To what extent does the species composition of Macaronesian laurel forests depend on their human disturbance history and environmental drivers?

Coarse woody debris (CWD) is a rarely studied component of the carbon cycle. We report the first measurements of both CWD wood density and necromass in humid, lowland northwestern Amazonia, using both line-intersect and plot-based methods. Average CWD densities were not significantly different between clay-rich and white sand unflooded forests, but lower in floodplain forest (p ≤ 0.001). Necromass of CWD lying on the ground was also lower in the floodplain (10.3 ± 6.1 Mg·ha–1, mean ± 1 SE) than in the clay-rich (30.9 ± 5.4) and white sand (45.8 ± 7.3) forests (p ≤ 0.001, using the line-intersect method). These patterns are likely driven by disturbance history, species composition, and decomposition rates. Plot-based data showed that standing and fallen CWD together accounted for 6.4%–15.4% of total coarse aboveground vegetative mass (trees ≥10 cm diameter). Across humid, lowland neotropical forests, we show that wood densities of intact and partially decayed CWD are significantly related with live wood density at the same site (p = 0.026 and 0.003, respectively). We show that these relationships can be applied generally to estimate CWD wood density for humid, lowland neotropical forests wherever destructive sampling is not possible.

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Composition and seasonality of Culicoides in three host environments in Rabat region (Morocco)

Revue d’élevage et de médecine vétérinaire des pays tropicaux ◽

10.19182/remvt.31838 ◽

2020 ◽

Vol 73 (1) ◽

pp. 37-46 ◽

Cited By ~ 1

Author(s):

Maria Bourquia ◽

Claire Garros ◽

Ignace Rakotoarivony ◽

Intissar Boukhari ◽

Moad Chakrani ◽

...

Keyword(s):

Species Composition ◽

Dynamic Models ◽

Transmission Risk ◽

Seasonal Abundance ◽

Environmental Drivers ◽

Vertebrate Species ◽

Culicoides Species ◽

Horse Riding ◽

Culicoides Imicola ◽

The Impact

Morocco has suffered several outbreaks of Culicoides-borne viruses in recent decades and most studies have focused on Culicoides imicola, considered for a long time as the only important vector. The change in bluetongue (BT) epidemiology in the Mediterranean Basin and Europe over the past two decades has highlighted the role of other Culicoides species in BT virus transmission. The objective of this study was to provide new insights on the Culicoides species composition and seasonality in three different host environments (a horse-riding center, a goat farm and a cattle farm) around Rabat, the capital of Morocco, where BT has been endemic since 2004. Light / suction trap collections were carried out on two consecutive nights at fortnight intervals from May 2016 to May 2017. Culicoides were identified morphologically at the species level when possible. Multivariate analyses were used to compare the impact of the site / vertebrate species, and the collection month on the species communities. In addition, statistical modeling was used to identify environmental drivers of the Culicoides seasonality. A total of 12,460 Culicoides individuals belonging to at least 15 different species were collected during the survey. Culicoides imicola was by far the most abundant species (71.4% of total catches). The site location, and thus the vertebrate species, did not influence the species composition, which was mainly impacted by the month of collection. Surprisingly, the atmospheric pressure was the environmental parameter the most frequently selected in seasonal models. The potential impact of this meteorological parameter along with the other selected variables is discussed. Identifying the environmental parameters driving Culicoides seasonal abundance is the first step to implementing robust Culicoides dynamic models that could later be used in transmission risk modeling

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High-resolution fisheries data reveal effects of bivalve dredging on benthic communities in stressed coastal systems

Marine Ecology Progress Series ◽

10.3354/meps13330 ◽

2020 ◽

Vol 642 ◽

pp. 21-38 ◽

Cited By ~ 2

Author(s):

C McLaverty ◽

OR Eigaard ◽

GE Dinesen ◽

H Gislason ◽

A Kokkalis ◽

...

