Quercus Rubra Research Articles

Developing Species-Age Cohorts from Forest Inventory and Analysis Data to Parameterize a Forest Landscape Model

Simulating long-term, landscape level changes in forest composition requires estimates of stand age to initialize succession models. Detailed stand ages are rarely available, and even general information on stand history often is lacking. We used data from USDA Forest Service Forest Inventory and Analysis (FIA) database to estimate broad age classes for a forested landscape to simulate changes in landscape composition and structure relative to climate change at Fort Drum, a 43,000 ha U.S. Army installation in northwestern New York. Using simple linear regression, we developed relationships between tree diameter and age for FIA site trees from the host and adjacent ecoregions and applied those relationships to forest stands at Fort Drum. We observed that approximately half of the variation in age was explained by diameter breast height (DBH) across all species studied (r2 = 0.42 for sugar maple Acer saccharum to 0.63 for white ash Fraxinus americana). We then used age-diameter relationships from published research on northern hardwood species to calibrate results from the FIA-based analysis. With predicted stand age, we used tree species life histories and environmental conditions represented by ecological site types to parameterize a stochastic forest landscape model (LANDIS-II) to spatially and temporally model successional changes in forest communities at Fort Drum. Forest stands modeled over 100 years without significant disturbance appeared to reflect expected patterns of increasing dominance by shade-tolerant mesophytic tree species such as sugar maple, red maple (Acer rubrum), and eastern hemlock (Tsuga canadensis) where soil moisture was sufficient. On drier sandy soils, eastern white pine (Pinus strobus), red pine (P. resinosa), northern red oak (Quercus rubra), and white oak (Q. alba) continued to be important components throughout the modeling period with no net loss at the landscape scale. Our results suggest that despite abundant precipitation and relatively low evapotranspiration rates for the region, low soil water holding capacity and fertility may be limiting factors for the spread of mesophytic species on excessively drained soils in the region. Increasing atmospheric temperatures projected for the region could alter moisture regimes for many coarse-textured soils providing a possible mechanism for expansion of xerophytic tree species.

Eighty-three years of vascular plant change at Alley Pond Park, Queens County, New York

The objective of the present study was to document change in arborescent vegetation at Alley Pond Park, Queens County, New York over 83 yr. We compared data generated from a Works Progress Administration (WPA) study map in 1936, with data generated at the same points on the map in 1975 by Stalter, and again at the same points in 2018. Quercus rubra L. was dominant in 1936, 1975, and 2018. There was little change in important overstory trees over 83 yr. Cornus florida L., the dominant subcanopy tree in 1936 and 1975, was nearly eliminated by dogwood anthracnose in 2018. Parsimony analysis reveals a branching break in 2018 and the early samples; this is best explained by community development, succession, and the presence of invasive taxa, Acer platanoides L., Morus alba L., and Prunus avium (L.) L.

How do invasive trees impact shrub layer diversity and productivity in temperate forests?

• Key messageInvasive tree species alter taxonomic diversity and functioning of forest shrub layers: Prunus serotina increases shrub layer biomass two to three times but decreases its biodiversity, Robinia pseudoacacia slightly increases shrub layer biomass and has no effect on its biodiversity, while Quercus rubra both biomass and biodiversity of the shrub layer.• ContextAlthough the impact of invasive trees on understory biodiversity is known, very little data exist about their influence on shrub layer biodiversity and productivity.• AimsTo assess impacts of Prunus serotina Ehrh., Quercus rubra L., and Robinia pseudoacacia L. on shrub layer aboveground biomass, species composition, and alpha diversity.• MethodsWe measured stand structures in a set of 168 study plots established in Wielkopolski National Park (W Poland), and we compared biomass and diversity metrics using generalized mixed-effects linear models.• ResultsWe found the lowest aboveground biomass of shrub layers in Q. rubra forests. P. sylvestris forests invaded by P. serotina had two to three times higher aboveground biomass than non-invaded forests. R. pseudoacacia forests had 27.8% higher shrub layer biomass than Quercus-Acer-Tilia forests. We found negative impacts of Q. rubra and negligible impacts of R. pseudoacacia on shrub layer alpha diversity metrics. However, the effect of Q. rubra was similar to native F. sylvatica. P. serotina negatively affected functional diversity, but its effects were lower in rich P. sylvestris forests than in poor P. sylvestris forests.• ConclusionThe introduction of alien tree species alters ecosystem services and species diversity of shrub layers. The direction and magnitude of these alterations are alien species-specific and context-dependent. Therefore, their management should account for their impacts.

