Influence of Resource Abundance on Use of Tree-Fall Gaps by Birds in an Isolated Woodlot

The Auk ◽  
1986 ◽  
Vol 103 (2) ◽  
pp. 328-340 ◽  
Author(s):  
John G. Blake ◽  
William G. Hoppes
Keyword(s):  
Bird Communities ◽  
Forest Understory ◽  
Trophic Groups ◽  
Resource Abundance ◽  
Insect Abundance ◽  
Fruit Abundance ◽  
Resource Levels ◽  
Total Species ◽  
Mist Net ◽  
Statistical Preference

Abstract The occurrence of birds in forest understory and tree-fall gaps during spring and fall migration periods was determined in an isolated woodlot. We used mist-net captures to test the hypothesis that birds are attracted to gaps because of higher resource levels. We captured 1,010 birds (74 species) in spring and 458 (44 species) in fall. Total captures and captures per net were higher (P < 0.001) in gaps during spring and fall. Mean number of species per net was higher in gaps (P < 0.001) during both seasons, but total species in gaps (69 spring, 43 fall) was not significantly higher than in forest understory (60 spring, 28 fall). Of 44 species represented by adequate sample sizes (n > 5) in spring, 9 were significantly (P < 0.05) more common in gaps and 2 were more common in forest understory. Nine of 17 species were captured more often (P < 0.05) in gaps during fall. During spring, flycatchers, ground insectivores, foliage insectivores, and granivore-omnivores were captured more frequently (P < 0.05) in gaps. Flycatchers showed no difference in fall, but other trophic groups, including frugivores, were captured more frequently (P < 0.05) in gaps than in forest understory sites. Bark foragers showed no statistical preference for gaps or forest understory in spring or fall. Total species per net and total captures per net correlated positively (P < 0.05) with density of foliage in the lower canopy and negatively with density of upper canopy foliage in both spring and fall. Total species and captures correlated positively (P < 0.05) with insect abundance in spring and with fruit abundance in fall. Foliage insectivores correlated positively with low canopy foliage and insect abundance in both spring and fall. Captures of frugivores correlated with fruit abundance in fall. These data support the hypothesis that birds are attracted to tree-fall gaps because of higher resource abundance and provide further evidence of the importance of habitat heterogeneity to the structure and composition of bird communities.

Bird species diversity in forest understory: Analysis of mist-net samples

Oecologia ◽  
1976 ◽  
Vol 25 (4) ◽  
pp. 373-379 ◽  
Author(s):  
Mary F. Willson ◽  
David J. Moriarty
Keyword(s):  
Species Diversity ◽  
Bird Species ◽  
Forest Understory ◽  
Bird Species Diversity ◽  
Mist Net

Developmentally programmed and plastic processes of growth in the multistemmed understory shrub Vaccinium hirtum (Ericaceae)

Botany ◽  
2008 ◽  
Vol 86 (3) ◽  
pp. 268-277 ◽  
Author(s):  
Koji Kawamura ◽  
Hiroshi Takeda
Keyword(s):  
Aboveground Biomass ◽  
Light Availability ◽  
High Stress ◽  
Growth Strategy ◽  
Forest Understory ◽  
Relative Growth Rates ◽  
Resource Pulses ◽  
Light Gradient ◽  
Age Related ◽  
Resource Levels

This paper investigates the developmentally programmed and plastic processes of growth in the multistemmed, deciduous shrub Vaccinium hirtum Thunb. We conducted the demographic censuses of stems and the measurements of stem growth and morphology along a natural light gradient in forest understory. With light availability from 5%–28%, the probability of sprouting new stems increased three-fold. Sprouts growing in well-lit conditions were larger than sprouts growing less light. In contrast, neither leaf area per unit aboveground biomass (LAR) nor relative growth rates of aboveground biomass (RGR) of individual stems changed significantly with light. Irrespective of light availability, LAR increased and RGR decreased with stem age. RGR approached zero in old stems > 12-years-old, and their aboveground biomass productions were mostly used to replace deciduous leaves. Our results suggest that the response of aboveground structures to increasing light availability occurs by the production of new sprouts, rather than by the increased growth of existing stems. This indicates a hierarchy of plasticities within the multistemmed structure. Age-related strong controls of stem development reflect the sprouting and multistemmed habits. This growth strategy is favorable under high-stress environments with generally low resource levels such as forest understory and with unpredictable resource pulses such as caused by canopy gap disturbances.