Keyword(s):

High Resolution ◽

Species Composition ◽

Nutrient Loading ◽

Spatial Scales ◽

Benthic Communities ◽

Natura 2000 ◽

Environmental Drivers ◽

Nutrient Inputs ◽

High Nutrient ◽

Suitable Reference

Commercial dredging for blue mussels (Mytilus edulis) and oysters (Ostrea edulis, Crassostrea gigas) constitute the main bivalve fisheries in Denmark. These activities predominantly take place in Limfjorden, a large microtidal sound, and in the Inner Danish waters. Both areas are shallow, estuarine, receive high nutrient inputs from agriculture, and are of nature conservation interest (Natura 2000 sites), thus presenting challenges for an ecosystem approach to fisheries management. Using high-resolution fisheries data (~10 m), we investigated the effects of bivalve dredging on benthic communities at both local (Natura 2000 site) and regional (fishery-wide) scales. Regionally, our results showed that dredging intensity correlated with shifts in species composition and reduced community biomass. We were, however, unable to detect an effect of dredging on community density, trait richness, and trait composition. These metrics were significantly related to other environmental drivers, such as sediment organic content (negative) and mussel bed biomass (positive). At the local scale, the observed relationships between dredging, biomass, and species composition varied significantly. This occurred as dredging impacts were greater in areas that contained suitable reference conditions and experienced relatively low levels of disturbance. By contrast, communities which experienced high nutrient loading, regular anoxic events, and high natural variability were relatively unaffected by dredging. Our results therefore highlight the importance of spatial scales in fishing impact estimations. Furthermore, we demonstrate how targeted sampling, high-resolution fisheries data, and suitable reference areas can be used to detect fishery effects in coastal areas that are highly stressed by eutrophication.

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Environmental and spatial drivers of taxonomic, functional, and phylogenetic characteristics of bat communities in human-modified landscapes

PeerJ ◽

10.7717/peerj.2551 ◽

2016 ◽

Vol 4 ◽

pp. e2551 ◽

Cited By ~ 10

Author(s):

Laura M. Cisneros ◽

Matthew E. Fagan ◽

Michael R. Willig

Keyword(s):

Species Composition ◽

Variation Partitioning ◽

Environmental Drivers ◽

Taxonomic Structure ◽

Relative Importance ◽

Niche Space ◽

Phylogenetic Structure ◽

Landscape Characteristics ◽

Phylogenetic Composition ◽

Phylogenetic Dispersion

BackgroundAssembly of species into communities following human disturbance (e.g., deforestation, fragmentation) may be governed by spatial (e.g., dispersal) or environmental (e.g., niche partitioning) mechanisms. Variation partitioning has been used to broadly disentangle spatial and environmental mechanisms, and approaches utilizing functional and phylogenetic characteristics of communities have been implemented to determine the relative importance of particular environmental (or niche-based) mechanisms. Nonetheless, few studies have integrated these quantitative approaches to comprehensively assess the relative importance of particular structuring processes.MethodsWe employed a novel variation partitioning approach to evaluate the relative importance of particular spatial and environmental drivers of taxonomic, functional, and phylogenetic aspects of bat communities in a human-modified landscape in Costa Rica. Specifically, we estimated the amount of variation in species composition (taxonomic structure) and in two aspects of functional and phylogenetic structure (i.e., composition and dispersion) along a forest loss and fragmentation gradient that are uniquely explained by landscape characteristics (i.e., environment) or space to assess the importance of competing mechanisms.ResultsThe unique effects of space on taxonomic, functional and phylogenetic structure were consistently small. In contrast, landscape characteristics (i.e., environment) played an appreciable role in structuring bat communities. Spatially-structured landscape characteristics explained 84% of the variation in functional or phylogenetic dispersion, and the unique effects of landscape characteristics significantly explained 14% of the variation in species composition. Furthermore, variation in bat community structure was primarily due to differences in dispersion of species within functional or phylogenetic space along the gradient, rather than due to differences in functional or phylogenetic composition.DiscussionVariation among bat communities was related to environmental mechanisms, especially niche-based (i.e., environmental) processes, rather than spatial mechanisms. High variation in functional or phylogenetic dispersion, as opposed to functional or phylogenetic composition, suggests that loss or gain of niche space is driving the progressive loss or gain of species with particular traits from communities along the human-modified gradient. Thus, environmental characteristics associated with landscape structure influence functional or phylogenetic aspects of bat communities by effectively altering the ways in which species partition niche space.

