Wet Pine Research Articles

Application of artificial neural network for description of the Earth remote sensing data to identify natural habitats used by European elk, Alces alces (Linnaeus, 1758), in autumn-winter period 2023

The paper presents the results of using neural networks of pixel-by-pixel image classification to decipher multichannel space images obtained by the Landsat 8 satellite. Natural habitats were identified based on differences in phytocenotic characteristics of land areas. The level of use of areas by elk was determined by the occurrence of elk presence indicators, which were the density of winter excrement piles (in spring) and the abundance of winged forms of the monoxenous ectoparasite of elk, Lipoptena cervi (Linnaeus, 1758), as measured by the number of individuals attacking the census taker (in the summer-autumn period). The material that forms the basis for deciphering was obtained by the route census method in different areas of the Leningrad Province. High values of the measured parameters were recorded in reforestation areas, in wet pine and birch forests, in aspen forests, on the edges of raised bogs and in overgrown fields – typical elk winter feeding habitats. Based on the data on the maximum values of the measured parameters, a positive correlation was established for the first time between the abundance of winged forms of L. cervi and the physiological activity of the host (the density of the piles of “winter” excrement). The paper also provides a valid reference to the material of schematic maps developed for a part of the territory of the Leningrad Province and Saint Petersburg. The scheme of the use of areas by elk is compiled on the basis of the relative index calculated from the measured parameters of the survey. Field observation areas and territories close to them were most reliably identified (90–95% accuracy). For areas not covered by field observations, the paper provides comments on the main inaccuracies of the schemes and the reasons for the identified discrepancies, based on an analysis of literary sources devoted to similar research topics. The results of the study indicate that the frequency of attacks of winged forms of L. cervi can be used as an additional criterion for assessing the stationary preferences of elk in the winter period using information on the period of active flight, and the decoding method mentioned in the paper can be used in limited areas of specific territories, including reserves, areas of hunting farms and district forestries.

Varied directions of heat flow and emission of volatiles impact evolution of products in pyrolysis of wet and dry pine needles

In pyrolysis of biomass via furnace heating, directions for travel of volatiles and heat flow are opposite. This is drastically different from simultaneously heating surface/inner core of a biomass particle with microwave heating. Changing direction of heat flow and volatiles affects volatiles-char interactions and evolution of pyrolytic products. This was investigated herein by pyrolysis of wet and dry pine needles via furnace or microwave heating at 600 °C. The results indicated that microwave heating induced intensive cracking of outer/inner structures of pine needles. This promoted gasification, decreased production of biochar/bio-oil, diminished formation of both light and heavy organics in bio-oil. Microwave heating also accelerated aromatization, forming biochar of higher C/O and C/H ratios and thermal stability. Additionally, formation of “hot spot” in pyrolysis of wet pine needles via microwave heating was evidenced by the phenomenon of decomposition of CaCO3 to CaO in pyrolysis, which also contributed to enhanced aromatic degree of biochar. Besides, pyrolysis of wet pine needles via microwave heating also generated developed pore structures in biochar (151.4 m2 g−1), as the inherent water and carbonaceous organics were heated simultaneously. Hydrogen bonding from inherent water was largely cracked only above 500 °C. Prolonged retention time of H2O reacted with carbonaceous intermediates, generating more aliphatic structures. Additionally, microwave heating also induced formation of unique morphology like massive thorn-like particulate matters on biochar.

Silvicultural Practices and Water Table Dynamics of Coastal Forested Wetlands

HighlightsForested wetland hydrology (WH) is characterized by changes in daily water table (WT) depth over time.Silvicultural operations (harvesting, thinning, bedding, and minor drainage and intensity) affect WT dynamics.Both WT dynamics and WH are also affected by tree stand age/growth and soil types, besides the climate.Knowledge gaps and future research using modeling, including machine learning methods are discussed.Abstract. Sustainable management of forested wetlands requires an understanding of water table (WT) dynamics affected by rainfall and evapotranspiration (ET) as well as management practices to sustain water quality, quantity, and ecosystem services. The hydrology, the most important factor influencing productivity of forested wetlands, may be characterized by measuring changes in WT depth over time. The hydrology of U.S. Southeastern Coastal Plain forested wetlands, particularly wet pine flats and pocosins, where drainage has been commonly used to improve tree growth, is relatively well understood. However, uncertainties remain regarding the effects of some silvicultural practices on WT dynamics of varying soil and drainage types and the role of climatic trends, including extreme events (precipitation and droughts), on WT dynamics of these forested lands. In this paper, we use information from long-term monitoring and modeling studies conducted at sites in the Southeastern Atlantic Coastal Plain to review the current state of research on potential effects of harvesting, thinning, bedding, and minor drainage on changes to WT dynamics in coastal non-riverine forested wetlands. We also briefly illustrate current gaps in knowledge and outline future potential research in this area. Keywords: Pine forest, Bedding, Harvesting, Minor drainage, Water table, Wetland hydrology, Hydrology models.

