Phenology

During the growing season, each of the treatments in Block 1 were examined every two weeks and whether plants had reached these major life stages was recorded: emerging growth, mature leaves, open flowers, ripe seeds, closed canopy, autumn leaf senescence, and leaf loss. A “t” for true was recorded if at least 50% of the plot had reached that life stage; an “f” for false was recorded if that condition was not observed. Also noted were visible signs of herbivore damage, leaf wilting, or extensive weed coverage. Criteria for each of the life stages monitored are given below.

Criteria of life stages

Emerging growth: Emergence occurs when plants are visible above-ground. For annual crops, it is evident by green growth on bare soil. Only emergence of the main crop is recorded, not the cover crop or weeds; i.e., emergence should not occur until after planting. For perennials, emergence is evident by green shoots appearing near the base of last year’s stalks. For poplar, “emergence” is the presence of small leaves, just emerged from the buds.

Mature leaves: Mature leaves are >95% of their full size.

Canopy closure: In row crops, canopy closure occurs when the spaces between rows are covered by over-hanging vegetation. For example, when corn leaves in adjacent rows touch one another or when the space between perennial plants is covered by over-hanging vegetation and leaves of adjacent plants are touching.

Autumn leaf senescence: Senesced leaves are dry and brown. Poplar leaves turn yellow.

Leaf loss: Generally, only applicable to poplars in the fall. If leaf loss occurs in other plots, note the circumstances (e.g., drought).

Other observations

Leaf wilting: Leaf wilting is distinct from senescence and could occur due to drought, disease, or pests. A “t” is recorded if wilting is evident in at least 50% of the plot.

Herbivore damage: Small amounts of herbivore damage are normal. If at least 50% of the plants have noticeable defoliation or extensive parts of leaves removed, a “t” is recorded.

Extensive weed growth: Scattered weeds are normal. If weeds cover at least 50% of the space between plants, a “t” is recorded. This is not applicable for the early successional treatment (G9).

Height

The average height of plants was measured roughly three times per year, including once at peak biomass. In monoculture treatments, the average height of 10 randomly selected plants was determined for each plot; For mixed culture treatments, either the average height of 10 plants of each species (G7) or the average height of 30 randomly selected plants (G9, G10) was determined for each plot.

When measuring poles are visible in camera images, they may be used to monitor relative changes in plant height.