scholarly journals Mistletoe as a keystone resource: an experimental test

2012 ◽  
Vol 279 (1743) ◽  
pp. 3853-3860 ◽  
Author(s):  
David M. Watson ◽  
Matthew Herring
Keyword(s):  
Species Richness ◽  
Bird Species ◽  
Small Scale ◽  
High Turnover ◽  
Total Species Richness ◽  
Before And After ◽  
The Status ◽  
Scale Experiment ◽  
Total Species ◽  
Keystone Resource

Various entities have been designated keystone resources, but few tests have been attempted and we are unaware of any experimental manipulations of purported keystone resources. Mistletoes (Loranthaceae) provide structural and nutritional resources within canopies, and their pervasive influence on diversity led to their designation as keystone resources. We quantified the effect of mistletoe on diversity with a woodland-scale experiment, comparing bird diversities before and after all mistletoe plants were removed from 17 treatment sites, with those of 11 control sites and 12 sites in which mistletoe was naturally absent. Three years after mistletoe removal, treatment woodlands lost, on average, 20.9 per cent of their total species richness, 26.5 per cent of woodland-dependent bird species and 34.8 per cent of their woodland-dependent residents, compared with moderate increases in control sites and no significant changes in mistletoe-free sites. Treatment sites lost greater proportions of birds recorded nesting in mistletoe, but changes in species recorded feeding on mistletoe did not differ from control sites. Having confirmed the status of mistletoe as a keystone resource, we suggest that nutrient enrichment via litter-fall is the main mechanism promoting species richness, driving small-scale heterogeneity in productivity and food availability for woodland animals. This explanation applies to other parasitic plants with high turnover of enriched leaves, and the community-scale influence of these plants is most apparent in low productivity systems.

Partial cutting reduces species richness of fungi on woody debris in oak-rich forests

2008 ◽  
Vol 38 (7) ◽  
pp. 1807-1816 ◽  
Author(s):  
Björn Nordén ◽  
Frank Götmark ◽  
Martin Ryberg ◽  
Heidi Paltto ◽  
Johan Allmér
Keyword(s):  
Species Richness ◽  
Woody Debris ◽  
Basal Area ◽  
Fruiting Bodies ◽  
Partial Cutting ◽  
Total Species Richness ◽  
Before And After ◽  
Closed Canopy ◽  
And Control ◽  
Total Species

Partial cutting is increasingly applied in European temperate oak-dominated forests for biofuel harvesting, and to counteract succession in protected stands. Effects on biodiversity of these measures need to be carefully evaluated, and species-rich but neglected taxa such as fungi should be considered. We studied the effects of partial cutting on fungal fruiting bodies on woody debris. In 21 closed canopy forests rich in large oaks in Sweden, on average 25%–30% of the basal area was cut. Fruiting bodies were counted and some were collected in treated and control plots before and after treatment. We found 334 basidiomycete and 47 ascomycete species. Species richness of basidiomycetes declined significantly more in treated plots (on average 26%) than in control plots (on average 13%) between seasons. Species richness of ascomycetes increased by 17% in control plots and decreased by 2% in treated plots. Total species richness was significantly reduced on fine woody debris (1–10 cm in diameter), but not on coarse woody debris (>10 cm). Overall species composition did not change significantly as a result of partial cutting, but red-listed species tended to decrease more in treated plots. We suggest that approximately 30% of the stands should not be thinned, and dead stems and fallen branches should not be removed, to favor saproxylic fungi and their associated fauna.

scholarly journals Variation within the Bird Community of a Rehabilitated Urban Environment, Case of the Félix Houphouët-Boigny University Campus (Côte d'Ivoire)