Mechanisms of fire‐maintained plant species diversity in species‐rich wet pine savannas

AbstractTemperate savannas and grasslands maintained by frequent, low‐intensity disturbances such as fire contain among the most species‐rich plant communities in the world. Precisely how these disturbances maintain such high fine‐scale diversity is poorly understood. This study examined the effects of the frequency of simulated fire (clipping combined with litter removal) and the relative importance of recruitment and survival on species diversity and trait and species composition at each of two pine savannas in southeastern Mississippi (USA) that had not been recently burned. Ten 2 × 2 m plots at each site were clipped/cleared annually from 2014 to 2019 and again in spring 2021 (annual frequency). The other 10 clipping plots were not clipped from 2018 to 2020 (reduced frequency). Vegetation in small subplots in annual frequency and reduced frequency plots was compared in August 2021 to test the effects of a short period without clipping on diversity and composition. To test the relative importance of recruitment and survival on diversity and composition, four 0.25 × 0.25 m quarter plots were established within each of 10 annual frequency plots per site following a clipping treatment in fall 2019 and assigned a 2 × 2 factorial arrangement of transplantation of sods from long‐unburned areas and herbicide application. Reducing the frequency of clipping reduced plant diversity and altered composition at both sites. A comparison of diversity and trait composition responses to transplant and herbicide treatments revealed how recruitment and survival combined to affect species diversity. Partial or complete recovery of diversity following clipping and litter removal at both sites was driven by rapid increases in short‐lived, resilient species that show fire‐stimulated emergence from a seed bank and the persistence of long‐lived species capable of surviving the prolonged period without fire or clipping. Species with reduced resilience and persistence were more likely to be lost in the reduced frequency treatment. Results are consistent with a model of short‐term coexistence of maximum species diversity maintained by the most frequent fire regime fuels will permit.

СОДЕРЖАНИЕ РТУТИ В ПОЧВЕННЫХ БЕСПОЗВОНОЧНЫХ РЕКРЕАЦИОННОЙ ЗОНЫ КРУПНОГО ПРОМЫШЛЕННОГО ГОРОДА (Г. ЧЕРЕПОВЕЦ)

Soil invertebrates are the main food resource for birds and small mammals. The migration of mercury into the food webs of terrestrial ecosystems is still poorly investigated. The mercury content in soil, earthworms, wolf spiders and harvesters of the forest park zone of Cherepovets (Vologda region) was determined. The collection of the material was carried out on 5 sites (birch-aspen forest, wet pine forest, dry pine forest, wet meadow, dry meadow) differing in the composition of vegetation and the position in the cascade of geochemical landscapes. The minimum mercury content was found in the soils of the dry meadow (eluvial landscape) – 25 ng/g, the maximum – in the soils of the wet meadow (accumulative landscape) – 188 ng/g. The maximum concentrations of mercury in all sites were found in earthworms – from 261 ng/g in the dry pine forest to 1095 ng/g in the wet meadow. The concentration of mercury in wolf spiders was lower than in earthworms. The minimum values were found in a dry meadow. In all sites, the mercury content in wolf spiders was significantly higher than in harvesters. There are no significant correlations between the mercury content in soils and the organism of the studied invertebrates.

Growth and tissue nutrient responses of adults of Sarracenia alata to prey exclusion, nutrient addition, and neighbor reduction.