scholarly journals Effects of habitat degradation on avian guilds in East African papyrus Cyperus papyrus swamps

2003 ◽  
Vol 13 (4) ◽  
pp. 283-297 ◽  
Author(s):  
Ilya M. D. Maclean ◽  
Mark Hassall ◽  
Rosalind Boar ◽  
Oliver Nasirwa
Keyword(s):  
Species Richness ◽  
Habitat Degradation ◽  
Bird Communities ◽  
Lake Naivasha ◽  
Cyperus Papyrus ◽  
East African ◽  
Point Counts ◽  
Total Species Richness ◽  
Avian Guilds ◽  
Total Species

The density and species richness of bird communities in disturbed and undisturbed stands of papyrus Cyperus papyrus were compared. Point counts, corrected for different probabilities of detection in different swamps, suggested that the species richness of bird communities in stands of papyrus disturbed by burning, grazing or pollution was higher than in nearby stands that were not disturbed. However, there were fewer species and individuals of highly specialized birds or species characteristic of papyrus, in disturbed stands than in undisturbed swamps. At < 1 ha-1, the density of Papyrus Gonolek Laniarius mufumbiri in Ugandan swamps was, for example, significantly lower in polluted and burnt sites than in undisturbed papyrus where up to 13 ha-1 were recorded in the centre of swamps. White-winged Swamp Warbler Bradypterus carpalis was only recorded in undisturbed papyrus. In the papyrus that fringes Lake Naivasha in Kenya, outside the geographical range of species restricted to papyrus, disturbance in the form of grazing selects against species classified as swamp-reliant. Species classified as generalist users of papyrus were much less sensitive to disturbance than specialists. The density of swamp specialists was also lower near the edge of swamps, where total species richness was higher. These results are discussed in relation to conservation management of papyrus swamps in East Africa.

Human Capital Accumulation and Resource Abundance

2011 ◽  
pp. 66-77
Author(s):  
O. Vasilieva
Keyword(s):  
Economic Growth ◽  
Human Capital ◽  
Capital Accumulation ◽  
Relevant Literature ◽  
Harmful Effect ◽  
Human Capital Accumulation ◽  
Resource Abundance ◽  
Empirical Results ◽  
Theoretical Predictions ◽  
Crowd Out

Does resource abundance positively affect human capital accumulation? Or, alternatively, does it «crowd out» the human capital leading to the deterioration of economic growth? The paper gives an overview of the relevant literature and discusses both theoretical and empirical results obtained regarding the connection between human capital accumulation and resource abundance. It shows that despite some theoretical predictions about the harmful effect of resource abundance on human capital accumulation, unambiguous evidence of such impact that would be robust with respect to the change of resource abundance parameter has not been obtained yet.

Mechanisms of Resource Curse and Economic Policy

2007 ◽  
pp. 4-27 ◽  
Author(s):  
V. Polterovich ◽  
V. Popov ◽  
A. Tonis
Keyword(s):  
Real Exchange Rates ◽  
Resource Curse ◽  
Budget Deficits ◽  
Resource Abundance ◽  
Fuel Prices ◽  
Use Of Resources ◽  
Resource Wealth ◽  
The One ◽  
The Right ◽  
Rich Countries

