Tree distribution patterns in the southwest Jemez Mountains Kamal Humagain 1, Robert Cox 1, and James Cain 2 1 Texas Tech University 2 New Mexico State University, 2 New Mexico Cooperative Fish and Wildlife Research Unit (1)Preliminary data exploration shows the bigger trees in the non-treatment sites for Ponderosa pine forests which constitutes the majority of the project area. (2)The trees are denser in the areas to be treated either with prescribed fire or thinning which supports accuracy of the selection of the sites for treatment. (3)Simple linear regression suggests that smaller trees are more densely distributed than the larger trees and they needs to be thinned or treated with fire. Conclusions Results Methods Introduction Preliminary Analysis Data Collection: There are 224 plots established in the CFLRP area based on vegetation type, canopy cover, aspect and fire history. Fig 2. Sample Transect (200m) Distance Figure 1 shows the decreasing order of number of plots based on vegetation type. The number of plots has been determined based on the proportion of area covered by vegetation type. A majority of the plots are south- and north-facing. The point centered quarter method was used for tree measurements at every 40m in a 200m transect. The distance and diameter-breast-height (DBH) to the nearest tree were recorded for each quarter for every 40m in a 200m transect which makes a total of 20 data points per transect. Fig 1. Number of plots (veg type and aspect) DBH: DBH of the trees was mostly low in the P-J woodlands, and increases in PON, ASP, S-F mixed forest, and grasslands (Fig 3). Mean/Median DBH in grasslands is the highest among all, since there are fewer trees and the trees are larger in these open areas. Most of the observations are in ponderosa (more than 30%), followed by S-F, P-J, GRA, OAK, and ASP(less than 10%) (Fig. 4). Fig 3. DBH by vegetation type Trees are a major part of ecosystem function locally and globally as they are a large reservoir of carbon. The herbaceous and shrub species constitute the understory mainly based on the tree types and canopy. Major vegetation types of the project area include forests (aspen, ponderosa pine, spruce-fir), woodlands (oak, pinyon-juniper) and grassland. Major trees include aspen (Populus tremuloides), ponderosa pine (Pinus ponderosa), pinyon pine (Pinus edulis), junipers (Juniperus spp.), white fir (Abies concolor), Douglas fir (Pseudotsuga menziesii), blue spruce (Picea pungens), Engelmann spruce (Picea engelmannii), and limber pine (Pinus flexilis). The treatments types being applied as the ecological restoration process in these vegetation types are prescribed burning (RX), thinning (TRT), and no treatment (NT). Fig 4. Observations by veg type Fig 5. Density by vegetation type Fig 6. DBH and Density relationship Density: In general, TRT or RX sites are denser than NT sites (Fig. 5). That is what we expected and the treatment is needed for the denser sites for herbaceous vegetation and better tree growth. Fig. 8 shows negative relationship between the DBH and density. As the DBH increases, the density decreases. In general, this suggests that smaller trees are distributed densely than the larger trees. Fig 7. Richness by vegetation typeFig 8. Cover by vegetation type Richness and Cover: Spruce-fir, grassland and oak vegetation types are the richest among others with up to 6 tree species (Fig. 7). Most of the ponderosa plots have fewer types of trees as they mostly have ponderosa pine trees. There is no particular pattern in cover based on treatment types (Fig 6). However, in most of the cases, basal area (cover) is larger for TRT sites as this is a function of DBH.