Open Pine Research Articles

Overstory and fuel traits drive moisture dynamics of mesophytic and pyrophytic leaf litter and 10-h woody debris fuels in a mixed longleaf pine-hardwood woodland

BackgroundFollowing decades of fire exclusion, many open pine and oak forests across the central and eastern US are shifting to closed-canopy forests that are increasingly dominated by shade-tolerant, fire-sensitive species (i.e., mesophytes). As mesophytes encroach into historically pyrophytic landscapes, changes in crown traits and understory microclimate may interact with fine fuel traits to influence fuel moisture retention, and ultimately, fire behavior. To better understand potential interactions among overstory trees and underlying fine fuels that occur during mesophyte encroachment, we measured in situ drying rates of leaf litter and 10-h woody debris of three functional groups (pyrophytic pine, pyrophytic oak, and mesophytic oak) in gaps and beneath overstory trees of each functional group within a longleaf pine-mixed oak woodland along with crown (area, volume, cover), leaf litter (curling, thickness, specific leaf area, volume), and woody debris (density) traits of each functional group and understory microclimate (vapor pressure deficit (VPD)).ResultsWe found that leaf litter from pyrophytic and mesophytic oaks had higher initial moisture content than pyrophytic pines, but pyrophytic pine and pyrophytic oak leaf litter dried 1.5 times faster than that of mesophytic oaks, likely due to their greater leaf curl, thickness, and volume. Initial moisture content of mesophytic oak woody fuels was lower than that of pyrophytic pine and pyrophytic oak, potentially because of higher wood density, but there were no differences in fuel drying rates. Regardless of fuel functional type, leaf litter and woody fuels dried 1.5 times faster in gaps and underneath pyrophytic pine compared to mesophytic oaks, likely due to the more open conditions in these areas. Notably overstory functional group and time of the day interacted to influence VPD, with VPD increasing throughout the day for all groups, but more so for gaps and beneath pyrophytic pines than either oak functional group.ConclusionsThus, fuel and crown traits differentially impacted understory microclimate and leaf litter and 10-h woody debris drying rates, leading to slower drying of fuels of encroaching mesophytes compared to pyrophytic pines and oaks, which could lead to reduced forest flammability, and consequently, the continued encroachment of mesophytic species into fire-dependent pine and oak forests.

Analysis of the Environments Where Natural Regeneration Is Established in the Absence of a Wildfire in the Open Pinus brutia Forests in the Middle Elevations of the Central Part of Cyprus

The objective of this research was to analyze the P. brutia natural regeneration and the environments where it was established in the absence of a wildfire in the open formations of the species in the middle elevations of the central part of Cyprus. Forty-eight rectangular plots of 0.1 ha were established in three site productivity types. Individuals of the species with a height from 0.1 m to 1.5 m were considered regeneration plants. Within each plot, various measurements and estimations were made. Moreover, 480 hemispherical photographs were taken. Additionally, hemispherical photographs were taken above each of the recorded naturally regenerated P. brutia plants. In all the site productivity types, the most regeneration plants were established and grew under the process of facilitation. In each of the site productivity types, there were no differences in the light condition diversity between the environments where the regeneration plants grew and the existing light conditions. Regeneration exhibited a small number of plants and constituted only a very small proportion of all trees in the three site productivity types. To achieve sustainability in P. brutia forests, forest practices must develop strategies for the enhancement of P. brutia regeneration in the studied area and in analogous environments.

Comparing Ant Activity and Plants Bearing Extrafloral Nectaries in Rockland Habitats of the Florida Keys with Those of the Everglades and the Bahamas

Rocklands are present in South Florida, both on the peninsula and in the Keys. Previous work has shown that extrafloral nectaries on pine rockland plants in the Florida Everglades and surrounding areas play a role in attracting ant protectors. Species with nectaries are more abundant and ant activity greater in more recently burned pine rockland habitats compared with longer undisturbed rockland hammock forest. The floristic composition and prevailing climate of Keys rocklands differs substantially from those on the mainland, so we sought to investigate ant activity and the abundance of plants with extrafloral nectaries in Big Pine Key rockland habitats. Standard baiting methods were used to assess ant abundance and potential predation activity in hardwood hammock, shrubby pine rockland, and open pine rockland sites. Ant activity was the lowest in open pine rockland, greatest in hardwood hammock, and intermediate in shrubby pine rockland, the opposite of what has been observed in previous studies in southern peninsular Florida and on Andros, Bahamas. Sampling vegetation at these same sites revealed a larger proportion of plant species with extrafloral nectaries in the pine rocklands than the hammock, as observed previously in Everglades habitats. Possible reasons for differences in ant activity in Keys rockland habitats are discussed.

