Pine Oak Research Articles

Use of Sodium Hydroxide DNA Extraction Methods for Nested PCR Detection of Bretziella fagacearum in the Sapwood of Oak Species in Minnesota

Oak wilt caused by Bretziella fagacearum is an important disease of Quercus spp.; however, its diagnosis may be confused with damage resulting from other diseases, insects, or abiotic factors. Laboratory diagnosis is important in such situations and when disease control action is desired. PCR tests can provide accurate lab diagnosis within 2 days. Two variations of a simple DNA extraction protocol using sodium hydroxide (NaOH) were compared with that of the proprietary protocol of a commercially available kit (CK) for nested PCR to detect the pathogen in oak sapwood. High frequencies of pathogen detection (98 to 100% of 48 branch segments assayed) were found for northern pin oak using the two NaOH-based and the CK methods. Detection rates were similar but lower for bur oak (ranged from 58 to 79%) and white oak (ranged from 54 to 71%) regardless of DNA extraction method. Using our alternative DNA extraction protocols may reduce total time and cost of B. fagacearum detection in PCR-based diagnosis and other downstream applications.

Rapid Ecological Integrity Assessment Metrics to Restore Wildlife Habitat and Biodiversity for Shortleaf Pine–Oak Ecosystems

Open woodlands dominated by shortleaf pine (Pinus echinata Mill.) and oak are historically an important component of the landscape across the southeastern United States. These ecosystems support numerous wildlife species, many of which have declined in recent years as the amount and condition of their habitat have declined. Land managers and private landowners need guidance on how to efficiently and accurately quantify the condition and wildlife habitat value of the pine stands that they manage. Here we provide a set of rapid assessment metrics, based on NatureServe’s ecological integrity assessment (EIA) method, to (a) identify exemplary tracts that provide the best habitat for key wildlife species, and (b) monitor restoration efforts to assess progress toward the improved quality of existing tracts. To ensure an ecologically appropriate scaling of metrics, we distinguished six types of shortleaf pine–oak woodland: A.—Interior Highlands shortleaf pine–oak (including A.1—shortleaf pine–oak forest and woodlands; A.2—shortleaf pine–bluestem woodlands); B—montane longleaf pine–shortleaf pine woodlands; C—southern Appalachian pine–oak woodlands; D—West Gulf coastal plain shortleaf pine–oak woodlands; and E—southeast coastal plain and Piedmont shortleaf pine–oak woodlands. We relied on a narrative conceptual model and peer review-based indicator selection to identify a core set of 15 stand-level metrics (two were optional). Individual assessment points (thresholds) and ratings (Excellent, Good, Fair, and Poor) were developed that were sensitive to the distinct attributes of each of the five shortleaf pine–oak and Appalachian pine–oak types. Values for the metrics can all be collected using rapid field methods, such as using basal area prisms and ocular (visual) estimates of cover. Protocols for the consistent application of these EIA methods are provided. A case study is presented from the Cherokee National Forest in Tennessee. These methods provide improved and rapid EIA metrics for all shortleaf pine–oak ecosystems in the southeastern US to help guide conservation-minded landowners in assessing the biodiversity and priority wildlife values of shortleaf pine–oak and southern Appalachian pine–oak ecosystems.

Great Tits’, Parus major (Passeriformes, Turdidae), Diet in Transformed Forest Ecosystems of Northeastern Ukraine

Abstract The diet spectrum of the great tit (Parus major L., 1758) was studied in transformed forests of northeastern Ukraine. Four forest ecosystems were surveyed: four model sites in oak woodlands and in a pine–oak forest with different stages of recreational digression. Forty-seven taxa of invertebrates (n = 325) were detected in the ration of great tit chicks. Insecta (72.4%): Lepidoptera (seven families, 35.9%), Hymenoptera (two families, 21.0%), Diptera (seven families, 2.7%) and Coleoptera (four families, 1.8%) were among them. In terms of the qualitative composition of invertebrates (20 species, 42.6%) and the proportion of seized food objects (159 objects), phytophages prevailed. The food composition of great tit chicks was the most similar in territories MS1 and MS4. It contained six common taxa for these territories (Stugren–Radulescu Index = 0.7, Jaccard = 0.2, Sorensen = 0.3).

Morphological and phylogenetic analyses reveal a new genus and two new species of Tubakiaceae from China.