First Report of Armillaria Root Disease Pathogen, Armillaria gallica, on Rhododendron and Quercus rubra in Georgia, USA.

Armillaria root and butt diseases, which are a global issue, can be influenced by changing environmental conditions. Armillaria gallica is a well-known pathogen of diverse trees worldwide (Brazee and Wick 2009). Besides A. gallica causing root rot of Hemerocallis sp. and Cornus sp. in South Carolina (Schnabel et al. 2005), little is reported on the distribution and host range of A. gallica in the southeastern USA. In July 2017, three Armillaria isolates were obtained from two naturally occurring hosts in Georgia, USA and cultured on malt extract medium (3% malt extract, 3% dextrose, 1% peptone, and 1.5% agar). One isolate (GA3) was obtained in Unicoi State Park near Helen, Georgia (Lat. 34.712275, Long. -83.727765, elev. 498 m) from the basal portion of Rhododendron sp. with extensive root/butt decay, but no crown symptoms were evident (Supplementary Figure 1). GA4 and GA5 (Lat. 33.902433, Long. -83.382453, elev. 215 m) were isolated from wind-felled Quercus rubra (red oak) with root disease at the State Botanical Gardens in Athens, Georgia. GA4 was associated with a large root ball (ca. 4-m diameter) (Supplementary Figure 2), and GA5 was obtained from a mature tree with infected roots, with characteristic spongy rot of Armillaria root disease. Crown symptoms could not be evaluated because the crowns had been removed before the collections. Several other oaks with Armillaria root disease were noted throughout the State Botanical Gardens. Pairing tests reduced these three isolates (whiteish mycelia with a dark, brownish crust and rhizomorphs), to two genets with GA4 = GA5. Both genets (GA3 and GA4) were identified as A. gallica using translation elongation factor 1α (tef1) sequences (Genbank Nos. MT761697 and MT761698, respectively) that showed ≥ 97% identity (≥ 98% coverage) with A. gallica sequences (KF156772, KF156775). Also, nine replications of somatic pairing tests showed 33 - 67% compatibility with A. gallica (occurs in southeastern USA), compared with 0 - 22% for A. mexicana, A. mellea (occurs in southeastern USA), A. solidipes, and Desarmillaria tabescens (occurs in southeastern USA). To our knowledge, this note represents the first report of A. gallica on Rhododendron and Q. rubra in Georgia, USA, which has experienced severe drought in recent decades (e.g., Park Williams et al. 2017) that could predispose trees to Armillaria infection (e.g., Wargo 1996). Quercus rubra was previously reported as a host of A. gallica in Arkansas (Kelley et al. 2009) and Massachusetts (Brazee and Wick 2009), USA. In Missouri, USA, A. gallica has been reported as a weak pathogen with potential biological control against A. mellea (Bruhn et al. 2000). Other reports from several regions on various hosts suggest pathogenicity of A. gallica is associated with changing climate (Nelson et al. 2013, Kim et al. 2017, Kubiak et al. 2017). Wide genetic variation and/or cryptic speciation within A. gallica may account for differences in ecological behavior (Klopfenstein et al. 2017), but this is difficult to evaluate because Armillaria pathogenicity tests cannot be used on most forest tree seedlings. This study suggests that A. gallica is more widespread than previously known and its adverse impacts on woody plants may intensify over time, depending on the environmental conditions. Further studies are needed to determine environmental influences on A. gallica, the full distribution of A. gallica, and its effects in forests of the southeastern USA.

