The Hume Creek study area was planted in the spring 

 of 1984 to western white pine and ponderosa pine. The 

 planting procedures were the same as on the other two 

 study areas. 



SAMPLING PROCEDURES 



To avoid any edge effect of the planting, only the center 

 of each plot was sampled. A 3-m buffer strip was defined 

 on the outside of each plot. This resulted in 26 tree rows 

 within each 0.4-ha plot available for sampling in the study. 



To define and quantify causes of damage and mortality 

 to tree seedlings during the first year of establishment, 

 each tree in the study was observed seven times, six times 

 at 3-week intervals during the first growing season and 

 one time the following spring. Frequent, periodic observa- 

 tions made it possible to determine not only what caused 

 damage but also when damage was occurring. Also, by 

 determining seasonal distribution patterns of deer and elk, 

 and timing observations around livestock turn-on and turn- 

 off dates, we were able to further reduce error in 

 observation. 



A damage assessment key was developed and used to 

 record specific types of tree damage on each site 

 (appendix). 



The following tabulation shows agent and the type of 

 seedling damage that was observed during the first year 

 of the study: 



Nonanimal Pocket gopher Other rodents Big game Livestock 



planting browsing browsing browsing browsing 



drought root removal girdling trampling trampling 



snow tree removal 



Utilization by livestock was determined by use of pro- 

 tected and unprotected 1-m square plots. Vegetation was 

 clipped and weighed on plots protected from grazing and 

 compared to that obtained from grazed plots. The dif- 

 ference in weight was used to determine the percentage of 

 utilization. 



ANALYSIS 



An analysis of variance was used to analyze the data. 

 The influence of three different grazing intensities on the 

 percentages of trees substantially damaged by livestock, 

 pocket gophers, other rodents, wildlife, and unknown 

 agents was computed for each row in the study. These 

 percentages were transformed (square root of arc sine) 

 and used in the analysis. At each site there were three 

 utilization levels, with 26 tree rows per utilization level. 

 Because conducting a true replicated study was logistically 

 and financially prohibitive, tree rows were used in the 

 analyses as replicates. Duncan's multiple range test was 

 used to detect differences among the utilization means. 

 The three tree species used in this study were analyzed 

 separately. 



RESULTS 



The following results assess the impact of animal and 

 nonanimal related factors on tree seedlings during the 

 first 12 months of establishment. The first year of estab- 

 lishment is the most important in the life of a forest 



plantation. It is at this time that tree seedlings are most 

 susceptible to numerous biotic and abiotic environmental 

 factors that can cause mortality or reduced growth. These 

 results identify the influence of livestock grazing intensity 

 on those factors damaging first-year plantations. This is 

 done for each of the three study areas. 



Indian Springs 



Grazing intensity appeared to influence the total per- 

 centage of ponderosa pine trees that were damaged in the 

 different utilization levels at Indian Springs. The factors 

 that most influenced tree damage and mortality were 

 nonanimal causes, rodents other than pocket gophers, and 

 wildlife (deer and elk). On the high-utilization site, 

 14.4 percent of the seedling damage was from nonanimal- 

 related causes as compared to 4.9 percent of the seedlings 

 damaged on the study site receiving an intermediate level 

 of utilization (table 1). It appeared that rodents other than 

 pocket gophers did the most damage in the low-utilization 

 area, with no differences in percentage of damage 

 detected between the intermediate and high levels. 



The sum of these damaging agents was the largest in 

 the low-utilization level (21.9 percent damage) and in the 

 high-utilization level (24.4 percent damage). The fewest 

 trees damaged were in the intermediate-utilization level. 



The results for Douglas-fir were similar to those of 

 ponderosa pine at the three different utilization levels. 

 Wildlife caused the largest amount of damage (6.5 per- 

 cent) on the low-utilization level (table 1). Nonanimal 

 damage for Douglas-fir was higher on the heaviest grazed 

 area (4.9 percent). Similar to ponderosa pine, the greatest 

 damage and mortality occurred on the areas receiving 

 light and heavy grazing intensities. Fewest trees were 

 damaged on the intermediate-utilization level, where only 

 3.7 percent of the trees were damaged. 



Tee Meadows 



Damage and mortality to ponderosa pine were signifi- 

 cantly different for each of the three utilization levels. 

 Pocket gophers caused the most damage to the ponderosa 

 pine seedlings. The greatest amount of damage occurred 

 at the intermediate-utilization level (66.3 percent), with 

 51.2 percent at the light-utilization level and 28.8 percent 

 damage at the heavy grazing intensity (table 2). 



Nonanimal damage was the greatest at the low- 

 utilization level (7.4 percent). In addition, no significant 

 differences were found in damage to ponderosa pine 

 among the grazing levels by livestock or wildlife. 



The differences found among the three utilization levels 

 for total damage were influenced most by pocket gophers, 

 with the highest amount of damage occurring at the inter- 

 mediate grazing intensity. Total damage was least on the 

 high-utilization level (33.8 percent), with 72.8 percent of 

 the trees damaged on the intermediate grazing level. 



Fewer differences in damage were found with western 

 white pine at the different grazing intensities than with 

 ponderosa pine. The largest amount of damage to western 

 white pine was caused by pocket gophers, with 61.2 per- 

 cent damage occurring at the light grazing intensity and 

 63.8 percent damage at the intermediate grazing intensity. 



3 