Species of Tubakiaceae have often been reported as plant pathogens or endophytes, commonly isolated from a wide range of plant hosts. The isolated fungi were studied through a complete examination, based on multilocus phylogenies from combined datasets of ITS/LSU/rpb2 and ITS/tef1/tub2, in conjunction with morphological characteristics. Five strains isolated from Lithocarpusfohaiensis and Quercuspalustris in China represented a new genus of Tubakiaceae, Obovoideisporodochium and three species, viz. Obovoideisporodochiumlithocarpi sp. nov., Tubakialushanensis sp. nov. and T.dryinoides.

Seasonal dynamics of Diptera in individual biotopes in the center of the European part of Russia

In a changing climate, phenological observations are gaining new importance. They can tell what changes are taking place in certain environmental conditions. The studies were conducted in 2019 within the territory of the Republic of Mordovia (the center of the European part of Russia). Beer traps (beer as a bait) were used to collect Diptera. The material was collected in the period from April to October in different forest biotopes (pine forest, lime forest, aspen forest, birch forest and oak forest) and the air temperature was recorded at the same time. In total, more than 14.000 specimens of Diptera were recorded. Overall, 29 families were recorded. The largest number of families was observed for birch (23 families) and pine (24 families) forests, the smallest number – in aspen forest (16 families). The families Muscidae, Drosophilidae, Calliphoridae had the largest number of captured individuals (44.5%, 35.2%, 7.6% of the total number of individuals respectively). The highest number of individuals was captured in oak forest. The dynamics of abundance in all biotopes were similar and were characterized by the same number of declines and rises. The first small significant peak in the number of Diptera occurred in the first half of summer. A slight increase in the number of specimenі occurred in mid-June. In the second half of September, there was a gradual increase in the number and the maximum peak was recorded in mid-October, then there was a decline. The autumn increase in the number of Diptera in all five biotopes exceeded the summer peak by several times. This dynamic was typical for most families. However, species from the family Lonchaeidae had the peak in July. For our better understanding of the changes in the seasonal dynamics of the number of Diptera, long-term observations in different climatic zones are needed.

Polycyclic aromatic hydrocarbon (PAH) accumulation in Quercus palustris and Pinus nigra in the urban landscape of Gothenburg, Sweden

Trees have the potential to improve urban air quality as leaves and needles capture air pollutants from the air, but further empirical data has been requested to quantify these effects. We measured the concentration of 32 polycyclic aromatic hydrocarbons (PAHs) in leaves of pin oak (Quercus palustris) and needles of black pine (Pinus nigra) in the City of Gothenburg, Sweden, during the summer of 2018. Oak leaves were collected twice (June, September), while one-year-old (C + 1) and three-year-old (C + 3) pine needles were sampled in June to study the temporal development of leaf/needle PAH concentrations. Specific leaf area (SLA) was estimated, which permitted calculation of leaf/needle area-based PAH content that were compared with the mass-based concentration. In addition, the air concentration of PAHs and NO2 was measured using passive samplers. There was a strong correlation between air concentrations of PAH and NO2, indicating that the pollutants to a large degree originate from the same sources. In the oak leaves there was a significant decrease in low molecular mass PAHs (L-PAH, mainly gaseous) between June and September, but a significant increase in high molecular mass PAHs (H-PAH, mainly particle-bound). There was a strong correlation between L-PAH concentration in leaves and in air indicating an influence of equilibrium processes between ambient air and leaf. In the pine needles, there was a significant increase of both L-PAH and H-PAH in three-year-old needles compared to one-year-old needles. Pine was superior to oak in accumulating PAHs from the air, especially for L-PAHs when comparing area-based content. However, H-PAH concentrations were higher in oak leaves compared to pine needles on a leaf mass basis, emphasizing the importance of how concentrations are expressed. The results from this study can contribute to the development of urban planning strategies regarding the effect of vegetation on air quality.

