Influence of eastern hemlock (Tsuga canadensis) forests on aquatic invertebrate assemblages in headwater streams

2002 ◽  
Vol 59 (2) ◽  
pp. 262-275 ◽  
Author(s):  
Craig D Snyder ◽  
John A Young ◽  
David P Lemarié ◽  
David R Smith
Keyword(s):  
Insect Pest ◽  
Hardwood Forests ◽  
Aquatic Invertebrate ◽  
Community Diversity ◽  
Forest Composition ◽  
Hemlock Decline ◽  
Recreation Area ◽  
Exotic Insect Pest ◽  
Invertebrate Community Structure

We conducted a comparative study in the Delaware Water Gap National Recreation Area to determine the potential long-term impacts of hemlock forest decline on stream benthic macroinvertebrate assemblages. Hemlock forests throughout eastern North America have been declining because of the hemlock woolly adelgid, an exotic insect pest. We found aquatic invertebrate community structure to be strongly correlated with forest composition. Streams draining hemlock forests supported significantly more total taxa than streams draining mixed hardwood forests, and over 8% of the taxa were strongly associated with hemlock. In addition, invertebrate taxa were more evenly distributed (i.e., higher Simpson's evenness values) in hemlock-drained streams. In contrast, the number of rare species and total densities were significantly lower in streams draining hemlock, suggesting that diversity differences observed between forest types were not related to stochastic factors associated with sampling and that streams draining mixed hardwood forests may be more productive. Analysis of stream habitat data indicated that streams draining hemlock forests had more stable thermal and hydrologic regimes. Our findings suggest that hemlock decline may result in long-term changes in headwater ecosystems leading to reductions in both within-stream (i.e., alpha) and park-wide (i.e., gamma) benthic community diversity.

scholarly journals Unexpected Diversity in Regenerating Sites Stresses the Importance of Baselines: A Case Study With Bats (Order Chiroptera) on the Osa Peninsula, Costa Rica

2021 ◽  
Vol 14 ◽  
pp. 194008292110281
Author(s):  
Elène Haave-Audet ◽  
Doris Audet ◽  
Michelle Monge-Velazquez ◽  
Eleanor Flatt ◽  
Andrew Whitworth
Keyword(s):  
Habitat Restoration ◽  
Insect Pest ◽  
Community Diversity ◽  
Baseline Survey ◽  
Cross Sectional ◽  
Osa Peninsula ◽  
The Family ◽  
Aerial Insectivores ◽  
Baseline State

Introduction: Background and Research Aims: Assessing biodiversity recovery is key to determine whether the objectives of habitat restoration for conservation are met. Many restoration initiatives use cross-sectional comparisons of wildlife communities to infer restoration impact instead of longitudinal assessments from a baseline state. Using an indicator of biodiversity in the neotropics— bats— we demonstrate how assessing community diversity and composition in an area targeted for restoration prior to implementation, and when compared to surrounding intact forest, provides the groundwork to track changes in the community post-restoration. Methods We assessed bat communities by 1) using mist-net surveys to identify species in the family Phyllostomidae (leaf-nosed bats), and 2) conducting acoustic surveys to identify non-phyllostomid species (aerial insectivores). Results For both groups, we found that areas targeted for restoration had similar diversity as the surrounding forest, but the two habitat types differed in community composition. Phyllostomids were captured at higher rates in forest, but aerial insectivores were detected at higher rates in restoration habitat. Conclusion Our baseline assessment revealed unexpected diversity in areas targeted for restoration. The presence of all trophic groups in restoration habitat suggests that bats provide key ecosystem services in the restoration process, such as through seed dispersal, pollination and insect pest control. Implications for Conservation: Conducting a baseline survey of bats in areas targeted for restoration demonstrated that the community was not species poor at the baseline and was different from the surrounding forest, allowing us to better track restoration success and the effects of different restoration treatments.

scholarly journals Unmapped exome reads implicate a role for Anelloviridae in childhood HIV-1 long-term non-progression

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Savannah Mwesigwa ◽  
◽  
Lesedi Williams ◽  
Gaone Retshabile ◽  
Eric Katagirya ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Diversity Index ◽  
Strong Association ◽  
Community Diversity ◽  
Added Value ◽  
Sequencing Platform ◽  
Public Health Burden ◽  
Survival Status ◽  
Significant Public Health