Overyielding in young tree communities does not support the stress‐gradient hypothesis and is favoured by functional diversity and higher water availability

Abstract Biodiversity effects on productivity and other ecosystem functions are strongly dependent on climate and resource availability. Based on the stress‐gradient hypothesis, under conditions of greater abiotic stress, diversity effects on plant performance are intensified due to the increased relative importance of positive plant interactions. However, whether this hypothesis is consistently applicable in forest systems remains unclear. A field trial was established to test the stress‐gradient hypothesis and examine diversity effects on above‐ground biomass production of young trees in mixtures exposed to different water availability. Six native tree species of northern temperate forests (Acer saccharum, Betula papyrifera, Larix laricina, Picea glauca, Pinus strobus and Quercus rubra) were planted as monocultures and as mixtures of two, four and six species. For five growing seasons, four replicates of each community were exposed to conditions of either low‐ or high‐water availability created by rainfall exclusion and weekly irrigation, respectively. Growth‐years 4 and 5 were significantly different when the climatic water balance of the growing seasons was compared. We tested the effects of functional diversity on: (a) total growth of mixtures under low‐ and high‐water availability, and (b) annual growth in years 4 (higher water availability, 2017) and 5 (lower water availability, 2018). Annual growth of most species in both years was greater under high‐ versus low‐water availability. Functional diversity had a significant positive effect on total biomass production and annual growth, and this effect was more strongly expressed under high‐water availability. Functional diversity effects on annual growth did not differ between years 4 and 5 regardless of their climatic water balance. Functional and species identity were key to understanding productivity responses to mixture and treatment effects. Synthesis. Contrary to the stress‐gradient hypothesis, the positive effects of functional diversity on productivity were enhanced by high‐water availability and were independent of seasonal water balance.

Forest land use discontinuity and northern red oak Quercus rubra introduction change biomass allocation and life strategy of lingonberry Vaccinium vitis-idaea

BackgroundMulti-purpose use of forests in a sustainable way forces a recognition of how introduction of alien woody species in forests with different land use histories affect native plants other than trees. Lingonberry Vaccinium vitis-idaea is an important understory component of temperate and boreal forests and provider of valuable non-wood forest products. Here we studied effects of land use changes and introduction of Northern red oak Quercus rubra on lingonberry in mesic Scots pine forests (in central Poland). We measured lingonberry cover, height of shoots, biomass of stems and leaves, and fruit productivity. Shoots were collected within 200 research plots located in recent and ancient Scots pine forests, with and without Q. rubra.ResultsWe found that V. vitis-idaea reached lower cover, aboveground biomass and fruit production in recent than ancient forests and in forests with than without Q. rubra. The fruit production in recent pine forest was only 2% of that reported in ancient pine forest, and V. vitis-idaea did not reproduce generatively in forests with Q. rubra. Biomass and carbon sequestration of V. vitis-idaea in forests with alien (invasive) trees decreased by 75% compared to ancient pine forest. Effects were also clear at the individual shoot level – in less suitable conditions we found taller heights and higher biomass allocation into stems than foliage. Biomass allocation in fruiting and non-fruiting shoots in pine forests was also different – less of the dry biomass of fruiting shoots was allocated to leaves than to stems.ConclusionsIn the age of high interest in ecosystem services and discussions about usage of alien tree species as alternatives in forest management, our results clearly indicate disruption of ecosystem services provided by V. vitis-idaea in the presence of Q. rubra. Lingonberry benefited from the continuity of forest land use, however, regardless of land-use legacy, alien tree introduction led to decline in abundance of species crucial for ecosystem functioning. Therefore, to maintain valuable native species and for conservation of ecosystem services delivery, we suggest limiting the introduction of Q. rubra in areas with abundant V. vitis-idaea, especially in forests with continuous forest land-use history.

Predisposing factors\u2019 effects on mortality of oak (Quercus) and hickory (Carya) species in mature forests undergoing mesophication in Appalachian Ohio