2021 ◽  
Vol 9 (4) ◽  
Author(s):  
Ekoun Michael KONAN ◽  
Valérie Florence GUETONDE ◽  
Coffi Jean Magloire NIAMIEN ◽  
Kouassi Hilaire YAOKOKORE-BEIBRO
Keyword(s):  
Species Richness ◽  
Ecological Impact ◽  
Bird Species ◽  
Bird Community ◽  
University Campus ◽  
Significant Drop ◽  
Bubulcus Ibis ◽  
Total Species Richness ◽  
Ploceus Cucullatus ◽  
Total Species

In order to understand the ecological impact of the rehabilitation of the Félix Houphouët-Boigny University Campus on the bird community, a study was carried out over two months (October-November 2016). The ornithological inventory carried out by the IPA method in five different habitats identified on the campus gave a total species richness of 51 bird species of 41 genera, 27 families and 13 orders for 1374 birds, with H' = 2.93 and J = 0.74. Five species dominate the population (819 individuals, Fr = 59, 61%). These are Bubulcus ibis (9.32 %), Apus affinis (8.95 %), Corvus albus (19.94 %), Ploceus cucullatus (10.48 %), Lonchura cucullata (10.92 %). The most diversified habitat is the Habitations (26 bird species), while the most abundant is the Brush (416 individuals). Only seven species are common to all sampled habitats. Thus, 12 species observed on campus formerly could not be observed during the present study. Similarly, 18 species observed in this study were not observed in the previous study. The profound transformation of the environment following the rehabilitation has led to a slight increase in diversity but a significant drop in numbers. It is therefore important to better understand the different interactions between the components of the habitat and the various species involved. Such data would be crucial in urban planning policies.

scholarly journals Temporal and Spatial Use of Even-Aged Reproduction Stands by Bird Communities in Central Pennsylvania

2003 ◽  
Vol 20 (3) ◽  
pp. 117-123 ◽  
Author(s):  
Susan C. Talbott ◽  
Richard H. Yahner
Keyword(s):  
Species Richness ◽  
Breeding Season ◽  
Tree Species ◽  
Management Practice ◽  
Bird Species ◽  
Basal Area ◽  
Total Species Richness ◽  
Species Richness And Abundance ◽  
Overstory Trees ◽  
Total Species

Abstract In 1992, the Pennsylvania Bureau of Forestry adopted a new forest management practice known as even-aged reproduction with reservation (EAR), which replaces clearcutting on state forestlands. The EAR guidelines mandate the retention of at least 12 trees/ha and 24–36 m2/ha of basal area, representing a diversity of overstory and understory species. During summer 1998, we compared the temporal (breeding season vs. mid-summer) and spatial (edge versus interior) use of EAR stands by birds. In addition, we compared observed vs. expected use of overstory trees in EAR stands. In each of ten representative EAR stands, we sampled birds twice per season along two-edge and two-interior transects. Total species richness and abundance (all species combined), species richness and abundance of ground-shrub foragers, and species richness of canopy-sallier foragers were significantly (P < 0.05) higher in the breeding season than in mid-summer. Eight of 20 common bird species analyzed also were significantly (P < 0.05) more abundant during the breeding season (e.g., black-and-white warbler and chestnut-sided warbler), and one species was significantly (P < 0.05) more abundant during mid-summer. Total species richness, total abundance, and abundance of ground-shrub foragers were significantly higher (P < 0.05) in interiors compared to edges of EAR stands. Five species also were significantly (P < 0.05) more abundant in interiors of EAR stands, whereas no species was more common in edges. All species combined and three foraging guilds showed differential use (P < 0.05) of overstory tree species; eight species also differed significantly in their use of abundant tree species. Based on our findings, we believe that EAR stands are excellent substitutes for clearcuts on state forestlands, although we caution that our findings were based only on one yr of data. We recommend the continued retention of a diversity of overstory trees, especially snags and rough-barked trees, in both edges and interiors of EAR stands for use by a variety of bird species during both the breeding season and mid-summer. North. J. Appl. For. 20(3):117–123.

scholarly journals Fish species diversity in headwaters streams of Paraguay and Paraná Basins

