scholarly journals Leaf-level resource use for evergreen and deciduous conifers along a resource availability gradient

2000 ◽  
Vol 14 (3) ◽  
pp. 281-292 ◽  
Author(s):  
B. D. Kloeppel ◽  
S. T. Gower ◽  
J. G. Vogel ◽  
P. B. Reich
Keyword(s):  
Resource Use ◽  
Resource Availability ◽  
Leaf Level

Resource use and defence by ruby-throated hummingbirds during stopover

Behaviour ◽  
2019 ◽  
Vol 156 (2) ◽  
pp. 131-153
Author(s):  
Theodore J. Zenzal ◽  
Frank R. Moore
Keyword(s):  
Resource Use ◽  
Resource Availability ◽  
Migratory Birds ◽  
Fuel Load ◽  
Resource Quality ◽  
Access To Resources ◽  
Stopover Duration ◽  
Resource Defence ◽  
Conspecific Density

Abstract Many migrants must forage en route when fuel reserves are depleted and access to resources can be influenced by a variety of factors, including the sex, age, and current fuel stores of individuals, as well as resource availability. The objective of this study is to determine the factors that influence the use and defence of resources by migrating ruby-throated hummingbirds (Archilochus colubris). Our results illustrate that resource use: (1) is dependent on sex and resource defence, (2) decreases with fuel load and (3) increases with stopover duration as well as the number of unique feeders visited. Resource defence is closely tied to (1) competition, with the greatest conspecific density resulting in focal individuals being chased from feeders and (2) the interplay between resource quality and fuel load. Our research enhances our understanding of strategies migratory birds use to acquire and defend resources during stopover.

Growth pattern and leaf morphology of Shorea parvistipulata saplings in a tropical rain forest of Sarawak, Malaysia

2005 ◽  
Vol 21 (2) ◽  
pp. 215-218
Author(s):  
Tsutomu Enoki ◽  
Hideyuki Kawaguchi ◽  
Tohru Nakashizuka ◽  
Abang A. Hamid
Keyword(s):  
Resource Use ◽  
Resource Availability ◽  
Morphological Traits ◽  
Leaf Morphology ◽  
Competitive Ability ◽  
Leaf Shape ◽  
Light Availability ◽  
Canopy Structure ◽  
Morphological Adaptations ◽  
Shoot Architecture

Spatial variation in canopy structure induces highly variable patterns of light availability for juveniles and understorey trees (Nicotra et al. 1999, Oberbauer et al. 1988, Tang et al. 1999). In the heterogeneous light environment, plasticity in resource use is essential for survival of juveniles and hence maintenance of populations (Valladares et al. 2000). One of the most striking characteristics of plants in their response to a given resource availability is their capacity to change morphological traits (Küppers 1994). Previous studies have attempted to understand the significance of morphological adaptations in their contribution to competitive ability, focusing on crown form (Kohyama 1987, Sterck et al. 2003), branching pattern (King 1998), shoot architecture (Canham 1988) and leaf shape (King & Maindonald 1999, Takenaka 1994, Yamada et al. 2000). Several studies have investigated the changes in morphology of saplings or seedlings growing under different light availability across canopy gaps (Ackerly & Bazzaz 1995, King 1994, Valladares & Pearcy 1998). However, the phenotypic plasticity in morphology of saplings adapting to the fluctuation of light availability has been investigated less (Blundell & Peart 2001, Poorter & Werger 1999).

scholarly journals Low leaf-level response to light and nutrients in Mediterranean evergreen oaks: a conservative resource-use strategy?

2000 ◽  
Vol 148 (1) ◽  
pp. 79-91 ◽  
Author(s):  
FERNANDO VALLADARES ◽  
ELSA MARTINEZ-FERRI ◽  
LUIS BALAGUER ◽  
ESTHER PEREZ-CORONA ◽  
ESTEBAN MANRIQUE
Keyword(s):  
Resource Use ◽  
Leaf Level ◽  
Evergreen Oaks

Resource Use, Competition, and Resource Availability in Hawaiian Honeycreepers

Ecology ◽  
1982 ◽  
Vol 63 (5) ◽  
pp. 1468-1480 ◽  
Author(s):  
Stuart L. Pimm ◽  
June W. Pimm
Keyword(s):  
Resource Use ◽  
Resource Availability ◽  
Hawaiian Honeycreepers

scholarly journals Relying on known or exploring for new? Movement patterns and reproductive resource use in a tadpole-transporting frog

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3745 ◽  
Author(s):  
Kristina B. Beck ◽  
Matthias-Claudio Loretto ◽  
Max Ringler ◽  
Walter Hödl ◽  
Andrius Pašukonis
Keyword(s):  
Spatial Memory ◽  
Resource Use ◽  
Resource Availability ◽  
Movement Patterns ◽  
Poison Frogs ◽  
Fluctuating Resources ◽  
Allobates Femoralis ◽  
First Time ◽  
Tadpole Transport ◽  
Home Territory

Animals relying on uncertain, ephemeral and patchy resources have to regularly update their information about profitable sites. For many tropical amphibians, widespread, scattered breeding pools constitute such fluctuating resources. Among tropical amphibians, poison frogs (Dendrobatidae) exhibit some of the most complex spatial and parental behaviors—including territoriality and tadpole transport from terrestrial clutches to ephemeral aquatic deposition sites. Recent studies have revealed that poison frogs rely on spatial memory to successfully navigate through their environment. This raises the question of when and how these frogs gain information about the area and suitable reproductive resources. To investigate the spatial patterns of pool use and to reveal potential explorative behavior, we used telemetry to follow males of the territorial dendrobatid frog Allobates femoralis during tadpole transport and subsequent homing. To elicit exploration, we reduced resource availability experimentally by simulating desiccated deposition sites. We found that tadpole transport is strongly directed towards known deposition sites and that frogs take similar direct paths when returning to their home territory. Frogs move faster during tadpole transport than when homing after the deposition, which probably reflects different risks and costs during these two movement phases. We found no evidence for exploration, neither during transport nor homing, and independent of the availability of deposition sites. We suggest that prospecting during tadpole transport is too risky for the transported offspring as well as for the transporting male. Relying on spatial memory of multiple previously discovered pools appears to be the predominant and successful strategy for the exploitation of reproductive resources in A. femoralis. Our study provides for the first time a detailed description of poison frog movement patterns during tadpole transport and corroborates recent findings on the significance of spatial memory in poison frogs. When these frogs explore and discover new reproductive resources remains unknown.

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