Modeling the forest dynamics of the Sierra Nevada under climate change using SORTIE-ND

Key messageModel simulation results suggest that forests in the Sierra Nevada mountains of California will tend to increase in density and basal area in the absence of fire over the next century, and that climate change will favor increases in drought-tolerant species.ContextClimate change is projected to intensify the natural summer drought period for Mediterranean-climate forests. Such changes may increase tree mortality, change species interactions and composition, and impact ecosystem services.AimsTo parameterize SORTIE-ND, an individual-based, spatially explicit forest model, for forests in the Sierra Nevada, and to model forest responses to climate change.MethodsWe use 3 downscaled GCM projections (RCP 8.5) to project forest dynamics for 7 sites at different elevations.ResultsBasal area and stem density tended to increase in the absence of fire. Climate change effects differed by species, with more drought-tolerant species such as Jeffrey pine (Pinus jeffreyi A.Murray bis) and black oak (Quercus kelloggii Newb.) exhibiting increases in basal area and/or density.ConclusionIncreasing forest density may favor carbon sequestration but could increase the risk of high-severity fires. Future analyses should include improved parameterization of reproduction and interactions of disturbance with climate effects.

Influence of avocado orchard landscapes on amphibians and reptiles in the trans‐Mexican volcanic belt

AbstractCommercial fruit orchards are embedded in a landscape of native forest and diverse kinds of agroecosystems. The landscape structure of these systems is a major driver of biodiversity response. Generally, it is assumed that high levels of biodiversity occur in perennial systems largely due to their high structural complexity. However, little is known about the influence of other landscape attributes on these levels of biodiversity. Avocado (Persea americana) constitutes about 25 percent of the global fresh fruit trade. In Mexico, avocado trees flourish about the same altitude as pine–oak forests (POFs). We studied the response of the local herpetofauna to conversion of POF to avocado orchards (AOs). We also explored the effects of forest cover on species that differ in their levels of habitat specialization. In the avocado belt in Michoacan, we sampled 12 sites representing a gradient of AO embedded in native POF to evaluate the variation in structure of local assemblages of amphibians and reptiles. Reduction of POF cover negatively affected specialist frog and snake species, but this relationship varied among buffers around sampling sites. Generalist species of amphibians and lizards showed increased abundances and richness in sites with low POF cover, whereas snake richness and abundance were higher in sites with high POF cover. Our study suggests that POF conversion to AO is a driver favoring the persistence and success of generalist but not specialist herpetofauna species. Therefore, to conserve the diversity of amphibians and reptiles in these agroecosystems, it is important to ensure high proportion of POF patches.Abstract in Spanish is available with online material.

Oak Competition Dominates Interspecific Interactions in Growth and Water-Use Efficiency in a Mixed Pine–Oak Mediterranean Forest

In the Mediterranean, mixed forests of Aleppo pine and holm oak are widespread. Generally considered a transition stage in the succession towards climax oak communities, niche segregation may also contribute to the prevalence of these communities. So far, there is increasing evidence of hydrological niche segregation, with the two species showing complementary water use and seasonal growth patterns. However, it remains unknown whether interspecific interactions affect the response to climate and the mid-term (decadal) growth and water-use efficiency of pines and oaks in mixed stands. Here, we combined tree-ring chronologies, built on different competition classes within a mixed stand, with a spatially explicit assessment of individual growth and wood carbon isotope discrimination (∆13C), as a proxy of intrinsic water-use efficiency, and compared these results with previously reported water uptake patterns. We found that competition with pines modulated the climate response of oaks, whereas pine climate response was insensitive to competition. On the other hand, pine density affected only pine growth, whereas oak competition affected both species. We conclude that the presence of pines had negligible or even positive effects on the oaks, but competition with neighbor oaks limited their ability to recover after drought. Conversely, pines experienced greater drought stress under competition, with both oaks and pines.

Legacy effects of seed dispersal mechanisms shape the spatial interaction network of plant species in Mediterranean forests