BackgroundMature oak (Quercus spp.) and hickory (Carya spp.) trees are gradually being replaced by more shade-tolerant tree species across the eastern U.S., likely due to fire suppression and increased precipitation. Oaks and hickories are highly valuable to wildlife; therefore, studying their mortality patterns can provide information on the longevity of habitat quality for many animal species. Oak mortality has most often been studied following large oak decline events, but background mortality rates in forests with aging oak and hickory canopies warrant equal attention, especially in the context of widespread oak and hickory regeneration failure.MethodsWe studied background mortality rates of five oak and one hickory species over a 23–25 year time period (1993–1995 to 2018), using 82 1/20th hectare permanent plots on the Marietta Unit of the Wayne National Forest in southeastern Ohio. We calculated mortality rates based on remeasurement of individual trees for white oak (Quercus alba), chestnut oak (Quercus montana), northern red oak (Quercus rubra), black oak (Quercus velutina), scarlet oak (Quercus coccinea), and pignut hickory (Carya glabra). For each of these species other than scarlet oak, we also modeled the relationships of mortality probability with a priori topographic, soil, stand structural, and individual tree covariates, using a mixed-effects logistic regression framework.ResultsThe species with the highest mortality rate was scarlet oak (61.3%), followed by northern red oak (41.4%), black oak (26.7%), pignut hickory (23.9%), white oak (23.4%), and chestnut oak (19.1%). In our models, northern red oak mortality was associated with more mesic slope positions, shallower solums, more acidic soils, and older stand ages. Pignut hickory and chestnut oak mortality rates were associated with higher basal areas on the plot, while white oak mortality showed the opposite pattern.ConclusionsOur data suggest that red oak subgenus trees in mature forests of our area will become increasingly uncommon relative to white oak subgenus trees, as the result of higher mortality rates likely related to the shorter lifespans of these species. Particularly vulnerable areas may include more mesic topographic positions, shallower or more acidic soil, and older stands. Since maintaining oak subgenus diversity is beneficial to wildlife diversity in the eastern U.S., managers in areas with extensive mature mixed-oak forests could choose to favor the red oak subgenus when conducting silvicultural treatments.

A compilation of North American tree provenance trials and relevant historical climate data for seven species

Tree provenance trials consist of a variety of seed sources (or provenances) planted at several test sites across the range of a species. The resulting plantations are typically measured periodically to investigate provenance performance in relation to abiotic conditions, particularly climate. These trials are expensive and time consuming to establish, but are an important resource for seed transfer systems, which aim to match planting sites with well-adapted (climatically suitable) seed sources. Provenance trial measurements may be underutilized because the data are scattered across publications, conference proceedings, and university theses. Here we document an effort to collect available provenance trial measurements and associated climate data for seven eastern North American tree species (Pinus strobus, Pinus banksiana, Picea glauca, Picea mariana, Quercus rubra, Larix laricina, Betula alleghaniensis). The resulting datasets included a total of 773 provenances and 62 test sites, with 65 historical climate variables appended to each location. We hope this data will support forest managers in making seed transfer decisions, particularly in an era of rapid climate change.

Overstorey composition shapes across‐trophic level community relationships in deciduous forest regardless of fragmentation context

Abstract Communities across trophic levels, and the functional roles they play, are vital for the sustained provision of ecosystem services. In forest systems, diversification of overstorey composition has been shown to be a key driver of biodiversity, but its influence on across‐trophic level relationships remains scarcely known. Species across trophic levels in varied overstorey compositions are also differentially susceptible to fragmentation context. We hypothesise that fragmentation will disrupt community relationships associated with particular overstorey compositions. We test this hypothesis using a tree diversity research platform across 53 deciduous woodland plots in central Belgium. We estimate species’ abundances within nine, generally taxonomic, community groups across trophic levels: understorey vegetation; leaf miners and gall formers; woodlice, millipedes; carabid beetles, harvestmen, spiders, birds, bats. We use multiple co‐inertia analyses to examine how taxonomic and trophic role community matrices covary across gradients of overstorey composition, via three different tree species diversification pathways, and fragmentation. For all trophic role groups, across all plots, there was at least one significant pairwise comparison. Apart from comparisons involving bats, there was at least one significant pairwise correlation between taxonomic groups too. These results indicate correlated community matrices across trophic levels. Overstorey composition related to community tightness, that is, the level of co‐ordinated change among taxonomic and/or trophic role groups as revealed by multiple co‐inertia analyses. Notably, diversifying woodlands of beech Fagus sylvatica or red oak Quercus rubra with pedunculate oak Quercus robur correlated with increased taxonomic community tightness. Diversifying pedunculate oak forest stands with other overstorey species related to unchanged community tightness. Evidence was lacking for fragmentation affecting community tightness, singly or by interacting with overstorey composition. Synthesis. Overall, changing tree species composition and fragmentation level affected across‐trophic level community relationships differently. Yet, we demonstrated a clear signal that diversifying monoculture stands with particular species correlated with greater community tightness, and co‐ordinated change among sets of community groups, across trophic levels and regardless of fragmentation context. We postulate that having tighter community relationships suggests that measures to improve biodiversity at one trophic level (i.e. trees) could affect other groups, and their associated roles, in a co‐ordinated manner.

