Influence of frugivore activity on the species abundance of seedlings and saplings in a lowland tropical forest in Colombia

2015 ◽  
Vol 31 (4) ◽  
pp. 291-303 ◽  
Author(s):  
Natalia Norden ◽  
Pablo R. Stevenson
Keyword(s):  
Seed Size ◽  
Tree Species ◽  
Census Data ◽  
Critical Role ◽  
Species Abundance ◽  
Total Variance ◽  
Relative Importance ◽  
Species Identity ◽  
Related Factors ◽  
Recruitment Success

Abstract:Although seed dispersal plays a critical role for plant regeneration, the long-term benefits of frugivores for recruitment success have been poorly explored. We evaluated the relative importance of tree species abundance and of frugivore-related factors for successful plant recruitment on 18 tree species in a lowland Colombian rain forest. We combined census data from four 1-ha plots of trees (>10 cm dbh), saplings (1–5 cm dbh) and seedlings (<1.7 m) with a dataset describing tree–frugivore interactions. Seedling abundance was higher for large-seeded species dispersed by the spider monkey, while sapling abundance was higher for large-seeded species dispersed by birds. The identity of the dispersal agent and its interaction with seed size explained 20–30% of the total variance in seedling and sapling abundance across scales. Seed size consistently influenced the species abundance of seedlings and saplings across scales, but in opposite ways. These developmental changes suggest that what is beneficial to seedlings is not necessarily beneficial to saplings. Species identity explained 10–50% of the total variance in seedling and sapling abundance among and within 1-ha plots. Overall, our findings suggest that recruitment success is context-dependent as the relative importance of the different variables addressed may shift along spatial and temporal scales.

scholarly journals Soil carbon and nutrient stocks under Scots pine plantations in comparison to European beech forests: a paired-plot study across forests with different management history and precipitation regimes

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Marco Diers ◽  
Robert Weigel ◽  
Heike Culmsee ◽  
Christoph Leuschner
Keyword(s):  
Scots Pine ◽  
Tree Species ◽  
European Beech ◽  
Organic Layer ◽  
Species Identity ◽  
Data Set ◽  
Nutrient Pools ◽  
Total N ◽  
Precipitation Regimes ◽  
Pine Stands

Abstract Background Organic carbon stored in forest soils (SOC) represents an important element of the global C cycle. It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity, but empirical evidence in support of this assumption from forests differing in tree species and productivity, while stocking on similar substrate, is scarce. Methods We determined the stocks of SOC and macro-nutrients (nitrogen, phosphorus, calcium, potassium and magnesium) in nine paired European beech/Scots pine stands on similar Pleistocene sandy substrates across a precipitation gradient (560–820 mm∙yr− 1) in northern Germany and explored the influence of tree species, forest history, climate, and soil pH on SOC and nutrient pools. Results While the organic layer stored on average about 80% more C under pine than beech, the pools of SOC and total N in the total profile (organic layer plus mineral soil measured to 60 cm and extrapolated to 100 cm) were greater under pine by about 40% and 20%, respectively. This contrasts with a higher annual production of foliar litter and a much higher fine root biomass in beech stands, indicating that soil C sequestration is unrelated to the production of leaf litter and fine roots in these stands on Pleistocene sandy soils. The pools of available P and basic cations tended to be higher under beech. Neither precipitation nor temperature influenced the SOC pool, whereas tree species was a key driver. An extended data set (which included additional pine stands established more recently on former agricultural soil) revealed that, besides tree species identity, forest continuity is an important factor determining the SOC and nutrient pools of these stands. Conclusion We conclude that tree species identity can exert a considerable influence on the stocks of SOC and macronutrients, which may be unrelated to productivity but closely linked to species-specific forest management histories, thus masking weaker climate and soil chemistry effects on pool sizes.

scholarly journals 1042. The Attitude of Patients With HIV about Telehealth for Their HIV Care

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S550-S551
Author(s):  
Dima Dandachi ◽  
Bich Dang ◽  
Thomas Giordano Giordano
Keyword(s):  
Hiv Transmission ◽  
Personal Information ◽  
Critical Role ◽  
Retention In Care ◽  
Hiv Care ◽  
Structural Factors ◽  
Personal Factors ◽  
Response Distribution ◽  
Related Factors ◽  
Clinic Visits