Abstract Seed dispersal by frugivores plays a key role in structuring and maintaining tree diversity in forests. However, little is known about how the spatial legacy of seed dispersal and early recruitment shapes spatial patterns and the spatial interaction network of plant species in mature forest communities. We analysed two fully mapped mixed Pine–Oak forest communities using spatial point pattern analysis to determine (a) the detailed structure of the intraspecific spatial patterns of saplings and adults, (b) the intra‐ and interspecific spatial interaction of saplings, adults and saplings relative to adults, (c) the spatial patterns of species richness at the community level and (d) whether seed dispersal mechanisms affect the plant–plant interaction networks and the ratio of adult to sapling neighbourhood densities used as surrogate for spatial self‐thinning. The intraspecific spatial patterns of saplings and adults showed in general complex nested cluster structures that were similar for sapling and adult stages, despite substantial self‐thinning in some dry‐fruited species. The spatial network of saplings was characterized by positive spatial interactions. Adults of several tree species facilitated saplings in their proximity; however, adults of dry‐fruited species, but not those of fleshy‐fruited ones, lost almost all positive interactions that occurred at the sapling stage. Besides, interaction strength between adults was positive and often significantly stronger if both species were fleshy‐fruited. At the community level, the forests were structured into multispecies clumps across all life stages. Synthesis. Our analyses highlight the importance of the spatial legacy of seed dispersal and early recruitment in the assembly of plant communities. Particularly, animal seed dispersal can lead to multispecies clusters and positive spatial associations across life stages in Mediterranean forests, with surprisingly little signatures of negative interactions. Our analysis suggests that changes of the spatial structure across plant life stages are driven by seed dispersal mechanisms and subsequent spatial self‐thinning, generating a spatial footprint at the sapling stage that conditions the long‐term interactions between adult plants. Combining spatial point pattern analysis with network analysis and species traits is a promising way to disentangle the processes underlying observed patterns of local diversity.

Features of coarse woody debris volume formation in fresh sudibrova conditions in Zmiini islands tract of Kaniv Nature Reserve

Dead wood (woody debris) is an important component of forest ecosystems. It performs a number of ecological and environmental functions. The article studies the peculiarities of the formation of coarse wood detritus volume and its qualitative structure in forests in the conditions of fresh sudibrova of the Zmiiini Islands tract of Kaniv Nature Reserve. The study of dead wood was carried out in 140-year-old pine-oak forests of natural origin on a permanent sample plot (0.24 ha) by identifying and measuring of standing and lying deadwood components. It was found that dead wood in the forest ecosystem was formed due to the dying of trees of five species: common oak (Quercus robur L.), Scots pine (Pinus sylvestris L.), Norway maple (Acer platanoides L.), small-leaved lime (Tilia cordata Mill.) and common hornbeam (Carpinus betulus L.), and has a volume 56.3 m3·ha–1. Dead wood volume is dominated by standing dead trees — 82.1%, and the share of lying dead wood, respectively, is 17.9%. The main part of dead wood volume is formed by two tree species — common oak and Scots pine, the share of which together is 94.3%. Common oak and Scots pine is characterized by a predominance of standing dead wood, while for other tree species — lying dead wood. In general, dead wood is formed by detritus of I–IV classes of destruction, at the same time detritus of class II decomposition has a significant advantage (70.5%), recently dead wood has a much smaller share (I class, 24.8%), and other classes of destruction have insignificant shares, which together do not exceed 5.0%. No woody detritus of the last (V) class of destruction was detected. Volume of standing dead wood is 46.2 m3·ha–1, and is formed by whole and broken dead trees. In terms of species composition, common oak has a significant advantage (74.5%), Scots pine has a much smaller share (25.1%), and the share of Norway maple is insignificant (0.4%). The total standing dead wood volume is dominated by wood of class II destruction (33.0 m3·ha–1, 71.4%) compared with class I (13.2 m3·ha–1, 28.6%). Lying dead wood is represented by four classes of destruction (I–IV), however, no woody debris was found at the late (last) stage of decomposition (class V). In terms of volume, the second class of destruction has an absolute advantage (6.7 m3·ha–1, 66.3%), much less class III detritus (2.3 m3·ha–1, 22.8%). Lying dead wood of common oak is represented by all four classes of destruction, among which III (40.5%) and I (33.3%) classes predominate. Lying dead wood of other tree species is characterized by the predominance of II or III classes of destruction. The main factors in the formation of woody detritus in the pine-oak forest in the Zmiiini Islands tract could be the impact of adverse climatic conditions (long periods without precipitation in summer), which led to the weakening of individual trees and their death, gusts of wind that broke individual tree trunks, low-intensity snow breaks, and the influence of biotic factors (insects, pathogens).