Flora of the Forest at Mountain Lake Biological Station, Giles County, Virginia

Local floras are a basis of biogeography, ecology, evolution, and systematics, and they add value to research sites. Mountain Lake Biological Station is located between 1,150 and 1,319 m elevation in southwestern Virginia on infertile, acidic soils supporting a second-growth forest strongly dominated by Quercus rubra about 150 years old. We sampled vascular vegetation on 352 randomly distributed plots 10m in diameter with 8 subplots of 1 m2 each. The plots contained 175 taxa (including 7 taxa that included 16 lumped species); other fieldwork added 43 species for a total of 227 species in the forest. We excluded disturbed areas around buildings, roadsides, and ponds that harbor many ruderal and invasive species. Average detection probability of a species on a plot was estimated to be 75%. We recorded binary occurrence (present or absent on a plot) and prevalence (occurrence on 0, 1, 2, … 8 subplots per plot) and a set of environmental variables measured in the field or laboratory, or estimated from LIDAR data collected by NEON. Nonmetric multidimensional scaling ordination rejected the null hypothesis of random distributions of herbaceous species among plots. Cluster analysis defined eight groups of plots based on prevalence of herbaceous species to illuminate rejection of the null hypothesis. The environments of these clusters, determined only by their floras, demonstrated the importance of rock type, soils, solar radiation, canopy height, and topography in determining the local distribution of species. Significant differences among assemblages and their environments occurred within a superficially homogeneous forest.

Natural forest regeneration-soil relationships in a fire disturbed urban natural area forest

Sustainability for urban natural area forests can be achieved with extensive natural regeneration of the native canopy species. A new urban forest management protocol “SAFE” (Soils Aliens Fire Exclosure) has the goal of increasing natural regeneration through: soil treatments; alien species treatments; fire surveillance; and large herbivores exclosure fencing. This research reports on the initial stages of the iterative process for the SAFE protocol. The soils and fire components of the SAFE protocol were examined for the seedlings and saplings of the seven canopy taxa growing in a loam and an extremely stony loam of the same soil series in the Good Woods, Philadelphia, Pennsylvania. Comparisons are made with data before and after an arson caused fire in 2015. Before the fire, seedlings for Carya spp., Prunus serotina, Quercus alba, and Quercus rubra and Q. velutina as well as Liriodendron tulipifera saplings had larger populations in the loam. The seedling populations for all seven taxa and saplings for Carya spp., Liriodendron tulipifera, and Prunus serotina were different in the burned and unburned areas of both soils. Post-fire sprouts, which were considered separately, had low survival rates four years after the fire. In the four combinations of soils and burned and unburned areas, pH, phosphorus, potassium, magnesium, and calcium were deficient except for phosphorus in the burned extremely stony loam. Negative binomial regression equations for seedlings of all seven taxa with the soil nutrients indicate fertilizer treatments to increase phosphorus, potassium, magnesium, and calcium would cause no change in natural regeneration. Regression variable estimates indicate increasing the pH would result in forest regeneration decreases for Acer rubrum, Fraxinus americana, and Prunus serotina. The next research steps for SAFE in the Good Woods are to monitor seedling populations changes after: a soil treatment; alien species control; a fire, and large herbivores exclusion.

Can coppicing planted saplings improve the growing position of mid-tolerant northern hardwood tree species in harvest gaps?