Abstract Background The world is facing a pandemic of SARS-CoV-2 that disrupted our healthcare system and the way we deliver healthcare. For people with HIV (PWH), the ability to be retained in care plays a critical role in improving health outcomes and in preventing HIV transmission. Several definitions exist for retention in care, but they are centered around outpatient clinic visits. It is now more important than ever to understand PWH’s attitudes about using telemedicine for HIV care instead of face-to face clinic visits. Methods We administered a one-time survey to PWH presenting to an outpatient HIV center in Houston, Texas, from February–June 2018. The survey items were used to assess PWH’s attitudes towards and concerns for telehealth and explanatory variables. Results 371 participants completed the survey; median age was 51, 36% were female, and 63% African-American. Overall, 57% of respondents were more likely to use telehealth for their HIV care if available, as compared to one-on-one in-person care, and 37% would use telehealth frequently or always as an alternative to clinic visits. Participants reported many benefits including ability to fit better their schedule, decreasing travel time, and privacy but expressed concerns about the ability to effective communication and examination and the safety of personal information. Factors associated with likelihood of using telehealth include personal factors (US-born, men who have sex with men, higher educational attainment, higher HIV-related stigma perception), HIV-related factors (long standing HIV), and structural factors (having difficulty attending clinic visits, not knowing about or not having the necessary technology). There was no association between participants with uncontrolled HIV, medication adherence, and likelihood of using telehealth. Survey items and response distribution Conclusion Telehealth programs for PWH can improve retention in care. A modification of the definition for retention in care, incorporating telehealth, should be considered. Availability and confidence using various telehealth technologies need to be addressed to increase acceptability and usage of telehealth among PWH. Disclosures All Authors: No reported disclosures

scholarly journals Effect of tree species identity and related habitat parameters on understorey bryophytes – interrelationships between bryophyte, soil and tree factors in a 50-year-old experimental forest

2021 ◽  
Author(s):  
Kaja Rola ◽  
Vítězslav Plášek ◽  
Katarzyna Rożek ◽  
Szymon Zubek
Keyword(s):  
Species Richness ◽  
Tree Species ◽  
Forest Floor ◽  
Vascular Plant ◽  
Soil Parameters ◽  
Species Identity ◽  
Habitat Factors ◽  
Positive Correlations ◽  
Old Trees ◽  
Habitat Parameters

Abstract Aim Overstorey tree species influence both soil properties and microclimate conditions in the forest floor, which in turn can induce changes in ground bryophyte communities. The aim of the study was to investigate the effect of tree species identity and the most important habitat factors influencing understorey bryophytes. Methods We assessed the effect of 14 tree species and related habitat parameters, including soil parameters, vascular plant presence and light intensity on bryophytes in monospecific plots covered by nearly fifty-year-old trees in the Siemianice Experimental Forest (Poland). Results The canopy tree species determined bryophyte species richness and cover. The strongest differences were observed between plots with deciduous and coniferous trees. Soils with a more acidic pH and lower content of macronutrients supported larger bryophyte coverage. We also found a positive correlations between vascular plants and availability of light as well as bryophyte species richness. Conclusion Tree species identity and differences in habitat conditions in the forest floor lead to changes of ground bryophyte richness, cover and species composition. Consequently, the changes in the dominant tree species in the stand may result in significant repercussions on ground bryophyte communities. We indicated that the introduction of alien tree species, i.e. Quercus rubra, has an adverse effect on bryophyte communities and suggested that the selection of tree species that contribute to the community consistent with the potential natural vegetation is highly beneficial for maintaining ground bryophyte biodiversity.

scholarly journals Competition Effects on Growth and Crown Dimensions of Shortleaf and Loblolly Pine in Mature, Natural-Origin, Pine–Hardwood Mixtures of the Upper West Gulf Coastal Plain of Arkansas, USA: A Neighborhood Analysis