Ecology typological assessment of forest vegetation of the North-Eastern Forest-Steppe of Ukraine

Recently, significantly increases the need for a detailed study of various aspects of the modern natural, spontaneous and artificially generated phytodiversity as the main element of the formation and regeneration of natural ecotypes structural elements for building national ecological network. It is necessary to examine various aspects of the natural and spontaneous vegetation formed. Based on the ecological specifics of the North-Eastern Forest-Steppe of Ukraine, a detailed analysis of natural and artificially formed forests on the floodplain, pine terrace and plateau of the rivers of the Dnieper and Seversky Donets basins, as well as in ravine-beam systems is required. Peculiarities of forest vegetation conditions, distribution of tree species and ecological conditions of their growth are given. According to forest management data, the area of the North-Eastern Forest-Steppe covered with forest vegetation is 336110.3 ha. The distribution of forest areas by edatopes is as follows: trophotopes — oak wood (220640.2 ha, 65.64%), sugruds (54739.2 ha, 16.29%), subors (52174.5 ha, 15.52%) and pine forests (8556.4 ha, 2.55%); hygrotopes — fresh conditions (282960.3 ha, 84.19%), dry (35576.7 ha, 10.59%), damp (12179.5 ha, 3.62%), moist (4634.3 ha, 1.38%), wet (749.0 ha, 0.22%) and very dry conditions (10.5 ha, 0.003%). There are 38 types of forests areas covered with forest vegetation, which are dominated by fresh maple-linden forest (183442.0 ha, 54.58%), a slightly smaller area occupied by fresh oak-pine forest (47040.9 ha, 14.00%) and linden-oak-pine sugrud (33999.3 ha, 10.12%), as well as dry maple-linden forest (28697.7 ha, 8.54%). The composition of forest-forming species is quite diverse and is represented by 60 species of woody and shrubby plants. The main forest-forming species is Quercus robur (190153.9 ha, 56.58%). Pinus sylvestris (86212.1 ha, 25.65%) and Fraxinus excelsior (20318.5 ha, 6.05%) have slightly smaller areas, all other species occupy small areas. Research a variety of forest habitats will provide an opportunity to plan the conservation, reproduction and protection of phytodiversity, including species of sozophytes from different conservation lists, as well as to balance the provision of ecosystem services by tree and shrub plantations of the North-Eastern Forest-Steppe of Ukraine.

Migratory Seasonality and Phenology by Birds in a Temperate Forest with Two Disturbance Conditions

Objective: The objective was to infer the effect of the variables phenology (migration-non-migration), seasonal (rainfall-dry season), sex and forest condition on the abundances of birds (resident-migratory) in a semi-preserved and disturbed oak pine forest.
 Design/methodology/approach: It was carried out in Monte Tlaloc, State of Mexico, under two conditions of apparent disturbance, semi-preserved oak pine forest and disturbed oak pine forest. Ten bird samplings were carried out with "count on point" with a fixed radius of 25 m, covering the 4 seasons of the year and migratory periods. With the previous data, the Relative Abundance Index (RAI) was estimated. To infer the effect of the variables phenology, seasonality, sex and forest condition on the abundances of birds, generalized linear models were elaborated.
 Results: The IAR of the birds registered in the semi-considered pine forest indicates that the species with the lowest presence was Aphelocoma ultramarina (0.002) and with the highest frequency Empidonax sp. (0.13), unlike to that found in the disturbed pine forest where the lowest IAR corresponded to Colaptes auratus (0.003) and with the highest appearance was Ptiliogonys cinereus (0.23). The Generalized Linear Model suggested that forest condition and phenology are significantly related to the frequency of species.
 Limitations on study/implications: In this study it was found that the abundance of birds was affected by the condition of the forest and that the phenology (migration-non-migration), seasonal (rain-dry season), sex and condition of the forest were related to the abundance of birds. Four species classified as under Special Protection and two Threatened according to NOM-059 were registered as well as the presence of four endemic species which highlights the importance of conserving these ecosystems.
 Findings/conclusions: The fauna communities present in Monte Tláloc highlight the importance of conserving the pine-oak forests since this site is part of the Eje Neovolcanico Transversal.

The initial effects of microclimate and invertebrate exclusion on multi-site variation in the mass loss of temperate pine and oak deadwoods

