Oak Quercus Research Articles

Do benefits of seed dispersal and caching by scatterhoarders outweigh the costs of predation? An example with oaks and yellow‐necked mice

Abstract Numerous interactions between plants and animals vary in their outcome between antagonism and mutualism. Interactions between plants and scatter‐hoarding animals provide a prime example of this phenomenon. Scatterhoarders consume large quantities of seeds (potentially reducing plant establishment), yet also disperse seeds and bury them in shallow caches (potentially improving recruitment). Despite intense work on mechanisms that cause these interactions to shift along an antagonism–mutualism continuum, it remains difficult to quantify their final outcomes. We demonstrate how readily available field data can be used to reach this goal, with interactions between rodents and two oaks species (sessile oak Quercus petraea, and red oak Q. rubra) as an empirical example. Our approach consists of quantifying the net outcome of the interaction through collecting data on different vital rates (e.g. probability that cached seeds survive to germination, probability of seedling recruitment with and without rodents; near and far from conspecific trees; with and without seed pilferage) and assembling them in a simple mathematical model. We found that during the period of the study, interactions between scatter‐hoarding rodents and both focal oaks were antagonistic. Even though caching increased the likelihood of seedling establishment, this effect was not strong enough to compensate for the costs of seed predation. Furthermore, there was no evidence that the short‐distance transportation that is usually provided by small mammals benefited early oak recruitment. Synthesis. Our empirical results demonstrated that certain common assumptions – that caching by rodents invariably benefits plant recruitment; that improved seedling establishment after seed burial is sufficient to make plant–scatterhoarder interactions mutualistic; that transportation away from maternal plants is highly beneficial—do not always hold and should be tested rather than taken for granted.

Genomic dissection of an extended phenotype: Oak galling by a cynipid gall wasp.

Galls are plant tissues whose development is induced by another organism for the inducer's benefit. 30,000 arthropod species induce galls, and in most cases the inducing effectors and target plant systems are unknown. Cynipid gall wasps are a speciose monophyletic radiation that induce structurally complex galls on oaks and other plants. We used a model system comprising the gall wasp Biorhiza pallida and the oak Quercus robur to characterise inducer and host plant gene expression at defined stages through the development of galled and ungalled plant tissues, and tested alternative hypotheses for the origin and type of galling effectors and plant metabolic pathways involved. Oak gene expression patterns diverged markedly during development of galled and normal buds. Young galls showed elevated expression of oak genes similar to legume root nodule Nod factor-induced early nodulin (ENOD) genes and developmental parallels with oak buds. In contrast, mature galls showed substantially different patterns of gene expression to mature leaves. While most oak transcripts could be functionally annotated, many gall wasp transcripts of interest were novel. We found no evidence in the gall wasp for involvement of third-party symbionts in gall induction, for effector delivery using virus-like-particles, or for gallwasp expression of genes coding for plant hormones. Many differentially and highly expressed genes in young larvae encoded secretory peptides, which we hypothesise are effector proteins exported to plant tissues. Specifically, we propose that host arabinogalactan proteins and gall wasp chitinases interact in young galls to generate a somatic embryogenesis-like process in oak tissues surrounding the gall wasp larvae. Gall wasp larvae also expressed genes encoding multiple plant cell wall degrading enzymes (PCWDEs). These have functional orthologues in other gall inducing cynipids but not in figitid parasitoid sister groups, suggesting that they may be evolutionary innovations associated with cynipid gall induction.

Дослідження впливу фосфітів як стимуляторів відпірності дерев дуба звичайного (Quercus robur L.) до збудників з роду Phytophthora на території Кротошинське плато (Польща)