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 935
Author(s):  
Mohammad Bataineh ◽  
Ethan Childs
Keyword(s):  
Loblolly Pine ◽  
Species Abundance ◽  
Basal Area ◽  
Pinus Echinata ◽  
Shortleaf Pine ◽  
Species Identity ◽  
Linear Mixed Effects ◽  
Natural Origin ◽  
Pinus Taeda L ◽  
Crown Dimensions

The need for a comprehensive and mechanistic understanding of competition has never been more important as plants adapt to a changing environment and as forest management evolves to focus on maintaining and enhancing complexity. With the recent decline in shortleaf pine (Pinus echinata Mill.) land area, it is critical to determine the effects of competition on shortleaf pine and its performance against loblolly pine (Pinus taeda L.), the preferred planted replacement. We evaluate differences in shortleaf and loblolly pine 10 year mean basal area increment (BAI) and crown dimensions across a gradient of neighborhoods. Linear mixed-effects regression models were developed using BAI and several crown metrics as responses and crowding, competitor species abundance and identity, and initial size and species identity of focal tree as predictors. Crowding of focal trees negatively impacted BAI and crown size (p < 0.001, respectively). Although loblolly pine had three times higher BAI as compared to shortleaf pine within similar neighborhoods, BAI was variable, and the crowding effect did not differ between shortleaf and loblolly pine (p ranged from 0.51–0.99). Competitive impacts on focal trees did not differ by competitor identity (p ranged from 0.07–0.70). Distance-independent competition indices better explained the variation in BAI and horizontal crown metrics, while distance-dependent size ratios were more effective at evaluating vertical crown metrics. These findings highlight shortleaf pine competitive potential in mature, natural-origin stands and provide support for the restoration of pine–hardwood and hardwood–pine stratified mixtures as well as management of shortleaf pine at long rotations.

MiR-296-5p ameliorates deep venous thrombosis by inactivating S100A4

2021 ◽  
pp. 153537022110230
Author(s):  
Zhichang Pan ◽  
Yu Zhang ◽  
Chuanyong Li ◽  
Yuan Yin ◽  
Rui Liu ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Deep Venous Thrombosis ◽  
Vascular Function ◽  
Critical Role ◽  
In Vivo Studies ◽  
Luciferase Reporter ◽  
Related Factor ◽  
Related Factors ◽  
Mesenchymal Transition ◽  
S100a4 Expression

Deep venous thrombosis is one of the most common venous thromboembolic diseases and has a low cure rate and a high postoperative recurrence rate. Furthermore, emerging evidence indicates that microRNAs are involved in deep venous thrombosis. miR-296-5p is an important microRNA that plays a critical role in various cellular functions, and S100A4 is closely related to vascular function. miR-296-5p is downregulated in deep venous thrombosis patients, and its predicted target S100A4 is upregulated in deep venous thrombosis patients. Therefore, it was hypothesized that miR-296-5p may play a vital role in the development of deep venous thrombosis by targeting S100A4. An Ox-LDL-stimulated HUVEC and deep venous thrombosis mouse model was employed to detect the biological functions of miR-296-5p and S100A4. Dual luciferase reporter assays and pull-down assays were used to authenticate the interaction between miR-296-5p and S100A4. ELISA and Western blotting were employed to detect the protein levels of thrombosis-related factors and the endothelial-to-mesenchymal transition (EndMT)-related factors. The miR-296-5p levels were reduced, while the S100A4 levels were enhanced in deep venous thrombosis patients, and the miR-296-5p levels were negatively correlated with the S100A4 levels in deep venous thrombosis patients. miR-296-5p suppressed S100A4 expression by targeting the 3ʹ UTR of S100A4. MiR-296-5p knockdown accelerated ox-LDL-induced HUVEC apoptosis, oxidative stress, thrombosis-related factor expression, and EndMT, while S100A4 knockdown antagonized these effects in ox-LDL-induced HUVECs. S100A4 knockdown reversed the effect induced by miR-296-5p knockdown. Moreover, the in vivo studies revealed that miR-296-5p knockdown in deep venous thrombosis mice exacerbated deep venous thrombosis formation, whereas S100A4 knockdown had the opposite effect. These results indicate that elevated miR-296-5p inhibits deep venous thrombosis formation by inhibiting S100A4 expression. Both miR-296-5p and S100A4 may be potential diagnostic markers and therapeutic targets for deep venous thrombosis.

