A remarkable remnant mesic deciduous forest stand: are composition and structure of old-growth retained?

Old-growth forests are declining throughout eastern North America, especially toward the northern limit of the deciduous formation where gently undulating topography and milder climate especially encourage human activity. Remnants exist, but do they retain the defining characteristics of the original vegetation? The objective was tomarshal information required to answer this question, and toward this objective we assessed vegetation in a small 1 ha remnant of maple-beech forest with no history of past logging and compared it to well known and larger old-growth areas in the region. We used Curtis. s (1959) Point Quarter method to provide full quantitative data for trees, saplings, shrub and herbs. Size class distribution of trees and successional status of the stand were assessed. As a general conclusion, we found that tree species richness of our remnant was higher than most recognized large old-growth forests and, while the herbaceous understorey was poorer in species than larger tracts, it exhibited three provincially rare species. Furthermore, the successional status and structural complexity of the remnant were typical of old-growth forests. In overall comparative terms, the remnant was found not be an outlier when ordinated with larger forests. It thus is safe to conclude that this remnant constitutes an ecological benchmark well worth protection, despite its limited size

Processing The Interspecies Quorum-Sensing Signal Autoinducer-2 (AI-2) Characterization Of Phospho-(S)-4,5-Dihydroxy-2,3-Pentanedione Isomerization By LsrG Protein

The molecule (S)-4,5-dihydroxy-2,3-pentanedione (DPD) is produced by many different species of bacteria and is the precursor of the signal molecule autoinducer-2 (AI-2). AI-2 mediates interspecies communication and facilitates regulation of bacterial behaviors such as biofilm formation and virulence. A variety of bacterial species have the ability to sequester and process the AI-2 present in their environment, thereby interfering with the cell-cell communication of other bacteria. This process involves the AI-2-regulated lsr operon, comprised of the Lsr transport system that facilitates uptake of the signal, a kinase that phosphorylates the signal to phospho-DPD (P-DPD), and enzymes (like LsrG) that are responsible for processing the phosphorylated signal. Because P-DPD is the intracellular inducer of the lsr operon, enzymes involved in P-DPD processing impact the levels of Lsr expression. Here we show that LsrG catalyzes isomerization of P-DPD into 3,4,4-trihydroxy-2-pentanone-5-phosphate. We present the crystal structure of LsrG, identify potential catalytic residues, and determine which of these residues affects P-DPD processing in vivo and in vitro. We also show that an lsrG deletion mutant accumulates at least 10 times more P-DPD than wild type cells. Consistent with this result, we find that the lsrG mutant has increased expression of the lsr operon and an altered profile of AI-2 accumulation and removal. Understanding of the biochemical mechanisms employed by bacteria to quench signaling of other species can be of great utility in the development of therapies to control bacterial behavior

Are patterns of fine-scale spatial genetic structure consistent between sites within tropical tree species?

JRS was funded by the Swiss National Science Foundation (SNF) (http://www.snf.ch/en/Pages/default.aspx) grant number PDFMP3_132479 / 1 awarded to JG. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Genetic diversity affects seedling survival but not growth or seed germination in the Bornean endemic dipterocarp Parashorea tomentella

Background: Logging and habitat fragmentation of tropical rain forests may disrupt patterns of gene flow and genetic diversity. Consequently, inbreeding in tree populations may reduce fitness and increase extinction risks, especially among species that are predominantly outcrossing, dependent on biotic pollination and/or display limited seed dispersal such as species of the Dipterocarpaceae. Aims: To test the hypothesis that heterozygosity of individual progeny affects their likelihood of germination and the growth and survival of seedlings. Methods: Standardised measure of multilocus heterozygosity (sMLH) was estimated from seven microsatellite loci for individual progeny collected from 18 mother trees of the large dipterocarp Parashorea tomentella. The relationships among sMLH, germination and seedling growth and survival were determined for the progeny. Results: Seedling survival over 18 months increased with greater sMLH and fresh fruit weight. This result was expressed under all experimentally controlled combinations of light and nutrient availability in the nursery and in the shaded understorey of primary forest where survival overall was much lower than in the nursery. sMLH did not affect the probability of germination or seedling growth rate in any experimental treatment. Conclusions: These results provide evidence that reduced heterozygosity is associated with reduced seedling survival in a tropical forest tree species

Impacts of an extreme precipitation event on dipterocarp mortality and habitat filtering in a Bornean tropical rainforest