Forest management for water yield: Assessing the barriers and impacts of privately-owned open pine woodlands in the Southeastern United States

In the Southeastern United States, freshwater resources are stressed due to human development, population growth, expansion of agricultural irrigation, and climate change. Restoring land to a low-density, fire-maintained longleaf pine (Pinus palustris) savanna and woodland ecosystem may provide distinct ecosystem services such as increases in water quantity for vulnerable watersheds. To understand how economic incentives may bolster restoration programs, we analyze the economic and hydrologic impacts of longleaf pine restoration scenarios. We compare these scenarios against other common land uses in the Coastal Plain of Georgia, a major forestry state located in the Southern United States, identifying the financial barriers and water use impacts of alternative forest management regimes. Longleaf pine restoration shows the greatest increase in water yield per acre at 66 % over baseline timber production scenarios but at a lower timber value return. Thinning planted loblolly pine (Pinus taeda) stands to low-density woodlands may offer a more cost-efficient, immediate alternative that improves water yields by 38 %. Current incentives to restore native habitats on private lands increase financial returns but lack sufficient incentives and governance to meet or exceed baseline forest income levels by $90-$235 ha-1 annually for longleaf savanna restoration. In the future, the emerging ecosystem service market in Georgia may steer decisions about competing values of carbon storage, water yield, and native habitat restoration.

Connectivity at the human-wildlife interface: starling movements relate to carriage of E. coli

Synanthropic bird species in human, poultry or livestock environments can increase the spread of pathogens and antibiotic-resistant bacteria between wild and domestic animals. We present the first telemetry-based spatial networks for a small songbird. We quantified landscape connectivity exerted by spotless starling movements, and aimed to determine if connectivity patterns were related to carriage of potential pathogens. We captured 28 starlings on a partridge farm in 2020 and tested them for Avian influenza virus, West Nile virus WNV, Avian orthoavulavirus 1, Coronavirus, Salmonella spp. and Escherichia coli. We did not detect any viruses or Salmonella, but one individual had antibodies against WNV or cross-reacting Flaviviruses. We found E. coli in 61 % (17 of 28) of starlings, 76 % (13 of 17) of which were resistant to gentamicin, 12 % (2 of 17) to cefotaxime/enrofloxacin and 6 % (1 of 17) were phenotypic extended spectrum beta-lactamase (ESBL) carriers. We GPS-tracked 17 starlings and constructed spatial networks showing how their movements (i.e. links) connect different farms with nearby urban and natural habitats (i.e. nodes with different attributes). Using E. coli carriage as a proxy for acquisition/dispersal of bacteria, we found differences across spatial networks constructed for E. coli positive (n = 7) and E. coli negative (n = 9) starlings. We used Exponential Random Graph Models to reveal significant differences between networks. In particular, an urban roost was more connected to other sites by movements of E. coli positive than by movements of E. coli negative starlings. Furthermore, an open pine forest used mainly for roosting was more connected to other sites by movements of E. coli negative than by movements of E. coli positive starlings. Using E. coli as a proxy for a potential pathogen carried by starlings, we reveal the pathways of spread that starlings could provide between farms, urban and natural habitats.

Bunium serdengectii (Apiaceae), a new species from South Anatolia, Turkey

A new species, Bunium serdengectii (Apiaceae), is described from South Anatolia, Turkey. It grows in open Pinus brutia forests and in macchia formation of the Taurus Mountains in the district of Akseki (Antalya province). The taxonomic affinities of the new species were determined by analyzing morphological data and a molecular phylogenetic study of nrITS. Bunium serdengectii belongs to the section Elegantia, and is related to B. pinnatifolium, but morphologically is more related to B. sayae. The anatomical structure of the fruit is given in detail. The diagnostic morphological characters of B. serdengectii are discussed. In addition, the geographical distribution of the new species and the morphologically related species is mapped.

