No abstract

The results suggest that, in contrast to the broader temperature effects that determine leaf out times, leaf senescence times are probably determined by a larger or different suite of local environmental effects, including temperature, soil moisture, frost and wind. Determining the importance of these factors for a wide range of species represents the next challenge for understanding how climate change is affecting the end of the growing season and associated ecosystem processes.

The diversity of a hummingbird plant community in the eastern Andes of southern Ecuador was studied on the equivalent of a hectare (two 500 ′ 10 m transects) at 1920 ‐ 2100 m a.s.l. over the course of a year. A total of 3186 flowering individuals, representing 12 plant families, 29 genera and 72 species, were found to be visited by hummingbirds. Bromeliaceae had the most species visited, followed by Orchidaceae and Ericaceae. The majority of visited plant species were represented by a very few individuals, and only a few species of the Bromeliaceae and Orchidaceae appeared in large numbers of visited individuals. With regard to life forms visited by hummingbirds, epiphytes predominated (59 %), followed by trees and shrubs (29 %), vines (8 %) and herbs (4 %). Visited flowers usually had short‐ to medium‐long floral tubes which were either functionally or morphologically tubiform or campanulate. Fifty percent of the species had red‐coloured flowers, and a considerable number of the blossoms (43 %) displayed contrasting colours. The 72 plant species received visits from 26 species of Trochilidae (hummingbirds) and two species of Coerebidae (honeycreepers). A mere eight species of hummingbirds were seen frequently at the study area; the remaining species were only occasionally sighted. The eight frequently sighted species of hummingbirds made use of a total of 74 % of all hummingbird‐visited plant species growing in the study area.