Journal: Ecological Entomology
Location: ?, Canada

The Elm Spanworm hatching boom is 2 weeks after the Sycamore Maple budburst. 85% more eggs were laid on the lower trunk than the crown (although those in later stages of development moved up towards the crown) and it had nothing to do with avoiding parasites (only one pupa was parasitised) or getting better quality leaves, although feeding on older leaves (three leaves expanded per bud) significantly improved the caterpillars’ chance of surviving to adulthood (90%, or 45% higher than when feeding on on younger leaves). Sycamore Maple leaves mature acropetally (from the base up).

Elm Spanworm – Ennomos subsignaria
Sycamore Maple – Acer pseudoplatanus

Fry HRC, Quiring DT, Ryall KL, Dixon PL, 2009. “Influence of intra-tree variation in phenology and oviposition site on the distribution and performance of Ennomos subsignaria on mature sycamore maple.” Ecological Entomology, DOI: 10.1111/j.1365-2311.2009.01091.x
Affiliations: University of New Brunswick, Canadian Forest Service, Agriculture and Agri-Food Canada (AAFC)

Journal: Basic and Applied Ecology
Location: Hainich, Germany

In Hainich National Park, and old-growth forest in Germany, leaves in the upper canopy of eight tree species varied in size from 12.9 to 19.4 m2 per kg, were covered in 125 to 313 stomata per mm, contained 95-175mol Nitrogen per m2, and had a delta 13C value (the degree of carbon enrichment compared to inorganic matter, the more negative the higher), of -27.81 to -25.85 parts per thousand (typical of C3 photosynthesis). Sycamore, Hornbeam, Ash, and Linden saplings had a maximum CO2 assimilation rate (Amax, indicating photosynthetic rate) of 5.0 and 6.4 mumol m–2s–1. Adult Hornbeams had the lowest Amax (10.5), and Ash the highest (16.3). Lower canopy Ash also had the highest Amax (12.0, compared to 5.0-5.6).

Sycamore – Acer pseudoplatanus
Hornbeam – Carpinus betulus
Ash – Fraxinus Excelsior
Linden – Tilia platyphyllos

Hölscher D, 2004. “Leaf traits and photosynthetic parameters of saplings and adult trees of co-existing species in a temperate broad-leaved forest.” Basic and Applied Ecology, 5(2): 163-172, DOI: 10.1078/1439-1791-00218
Affiliations: University of Göttingen