This paper compares various mechanisms of resource curse leading to a potentially inefficient use of resources; it is demonstrated that each of these mechanisms is associated with market imperfections and can be "corrected" with appropriate government policies. Empirical evidence seems to suggest that resource abundant countries have on average lower budget deficits and inflation, and higher foreign exchange reserves. Besides, lower domestic fuel prices that are typical for resource rich countries have a positive effect on long-term growth even though they are associated with losses resulting from higher energy consumption. On top of that resource abundance allows to reduce income inequalities. So, on the one hand, resource wealth turns out to be conducive to growth, especially in countries with strong institutions. However, on the other hand, resource abundance leads to corruption of institutions and to overvalued real exchange rates. On balance, there is no solid evidence that resource abundant countries grow more slowly than the others, but there is evidence that they grow more slowly than could have grown with the right policies and institutions.

Functional evenness of bird communities varies along the elevational gradient in Europe: Conservation implications

2019 ◽  
Author(s):  
Federico Morelli ◽  
Yanina
Keyword(s):  
Species Richness ◽  
Elevation Gradient ◽  
Bird Species ◽  
Elevational Gradient ◽  
Negative Association ◽  
Bird Communities ◽  
Breeding Bird ◽  
Bird Species Richness ◽  
Large Spatial Scale ◽  
Functional Evenness

ContextThe negative association between elevation and species richness is a well-recognized pattern in macro-ecology. ObjectivesThe aim of this study was to investigate changes in functional evenness of breeding bird communities along an elevation gradient in Europe. MethodsUsing the bird data from the EBCC Atlas of European Breeding Birds we estimated an index of functional evenness which can be assumed as a measure of the potential resilience of communities.ResultsOur findings confirm the existence of a negative association between elevation and bird species richness in all European eco regions. However, we also explored a novel aspect of this relationship, important for conservation: Our findings provide evidence at large spatial scale of a negative association between the functional evenness (potential community resilience) and elevation, independent of the eco region. We also found that the Natura2000 protected areas covers the territory most in need of protection, those characterized by bird communities with low potential resilience, in hilly and mountainous areas.ConclusionsThese results draw attention to European areas occupied by bird communities characterized by a potential lower capacity to respond to strong ecological changes, and, therefore, potentially more exposed to risks for conservation.

Species composition and distribution of marine macro algae at Co To and Thanh Lan archipelago

2020 ◽  
Vol 20 (3) ◽  
pp. 267-276
Author(s):  
Dam Duc Tien ◽  
Nguyen Thi Mai Anh ◽  
Linh Manh Nguyen ◽  
Pham Thu Hue ◽  
Lawrence Liao
Keyword(s):  
Species Composition ◽  
Littoral Zone ◽  
Marine Algae ◽  
Similarity Coefficient ◽  
Algal Flora ◽  
Average Value ◽  
Site Number ◽  
Species Composition And Distribution ◽  
Total Species ◽  
Macro Algae

This paper exhibites species composition and distribution of marine seaweed at 10 sites of Co To and Thanh Lan islands in May 2019. The studies record 76 species of marine algae in the area, belonging to four divisions: Cyanophytes, Rhodophytes, Ochrophytes and Chlorophytes. Among them, five species are classified into Cyanophytes (comprising 6.6% of total species); thirty-four species into Rhodophytes (44.7%); twenty-one species into Ochrophytes/Phaeophytes (27.6%) and sixteen species into Chlorophytes (21.1%). The species composition of marine seaweeds in Co To and Thanh Lan shows significant differences as follows: 22 species (sites number 4 and 10) to 58 species (site number 2) and the average value is 38.7 species per site. Sørensen similarity coefficient fluctuates from 0.33 (sites number 5 and 10) to 0.84 (sites number 1 and 3) and the average value is 0.53. The current investigations show that four species of twenty-one species are collected in the littoral zone and forty-two species in the sub-littoral zone (in which there are thirteen species distributed in both littoral zone and sub-littoral zone). The algal flora in Co To and Thanh Lan is characterized by subtropics.

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