Group harvesting is often used to regenerate mid-tolerant tree species. However, in managed northern hardwood forests of the Great Lakes region, regeneration failures are common among mid-tolerant species regardless of gap size. Coppicing advance regeneration has the potential to alter recruitment patterns within harvest gaps, as some mid-tolerant species have large dormant season carbohydrate reserves in the root system. However, the comparative sprouting abilities of northern hardwood saplings are not well quantified. Furthermore, variation in light availability and chronic browsing from white-tailed deer may modify comparative sprouting abilities. In this study, we tracked the effects of dormant season coppicing and deer exclusion on the initial sprouting response and five-year survival, height growth, and final height of seven-year-old volunteer white ash saplings and planted yellow birch, paper birch, northern red oak, sugar maple, red maple, and American beech saplings across a gradient of harvest gap sizes (10–35 m diameter, <0.5–1.25 tree height) in a mature even-aged northern hardwood stand in northern Lower Michigan, USA. In addition, saplings were given a growing position ranking, which integrated sapling final height and survival status relative to competitors to evaluate the effects of coppicing and deer exclusion on sapling development. Overall, coppicing produced a strong initial sprouting response with nearly all red maple and northern red oak stems initially sprouting. In the absence of deer, appreciable differences in sprout survival and height growth occurred among mid-tolerant and intolerant species and contributed to changes in growing position. Northern red oak sprouts significantly gained growing position over all species through a combination of high survival and modest height growth across all gap sizes. In contrast, coppiced yellow birch and paper birch sprout survival was significantly lower than uncoppiced stems, which contributed to declines in growing position for both species across all gap sizes. Coppicing in the absence of deer had less effect on the growing position of mid-tolerant red maple and white ash and shade tolerant sugar maple and American beech. Without deer exclusion, browsing limited the effectiveness of coppicing by reducing height growth and final height of all mid-tolerant species. Collectively, our results indicate that coppicing does not benefit mid-tolerant species equally and is unlikely to benefit browsing-preferred species in areas with high deer density. Nevertheless, in areas of lower deer density or in situations where sprouts can be protected, coppicing may improve the competitiveness of northern red oak saplings within harvest gaps.

Climate sensitivity of understory trees differs from overstory trees in temperate mesic forests.

The response of understory trees to climate variability is key to understanding current and future forest dynamics. However, analyses of climatic effects on tree growth have primarily focused on the upper canopy, leaving understory dynamics unresolved. We analyzed differences in climate sensitivity based on canopy position of four common tree species (Acer rubrum, Fagus grandifolia, Quercus rubra, and Tsuga canadensis) using growth information from 1,084 trees across eight sites in the northeastern United States. Effects of canopy position on climate response varied, but were significant and often nonlinear, for all four species. Compared to overstory trees, understory trees showed stronger reductions in growth at high temperatures and varied shifts in precipitation response. This contradicts the prevailing assumption that climate responses, particularly to temperature, of understory trees are buffered by the overstory. Forest growth trajectories are uncertain in compositionally and structurally complex forests, and future demography and regeneration dynamics may be misinferred if not all canopy levels are represented in future forecasts.

Comparative analysis of the complete chloroplast genomes of six white oaks with high ecological amplitude in China

Quercus L. has significant societal, ecological and economic benefits in the Northern Hemisphere. However, species identification among oaks is notoriously difficult. China harbours highly diverse oaks, of which the diversity of white oaks is the most extensive; however, to date, the evolution of chloroplast (cp) genomes in white oaks in China has not been comprehensively studied. Thus, we sequenced the complete cp genomes (161,254 bp, 161,229 bp and 161,254 bp in size) of three white oak species (Quercus serrata Thunb. var. brevipetiolata A. DC. Nakai, Quercus wutaishansea Mary and Quercus mongolica Fischer ex Ledebour, respectively). Six white oak species (Quercus aliena Blume, Quercus dentata Thunb., Quercus aliena Blume var. acutiserrata Maximowicz ex Wenzig, Q. serrata var. brevipetiolata, Q. wutaishanica and Q. mongolica) and five other Fagaceae species (Quercus rubra L., Quercus variabilis Bl., Quercus aquifolioides Rehd. et Wils., Fagus engleriana Seem. and Castanea henryi Skan Rehd. et Wils.) were retrieved for comparative analyses. We detected 11 highly divergent regions (psbA, matK/rps16, rps16, trnS-GCU/trnG-GCC, trnR-UCU/atpA, trnT-GGU/psbD, ndhJ, ndhJ/ndhK, accD, ndhF and ycfI) through comparative analyses and these regions might be used as molecular markers. The ω ratio of the rps12, rpoC2 and ycf1 genes was greater than 1 in several comparison groups between white oaks and the petA gene was subjected to significant positive selection between the comparison of six white oaks and Q. variabilis. Phylogenetic analyses revealed that six white oaks were grouped with Q. rubra, forming a single clade.

