identified whenever possible. Canopy dieback as identified by chlorotic foliage should be noted. Canopy class was assigned to each tree on plot using the following classes:
Canopy Classes
• O – Open grown, or the tree is not near any other tree
• E – Emergent, or the crown is totally above the canopy of the stand.
• D – Dominant, or the crown receives light from at least 3-4 directions
• C – Codominant, or the crown receives light from at least 1-2 directions
• I – Intermediate, or the crown only receives light from the top.
• S – Suppressed, or the crown is entirely shaded and underneath the stand canopy
Decay class was assessed on a 1 to 5 scale based on the findings of Raphael and White (1984).
• 1 – Needles present, twigs present, branches present and in tact
• 2 – No needles present, twigs present, branches present and in tact
• 3 – No needles present, no twigs present, branches mostly in tact
• 4 – No needles present, no twigs present, branches mostly broken
• 5– No needles present, no twigs present and no branches present.
Defoliation
Measurement of defoliation was based on United States Forest Service Forest Health Monitoring Protocols (Schomaker et al. 2007). The protocol for this technique is as follows:
• Two people should participate in this task because a single viewpoint can lead to incorrect estimates.*
• Observers should stand ½-1 tree length from the subject tree.
• Observers should attempt to stand either at the same levels as the tree or upslope
• Observes should stand 90 degrees apart if at all possible. Observing trees from the same side or 180 degrees opposed is not desirable.
• Special care should be taken under cloudy or dim conditions
• Use binoculars to distinguish heavy defoliation from dieback
• Estimate it as a % of the total crown area (live plus dieback)
• Exclude dead lower branches (attributable to self-pruning), snag branches, and large gaps or holes in the crown.
* If an additional crewmember is unavailable, two measurements may be taken by one crewmember.
Defoliation was sketched on a transparency using the guidelines listed below. Percent defoliation was digitally analyzed post data collection using the dot diagram techniques established by Millers et al. 1991 using Adobe Photoshop.
Regeneration
Seedlings (trees <1.37 m height) and saplings (trees >1.37 m height and <12.7 cm dbh) were measured in five 0.001 ha nested plots established at plot center and 3.95m in each cardinal direction from plot center. Non host seedlings were tallied by species in 0.15m height classes and sapling height was recorded along with DBH (table 1). Host species (Pseudotsuga menziesii, Abies concolor, Abies lasiocarpa, Picea pungens and Picea engelmannii) wasalso be recorded in 0.15m height classes but treated as individuals. Defoliation of host regeneration was visually measured using 10% increments while applying the same techniques as outlined by the above image and recorded on site.
Table 1: Height Class for Seedlings
Height Class (m)
Height
1 0 – 0.15
2 0.15 – 0.3
3 0.3 –.45
4 0.45 – 0.6
5 0.6 – 0.75
6 0.75 – 0.9
7 0.9 – 1.05
8 1.05 – 1.2
9 1.2 – 1.35
10 1.35 – 1.5
Literature Cited
Millers, I., Lachance, D., Burkman, W.G and Allen, D.C. 1991. North American sugar maple decline project: organization and field methods. USDA Forest Service Northeastern Forest Experiment Station, General Technical Report NE-154. 26p.
Plant Associations of Arizona and New Mexico. Albuquerque, N.M.?: U.S. Dept. of Agriculture, Forest Service, Southwestern Region, 1997. Print.
M.G Raphael, M White. 1984. Use of snags by cavity-nesting birds in the Sierra Nevada. Wildlife Monographs. 86. p. 1–66
Schomaker ME, Zarnoch SJ, Bechtold WA, Latelle DJ, Burkman WG, Cox SM. 2007. Crown-condition classification: a guide to data collection and analysis. Gen. Tech. Rep. SRS-102. Asheville, North Carolina: U.S. Department of Agriculture, Forest Service, Southern Research Station, p. 2-28.