Carnivorous plants are often associated with nutrient-poor soils and fires. Fire can decrease available soil nitrogen (N) and increase light availability, thus potentially favoring carnivory if prey provide N. Prey can also be a source of phosphorus (P), however, and soil P-availability often increases and competition for prey can decrease following fire. Carnivory thus might be more advantageous before fire when prey and/or soil P are more limiting. We examined nutrient limitation of growth in a carnivorous plant, Sarracenia alata, in a wet pine savanna in southeastern Mississippi, USA. We measured growth and N:P tissue concentration responses of adult plants to a factorial arrangement of prey capture, neighbor reduction, and addition of N, P, and ash to the soil. We tested two hypotheses: (1) Prey provide N, and neighbor reduction and ash addition increase light and soil P and thus the benefit of carnivory; and (2) Prey provide P, neighbor reduction increases prey and/or P, and prey exclusion reduces growth the most when neighbors are not reduced. The exclusion of prey reduced growth more when neighbors were not reduced, an effect that was ameliorated slightly by the addition of P to the soil (the P-limitation hypothesis). Prey exclusion caused a decrease in tissue P when N was added to the soil. The results of this study with adult plants differed from those of a previous study using small juvenile plants, suggesting a shift from light limitation to P and prey limitation with increasing size.

Infertile and Less Infertile Forest Types in the Ukrainian Carpathians: Classification and Complementation

Forest typology is yet to get sufficiently integrated into related ecological and geographical sciences. The succession of plant phytocenoses necessitates constant adjustments to forest types. The discussed studies have been conducted to improve the classification of forest types in the Ukrainian Carpathians and bring the description closer to the actual distribution of vegetation within the studied area. The paper provides a detailed analysis of forest typology research for the Ukrainian Carpathians area during late 20th and early 21st century. The forest fund areas of the Carpathian region, which are subordinated to the State Agency of Forest Resources of Ukraine, have been classified by forest vegetation types. Total area of subor and coniferous forest types is 1,493.1 ha and 28,910.2 ha, respectively. The study involved establishing of permanent sample plots on the territory of nature protection institutions and forest management enterprises. According to the findings, it is proposed to complement the classification of subor and coniferous forest type as defined by Z.Yu. Herushynskyi on the territory of the Ukrainian Carpathians with the following types: fresh pine subor forest type, wet pine subor forest type, and wet pine coniferous type. The paper defines the main diagnostic features of the suggested forest types. These subor and coniferous forest types can be clearly distinguished from other forest types by soil and hydrological conditions, and can be used to describe the corresponding forest vegetation types. The correctness of definition of new forest types is confirmed with a set of plant indicator species that have been identified within the relevant areas. The findings provide a better understanding of forest ecology and make a significant contribution to forest typology studies on the territory of the Ukrainian Carpathians. Another step towards researching the patterns of the establishment of plant complexes in the Ukrainian Carpathians has been taken. Forest formations of the Carpathians are presented in more detail in forest typological science

Fire effects on post-invasion spread of Chinese tallow (Triadica sebifera) in wet pine flatwood ecosystems in the southeastern United States

Prescribed fire has been increasingly used in restoring endangered slash pine (Pinus elliottii) flatwood ecosystems in the southeastern United States. We collected overstory and understory data to study the impact of fire on the post-invasion spread of Chinese tallow tree (Triadica sebifera) in a wet slash pine flatwood in the Grand Bay National Wildlife Refuge, Mississippi, USA. A total of 70 contiguous 30-m2 quadrats were installed and measured prior to fire (2018) and remeasured post-fire (2019 and 2020) to study the spatial distribution of the tallow soil seedbank and seedling recruitment. In addition, the same data were collected around 11 randomly selected tallow seed trees with varying burn intensities (estimated by stem-bark char heights) to evaluate the changes in seedling recruitment and survial by burn intensity. Soil tallow seedbanks around seed trees (427.7 ± 43.9 seeds m−2) were significantly greater than elsewhere (34.6 ± 13.2 seeds m−2) (p < 0.001). Tallow’s soil seedbank varied spatially with more tallow seeds confined in areas with low elevation, canopy closure, and grass cover. Tallow seedling density was negatively correlated with litter and shrub cover; seedling recruitment rates increased with fire intensity with the mean seedling:seed ratio averaging 0.25 in burned areas, significantly higher than that in unburned areas (0.01–0.02). However, most germinants died by the end of the second year, resulting in nonsignificant differences in the density and height of surviving seedlings between burned and unburned areas. These findings suggest that prescribed fire is an effective management tool for depleting the tallow seedbank while not contributing to post-invasion spread.

