Total leaf production, vertical foliage profiles, and the timing of leaf production and loss were compared in fertilized and unfertilized 3-year-old sweetgum (Liquidambar styraciflua L.) saplings. Nitrogen (N) fertilization increased total leaf area and mass through increased leaf size rather than changes in leaf number or specific leaf mass. Both the vertical and temporal distribution of foliage shifted in response to N. Fertilization increased leaf area primarily in the mid- to upper crown. The midheight of the tree crowns shifted upward throughout the season as leaf abscission occurred from the base to the top of the tree and acropetally along the branches. Peak leaf display occurred in July regardless of N supply. However, fertilized trees had twice the leaf area of the unfertilized trees by early autumn. Leaf area production and loss were modeled separately as a function of fertilization and crown height and the equations combined to model temporal changes in leaf area display.

Shade-tolerant Engelmann spruce (Picea engelmannii) is a difficult species to reforest successfully in the high-elevation spruce-fir forests of the Rocky Mountains. This study investigated the use of plastic tree shelters as a form of shade protection and a means to improve the growth and survival of planted Engelmann spruce seedlings in southwest Colorado. A total of 1500 seedlings were planted into a 48 ha clearcut site at an average elevation of 3273 m. Treatments included four different colors of tree shelters and a control where seedlings were planted using the traditional shading method. This consisted of shading the seedlings using logging slash, stumps, and vegetation within the site. After two growing seasons, survival was 58% for the control treatment and ranged from 95 to 99% in the lighter three shelter color treatments. The darkest shelter color resulted in 95% mortality after the first growing season. Both height and diameter growth of surviving seedlings were significantly greater in the lightest two shelter color treatments as compared to the control treatment. These results indicate that tree shelters may provide an effective method of improving high-elevation Engelmann spruce reforestation programs. West. J. Appl. For. 16(3):114–120.

Four random clones of American sycamore supplied with four concentrations of Hoagland's solution differed in their response to and interacted with treatment as far as height and diameter growth and total dry matter production in the first growing season were concerned. Varying nutrient intensity did not affect the time of the seasonal peak of height and diameter growth; better growth was maintained subsequent to the seasonal peak at the higher concentrations, however. The proportions of the trees in terms of dry-matter distribution and branching characteristics changed with nutrient concentration.

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