Quantifying deadwood decomposition is prioritized by forest ecologists; nonetheless, uncertainties remain for its regional variation. This study tracked variations in deadwood decomposition of Korean red pine and sawtooth oak in three environmentally different regions of the Republic of Korea, namely western, eastern, and southern regions. After 24 months, dead pine and oak woods lost 47.3 ± 2.8% and 23.5 ± 1.6% in the southern region, 13.3 ± 2.6% and 20.2 ± 2.8% in the western region, and 11.9 ± 7.9% and 13.9 ± 2.3% in the eastern region, respectively. The regional variation in the decomposition rate was significant only for dead pine woods (P < 0.05). Invertebrate exclusion treatment reduced the decomposition rate in all region, and had the greatest effect in the southern region where warmer climate and concentrated termite colonization occurred. The strongest influential factor for the decomposition of dead pine woods was invertebrate exclusion (path coefficient: 0.63). Contrastingly, the decomposition of dead oak woods was highly controlled by air temperature (path coefficient: 0.88), without significant effect of invertebrate exclusion. These findings reflect the divergence in regional variation of deadwood decomposition between pine and oak, which might result from the different sensitivity to microclimate and decomposer invertebrates.

Effects of fire seasonality and intensity on resprouting woody plants in prairie‐forest communities

Woody plant expansion is one of the greatest contemporary threats to fire‐dependent ecosystems. Reducing woody plant prevalence is often a primary objective of prescribed burns, yet little attention has been given to understanding the efficacy of burning to reduce their abundance. Fire intensity characteristics and plant phenology/physiology, which are sometimes presented as competing hypotheses, influence how woody plants respond to a fire event. Little work has been done in the prairie‐forest region of the upper Midwest to understand how fire characteristics interact with woody species phenology and/or physiology. Using a controlled field experiment, we examined effects of timing (seasonality) and intensity (temperature and duration) of fires on top‐kill and resprouting of three invasive woody plants in this region (common buckthorn,Rhamnus cathartica; bush honeysuckles,Loniceraspp.; and a native species, northern pin oakQuercus ellipsoidalis). Honeysuckles and pin oak burned in the spring dormant period, a common practice in the region, resulted in low levels of top‐kill and high levels of resprouting. Burning during the late growing season yielded highest levels of top‐kill and lowest levels of resprouting for honeysuckles and pin oaks. However, there was no apparent effect of season or fire intensity treatment for buckthorn stems. Under all treatment combinations, buckthorn was easily top‐killed but resprouted prolifically. Collectively, most prescribed burning in the Midwest appears to be conducted during the least effective season (early growing season), when top‐kill is reduced and/or resprouting most pronounced. Our results indicate that fire use could be better prescribed in this region for controlling woody plants.

How Timber Harvest Affects the Structure and Diversity of a Montane Forest in Southern Mexico

Timber extraction directly affects forest structure by opening the canopy, reducing the density and volume of dominant species, and transforming the composition, diversity, and functioning of the forest. We analyze the richness, diversity, and basal area of tree species in a pine–oak montane forest under two stages of the Silvicultural Development Method (thinning and liberation cut treatments) in comparison with remnants of forest considered to be control treatment in the Ocotones forest. Timber extraction began 14 years previously but its effect on the tree structure has not been studied to date in this area. We quantified and measured all the trees with a diameter at breast height &gt;5 cm in 12 0.1 ha circular plots in each treatment. Diversity (Hill numbers) and the importance value index were calculated in each treatment. Observed species richness did not differ between treatments; Pinus oocarpa Schiede ex Schltdl. and Quercus sapotifolia Liebm. were the dominant species regardless of treatment. The principal differences in density and basal area among the treatments were found between the small oaks and small pines. In general, tree density recovered in managed areas because of newly recruited pines and re-sprouting oaks. Although no significant reduction in species richness was detected between treatments, species composition and vegetation structure were modified by the extraction of pine timber and the permanence of many large oaks. Silvicultural treatments appear to create conditions favorable to the maintenance of species richness. The silvicultural interventions in the site meet the objectives of timber production, regeneration, and biodiversity conservation; however, the question of how long the forest can maintain its species diversity and structure after timber extraction remains to be addressed.

Historical Fire Regimes and Stand Dynamics of Xerophytic Pine–Oak Stands in the Southern Appalachian Mountains, Virginia, USA

Fire-dependent yellow pine (Pinus) forests are included within the temperate deciduous forest of eastern North America. These forests, which occupy dry slopes and typically contain xerophytic oaks (Quercus), have receded under fire suppression. Understanding historical fire regimes is essential for interpreting and managing these stands. To characterize fire history and vegetation dynamics, we conducted a dendroecological study of fire-scarred trees and age structure in pine stands at four sites in the Appalachian Mountains. Fire interval estimates suggest that before fire suppression began in the early to middle 1900s, fires occurred at approximately three- to eleven-year intervals. Short intervals were probably maintained in part by large-extent fires that spread from sparse ignition points. Fire frequency showed no long-term temporal trend (e.g., no wave of fire) from the middle 1700s through early 1900s despite land–use intensification, including industrial logging and associated wildfires during the late nineteenth and early twentieth centuries. Fire occurrence was associated with drought at two sites. Age–structure analyses evoke pyrogenic pine–oak communities that predated industrial disturbances and persisted under a regime of frequent, mixed-severity fires that was likely maintained through a positive feedback with the flammable vegetation. Competing species were established under more recent fire suppression, however, and are poised to replace the pines.