Comparison of the Stand Structure Diversity of Open Pinus brutia Ten. Forests in Areas of Different Productivity in Central Cyprus

The goal of this study is to compare the diversity of the stand structure of open P. brutia forests in areas of different productivity at middle elevations in central Cyprus. This will help us figure out how much biodiversity they can hold. Two plots of 4 ha were randomly established. One 200 m × 200 m square-shaped plot was established in a P. brutia formation in a medium productivity site, and one in a P. brutia formation in a bad productivity site. In each plot, dendrometrical data were recorded. In total, 160 hemispherical photographs were taken on both plots. The stand structure is more heterogeneous and complex at medium productivity sites compared to bad productivity sites. P. brutia formations in medium productivity sites can support greater biodiversity than the corresponding formations in bad productivity sites. In the open P. brutia formations of central Cyprus, forest practice must aim to increase the density of P. brutia trees in some tree groups to reduce light intensity under the group canopy. Moreover, trees with large diameters and/or heights must be protected from disturbances. This approach will increase the ability of formations to support biodiversity.

Remotely sensed habitat quality index reliably predicts an umbrella species presence but not demographic performance: A case study with open pine forests and red-cockaded woodpeckers

Remote sensing data can be a powerful and cost-effective method for determining the extent, composition, and structure of ecosystems across large areas. To use this tool for effective conservation of individual species, we need to test the assumption that remotely sensed habitat indices correspond to both patch suitability (i.e., presence) and value (i.e., demographic rates) for the species reliant on those habitats. We built an open pine habitat quality index (HQI) from remotely sensed spectral data to identify the condition of pine stands. We correlated the HQI with presence, group size, and fledgling production of an avian species (red-cockaded woodpecker, Dryobates (=Picoides) borealis, RCW) associated with longleaf pine (Pinus palustris) using Bayesian logistic regressions and structural equation models. The HQI was correlated with RCW cavity tree and foraging area presence, with 10.8 and 16.0 increased odds of RCW presence with each unit increase in the HQI, respectively. However, the HQI was not correlated with RCW demographic performance. Given that RCWs are an umbrella species and are currently limited by habitat, that the HQI successfully identifies areas of higher quality habitat for RCW is useful for conservation planning. Improving the specificity of the remotely sensed index could improve the link between the HQI and RCW demographic performance, but might limit its application to RCW, instead of the entire open pine endemic community. Our study suggests that linking generalized habitat indices to species habitat suitability is possible and strengthens the justification for their use in cost-effective, large-scale conservation of imperiled ecosystems.

Territory establishment and microhabitat selection of Bachman's sparrows in a Mississippi pine forest

AbstractBachman's sparrows (Peucaea aestivalis) are an obligate southern open pine forest species linked to disturbance regimes (e.g., fire, windthrow) that reduce canopy cover and promote herbaceous groundcover needed for nesting, foraging, and concealment from predators. Early successional groundstory characteristics suitable for Bachman's sparrows are ephemeral in nature, raising questions about the perceived visual cues created by vegetation structural characteristics and how these characteristics influence multi‐scale habitat selection. We quantified habitat selection for 40 breeding and post‐breeding male Bachman's sparrows within 5 separately managed open pine management sub‐units at Sam D. Hamilton Noxubee National Wildlife Refuge in east‐central Mississippi, USA, from 2020–2021. We captured and color‐banded 20 individuals each year and used weekly resight locations and resource selection function models to assess factors influencing territory establishment (i.e., second‐order selection) within our study area, and microhabitat selection (i.e., third‐order selection) within territories. Bachman's sparrow territory establishment was positively influenced by evergreen cover and fire disturbance, and negatively influenced by tree canopy cover, and distance to unpaved roads. Within territories, sparrows selected areas with a greater basal area of pine (18 m2/ha), more available perching options (>9), and an abundance of native herbaceous groundcover (>36%). They also selected recently burned areas (1–3 yr) with low visual obstruction (<40 cm), and a low percent coverage of leaf litter (<33%). A better understanding of territory establishment and microhabitat selection of the Bachman's sparrow underscores the importance of frequent fire and is helpful in guiding conservation and management efforts for this declining species.