Experimental tests of PVD AlCrN-coated planer knives on planing Scots pine (Pinus sylvestris L.) under industrial conditions

Raw pine wood processing and especially its mechanical processing constitute a significant share among technological operations leading to obtaining a finished product. Stable implementation of machining operations, ensuring long-term repeatable processing results depends on many factors, such as quality and invariability of raw material, technical condition of technological equipment, adopted parameters of work, qualifications and experience of operators, as well as preparation and properties of the machining tools used. It seems that the greatest potential in the search for opportunities to increase the efficiency of machining operations has the modification of machining tools used in it. This paper presents the results of research work aimed at determining how the life of cutting tools used in planing operations of wet pine wood is affected by the application of chromium aluminum nitride (AlCrN) coating to planar industrial planing knives in the process of physical vapour deposition. For this purpose operational tests were carried out under production conditions in a medium-sized wood processing company. The study compares the effective working time, rounding radius, the profile along the knife (size of worn edge displacement, wear area of the cutting edge), selected texture parameters of the planar industrial planing knife rake face and visual analyses of cutting edge condition of AlCrN-coated planar knives and unmodified ones. The obtained experimental results showed the possibility of increasing the life of AlCrN-coated knives up to 154% compared to the results obtained with uncoated ones. The proposed modification of the operational features of the knives does not involve any changes in the technological process of planing, does not require any interference with the machining station nor its parameters, therefore enabling rapid and easy implementation into industrial practice.

Linking responses of native and invasive plants to hurricane disturbances: implications for coastal plant community structure

Hurricane disturbances produce significant changes in forest microclimates, creating opportunities for seedling regeneration of native and invasive plant species alike. However, there is limited information on how changes in microclimates and pre-existing forest conditions affect native and invasive plants responses to hurricane disturbances. In this manipulative study, we examined the responses of three common shrub/small stature tree species, two of which are native to the coastal region of the southeastern USA (Baccharis halimifolia and Morella cerifera) and one that is invasive (Triadica sebifera), to two key components of hurricane disturbance (canopy damage and saline storm surge). In a greenhouse, we grew seedlings of these species under a range of shade levels that mimicked pre-and post-hurricane canopy conditions for wet pine forest and mixed hardwood forest, two forest communities common in coastal areas of the southeastern USA. Seedlings were subjected to saline storm surges equivalent to full strength sea water for 3 days. Seedling responses (mortality and growth) to the treatments were monitored for 16 months. All species benefitted from higher canopy openness. Storm surge effects were short-lived and seedlings readily recovered under high light conditions. The storm surge had stronger negative effects on survival and growth of all species when coupled with high shade, suggesting storm surge has greater negative impacts on seedlings where hurricane winds cause minimal or no canopy damage. The invasive T. sebifera was by far more shade tolerant than the natives. Survival of T. sebifera seedlings under highly shaded conditions may provide it a competitive edge over native species during community reassembly following tropical storms. Differential responses of native and invasive species to hurricane disturbances will have profound consequences on community structure across coastal forest stands, and may be regulated by legacies of prior disturbances, community structure, extent of canopy damage, and species’ tolerance to specific microclimates.

Population Genetic Structure and Natural Establishment of Hybrids Between Sarracenia flava and Sarracenia minor in Francis Marion National Forest

We assessed population genetic structure and rate of hybridization in Sarracenia flava and S. minor in Francis Marion National Forest. The forest has an abundance of potential habitat for our study species and has suffered less human mediated disturbance than much of the county's longleaf pine savanna and wet pine savanna ecosystems. We examined 63 S. flava and 62 S. minor individuals, as well as one hybrid across a 486.02 km2 study site. We used eight nuclear microsatellite loci and one non-coding chloroplast marker to assess population genetic structure and describe the parentage of the hybrid. We found relatively little population genetic structure across many distinct field sites, even when those sites were separated by unsuitable habitat. In very small populations surviving in shrub-dominated longleaf pine savanna, genetic divergence was greater than in larger populations with more suitable habitat. The single hybrid discovered was an F1 hybrid for which S. flava served as the maternal parent. We found no signs of introgression. We hope that these data can help inform conservation decisions regarding Sarracenia species, as the low genetic structure seems to suggest a high degree of connectivity between geographically distinct populations of plants.