Досліджено перспективи використання фосфітів як стимуляторів відпірності дерев дуба звичайного до патогенів з роду Phytophthora. Для цього на території надлісництва "Кротошин" Регіональної дирекції державних лісів у Познані (Польща) закладено пробні площі, на яких з літака оброблено дубові деревостани препаратами Kalex та Actifos. Для порівняльного аналізу вибрано 30 оброблених препаратами дерев та 30 контрольних. Усі вкриті лісом ділянки характеризуються типом лісорослинних умов свіжий сугруд (C2) та типом лісу – свіжа грабова судіброва. Встановлено статистично обґрунтовану відмінність у середніх значеннях досліджуваних ознак коріння для оброблених фосфітами та контрольних дерев. Встановлено, що сукупний вплив біотичних та абіотичних чинників на ріст дерев та формування їхніх кореневих систем у досліджуваних деревостанах є подібним. Зважаючи на наявність у ґрунті патогенів з роду Phytophthora, дерева, оброблені фосфітами, мають кращі значення стану крони, що було використано як індикатор загального санітарного стану досліджуваних дерев. Здійснений аналіз зміни середніх значень ознак коренів показав відмінність у формуванні власне цих ознак у здорових, пошкоджених та замираючих оброблених фосфітами та контрольних дерев. Зважаючи на певні особливості, формалізовано залежність ступеня дефоліації та синтетичного індексу Syn від відповідних морфолого-таксаційних ознак дерев та ознак коріння. Отримані регресійні рівняння дають змогу пояснити тенденції та здійснити наближений прогноз модельваних залежностей для оброблених фосфітами та контрольних дерев.

Pruning promotes the formation of an insufficient number of cavities for hollow-dependent birds in Iberian Holm-oak dehesas

Holm oak Quercus ilex dehesas cover large areas in the Mediterranean region, and constitute a paradigm of well preserved low-intensity agro-ecosystem supporting a high number of bird species. The canopy of holm oak trees is periodically pruned, but the role of pruning in the process of tree-hollow formation remains unstudied. Here I investigate the occurrence of tree-hollows in relation to tree characteristics (vitality, trunk diameter and fork height), infection by drilling Coleoptera and pruning intensity, and assess likely origin, use and suitability of hollows for non-excavator birds in dehesas of Spain. 26.3% of all sampled oaks had at least one hollow, and the number of pruning cuts predicted the occurrence of hollows. 97.0% of hollows were situated on pruning cuts suggesting that pruning may have favored decay cavity formation in Iberian dehesas. 43.6% of hollows were estimated suitable to hold the nest of a small-sized cavity-nesting bird, but only 11.9% might have potentially held the nest of a medium-sized cavity-nesting bird, rendering estimated 3.9 and 1.1 potential cavities/ha, respectively. The low densities of suitable hollows would point toward a lack of nest-sites which might limit cavity-nesting birds in holm oak dehesas. Future conservation actions targeting in protection of old and dead holm oak trees instead of selective removal, together with land-scale measurements of enhancement of riverine forests stands may enrich and ensure the persistence of cavity-using species in Iberian dehesas.

Antioxidative system response of pedunculate oak (Quercus robur L.) seedlings to Cd exposure

The use of pedunculate oak (Quercus robur L.), along with other tree species, for the afforestation of heavy metal contaminated lands is an attractive prospect. Little, however, is known of Q. robur tolerance and its antioxidative system response to heavy metal exposure. The main objective of the study was to determine the cadmium-induced changes in antioxidative system of pedunculate oak in an attempt to identify molecular mechanisms underlying Cd tolerance. This may be of great importance in respect of using Q. robur for phytoremediation purposes. As the response of the antioxidative system to heavy metal contamination can vary within species, the research was conducted on oak seedlings from two different regions of origin. Differences in antioxidative system response of seedlings derived from tested regions of origin were noticed both at the transcript and enzyme activity levels. The obtained results indicate that ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) play a first barrier role in oak seedlings response to the oxidative stress caused by Cd exposure. Catalase (CAT; EC 1.11.1.6) is involved in reducing the negative effects of prolonged Cd treatment.