Opportunities for Research on Carbon Management in Longleaf Pine Ecosystems

Longleaf pine (Pinus palustris Mill.) savannas and woodlands are known for providing numerous ecosystem services such as promoting biodiversity, reducing risk of wildfire and insect outbreaks, and increasing water yields. In these open pine systems, there is also interest in managing carbon (C) in ways that do not diminish other ecosystem services. Additionally, there may be management strategies for accomplishing these same objectives in plantations and degraded stands that developed from natural regeneration. For example, C accumulation in live trees and C storage in harvested wood products could be increased by extending rotations and converting plantations to multi-aged stands. Belowground C storage could be enhanced by incorporating pyrogenic C into the mineral soil before planting longleaf pines in clearcut areas, but this may be contrary to findings that indicate that minimizing soil disturbance is important for long-term soil C storage. We suggest examining approaches to reduce total ecosystem C emissions that include using targeted browsing or grazing with domesticated livestock to supplement prescribed burning, thereby reducing C emissions from burning. The mastication of woody vegetation followed by a program of frequent prescribed burning could be used to reduce the risk of substantial C emissions from wildfires and to restore function to savannas and woodlands with hardwood encroachment and altered fire regimes. Many of these approaches need to be validated with field studies or model simulations. There is also a need to improve the estimates of dead wood C stocks and C storage in harvested wood products. Finally, eddy covariance techniques have improved our understanding of how disturbances influence longleaf pine C dynamics over multiple time scales. However, there is a need to determine the degree to which different silvicultural approaches, especially those for adapting ecosystems to climate change, influence C accumulation. Overall, our review suggests that there are numerous opportunities for research on C dynamics in longleaf pine ecosystems, and these systems are likely well-positioned to accomplish C objectives while offering other ecosystem services.

Akdeniz iklim bölgesindeki alt yükselti orman ve çalılıklarında yangın sonrası hızlı ekolojik değerlendirme ile restorasyon önerilerinin geliştirilmesi: Datça-Bozburun Özel Çevre Koruma Bölgesi örneği

The Mediterranean Basin is a biogeography shaped by fires for millions of years. For the restoration of burned areas in the Mediterranean Basin, therefore, planning should increase resistance and resilience of plant communities to fire by considering adaptation strategies of plant species to fire. In this study, following the fire of 2021, affected approximately 12,500 hectares in Marmaris region, a rapid assessment method and post-fire restoration prescriptions were developed for the Datça-Bozburun Special Environmental Protection Area. By using EFFIS and Sentinel-2 satellite images, the burned area was determined and classified to fire severity with normalized burn ratio difference The regeneration potential of burned areas was revealed by counting the number of serotinous cones of Turkish red pine (Pinus brutia) and estimating potential coverage of maquis species in sampling areas based on stand type and burn severity levels. Open pine stands had the highest serotiny and high resprouting potential following maquis vegetation, while the young pine stands have the lowest level of serotiny. Considering results and slope degrees, six restoration prescriptions were developed for burned areas. While 6% of the burned area was recommended to be left unmanaged, natural regeneration + laying out branches with cones and natural regeneration with additional seeding, and artificial regeneration by planting saplings after terracing and tillaging were foreseen for the remaining areas. This simple and cost-effective methodology developed in this study is highly applicable to local practitioners and decision makers, as it can be carried out within two months following the fire.

Почвенные характеристики эмбриоземов под покровом сосновых насаждений на техногенных элювиях Кузбасса

The article studies the edificatory role of pine growing on the technogenic landscapes of the Kuznetsk coal basin and considers the influence of plantations of Scots pine (Pinus sylvestris L.) with different crown density on the main characteristics of embryozems on the overburden dumps of the coal mining industry. The object of the study was soil samples collected in various zones of the phytogenic fields of pine growing on the transport-free dump of the Kedrovsky coal mine. When choosing test plots, the plantations were ranked according to crown density into unclosed (crown density about 30 %), medium-closed (about 60 %) and closed (about 90 %). In each gradation of closeness, the following zones of influence (phytogenic fields) of trees were identified: undercrown, near-crown (intermediate). The selection of sampling points was carried out taking into account the presence of the identification signs: solid pine litter (undercrown zone), developed moss cover (near-crown zone) and developed meadow vegetation (outer zone). External zones are not found in unclosed and medium-closed plantations. In total, according to the degree of crown density and zoning of phytogenic fields, 7 plantation sites of Pinus sylvestris were identified. Soil samples were taken at each of them from a depth of 0–20 cm in the 3rd decade of September. The enzyme activity was studied in recently collected soil in in 3-fold replications. The fractional composition of soils and their agrochemical properties were determined in dried soil on the basis of the Center for Agrochemical Service “Kemerovo”. The analysis of the results showed that pine stands contribute to accelerated disintegration of technogenic residual rocks with the formation of fine-grained fractions, which are of great soil and environmental importance. Litter combined with grassy vegetation in open pine stands favors the accumulation of total nitrogen in embryozems. It was revealed that the content of readily available forms of phosphorus and potassium depends on lithogenic rather than phytocenotic factors. The study of the enzymatic activity of soils showed that the phosphatase activity decreases with an increase in the phosphorus content, and the protease activity increases with an increase in the nitrogen content. Agrochemical indicators of embryozems are favorable for the growth of herbaceous plants due to horizontal differentiation of space under the influence of stands of Scots pine.

