Clive Welham

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Heterogeneity in resource distribution has been an important selective force shaping morphological plasticity in plants. When resources are patchily distributed, changes in morphology are assumed to affect placement of the resource-acquiring structures (roots and leaves) such that they enhance the plant's capacity for resource uptake. Morphological(More)
Timber volume is an important ecological component in forested landscapes. The application of terrestrial laser scanning (TLS) to volume estimation has been widely accepted though few species have well-calibrated taper functions. This research uses TLS technology in poplar (Populus ˆ canadensis Moench cv. ‘I-72/58’) to extract stem diameter at different(More)
We estimated the reproductive success of black terns (Chlidonias niger) based on three optimal foraging currencies (maximizing the net rate of energy intake, daily delivery rate, and efficiency, respectively) and a state variable model. There was a broad range of capture intervals (the time required for the parent to capture a single prey) when the flight(More)
Ring-billed gulls (Larus delawarensis) breeding at Dog Lake, Manitoba often feed by following tractors pulling cultivating implements around fields. Tractor-following gulls always land immediately behind the cultivating implement, where they feed on earthworms or grain. Afeer a feeding bout on the ground (patch residence time), gulls fly up, pursue the(More)
Climate change introduces considerable uncertainty in forest management planning and outcomes, potentially undermining efforts at achieving sustainable practices. Here, we describe the development and application of the FORECAST Climate model. Constructed using a hybrid simulation approach, the model includes an explicit representation of the effect of(More)
Supplementary material is available online for this article. This work was presented at the 12th North America Forest Soils Conference, Whitefish, MT, 16–20 June 2013, in the New Technologies in Soil Research session. Soil Sci. Soc. Am. J. doi:10.2136/sssaj2013.06.0214nafsc Received 5 June 2013. *Corresponding author ( © Soil Science(More)
Generally, only the net outcome of plant–plant interactions is measured in population and community ecology research, with few attempts to determine the relative importance of negative (competition) and positive (facilitation) interactions between subordinate species. Changes in the intensity of interactions along gradients, between life-stages, or with(More)
Soil carbon (C) in three Ginkgo (Ginkgo biloba L.) agroforestry systems, afforestation (Ginkgo alone; G), and an agricultural cropping system were compared over a five-year period. The agroforestry systems were Ginkgo + Wheat (Triticum aestivum L.) + Peanut (Arachis hypogaea L.; GWP); Ginkgo + Mulberry (Morus alba L.; GM); and Ginkgo + Rapa (Brassica napus(More)
Forests in tropical and sub-tropical countries face severe pressures due to a combination of poverty and environment degradation. To be effective, measures to protect these forests must therefore consider both economic and ecological dimensions synergistically. The purpose of this paper was to synthesize our long-term work (1994–2015) on a Ginkgo (Ginkgo(More)