AbstractHuman immunodeficiency virus (HIV) infection remains a significant public health burden globally. The role of viral co-infection in the rate of progression of HIV infection has been suggested but not empirically tested, particularly among children. We extracted and classified 42 viral species from whole-exome sequencing (WES) data of 813 HIV-infected children in Botswana and Uganda categorised as either long-term non-progressors (LTNPs) or rapid progressors (RPs). The Ugandan participants had a higher viral community diversity index compared to Batswana (p = 4.6 × 10−13), and viral sequences were more frequently detected among LTNPs than RPs (24% vs 16%; p = 0.008; OR, 1.9; 95% CI, 1.6–2.3), with Anelloviridae showing strong association with LTNP status (p = 3 × 10−4; q = 0.004, OR, 3.99; 95% CI, 1.74–10.25). This trend was still evident when stratified by country, sex, and sequencing platform, and after a logistic regression analysis adjusting for age, sex, country, and the sequencing platform (p = 0.02; q = 0.03; OR, 7.3; 95% CI, 1.6–40.5). Torque teno virus (TTV), which made up 95% of the Anelloviridae reads, has been associated with reduced immune activation. We identify an association between viral co-infection and prolonged AIDs-free survival status that may have utility as a biomarker of LTNP and could provide mechanistic insights to HIV progression in children, demonstrating the added value of interrogating off-target WES reads in cohort studies.

Late Quaternary vegetation dynamics in a biodiversity hotspot, the Uluguru Mountains of Tanzania

2009 ◽  
Vol 72 (1) ◽  
pp. 111-122 ◽  
Author(s):  
Jemma Finch ◽  
Melanie J. Leng ◽  
Rob Marchant
Keyword(s):  
Environmental Changes ◽  
Vegetation History ◽  
Late Quaternary ◽  
Anthropogenic Activities ◽  
Significant Loss ◽  
Environmental Stability ◽  
Forest Composition ◽  
Eastern Arc ◽  
Uluguru Mountains

AbstractLate Quaternary vegetation history and environmental changes in a biodiverse tropical ecosystem are inferred from pollen, charcoal and carbon isotope evidence derived from a ∼ 48,000-yr sedimentary record from the Uluguru Mountains, a component of the Eastern Arc Mountains of Kenya and Tanzania. Results indicate that Eastern Arc forest composition has remained relatively stable during the past ∼ 48,000 yr. Long-term environmental stability of the Eastern Arc forests has been proposed as a mechanism for the accumulation and persistence of species during glacial periods, thus resulting in the diverse forests observed today. The pollen and isotope data presented here indicate some marked changes in abundance but no significant loss in moist forest taxa through the last glacial maximum, thereby providing support for the long-term environmental stability of the Eastern Arc. Anthropogenic activities, including burning and forest clearance, were found to play a moderate role in shaping the mosaic of forest patches and high-altitude grasslands that characterise the site today; however, this influence was tempered by the inaccessibility of the mountain.

scholarly journals Does the long-term success of REDD+ also depend on biodiversity?

Oryx ◽  
2014 ◽  
Vol 49 (2) ◽  
pp. 216-221 ◽  
Author(s):  
Amy Hinsley ◽  
Abigail Entwistle ◽  
Dorothea V. Pio
Keyword(s):  
Carbon Storage ◽  
Financial Incentives ◽  
Global Climate ◽  
Forest Degradation ◽  
Forest Tree ◽  
Carbon Stocks ◽  
Tree Cover ◽  
Forest Composition ◽  
Tree Survival

AbstractOriginally proposed in 2005 as a way to use financial incentives to tackle global climate change, Reducing Emissions from Deforestation and forest Degradation (REDD) has evolved to include conservation, sustainable management of forests and enhancement of forest carbon stocks, in what is now known as REDD+. Biodiversity protection is still viewed principally as a co-benefit of the REDD+ process, with conservation of forest tree cover and carbon stocks providing the main measure of success. However, focusing solely on tree cover and carbon stocks does not always protect other species, which may be threatened by other factors, most notably hunting. We present evidence from the literature that loss of biodiversity can affect forest composition, tree survival and forest resilience and may in some cases ultimately lead to a reduction in carbon storage. We argue that REDD+ projects should specifically mitigate for threats to biodiversity if they are to maximize carbon storage potential in the long term.

scholarly journals Understanding the Evolutionary Ecology of host–pathogen Interactions Provides Insights into the Outcomes of Insect Pest Biocontrol

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 141
Author(s):  
David J. Páez ◽  
Arietta E. Fleming-Davies
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Transmission Rate ◽  
Insect Pest ◽  
Pathogen Transmission ◽  
Single Strain ◽  
Classical Biocontrol ◽  
Life History Tradeoffs ◽  
Pathogen Strains