Major construction risk factors considered by general contractors in Qatar

2015 ◽  
Vol 13 (1) ◽  
pp. 165-194 ◽  
Author(s):  
Abdulaziz M. Jarkas ◽  
Theodore C. Haupt
Keyword(s):  
Risk Factors ◽  
Cost Effective ◽  
The State ◽  
Risk Allocation ◽  
Relative Importance ◽  
Related Factors ◽  
Policy Makers ◽  
Content Type ◽  
Construction Risk ◽  
General Contractors

Purpose – The purpose of this paper is to identify, explore, rank the relative importance and determine the prevalent allocation response trends of the major construction risk factors considered by general contractors operating in the State of Qatar. Design/methodology/approach – A structured questionnaire survey comprising 37 potential risk factors was distributed to a statistically representative sample of contractors. The influence ranks of the factors explored were determined using the “Relative Importance Index (RII)” technique, whereas the prevalent trend of contractors’ attitudes toward risk allocation of each factor investigated was quantified and expressed as a percentage, based on the number of respondents who selected a specific option, in relation to the total number of respondents. Findings – The results obtained indicate that risks related to the “client” group are perceived as most critical, followed by the “consultant”, “contractor” and “exogenous” group-related factors, respectively. The outcomes further show that the “transfer” option is the contractors’ prevalent response to “client” and “consultant”-related risks, while the “retention” decision is the principal pattern linked to “contractor” and “exogenous” group-related risk factors. Research limitations/implications – The dominant respondents’ perception that the crucial construction risks are related to clients and consultants suggests that these two parties have an essential role in controlling the negative ramifications of the associated factors. Practical implications – The findings suggest that increasing designers’ awareness of the significant effect of applying the constructability concept can considerably help reducing the risks concomitant of the construction operation. Policy makers may contribute, moreover, in alleviating the risk of incompetent technical staff and operatives’ employment by controlling the migration of inexperienced and unskilled construction workforce into the State. Originality/value – Given the knowledge gap for the major construction risk factors considered by general contractors in Qatar, the results reported in this study can provide clients, industry practitioners and policy makers with guidance to effectively manage the significant risks determined, which can further assist in achieving a reasonable level of competitiveness and cost-effective operation.

scholarly journals The Exploitation of Animals in Roman Britain

2014 ◽  
Author(s):  
Mark Maltby
Keyword(s):  
Species Abundance ◽  
Cultural Factors ◽  
Relative Importance ◽  
Roman Britain ◽  
Human Animal ◽  
Regional Settlement ◽  
Domestic Stock

Concentrating mainly on the zooarchaeological data, this chapter reviews the evidence for the exploitation of animals in Roman Britain. The review focuses initially on domestic mammals and their exploitation, with particular attention being paid to the species that contributed the most to the diet—cattle, pig, and sheep. This discussion is followed by a shorter summary of the evidence for the exploitation of other mammals, birds, and fish. The relative importance of the different species for their meat and other commodities is outlined, and reasons for variations in species abundance, mortality patterns, butchery methods, and the stature of domestic stock are discussed. Chronological, regional, settlement, and cultural factors all need to be taken into account when considering the complexities of human–animal relationships in Roman Britain.

scholarly journals Effect of disturbance on plant species abundance and density distribution in tropical forest of Sunsari district, Eastern Nepal

2016 ◽  
Vol 6 (1) ◽  
pp. 1-12
Author(s):  
Tilak Prasad Gautam ◽  
Tej Narayan Mandal
Keyword(s):  
Carbon Sequestration ◽  
Species Composition ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Tree Species ◽  
Forest Disturbance ◽  
Species Abundance ◽  
Forest Degradation ◽  
Tree Density ◽  
Shrub Species

The disappearance of global tropical forests due to deforestation and forest degradation has reduced the biodiversity and carbon sequestration capacity. In these contexts, present study was carried out to understand the species composition and density in the undisturbed and disturbed stands of moist tropical forest located in Sunsari district of eastern Nepal. Study revealed that the forest disturbance has reduced the number of tree species by 33% and tree density by 50%. In contrary, both number and density of herb and shrub species have increased with forest disturbance.