Differences in phenolics produced by invasive Quercus rubra and native plant communities induced changes in soil microbial properties and enzymatic activity

Invasive trees can alter soil properties and ecosystem functioning by producing phenolic compounds. Phenolics can influence carbon and nitrogen availability as well as enzymatic activity or act as signaling molecules. In plant-microorganism interactions, species-specific phenolics can be the source of food or toxicity. They may have antimicrobial, stimulatory or both (ambiguous) properties and thus affect soil microbial properties, enzymatic activity, and plant-soil feedbacks differently. We hypothesized that phenolic compounds with antimicrobial properties produced by invasive Quercus rubra would reduce soil microbial biomass and enzymatic activity, and alter microbial community structure. We expected these changes to be most pronounced in the soil organic horizon as they are driven by litter chemistry. We tested changes, potentially associated with the concentrations of 12 phenolic compounds in Q. rubra litter and soil, in microbial properties (respiration rate, bacterial and fungal biomass), enzymatic activity, and microbial community structure in organic and mineral soil horizons as well as in arbuscular mycorrhizal fungi (AMF) spore number and species richness in mineral soil horizon. We found that Q. rubra reduced several soil parameters, namely respiration rate, phosphatase activity, total microbial biomass, bacterial (both G + and G–) biomass, and 16:1ω5 NLFA AMF storage lipid marker as well as changed microbial community structure, which supports our hypothesis that the phenolics produced by Q. rubra have mostly toxic effect on native soil communities. However, Q. rubra did not affect arylsulfatase and urease activity, saprotrophic fungi population, and the number of AMF spores and species. The changes in soil microbial properties and enzymatic activity may be related to high amounts of ellagic acid, ferulic acid, phloridzin, and syringic acid provided with newly shed Q. rubra litter to the soil surface. Some phenolics found in soil, i.e., phloridzin and (–)-epicatechin, correlated negatively, while others, i.e., quercetin and chlorogenic acid, correlated positively with soil microbial parameters and/or enzymatic activity, which suggest either antimicrobial or stimulatory properties of these compounds. Our study demonstrated that invasive Q. rubra has multiple potential effects on soil microbial communities, which can mediate plant-soil feedbacks. Future research should address the long-term consequences of these changes for forest ecosystems and the fitness of native flora.

Performance and genetic diversity of 23 provenances of northern red oak (Quercus rubra L.) after 25 years of growth in South Korea

Growth traits and genetic diversity of 23 provenances of Quercus rubra introduced from North America were analyzed in a provenance trial established with a randomized block design in Hwaseong, Gyeonggi, South Korea in 1993. Growth variables and survival at age 25 were compared with results from early stages. Height, DBH, volume and stem straightness of Q. rubra was better than those of the domestic oak (Quercus accutissima). Growth of the Dunham Island provenance from New York was the best among the 23 provenances that of the Eagle River provenance from Wisconsin was poorest. Survival rate at age 25 was on average 52%. The longitude of seed origin and growth of provenance were consistently significantly negatively correlated at all ages. Growth of coastal provenances was superior to that of the inland provenances, which were separated by the Appalachian Mountains. Genetic diversity and genetic distance among the provenances were evaluated using microsatellite markers. The allelic frequencies showed high polymorphism in 10 microsatellite loci, and 292 alleles were found. Of 10 loci, two were commonly found in the 23 provenances. The mean allelic diversity and heterozygosity observed among the provenances were similar to those from the native populations of Q. rubra in North America. Nei′s genetic distance among the 23 was estimated and showed that a clear trend between geographic and genetic distances, indicating that some provenances have high genetic diversity with superior growth performance.

Fizička i mehanička svojstva drveta crvenog hrasta u okolini Beograda (Srbija)

The wood of northern red oak (Quercus rubra L.), considered to be a very high-quality material for processing in the wood industry, has not been tested in Serbia so far. To date, there are only small areas under northern red oak in Serbia, but there are significant stands of this species in the vicinity of Belgrade. In this paper, the basic physical and mechanical wood properties of northern red oak in Serbia were tested. The examined 57 years old tree was located in the forest of Lipovica, near Belgrade. The tree was cut down and two small logs were taken to the laboratory for analysis. The results show that the properties of wood of northern red oak do not differ significantly from the properties of native oak species in Serbia - sessile and pedunculate oak. In addition, the values of basic mechanical properties of wood of northern red oak in Serbia were similar to the relevant values obtained by other researchers in Europe and the USA. Thus, the utilization of wood of northern red oak in the local wood processing industry should be considered.