Chronology and dynamics of fluvial style changes in the Younger Dryas and Early Holocene in Central Europe (lower San River, SE Poland)

Reconstruction of fluvial style changes in the San River in the Subcarpathian Basins is based on geomorphological and sedimentological analyses. The time control of alluvial fills and temporal changes in the river channel are derived from radiocarbon and optically stimulated luminescence dating combined with independent pollen-based biochronostratigraphy. The results showed that the alluvial plain of the braided (BR) or braided-meandering (BR-M?) river was abandoned before 12,800 cal BP. Large meanders (LM) were cut off in the older part of the Younger Dryas (YD; ca. 12,600 cal BP), and in the younger part of this period (ca. 12,450 cal BP). The small meanders (SM) developed at the end of the YD and were abandoned at the onset of the Preboreal (PB; ca.11,550 cal BP). The erosion phase at the YD-PB transition, reported from many valleys in Central Europe, was not confirmed in the study area. The full cycle of San River channel transformation (BR (BR-M?) → LM → SM); was estimated to be approximately 1200 years. According to the palynological data, open pine forests with birch that survived from the end of the Allerød dominated the landscape of the river valley during the YD cooling and did not undergo major changes during the warming in the early PB. Therefore, we assume that the influence of vegetation changes in the San River channel pattern transformation was nonsignificant. The location of the studied palaeochannels in the floodbasin filled with silty clayey deposits may have influenced the formation of relatively narrow and deep channels, than that of much the wider and shallower meanders from the YD, situated several kilometres downstream of the surveyed sites.

Late Pleistocene palaeoenvironments and a possible glacial refugium on northern Vancouver Island, Canada: Evidence for the viability of early human settlement on the northwest coast of North America

Multi-proxy palaeoecological analyses of lake cores from two sites on northern Vancouver Island reveal previously undocumented non-arboreal environments in the region during the late Pleistocene. Radiocarbon, pollen, sedimentary ancient DNA (sedaDNA), diatom, and grain size analyses indicate that Topknot Lake on the west coast of northern Vancouver Island was not glaciated in the last 18,500 years, extending into the hypothesized regional glacial maximum. A cold herb-shrub coastal tundra existed at the site from ca. 17,500–16,000 cal BP with species including willows (Salix), grasses (Poaceae), sedges (Cyperaceae), heathers (Ericaceae), and sagebrush (Artemisia). SedaDNA analysis also supports the presence of rare non-arboreal taxa at Topknot Lake during this interval including Jacob's-ladder (Polemonium), bistort (Bistorta), and wild berries (Rubus). After ca. 16,000 cal BP and through the terminal Pleistocene, pine (Pinus), alder (Alnus), and ferns formed open forests under cool and dry conditions. At Little Woss Lake in the mountains of north-central Vancouver Island, fir (Abies) stands dominated from ca. 14,200–14,100 cal BP, then were replaced by open pine woodland with alder and ferns from ca. 14,100–12,000 cal BP. SedaDNA corroborates these plant taxa as well as indicating grizzly bear (Ursus arctos horribilis) and Chinook salmon (Oncorhynchus tshawytscha) in and around the basin by ca. 14,100 cal BP. Mixed conifer forests of pine, western hemlock (Tsuga heterophylla), and alder spread into the island's interior ca. 12,000–11,100 cal BP during the Pleistocene-Holocene transition. The records from these two lakes demonstrate the diachronous development of postglacial ecosystems on northern Vancouver Island. Furthermore, these data provide key evidence for environments that could have supported human populations on the northwest coast of North America for several millennia during the terminal Pleistocene.