Моделювання розмірно-якісної структури стовбурів дуба звичайного за європейськими стандартами

Розглянуто проблеми, які виникли внаслідок набуття чинності нових стандартів на продукцію лісозаготівель. Невідповідність нормативно-інформаційної бази для таксації лісосік новим вимогам призводить до значних недоліків у плануванні виробничої діяльності лісогосподарських підприємств. Дослідження виконано на підставі дослідного матеріалу, зібраного в дубових насадженнях Придніпровського Правобережного Лісостепу на тимчасових пробних площах. Проаналізовано розподіл об'єму ділових стовбурів дуба звичайного (Quercus robur L.) на якісні категорії деревини залежно від діаметра, висоти та об'єму. Найбільш тісну лінійну залежність виявлено для абсолютних значень якісних категорій деревини від об'єму стовбура в корі. Між іншими біометричними показниками стовбура лінійна залежність відсутня або менш значуща на 5 %-му рівні. Завдяки аналізу модельовано вихід якісних категорій деревини залежно від об'єму стовбура на підставі степеневого рівняння. Пошук параметрів рівнянь виконано у MS Excel. Систематична похибка математичних моделей виходу ділової деревини виявилася близькою до нуля (1,0 %), дров та відходів – у допустимих межах (5,1 та 8,0 %), що дало змогу прийняти їх для розробки відповідних таблиць. Опрацьовані таблиці дають змогу за новими стандартами прогнозувати розподіл об'єму ділових стовбурів дуба зі стандартною похибкою 0,063-0,118 м3. Для отримання даних розподілу об'єму ділової деревини за класами розмірів, передбачених ДСТУ 1315-1-2011, розроблено в системі R алгоритм умовного розкряжування модельних дерев. Він оснований на апроксимації твірної поверхні стовбура за допомогою математичної моделі твірної A. Kozak (1988). На підставі одержаного розподілу об'єму ділової деревини за класами діаметрів досліджено його залежність від біометричних показників стовбурів. Практично для всіх розмірних категорій деревини виявлено нелінійний зв'язок. Узагальнення розмірної структури ділової деревини проведено за методикою, яка базується на дослідженні закономірностей розподілу об'єму за класами розмірів у відносних величинах. Виявлено тісну залежність відносних величин розмірної структури від діаметра модельних дерев на висоті 1,3 м. Незначна систематична похибка отриманих математичних моделей розподілу ділової деревини (-1,1-0,9 %) дала змогу прийняти їх для складання об'ємних таблиць. Розроблені за новими стандартами таблиці забезпечують прогнозування розподілу об'єму ділової деревини ділових стовбурів дуба за класами розмірів залежно від серединного діаметра лісоматеріалів без кори.

The influence of management and environmental factors on insect attack on cork oak canopy

The decline of oak (Quercus spp.) forests is a current trend in Northern Hemisphere and is characterized by a loss in tree vigour and increased mortality. The canopy insects are suspected to have role in this decline, but there is poor knowledge about their incidence in evergreen-oak stands. The main aim of this study is to characterize the incidence of main insect groups affecting branches and leaves of an evergreen-oak species (the cork oak Quercus suber) and evaluate which management practices and environmental traits of agroforestry systems affect it. In the spring/summer of 2018, we measured the incidence of attacks on branches and leaves by gall-makers (Diptera, Cecidomyiidae), blade-miners (Lepidoptera and Coleoptera), midrib-miners (Lepidoptera, Heliozelidae), chewer caterpillars (Lepidoptera), chewer sawflies (Hymenoptera, Tenthredinidae), weevils (Coleoptera, Curculionidae) and branch-borers (Coleoptera, Buprestidae). We analysed the frequency of pest signs according to different indicators: management practices, tree maturity, forest diversity, forest fragmentation, and latitude and longitude. The most frequent signs of insect pests on tree leaves corresponded to blade-miners, midrib-miners, chewer caterpillars and chewer sawflies. With exception of midrib-miners and branch-borers, all insect pests were found on cork oak stands experiencing decline and benefited from management intensification. Our study suggests that a diverse-aged stand may reduce the frequency of midrib-miners and chewer caterpillars, as well the attack of branch-borers. Moreover, a high plant diversity in forests can contribute to reduce the impact of defoliators on cork oaks (e.g., chewer sawflies) and understory reduction decreased the exposure of trees to gall-makers. Moreover, we found that forest fragmentation may increase the frequency of blade-miners and chewer caterpillars. We conclude that insect pests have a high incidence in cork oak stands and thus, may have and important role in its decline. Considering that a high frequency of pests is often associated with increased management intensity, a change to a more sustainable use of these systems is urgently needed.