The use of viral pathogens to control the population size of pest insects has produced both successful and unsuccessful outcomes. Here, we investigate whether those biocontrol successes and failures can be explained by key ecological and evolutionary processes between hosts and pathogens. Specifically, we examine how heterogeneity in pathogen transmission, ecological and evolutionary tradeoffs, and pathogen diversity affect insect population density and thus successful control. We first review the existing literature and then use numerical simulations of mathematical models to further explore these processes. Our results show that the control of insect densities using viruses depends strongly on the heterogeneity of virus transmission among insects. Overall, increased heterogeneity of transmission reduces the effect of viruses on insect densities and increases the long-term stability of insect populations. Lower equilibrium insect densities occur when transmission is heritable and when there is a tradeoff between mean transmission and insect fecundity compared to when the heterogeneity of transmission arises from non-genetic sources. Thus, the heterogeneity of transmission is a key parameter that regulates the long-term population dynamics of insects and their pathogens. We also show that both heterogeneity of transmission and life-history tradeoffs modulate characteristics of population dynamics such as the frequency and intensity of “boom–bust" population cycles. Furthermore, we show that because of life-history tradeoffs affecting the transmission rate, the use of multiple pathogen strains is more effective than the use of a single strain to control insect densities only when the pathogen strains differ considerably in their transmission characteristics. By quantifying the effects of ecology and evolution on population densities, we are able to offer recommendations to assess the long-term effects of classical biocontrol.

scholarly journals Erratum to: Long-term forest composition and its drivers in taiga forest in NW Russia

2015 ◽  
Vol 25 (3) ◽  
pp. 237-238
Author(s):  
Niina Kuosmanen ◽  
Heikki Seppä ◽  
Triin Reitalu ◽  
Teija Alenius ◽  
Richard H. W. Bradshaw ◽  
...  
Keyword(s):  
Forest Composition ◽  
Taiga Forest

Recruitment patterns following a severe drought: long-term compositional shifts in Patagonian forests

2008 ◽  
Vol 38 (12) ◽  
pp. 3002-3010 ◽  
Author(s):  
María L. Suarez ◽  
Thomas Kitzberger
Keyword(s):  
Vegetation Change ◽  
Forest Canopy ◽  
Tree Mortality ◽  
Forest Composition ◽  
Future Climate Change ◽  
Severe Drought ◽  
Climate Change Scenarios ◽  
Recruitment Pattern ◽  
Recruitment Patterns

Severe droughts have the potential of inducing transient shifts in forest canopy composition by altering species-specific adult tree mortality patterns. However, permanent vegetation change will occur only if tree recruitment patterns are also affected. Here, we analyze how a massive mortality event triggered by the 1998–1999 drought affected adult and sapling mortality and recruitment in a mixed Nothofagus dombeyi (Mirb.) Blume – Austrocedrus chilensis (D. Don) Flor. et Boult. forests of northern Patagonia. Comparing drought-induced and tree-fall gaps, we assessed changes in forest composition, microenvironments, and seedling density and survival of both species. Drought-kill disturbance shifted species composition of both canopy and sapling cohorts in favour of A. chilensis. Drought gaps were characterized by a shadier and more xeric environment, affecting the recruitment pattern of N. dombeyi seedlings. The seedling cohort was composed mostly of A. chilensis, and its survival was always higher than that of N. dombeyi. Additionally, A. chilensis seedlings showed higher plasticity than N. dombeyi seedlings, increasing its root to shoot ratios in drought gaps. The results suggest that extreme drought itself is a strong driving force in forest dynamics, with important imprints on forest landscapes. Future climate-change scenarios, projecting an increased in frequency and severity of droughts, alert us about expected long-term compositional shifts in many forest ecosystems.

scholarly journals Long-term seasonal forecasting of a major migrant insect pest: the brown planthopper in the Lower Yangtze River Valley

2018 ◽  
Vol 92 (2) ◽  
pp. 417-428 ◽  
Author(s):  
Gao Hu ◽  
Ming-Hong Lu ◽  
Don R. Reynolds ◽  
Hai-Kou Wang ◽  
Xiao Chen ◽  
...  
Keyword(s):  
Yangtze River ◽  
Insect Pest ◽  
Brown Planthopper ◽  
Yangtze River Valley ◽  
River Valley ◽  
Seasonal Forecasting ◽  
Lower Yangtze
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