The frequency of extreme precipitation events is predicted to increase in some tropical regions in response to global climate change, but the impacts of this form of disturbance on the structure and dynamics of tropical tree communities across heterogeneous landscapes remain understudied. We determined the effects of an extreme precipitation event (EPE) in July 2006 on mortality of dipterocarps on a 68 ha permanent inventory plot in Sepilok Forest Reserve, Sabah. For stems ≥30 cm dbh, 12 of the 15 species of Dipterocarpaceae on this plot have significant positive and/or negative associations to habitats defined by topography and soil type. Short-term mortality induced by the EPE was much greater for individuals growing on the alluvial floodplain (13.7%) than in the mudstone (1.4%) or sandstone (0.0%) habitats, but mortality of dipterocarps did not differ among these habitats in the subsequent 5-yr interval. The likelihood of mortality in response to the EPE was highest for a small group of fast growing dipterocarps that possess low wood density and a strong association to the alluvial forest habitat. This group of species represents a high percentage of dipterocarp individuals but a low proportion of dipterocarp diversity in this habitat. We conclude that disturbance induced by high rainfall events contributes to the episodic nature of tropical forest dynamics, and that increases in the frequency of these events would disproportionately impact low-lying alluvial forest environments and some of the species growing in them

Roundabout accident prediction model: random-parameter negative binomial approach

Roundabouts have been used widely on all road classes in the United Kingdom because they are considered safer than other types of intersections in general. The objective of this study was to examine geometric and traffic characteristics and their influences on the number of accidents. Data from each of 70 roundabouts (with 284 approaches) included all recorded vehicle accidents as well as geometric and traffic characteristics for the entire roundabout, within circulatory lanes, and at roundabout approaches. Resulting estimates were compared with those from random-parameter and fixed-parameter negative binomial count data models. The random-parameter results provided better goodness of fit than the fixed-parameter results, and more variables were found to be significant. Significant variables that influenced the number of accidents were total approach traffic, truck percentage, entry width, inscribed circle diameter, number of lanes, and presence of traffic signals

Process evaluation of a peer-led antenatal breastfeeding class for fathers: perceptions of facilitators and participants

Background: The Parent Infant Feeding Initiative (PIFI) was a factorial, randomised controlled trial that aimed to prolong exclusive breastfeeding by targeting expecting fathers. One of the intervention strategies evaluated was a father-focused breastfeeding class facilitated by a male peer facilitator. The aim of this mixed-methods descriptive study was to 1) evaluate the feedback provided from participants of the class and 2) explore the motivations and experiences of volunteer male peer facilitators trained to deliver the class. Methods: Father-focused breastfeeding antenatal (FFAB) classes were conducted in six Western Australian hospitals between August 2015 and December 2016. Following each peer facilitated FFAB class, expecting father participants completed an evaluation form to assess their satisfaction with the format, facilitation and content, in addition to whether their expectations and confidence to manage breastfeeding problems had changed. Feedback to open-ended questions was analysed using content analysis to identify learnings and suggestions for improvements. At the completion of PIFI, individual telephone interviews were undertaken with 14 peer facilitators to gain insight into their motivations for volunteering and experiences of conducting the classes. Transcripts from interviews were analysed using Braun and Clarke’s six phases for thematic analysis. Results: Participant evaluation forms were completed by 678 of the 697 father participants (98%). Overall satisfaction with class format, facilitation and content was high with 90% or more of fathers either strongly agreeing or agreeing with each positively-phrased evaluation item. Class participants enjoyed interacting with other fathers, appreciated validation of their role, were not always aware of the importance of breastfeeding or potential difficulties, valued the anticipatory guidance around what to expect in the early weeks of parenting and appreciated learning practical breastfeeding support strategies. Peer facilitators indicated they felt well prepared and supported to conduct FFAB classes. Analysis of interview transcripts revealed common experiences of the peer facilitators incorporating four themes: ‘Highlights of being a facilitator’, ‘Challenges’, ‘Mourning the project completion’ and ‘Satisfaction with training and support’. Conclusion: Father-focused breastfeeding classes supported by volunteer male peer facilitators are a feasible and acceptable way of engaging fathers as breastfeeding supporters. Trial registration: ACTRN12614000605695. Registered 6 June 2014

Ecological implications of a flower size/number trade-off in tropical forest trees

Peer reviewedPublisher PD