Article Figures & Data
Figures
- Figure 1.
Tree protectors were evaluated for effects on survival and growth of three oak species and Douglas fir in irrigated (background) and nonirrigated (foreground) plots. Two tree guards, Hopland tents (plastic mesh) and wire screens, were used as well as ventilated (holes in sidewall) and nonventilated treeshelters.
- Figure 2.
Irrigated blue oak survival for protected trees ranged from 83 to 100%, while only half of irrigated but unprotected trees (controls) survived. Protection also substantially improved tree survival in nonirrigated plots. C = Control, HT = Hopland Tent, NVTS = Non ventilated Treeshelter, VTS = Ventilated Treeshelter, WS=Wlre Screen.
- Figure 3.
All irrigated live oak trees with protectors survived, while 66% of unprotected trees survived. Survival of nonirrigated trees with protectors varied from 30 to 50%, with only 10% of unprotected trees surviving.
- Figure 4.
Irrigated valley oak survival was high for both protected and unprotected trees. Except for unprotected trees, nonirrigated tree survival also was high. In nonirrigated plots, valley oak survival was substantially greater than that for blue and live oaks.
- Figure 5.
Survival of irrigated Douglas fir trees with protectors varied from 33 to 66%, while only 16% of unprotected trees survived. Survival in nonirrigated plots was very poor.
- Figure 6.
Height growth of irrigated live oaks was substantially greater than that of nonirrigated trees. Protected trees were taller than nonprotected trees. In years two and three, live oaks with ventilated or nonventilated treeshelters were significantly taller than trees with wire screens, Hopland tents, or controls. In year 4, nonirrigated trees with nonventilated treeshelters were significantly taller than control and Hopland tent treatments.
- Figure 7.
Irrigated valley oaks were substantially taller than nonirrigated trees. Protected trees were taller than unprotected trees in both irrigated and nonirrigated plots. In year 3, irrigated valley oaks with ventilated and nonventilated treeshelters were significantly taller than control or Hopland tent treatments, while trees with wire screens were significantly taller than controls but not different from treeshelters. In year 4, only irrigated trees with ventilated treeshelters were significantly taller than control and Hopland tent trees.
- Figure 8.
Irrigated blue oaks were substantially taller than nonirrigated trees. In irrigated and nonirrigated plots, trees with protectors were taller than unprotected trees. In years 3 and 4, trees with ventilated treeshelters were significantly taller than Hopland tent and control treatments.
- Figure 9.
In nonirrigated plots, tree growth and survival was substantially less than that found in irrigated plots. Tree guards and treeshelters improved survival, but showed little difference in growth effects.
- Figure 10.
After four years, many oaks had grown well above treeshelters in irrigated plots. After removal of treeshelters, most trees had sufficiently well-developed trunks to maintain an upright position.
Tables
- Table 1.
Cumulative diameter growth (mm) for irrigation treatments and species. Data for protection treatments was combined since no significant differences in diameter growth were found for these treatments. Diameter growth for irrigated oaks was significantly greater than that for nonirrigated trees. Nonirrigated Douglas fir trees did not survive.
Species Treatment Diameter (mm) Yr 1 Yr 2 Yr 3 Yr 4 Blue oak Irrigated 1.0 4.4 8.5 10.0 Nonirrgated 0.1 1.4 2.5 4.8 Live oak Irrigated 2.3 10.1 29.1 45.2 Nonirrigated 0.7 3.1 6.4 9.8 Valley oak Irrigated 2.9 8.8 19.8 24.3 Nonirrigated 0.6 2.4 5.2 8.8 Douglas fir Irrigated 1.9 7.2 14.6 21.0 Nonirrigated 1.2 0.0 0.0 0.0
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