Soil quality assessment of an agroforestry system following long‐term management in the Ozark Highlands

AbstractThe Soil Management Assessment Framework (SMAF) is a quantitative soil quality (SQ) evaluation tool that is widely applied to assess soil response to specific agricultural management practices over time. Considering the reported SQ benefits of agroforestry (AF) systems and the potential usefulness of SMAF, the objective of this study was to evaluate the effects of tree species (pecan [Carya illinoinensis (Wangenh.) K. Koch] and northern red oak [Quercus rubra L.]), soil fertility source (poultry litter [PL] and inorganic N fertilizer [control]), and soil depth (0–15 and 15–30 cm) on SMAF‐derived SQ indices after 17 yr of management at an AF site in northwest Arkansas. Averaged across soil depth, soil organic C scores under red oak with PL application had a lower score (0.48) than red oak fertilized with inorganic N (0.60) and pecan receiving long‐term PL applications (0.60), which did not differ from pecan with inorganic N fertilizer application (0.51). Averaged across soil depth, the soil quality index (SQI) for pecan receiving PL applications was 1.1 times greater than that under red oak receiving PL and soils under pecan receiving inorganic N fertilizer. Soil quality assessments use in AF are novel, as SMAF has not been used to identify soil health in these systems, although specific tree crop codes need to be developed in SMAF. Results of this study demonstrate that soils planted under various tree species respond dissimilarly to fertilizer sources and that management may improve overall SQ.

ADDITIONS TO THE VASCULAR PLANT FLORA OF THE REPUBLIC OF MORDOVIA (RUSSIA): CONTRIBUTION OF THE iNATURALIST PLATFORM

"The (re)check of the iNaturalist data related to the Republic of Mordovia (European Russia) allowed us to find 16 vascular plant species, considered to be new taxa for the vascular plant flora of this region, in comparison to Silaeva et al. (2010). These species are Nonea rossica, Erigeron strigosus, Medicago × varia, Dianthus chinensis, Symphytum × uplandicum, Lamprocapnos spectabilis, Petunia × atkinsiana, Oenothera villosa, Parthenocissus inserta, Reynoutria × bohemica, Eschscholzia californica, Quercus rubra, Digitaria sanguinalis, Lysimachia punctata, Acer ginnala and Stachys byzantina. In addition, we present new data about the distribution of the five species (Silene wolgensis, Amaranthus cruentus, Cruciata laevipes, Euphorbia cyparissias and Achillea leptophylla) found in the Republic of Mordovia since publication of Silaeva et al. (2010). A majority of the species under discussion are alien plants arrived in Mordovia accidentally or considered as cultivated plants escaping in the wild. Taking into account the newly revealed species, the vascular plant flora of the Republic of Mordovia currently includes 1464 species. In this study, we highlight again the relevance and feasibility of the use of the iNaturalist platform, as an effective tool for the study and monitoring of regional and national biodiversity."

Properties of the northern red oak (Quercus rubra L.) wood determined by fractometric measurements - preliminary results

This study presents preliminary results of the basic properties of the northern red oak wood as well as the relationship between the properties of the core samples obtained on the live tree and the tested properties. The core samples 5 mm in diameter were extracted from the tree and used for determining the fractometer properties: compressive strength parallel to grain, radial bending strength and braking angle. Using descriptive statistics and multiple regression, the relationship between fractometric parameters and basic physical and mechanical properties of wood determined by destructive methods (wood density, compressive strength in parallel with fibers and bending properties (bending strength and modulus of elasticity). The obtained values of the examined properties of northern red oak are within the limits of the literature data. Statistical analysis has shown that radial bending strength cannot be used as a reliable fractometric parameter in assessing wood quality. On the other hand, the obtained results suggest that the relationship between the other two parameters (compressive strength parallel to grain and fracture angle) and the properties of the northern red oak wood can be successfully described using the multiple regression models (coefficient of determination ranged from 0.945 to 0.990).