2007 ◽  
Vol 50 (6) ◽  
pp. 1033-1042 ◽  
Author(s):  
Yzel Rondon Súarez ◽  
Sabrina Bigatão Valério ◽  
Karina Keyla Tondado ◽  
Alexandro Cezar Florentino ◽  
Thiago Rota Alves Felipe ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Environmental Factors ◽  
Fish Species ◽  
Total Species Richness ◽  
Paraná Basin ◽  
Parana Basin ◽  
Number Of Individuals ◽  
Total Species ◽  
Fish Species Diversity

The influence of spatial, temporal and environmental factors on fish species diversity in headwater streams in Paraguay and Paraná basins, Brazil was examined. A total of 4,605 individuals were sampled, distributed in 60 species. The sampled streams in Paraná basin presented a larger total species richness (42) than Paraguay streams (40). However the estimated richness was larger in Paraguay basin (53) than Paraná streams (50). The streams of Paraná basin had a greater mean species richness and evenness, while more individuals per sample were found in the Paraguay basin. Difference between the sub-basins were found in the Paraguay basin, while for the basin of Paraná, richness and evenness vary significantly between the sub-basins, but the number of individuals varied seasonally. The most important environmental factors to species diversity and abundance were altitude, water temperature, stream width and stream depth for both the basins.

scholarly journals Increased mosquito abundance and species richness in Connecticut, United States 2001–2019

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tanya A. Petruff ◽  
Joseph R. McMillan ◽  
John J. Shepard ◽  
Theodore G. Andreadis ◽  
Philip M. Armstrong
Keyword(s):  
United States ◽  
Species Richness ◽  
Community Composition ◽  
Pathogen Transmission ◽  
Public Health Importance ◽  
Data Set ◽  
Mosquito Abundance ◽  
Total Species Richness ◽  
Multiple Species ◽  
Total Species

Abstract Historical declines in multiple insect taxa have been documented across the globe in relation to landscape-level changes in land use and climate. However, declines have either not been universally observed in all regions or examined for all species. Because mosquitoes are insects of public health importance, we analyzed a longitudinal mosquito surveillance data set from Connecticut (CT), United States (U.S.) from 2001 to 2019 to identify changes in mosquito community composition over time. We first analyzed annual site-level collections and metrics of mosquito community composition with generalized linear/additive mixed effects models; we also examined annual species-level collections using the same tools. We then examined correlations between statewide collections and weather variables as well as site-level collections and land cover classifications. We found evidence that the average trap night collection of mosquitoes has increased by ~ 60% and statewide species richness has increased by ~ 10% since 2001. Total species richness was highest in the southern portion of CT, likely due to the northward range expansion of multiple species within the Aedes, Anopheles, Culex, and Psorophora genera. How the expansion of mosquito populations in the northeast U.S. will alter mosquito-borne pathogen transmission in the region will require further investigation.

The Westphalian–Stephanian macrofloral record from the South Wales Coalfield, UK

2007 ◽  
Vol 144 (3) ◽  
pp. 465-486 ◽  
Author(s):  
CHRISTOPHER J. CLEAL
Keyword(s):  
Species Richness ◽  
Detailed Comparison ◽  
The South ◽  
Significant Drop ◽  
South Wales ◽  
Total Species Richness ◽  
Total Species

The South Wales Coalfield has the most complete Westphalian macrofloral record anywhere on the Variscan Foreland or adjacent basins, with 135 biodiversity-meaningful morphospecies having been recognized. All of the standard macrofloral biozones of the Westphalian Stage have been recognized, although a detailed comparison with the Central Pennines Coalfields has indicated some discrepancies in the relative positions of the biozonal boundaries. Total Species Richness progressively increases through the Langsettian Substage, and then remains relatively stable through most of the Duckmantian and Bolsovian substages. There is a distinct reduction in Total Species Richness towards the top of the Bolsovian Substage, but this partially recovers in the middle Asturian Substage with the appearance of a range of marattialean ferns, and medullosalean and callistophytaleans pteridosperms. There is no evidence of any significant drop in Total Species Richness towards the top of the succession, indicating that conditions at this time were relatively stable. The change from coastal floodplain to alluvial braidplain conditions in middle Bolsovian times correlates with a marked increase in the proportion of medullosalean remains being preserved in the adpression record, reflecting an expansion of the clastic-substrate habitats.

