Evaluation of physical barriers to protect ponderosa pine seedlings from pocket gophers

A 2 yr study on the Rogue River and Mt. Hood National Forests in Oregon evaluated physical barriers for protection of Pinus ponderosa seedlings against damage by Thomomys talpoides. Seedlings protected with one of three weights of: (1) plastic mesh tubing (Vexar) or (2) sandpaper tubing (Durite) were evaluated against control seedlings. On the Rogue River sites, Vexar seedlings had the highest survival (62.6%), followed by the controls (59.1%), then Durite seedlings (17.9%). Gophers were the primary cause of death for the Vexar seedlings, versus desiccation for the Durite seedlings. On the Mt. Hood sites, heavyweight Vexar seedlings had the highest survival (35.4%), medium-weight Durite seedlings the lowest (2.7%). Seedling mortality caused by gophers was highest for controls (70.2%), followed by light-weight (62.2%) and heavy-weight (53.9%) Vexar treatments. Overall survival was low (Rogue River = 42%, Mt. Hood = 19.8%). Growth was greatest for the control seedlings but only significantly greater than growth of Durite seedlings on the Rogue River sites. Growth of seedlings was not compromised by the Vexar tubing. Although neither type of tubing was highly protective, Vexar tubes performed better than Durite tubes.