Морфофункціональні особливості Pinus sylvestris L. у лісостанах борів Малого Полісся

&#x0D; Досліджували формування та морфофізіологічні особливості функціонування 27-145-річних соснових деревостанів природного насінного походження, які ростуть в сухих, свіжих, вологих, сирих і мокрих борах Малого Полісся. Встановлено, що Pinus sylvestris L. в борах Малого Полісся росте за V-І класами бонітету. Переважно тут формуються чисті соснові деревостани. Однак у складі близько половини деревостанів трапляється також Betula pendula Roth., частка якої коливається від поодиноких екземплярів до 10%. Вона характеризується істотним відставання за ростом від сосни, яке за висотою становить 22,1-78,9%, а за діаметром – 17,4-70,1%. Повнота деревостанів природного походження, не залежно від віку, коливається в межах 0,50-0,93.&#x0D; Найкращі умови для росту і функціонування P. sylvestris серед борових типів лісу складаються в свіжих і вологих борах. У цих умовах сосна характеризується найвищою продуктивністю. Вона формує хвою, яка за морфолого-анатомічними показниками та вмістом пластидних пігментів найбільшою мірою наближена до генетично-зумовленого рівня. В сирих борах виявлено істотне погіршення стану P. sylvestris, яке проявляється у зниженні інтенсивності росту дерев, зменшенні морфолого-анатомічних показників хвої та біосинтезу зелених і жовтих пігментів. Встановлено, що серед молодняків істотно вищими середньоденними показниками біоелектричних потенціалів характеризується сосна в сухих і свіжих борах. У середньовікових і пристиглих деревостанах виявлено істотне зниження біоелектричної активності сосни в сухих і свіжих борах та зростання – у вологих, сирих і мокрих. У молодняків, середньовікових і пристиглих деревостанів простежується достатньо чітке зростання показників імпедансу і зменшення поляризаційної ємності зі збільшенням вологості ґрунту. Найменш сприятливі умови для життєдіяльності P. sylvestris складаються в мокрому борі. Найбільш чутливими до зміни умов зволоження в борах виявились довжина, площа перетину і поверхні хвої, вміст хлорофілів і діелектричні показники.

Особливості росту біогрупи гіркокаштана звичайного у Зіболківському лісництві ДП "Жовківське лісове господарство"

Наведено коротку характеристику гіркокаштана звичайного та досліджено історію створення насадження за участю інтродуцента у Зіболківському лісництві ДП "Жовківське лісове господарство" на початку ХХ ст. Визначено особливості росту досліджуваної породи. Встановлено, що у віці 95 років дерева гіркокаштана звичайного досягають середньої висоти 19,5 м та середнього діаметра 44,3 см. Вивчено процеси природного поновлення інтродуцента та досліджено основні чинники, що впливають на формування підросту. Зроблено порівняльний аналіз природного поновлення гіркокаштана звичайного та клена-явора під наметом деревостану інтродуцента. Встановлено, що самосів гіркокаштана відстає в рості, кількості та життєвості і, перебуваючи в умовах надмірного затінення, "випадає" із підросту до 8-річного віку. Проведені дослідження свідчать, що гіркокаштан звичайний в умовах вологої грабово-соснової судіброви Малого Полісся України досяг найвищого рівня акліматизації – натуралізації, що підтверджує здатність виду до природного поновлення. Розпочаті дослідження мають на меті встановлення перспектив використання породи у лісокультурному виробництві регіону, визначення ступеня натуралізації виду та агресивності його поведінки щодо автохтонних деревних видів рослин у корінних типах лісу.

Winter use of wet pine savannas by Yellow Rail (Coturnicops noveboracensis) along coastal Alabama and Mississippi

ABSTRACT With the exception of sites along coastal Texas, southeast Oklahoma, and coastal South Carolina, the winter distribution and abundance of Yellow Rail (Coturnicops noveboracensis) is poorly understood. Along the northern Gulf Coast region, winter occurrence is suspected based on a scattered collection of museum specimens and anecdotal observations, although the extent of this species' distribution is uncertain. To address this lack of information, we performed systematic rope-dragging surveys at night targeting Yellow Rails at 17 wet pine savanna patches (size range 1.9–83.3 ha) and one high salt marsh site (13.1 ha) located along coastal Alabama and Mississippi during the winter/spring seasons (Dec–Apr) of 2011–2013. For all sites combined, we flushed 123 Yellow Rails over 117.4 survey hours, yielding 1.0 rail/h. Of these, we captured and banded 61 rails (50%). The sex ratio for birds, discernable through morphometric measurements (n = 40 ind.), was ∼1:1 male-to-female. The relative abundance of ...