scholarly journals Diversity of Tree Species in Rivers State University, Port Harcourt, Nigeria

2021 ◽  
pp. 67-72
Author(s):  
P. C. Nnadi ◽  
B. B. Otene ◽  
Nwiisator David-Sarogoro
Keyword(s):  
Plant Species ◽  
Tree Species ◽  
Dominant Species ◽  
Species Abundance ◽  
State University ◽  
University Campus ◽  
Management Interventions ◽  
Port Harcourt ◽  
Pinus Spp ◽  
Rivers State

This study was carried out to examine the distribution of plant species in Rivers State University campus at different locations at the Rivers State University Nkpolu-Oroworukwo Port Harcourt Nigeria. The general objective of this study was to examine the Ecological distribution of plant species in Rivers State University campus at different locations. The specific objective was to determine the species abundance of various plants in the study area and also to examine the ecological diversity of tree species in the various groups. The study area was divided into three groups (stations) with the various plants species identified and recorded. Data gotten from the field was analyzed using descriptive statistic and some ecological indices such as Margalef, Mehinick, Shannon diversity, Shannon Wiener, Evenness/Equitability and Simpson dominance.  A total of one thousand Sixty-nine (1069) individual plant were identified with 16, 17 and 12 species in stations 1-3 respectively. The highest individual plants (561) were observed in station 1 while the least (87) were observed in station 3. The mean values of stations 1 and 2 were significantly and statistically different from site 3 at p<0.05. The results obtained showed some dominant species to include Elaeis guincensis, Polyaithia longifolia, Pinus spp, Gmelina arborea, Wodyetia bifareata, Citrus sinensis, Cocos nuciferia while others were the least dominant species found in the study area. The Margalef, Mehinicks and Shannon Wiener values were consistently highest in station 2 but lowest in station 3.  Human disturbances had negative impact on tree species abundance especially in site 3. It is therefore recommended that management interventions are necessary in other to stop indiscriminate felling of the various trees species that made up the different groups.

scholarly journals Plant, fungal, bacterial, and nitrogen interactions in the litter layer of a native Patagonian forest

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4754 ◽  
Author(s):  
Lucía Vivanco ◽  
Nicolás Rascovan ◽  
Amy T. Austin
Keyword(s):  
Bacterial Community ◽  
Litter Decomposition ◽  
Plant Species ◽  
Tree Species ◽  
Microbial Interactions ◽  
N Addition ◽  
Litter Layer ◽  
Species Identity ◽  
Single Tree ◽  
Stimulation Of

Plant–microbial interactions in the litter layer represent one of the most relevant interactions for biogeochemical cycling as litter decomposition is a key first step in carbon and nitrogen turnover. However, our understanding of these interactions in the litter layer remains elusive. In an old-growth mixed Nothofagus forest in Patagonia, we studied the effects of single tree species identity and the mixture of three tree species on the fungal and bacterial composition in the litter layer. We also evaluated the effects of nitrogen (N) addition on these plant–microbial interactions. In addition, we compared the magnitude of stimulation of litter decomposition due to home field advantage (HFA, decomposition occurs more rapidly when litter is placed beneath the plant species from which it had been derived than beneath a different plant species) and N addition that we previously demonstrated in this same forest, and used microbial information to interpret these results. Tree species identity had a strong and significant effect on the composition of fungal communities but not on the bacterial community of the litter layer. The microbial composition of the litter layer under the tree species mixture show an averaged contribution of each single tree species. N addition did not erase the plant species footprint on the fungal community, and neither altered the bacterial community. N addition stimulated litter decomposition as much as HFA for certain tree species, but the mechanisms behind N and HFA stimulation may have differed. Our results suggest that stimulation of decomposition from N addition might have occurred due to increased microbial activity without large changes in microbial community composition, while HFA may have resulted principally from plant species’ effects on the litter fungal community. Together, our results suggest that plant–microbial interactions can be an unconsidered driver of litter decomposition in temperate forests.

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