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Human Disturbance, Plant Species Composition, Diversity and Community Types of Kafta-Sheraro National Park, Tigray Region, Ethiopia

10.21203/rs.3.rs-230558/v1 ◽

2021 ◽

Author(s):

Fitsum Temesgen Hailemariam ◽

Bikila Warkineh Dullo ◽

Addisu Asefa Mitiku

Keyword(s):

Species Richness ◽

Species Composition ◽

Plant Species ◽

Human Disturbance ◽

Anthropogenic Disturbance ◽

National Park ◽

Livestock Grazing ◽

Strongly Correlated ◽

Species Richness And Diversity ◽

Community Types

Abstract Background: Ethiopia is rich in woodland natural forest although of increasingly subjected to deforestation and forest degradation with extensive expansion of settlement and agricultural practices. In developing countries like Ethiopia forest is one of the vital resources that determine the livelihood of the local communities. Consequently, woodlands’ of the country’s are under heavy pressure by shifting cultivation and charcoal production. Kafta-sheraro national park is newly established woodland area which lacks documented vegetation diversity and human disturbance on the forest. The study was conducted to quantify plant species richness and diversity along altitude; and identify anthropogenic disturbance on vegetation composition and community diversity of the park. Methods: a Systematic sampling method was used to determine species composition, abundance, and diversity. 161 quadrats each (400 m2) lying 200 m far apart for trees and shrubs while sub-plots (1 m2) for herbs and grasses along transects were established over an altitudinal gradient of 539-1111 m.a.s.l. All vascular plant species were collected and brought to National Herbarium, Addis Ababa University for identification.The degree of disturbance data as (low, moderate and heavy) were visually estimated for each plot. Result: a total of 182 plant species: 63 (34.6%) herbs,46 (25.3%) trees, 38 (20.9%) grasses, 18(9.89%) shrubs, 11 climbers (6.04%), and 6 (3.3%) tree ̸ shrub), belonging to 142 genera and 53 families, were identified. Fabaceae was represented by the highest number of species (37 species; 20.3%) followed by Poaceae (36 species; 19.8%) and Asteraceae, 10 species (5.49%). Three plant communities’ types were identified: Acacia mellifera-Balanites aegyptiaca (1); Hyphaene thebaica-Ziziphus spina-christi (2); Combretum hartmannianum-Terminalia brownii-Boswellia papyrifera (3). Species richness was highest in community 1 (mid-altitude: 607-640 m.a.s.l.).The highest Shannon-Wiener diversity index (H`=2.82) for the forest was in community 2 (low altitude: 539-610 m.a.s.l.) while evenness (J=0.72) was highest in community 3 (high altitude: 674-1111 m.a.s.l.) There was a significant correlation between species richness (p=0.024) and altitude per plot while species diversity was non significant (p>0.05) over altitude. Human activities also strongly correlated with species richness and diversity of specific community type. Conclusion: the site has pronounced floristic composition and diversity. Altitudinal difference and the degree of human disturbance determine variation in species composition and richness among communities. Altitude is significantly correlated with species richness of all community types while it is more strongly correlated with community type1.Crop cultivation, illegal fire, and overpopulation of livestock grazing are the main threats in community types 2 and 3. However, this document is a baseline to vegetation information of the park. detailed study on conservation challenges (anthropogenic disturbance) of the park vegetation and prioritize their mitigation measures should be arranged.

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Species composition and dynamics in two hardwood stands in Vermont: a disturbance history

Forest Ecology and Management ◽

10.1016/s0378-1127(98)00535-0 ◽

1999 ◽

Vol 120 (1-3) ◽

pp. 105-116 ◽

Cited By ~ 8

Author(s):

Peter R Hannah

Keyword(s):

Species Composition ◽

Disturbance History

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