Land use/land cover change as a major driver of current landscape flammability in Eastern Mediterranean region: A case study in Southwestern Turkey

Land use/land cover (LULC) change has been one of the main drivers of landscape changes in the Mediterranean region where there has been an increase in the forested lands. LULC change in the region has not only changed forest stand structure and composition but also resulted in increase in the available combustible fuels. There have been few studies on fuel accumulation in relation to LULC, however, no study explaining quantitatively the relationship between LULC change and canopy fuel load in the Mediterranean region. The objective of this study is to evaluate the effects of LULC changes on overall crown fire hazard through examining stand structure, composition, and canopy fuel loads in Eastern Mediterranean forests for 35 years. Forest stand type maps generated from the stereo interpretation of aerial photographs and field survey data were used for the analyses. The results of the study showed significant changes in LULC during the period of 1977-2012. There was a 16.6 % decrease in agricultural areas, 144.5 % increase in settlement areas and 6.8 % increase in pine forests. As for the structural and compositional changes in forested lands, open pine stands that included Mediterranean shrub communities decreased (77.2 %); nonetheless, closed pure pine stands increased (49.9 %), resulting in an increase in the total canopy fuel load in pine stands (86.4 %). Results indicated that landscapes tended to become more homogeneous, fully closed pine stands, resulting in an increase in the continuity and the buildup of fuels available for combustion.

Specialist or generalist? It depends. Context-dependent habitat relationships provide insight into forest disturbance effects for a boreal bird species

Understanding how disturbance affects species is a critical component of management in the boreal forest, particularly for disturbance specialist species that often help initiate the succession process through seed dispersal, nutrient cycling, and other means. Unfortunately, emulation of natural disturbance rarely incorporates the disturbance response of those specialist species, which may be potentially sensitive to disturbance characteristics because they are attracted to resources provided by the disturbance itself. Identifying disturbance specialist species and the reasons they occur in post-disturbance habitat is thus a priority for maintaining biodiversity in managed forests. We compared two types of habitat use to fill this information gap for a potential boreal forest disturbance specialist, the Common Nighthawk (Chordeiles minor). The Common Nighthawk is of particular interest to forest managers because this wide-ranging species is declining and listed as of conservation concern in multiple jurisdictions. We used passive acoustic monitoring to survey for nighthawks at 326 locations in the boreal forest of northeastern Alberta, Canada where land use pressure for resource extraction is high. We used an occupancy modelling framework to evaluate two hypotheses for why nighthawks use post-disturbance habitat: nesting or foraging resources. The nesting resource hypothesis was supported by all three lines of evidence that we examined. First, time since disturbance negatively affected territorial habitat use, but not extraterritorial habitat use, confirming that this species is only a disturbance specialist for the territorial component of its home range. Second, territorial habitat use differed between disturbance types, with a higher probability of habitat use for post-harvest and abandoned well sites, which are more likely to have lower amounts of residual vegetation. For our third line of evidence, open pine forest mitigated the effects of time since disturbance for territorial habitat use for all three disturbance types, but especially for postfire areas. We conclude that breeding Common Nighthawks require a combination of open habitat for nesting and wetland areas for foraging and provide industry-specific recommendations for incorporating the Common Nighthawk into boreal forest management plans. Our research emphasizes that understanding the context-dependence of species responses to disturbance provides insights that facilitate effective forest management. We advocate that understanding the behavioural context of habitat use can provide this insight and is often more likely to be aligned with the operational scale of forest management.

Transition from Fire-Dependent Open Forests: Alternative Ecosystem States in the Southeastern United States

Land use and fire exclusion have influenced ecosystems worldwide, resulting in alternative ecosystem states. Here, I provide two examples from the southeastern United States of fire-dependent open pine and pine-oak forest loss and examine dynamics of the replacement forests, given continued long-term declines in foundation longleaf (Pinus palustris) and shortleaf (Pinus echinata) pines and recent increases in commercial loblolly (Pinus taeda) and slash (Pinus elliottii var. elliottii) pines. Shortleaf pine-oak forest historically may have been dominant on about 32 to 38 million ha, a provisional estimate based on historical composition of 75% of all trees, and has decreased to about 2.5 million ha currently; shortleaf pine now is 3% of all trees in the northern province. Longleaf pine forest decreased from about 30 million ha, totaling 75% of all trees, to 1.3 million ha and 3% of all trees in contemporary forests of the southern province. The initial transition from open pine ecosystems to closed forests, primarily comprised of broadleaf species, was countered by conversion to loblolly and slash pine plantations. Loblolly pine now accounts for 37% of all trees. Loss of fire-dependent ecosystems and their foundation tree species affect associated biodiversity, or the species that succeed under fire disturbance.