Soil properties in site prepared loblolly pine (Pinus taeda L.) stands 25 years after wet weather harvesting in the lower Atlantic coastal plain

Abstract Harvesting traffic may alter soil properties and reduce forest productivity if soil disturbances are not mitigated. Logging operations were conducted during high soil moisture conditions on the South Carolina, USA coast to salvage timber and reduce wildfire potential following Hurricane Hugo in 1989. Long term study sites were established on wet pine flats to evaluate effects of primary skid trails and site preparation on soil properties and loblolly pine productivity. The experiment was analyzed as a split-plot within an unbalanced randomized complete block design having 12 blocks, two levels of traffic (primary skid trail (On), no obvious traffic (Off)) and four levels of site preparation (bedding (Bed), disking with bedding (D/B), disking (Disk), no site preparation (None)). Remeasurement of the study was conducted in 2015 at 25 years after salvage logging (stand age 23 years). Bed and D/B treatments had greater saturated hydraulic conductivity (p = 0.0567) and macroporosity (p = 0.0071) and lower bulk density (p = 0.0226) values than Disk and None treatments. Macroporosity benefits were evident two years after site preparation installation, but bulk density and saturated hydraulic conductivity were not, suggesting these two measurements were affected over time by differences in rooting activity influenced by initial aeration benefits. Depth to iron depletion (p = 0.0055) was significantly greater and soil carbon (p

Loblolly pine (Pinus taeda L.) productivity 23 years after wet site harvesting and site preparation in the lower Atlantic coastal plain

Ground based timber harvesting on wet sites has been linked to alteration of soil properties that may result in reduced long term site productivity. Following Hurricane Hugo in the fall of 1989, numerous salvage logging operations were conducted under high soil moisture conditions to reduce wildfire risk and salvage timber within the Francis Marion National Forest in the lower coastal plain of South Carolina. Study sites were established on wet pine flats to examine the long term effects of primary skid trails and site preparation on planted loblolly pine (Pinus taeda L.) growth. Treatment effects were analyzed as a split-plot within a randomized complete block design with 12blocks, four levels of site preparation (none, disking, bedding, disking with bedding), and two levels of machine traffic (primary skid trail, no obvious traffic). After 23years, bedding and disking with bedding enhanced stand density (p<0.0001) and above ground stand biomass (p<0.0001) relative to the disking and non-site prepared treatments. None of the site preparation treatments were effective at increasing biomass of individual trees. Mean height (p<0.0001), DBH (p<0.0001), and biomass of individual trees (p<0.0001) were lower on primary skid trails than in non-trafficked areas. Traffic did not have a significant effect on stand density (p<0.4662) or stand biomass (p=0.1564). Selected soil physical properties and productivity measurements were similar for the non-site prepared treatment on and off primary skid trails, suggesting that 23years is sufficient time for soils in wet flats to naturally recover from wet weather harvest disturbance. This study indicates that bedding may be the most efficient management practice to enhance long term stand productivity for loblolly pine on aeration-limited sites by increasing seedling survival. Minimizing the spatial extent of skid trails may increase growth of individual trees.

Stochastic losses of fire-dependent endemic herbs revealed by a 65-year chronosequence of dispersal-limited woody plant encroachment.

The factors responsible for maintaining diverse groundcover plant communities of high conservation value in frequently burned wet pine savannas are poorly understood. While most management involves manipulating extrinsic factors important in maintaining species diversity (e.g., fire regimes), most ecological theory (e.g., niche theory and neutral theory) examines how traits exhibited by the species promote species coexistence. Furthermore, although many ecologists focus on processes that maintain local species diversity, conservation biologists have argued that other indices (e.g., phylogenetic diversity) are better for evaluating assemblages in terms of their conservation value. I used a null model that employed beta‐diversity calculations based on Raup–Crick distances to test for deterministic herbaceous species losses associated with a 65‐year chronosequence of woody species encroachment within each of three localities. I quantified conservation value of assemblages by measuring taxonomic distinctness, endemism, and floristic quality of plots with and without woody encroachment. Reductions in herb species richness per plot attributable to woody encroachment were largely stochastic, as indicated by a lack of change in the mean or variance in beta‐diversity caused by woody encroachment in the savannas studied here. Taxonomic distinctness, endemism, and floristic quality (when summed across all species) were all greater in areas that had not experienced woody encroachment. However, when corrected for local species richness, only average endemism and floristic quality of assemblages inclusive of herbs and woody plants were greater in areas that had not experienced woody encroachment, due to the more restricted ranges and habitat requirements of herbs. Results suggest that frequent fires maintain diverse assemblages of fire‐dependent herb species endemic to the region. The stochastic loss of plant species, irrespective of their taxonomic distinctness, to woody encroachment suggests that the relevance of niche partitioning or phylogenetic diversity to the management of biodiversity in wet pine savannas is minimal.

