Bird species distributions across woodland canopy structure gradients

The tree canopy characteristics of two broadleaved woods in southern England were quantified in terms of two independent measures of structure, canopy height (calculated using heights ≥ 1 m) and percentage canopy cover (derived using heights 0.90, p < 0.001), there was a positive correlation across bird species between the mean values of canopy height and canopy cover associated with the mapped locations of each species. We suggest that canopy height acts as an effective surrogate of woodland structure and can be applied as a predictor of bird community composition and distribution, at least in lowland British conditions. Species associated with young growth had narrower niche breadths, as measured by differences in canopy height and canopy cover between the two woods, than did species associated with taller canopies. Remote sensing of canopy height potentially offers a simple, effective way of assessing habitat availability for many species, at both woodland and landscape scales. This may be especially relevant for species dependent on highly transient vegetation structures associated with the early pre-canopy closure stages of forest growth

ON BECOMING MORE OF A POLICY SCIENTIST

This essay presents some subjective thoughts on becoming more of a policy scientist, based on nearly thirty years of intense interest in policymaking and its improvement. Written as a token of gratitude for the privilege of receiving the first Harold Lasswell Award from the Policy Studies Organization, the essay takes the form of advice to striving policy scientists in nine desiderata followed by five operational recommendations. Some readings for exploring the suggestions presented in this paper are included in the reference section. Copyright 1984 by The Policy Studies Organization.

Make EU trade with Brazil sustainable

Cellular mechanisms in basic and clinical gastroenterology and hepatolog