First genome size assessments for Marshallia and Balduina (Asteraceae, Helenieae) reveal significant cytotype diversity

The genus Marshallia is made up by seven to ten species of perennial herbs growing mainly in open habitats, whereas the genus Balduina is represented by three sympatric species; two perennial herbs and one annual, growing in open pine forest habitats. Both genera belong to the family Asteraceae, tribe Helenieae, and are endemic to the southeast United States, in North America. Cytogenetic studies concerning these two genera are scarce and genome size data is lacking for both. The main goals of this study were to (i) generate novel insights into the evolution of the genome size and (ii), contribute to filling existing gaps on our knowledge of the Asteraceae family from this point of view. Nuclear DNA contents range from 11.42 pg/2C in Marshallia trinervia to 31.58 pg/2C in Marshallia mohrii. The combination of genome size with chromosome data (and inferred cytotypes) suggests the existence of multiple cytotypes, and provides interesting insights into the potential impact of polyploidy in the evolution of these genera in general, and the shaping of genome size diversity, in particular.

Population dynamics of the heather vole (Phenacomys intermedius) in commercial forest landscapes of south-central British Columbia, Canada

AbstractLong-term population dynamics are essentially unknown for the western heather vole (Phenacomys intermedius), a relatively rare microtine species. Our objectives were to provide a description of demographic changes in populations of P. intermedius and determine possible causes of these changes. We analyzed four detailed 12- to 22-year data sets that recorded changes in abundance of P. intermedius in a variety of managed forests in south-central British Columbia, Canada from 1993 to 2018. We evaluated three hypotheses (H) that may help explain population changes: heather voles will (H1) have higher populations in sites with (i) abundant dwarf shrubs or (ii) cover of woody debris; (H2) colonize new clear-cuts as dispersal sinks for young voles; and (H3) be at lower abundance when other Microtus species are present at equal or higher numbers. Populations of P. intermedius occurred commonly at ≤ 1 animal/ha (as a density index). However, in favorable habitats such as some new clear-cuts and in “open” pine stands, P. intermedius occurred at mean annual peak numbers of 5–6/ha (as a density index). There were two relatively high populations of P. intermedius in 1994–1995 and 1998, and possibly again in 2002 in the open pine stands. Mean numbers of lactating females and recruits per year tended to follow the pattern of changes in abundance. High populations of P. intermedius occurred in stands with abundant dwarf shrubs in open pine stands but not those with a cover of woody debris structures in clear-cuts, H1, therefore, was only partially supported. A relatively higher proportion of adult than juvenile heather voles on clear-cuts did not support H2: that these harvested sites would be dispersal sinks for young voles. Mean annual numbers of P. intermedius were positively correlated with those of M. longicaudus, at least on clear-cut sites, hence H3 was not supported. Phenacomys intermedius was essentially absent from our closed-canopy mature/old-growth forests but occurred in many managed forest habitats at low abundance (density index of ≤ 1/ha). In early successional habitats after clear-cutting and in open young pine stands this species occurred at moderate abundance and generally appeared stable in numbers across these forest landscapes.

Patterns of Genetic Divergence across Geographically Variable Populations of Xanthisma gracile (Asteraceae)

Premise of research. Numerous biotic and abiotic factors can contribute to local selection and lead to geographic structure and genetic divergence between populations. The southwestern United States contains many distinctive plant communities, ranging from woodlands to desert scrub, that are shaped by species adapting to local variation in elevation, precipitation, seasonality, and soils. Given this variation, species occurring across diverse habitats are expected to harbor high genetic diversity and exhibit significant genetic differences associated with environmental variation.Methodology. Here, we studied the genetic divergence of populations of Xanthisma gracile (Asteraceae) across Arizona using amplified fragment length polymorphisms and evaluated associations between genetic structure, geographic distance between populations, and variation in climatic factors. This species occurs in desert grasslands at low altitudes as well as in open pine forests at intermediate altitudes and exhibits phenotypic variation in plant height, leaf shape and pubescence, and floral traits.Pivotal results. We detected significant genetic structure across populations and found that a population from arid central Arizona is much more genetically distant than samples from northern and southern Arizona that occur in more mesic habitats. We also detected evidence for selection on numerous loci associated with variation in temperature and precipitation.Conclusions. Major changes have occurred across the Southwest since the Last Glacial Maximum, and genetic divergence in X. gracile across Arizona likely reflects selection for survival in climatically diverse habitats.