Influence of Soil Saturation on Survival and Growth of Bottomland Oaks Six and Fourteen Years after Planting

Bottomland oak restoration projects have been marginally successful because professionals often recommend conventional tree-planting procedures that prove problematic in hydric soils. A reliable method of matching oak species to bottomland sites is needed prior to planting. To address the issue, we planted 8 different species of oak seedlings into previously farmed hydric soil in West Tennessee in 2004. We took measurements after 6 and 14 growing seasons to ascertain survival and growth trends based on soil mottling and the depth to gleyed matrix. The later measurements mostly supported early findings that Quercus lyrata (Overcup Oak), Q. texana (Nuttall Oak), Q. palustris (Pin Oak), and Q. phellos (Willow Oak) are most tolerant of poorly drained soil and that as soil drainage improves, species diversity may expand.

Mixedwood management positively affects forest health during insect infestations in eastern North America1

Mixedwood stands are composed of hardwoods and softwoods, with neither comprising greater than 75%–80% of basal area or aboveground biomass. By conferring associational resistance and greater resilience to forests when stressed or disturbed, the more diverse composition of mixedwood stands contributes to forest health. We analyzed three examples where mixedwood stands are more resistant to insect infestations in eastern North America. In balsam fir (Abies balsamea L. Mill.) and spruce (Picea spp.) forests, susceptibility and vulnerability to spruce budworm infestations is reduced with increasing hardwood density. In mid-Atlantic oak-dominated forests, oak mortality following gypsy moth infestations was much greater in oak-dominated forests than in oak–pine mixedwoods, while pine mortality during southern pine beetle infestations was greater in pine-dominated forests than in oak–pine mixedwoods. Overall, mixedwood stands have greater resistance to infestations of defoliators and bark beetles and recover more rapidly from disturbances, reducing economic losses associated with tree mortality and mitigating short-term impacts to ecosystem functioning resulting from insect damage, especially carbon sequestration. Finally, we discuss challenges and opportunities for mixedwood management to minimize insect damage. Management strategies that incorporate mixedwood stands may provide better continuity in supply of forest products and ecosystem services in the face of projected increases in insect infestations associated with changing climate.

Analysis of species diversity of forests on the territory of Kharkivska Oblast

The paper presents the findings of a study of species diversity of forests in the Kharkivska Oblast. The study was conducted on the territory of ten forestry enterprises and the State Enterprise Kharkiv Forest Research Station and the Homilsha Woods National Nature Park on an area of 282.3 thousand ha (area is subordinated to the State Forest Resources Agency of Ukraine). The purpose of the study was to analyse the species diversity and typological structure of forests in the Kharkivska Oblast. The study of species diversity was carried out based on analysis of the subcompartment database of the VO Ukrderzhlisproekt. The plantations were classified by the trophotope on the territory of the research facility in accordance with the main methodological provisions of the Ukrainian forestry and forest typology. A diagrammatic map of forests and dominant species (common oak and Scots pine) was compiled using the MapInfo Professional 12.5 software package and a vector map of 12 forestries in the Kharkivska Oblast. It has been established that 56 species of trees grow in the Kharkivska Oblast. Among these tree species, the predominant ones are common oak (53.4%) and Scots pine (32.7%). The distribution of plantations by trophotope is characterised by certain features. For example, dubrava conditions prevail in the stands (65.6% of the total area covered by forest vegetation), subor forests are 3.5 times less represented, and sudubravas and pine forests are the least common. Among the forest types, the most common are fresh maple-linden dubravas (43.7%) and fresh oak-pine subors (18.9%). The practical significance of the study is that the analysis of species diversity and typological structure of forests must be taken into account during the planning, organisation, and conduct of forestry activities in the Kharkivska Oblast