Pyrolysis and spontaneous ignition of wood under time-dependent heat flux

This work investigates experimentally and theoretically the effect of time-dependent incident heat flux (HF), which is more reasonable in fire-like environment, on thermal degradation process of wet pine wood. A feedback method was utilized to generate a time-dependent heat flux by controlling the output power of radiative heater. Both quadratic and linear heat fluxes were studied in this study. Comparison between measured heat fluxes and designed values indicates that the method provides high accuracy. Measurements of temperature distribution at different depths of material, ignition time and mass loss rate were implemented in the tests to examine the effects of time-dependent heat fluxes. Additionally, analytical model and numerical model were developed to predict the pyrolysis behaviors, and good agreement exists between the experimental and simulational results. Results showed that the heat penetration layer is restricted to a thinner depth for HF with higher increasing rate. A linear relationship was found between ignition time and HF parameters, which is also validated by experimental data and reexamined by constant heat flux circumstance. Mass loss rate was affected significantly by the changed heat flux compared with constant scenario. Furthermore, critical mass flux, which keeps almost unchanged, can be employed as ignition criterion due to the fact that the ignition temperature increases with increasing heat flux, which also certifies the conclusions of other researchers.

Important Biological Knowledge for Management of Cooley's Meadowrue (Thalictrum cooleyi), a Federally Endangered Endemic of Pine Savannas

ABSTRACT Thalictrum cooleyi (Cooley's meadowrue, Ranunculaceae) is a federally endangered dioecious herb of wet pine savannas of the southeastern United States. We studied aspects of T. cooleyi biology crucial to conservation including its association with woody species, reproduction, and genetic structure in 11 populations in North Carolina and Georgia. Thalictrum cooleyi presence was negatively associated with canopy closure, but positively associated with shrub cover, including wax myrtle Morella cerifera. Deviations from strict dioecy are uncommon in T. cooleyi. Sex ratios differed significantly from 1:1, but despite male-bias in populations, pollen supplementation experiments found evidence for pollen limitation to seed set. Seeds are dormant at maturity. Cold stratification or gibberellic acid can break dormancy. Warm temperatures followed by cold stratification may increase germinability. Germination rates were low, likely due to low seed viability. Thalictrum cooleyi can be propagated vegetatively...

Feral swine damage to globally imperiled wetland plant communities in a significant biodiversity hotspot in Florida

We studied rooting damage during five-years of feral swine control at Avon Park Air Force Range, a significant botanical biodiversity hotspot in peninsular Florida with many globally imperiled plant species and communities. While control reduced swine abundance, remaining animals consistently rooted the 49 studied sites in both middle-dry season (MDS) and late-dry season (LDS) each year. At each study site, we measured rooting with sub-meter accuracy. Neither total nor proportional area rooted differed in either season, across study years, or among plant community types: herbaceous seepage slopes, wet pine savannas, wet grasslands. The proportion of sites with damage during MDS was at least 25 % less than pre-control baseline. During LDS, the proportion of sites with damage increased over years but remained below the initial 2 years’ MDS results. Fresh rooting frequency (rooting <1 week-old) across sites dropped precipitously from baseline and remained low for MDS. Fresh rooting frequency among sites during LDS was lower than MDS for all but year two of the study. Canopied habitat <50 m from a study site almost guaranteed rooting at the site each observation period. We propose actions for protecting wetlands, integrating swine control into other compatible land use practices, and improving swine control efficacy. While we measured damage amounts at each site very accurately, our approach of also considering frequency of rooting and frequency of fresh rooting across sites offers low-labor means to broadly assess swine damage and control efficacy at large geographic scales because in-field measurements of damage amounts are not needed.