scholarly journals Inferring global species richness from megatransect data and undetected species estimates

2019 ◽  
Vol 88 (1) ◽  
pp. 42-53 ◽  
Author(s):  
Bernhard A. Huber ◽  
Anne Chao
Keyword(s):  
Species Richness ◽  
New Species ◽  
Confidence Interval ◽  
Incidence Data ◽  
Total Species Richness ◽  
Species Incidence ◽  
Biogeographic Regions ◽  
Global Patterns ◽  
The Impact ◽  
Total Species

Ratio-like approaches for estimating global species richness have been criticised for their unjustified extrapolation from regional to global patterns. Here we explore the use of cumulative percentages of ‘new’ (i.e., not formally described) species over large geographic areas (‘megatransects’) as a means to overcome this problem. In addition, we take into account undetected species and illustrate these combined methods by applying them to a family of spiders (Pholcidae) that currently contains some 1,700 described species. The raw global cumulative percentage of new species (‘new’ as of the end of 2008, when 1,001 species were formally described) is 75.1%, and is relatively constant across large biogeographic regions. Undetected species are estimated using the Chao2 estimator based on species incidence data (date by species and locality by species matrices). The estimated percentage of new species based on the date by species matrices is 76.0% with an estimated standard error (s.e.) of 2.6%. This leads to an estimated global species richness of about 4,200 with a 95% confidence interval of (3,300, 5,000). The corresponding values based on locality by species matrices are 84.2% (s.e. 3.0%) and 6,300 with a 95% confidence interval of (4,000, 8,600). Our results suggest that the currently known 1,700 species of Pholcidae may represent no more than about 25–40% of the total species richness. The impact of further biasing factors like geography, species size and distribution, cryptic species, and model assumptions needs to be explored.

scholarly journals Predicting continental-scale patterns of bird species richness with spatially explicit models

2006 ◽  
Vol 274 (1607) ◽  
pp. 165-174 ◽  
Author(s):  
Carsten Rahbek ◽  
Nicholas J Gotelli ◽  
Robert K Colwell ◽  
Gary L Entsminger ◽  
Thiago Fernando L.V.B Rangel ◽  
...  
Keyword(s):  
Species Richness ◽  
Bird Species ◽  
Small Scale ◽  
Spatially Explicit ◽  
Bird Species Richness ◽  
Continental Scale ◽  
Historical Factors ◽  
Biotic Diversity ◽  
Correlative Models ◽  
Richness Patterns

The causes of global variation in species richness have been debated for nearly two centuries with no clear resolution in sight. Competing hypotheses have typically been evaluated with correlative models that do not explicitly incorporate the mechanisms responsible for biotic diversity gradients. Here, we employ a fundamentally different approach that uses spatially explicit Monte Carlo models of the placement of cohesive geographical ranges in an environmentally heterogeneous landscape. These models predict species richness of endemic South American birds (2248 species) measured at a continental scale. We demonstrate that the principal single-factor and composite (species-energy, water-energy and temperature-kinetics) models proposed thus far fail to predict ( r 2 ⩽0.05) the richness of species with small to moderately large geographical ranges (first three range-size quartiles). These species constitute the bulk of the avifauna and are primary targets for conservation. Climate-driven models performed reasonably well only for species with the largest geographical ranges (fourth quartile) when range cohesion was enforced. Our analyses suggest that present models inadequately explain the extraordinary diversity of avian species in the montane tropics, the most species-rich region on Earth. Our findings imply that correlative climatic models substantially underestimate the importance of historical factors and small-scale niche-driven assembly processes in shaping contemporary species-richness patterns.

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