Bur oak (Quercus macrocarpa) biomass production on a former coal mine site: positive effects of coppicing on rapid recovery of growth and yield

Ten-year-old bur oak (Quercus macrocarpa Michx.) saplings established on the exposed, infertile, treeless barrens of a former coal mine site in New Brunswick, Canada, were harvested to assess the effects of subsequent coppicing on regrowth parameters and biomass production. Two years after harvesting, coppice height growth exceeded that of the original 10-year-old saplings by 20%. Mean stem numbers were 1.2 and 6.7 for 10-year-old and coppiced trees, respectively. Mean dry mass recovered after 2 years with 214, 112, and 207 g for 10-year-old saplings and the 1- and 2-year-old coppices, respectively. Site quality of the broken shale rock overburden was similar across four of the five sites, with the exception that one site had twice the soil nitrogen (N) at 0.123% than the other four site types, which had an average of 0.064% N. This high N site had 2.3-fold the productivity of the mean for the other four sites. Mean coppice stem height showed the strongest predictive relationship to total coppice dry mass when compared with the greatest stem height, greatest or mean stem basal diameter, or coppice stem number. The most dramatic result of this bur oak coppicing experiment was the rapid recovery of height growth, biomass production, and observable stem quality within coppices over the 2-year period following harvesting of the original, 10-year-old saplings.

One acorn produces two seedlings in Chinese cork oak Quercus variabilis

ABSTRACTAlthough the early germination of white oaks has long been considered an adaptation to counter animal predation, the role of the robust radicles of white oak acorns has been largely neglected in the interaction between acorns and seed-eating animals. Here, the regeneration capabilities of the pruned radicles of intermediate oak Quercus variabilis left by the acorn-eating animals were compared to test the ‘one acorn produce two seedlings’ hypothesis stating that the remnant radicles exhibit the capability to produce normal seedlings owning to their atypical nutritional and anatomical characteristics. Our results first showed that both pruned radicle and cotyledons from single acorn successfully established seedlings, providing strong evidence on an old puzzle that the robust radicles of early-germinating oak acorns act as reserved propagules, allowing them to escape animals’ predation. Our study also suggests that much of the investment in the food reserves of an acorn may be important as a food reward for the animals that disperse the acorns, rather than simply serving as energy for the young seedling.

Wind pollination over 70 years reduces the negative genetic effects of severe forest fragmentation in the tropical oak Quercus bambusifolia.

Whether wind pollination in trees can offset the negative genetic consequences of anthropogenic forest fragmentation is not clearly established. To answer this question, we examined the demographic genetics of Quercus bambusifolia over a 70-year recovery period in highly fragmented forests in Hong Kong. We sampled 1138 individuals from 37 locations, and genetically analysed the chronosequence through the classification of tree diameters from the same populations using 13 microsatellite markers. Our study reveals that severe fragmentation caused a significant genetic bottleneck with very few remaining but genetically diverse individuals. We observed an enhanced genetic diversity during demographic recovery. We found full-sibs within populations and half-sibs across the study range. This reflects a limited seed dispersal and extensive pollen flow. Despite reduced genetic structure both among and within populations, overall a strong persisting genetic differentiation (F'ST = 0.240, P < 0.01) and significant small-scale spatial genetic structure (F(1) = 0.13, Sp = 0.024, P < 0.01) were observed. Existing bottlenecks and low effective population sizes within the temporal chronosequence suggest that the long-term effect of severe fragmentation cannot be entirely eliminated by wind pollination with demographic recovery in the absence of effective seed dispersal. Our results lead to recommendations for forest management.

Resilience of Oregon white oak to reintroduction of fire

BackgroundPacific Northwest USA oak woodlands and savannas are fire-resilient communities dependent on frequent, low-severity fire to maintain their structure and understory species diversity, and to prevent encroachment by fire-sensitive competitors. The re-introduction of fire into degraded ecosystems is viewed as essential to their restoration, yet can be fraught with unintended negative consequences. We examined the response of mature Oregon white oak (Quercus garryana Douglas ex Hook.; Garry oak) to “first entry” woodland restoration burns following long fire-free periods.ResultsThirteen to twenty-five months post burn, topkill of oaks was minimal (3%) and mortality was rare in three prescribed burns, despite high levels (mean = 92%) of crown scorching, and irrespective of proportional duff consumption around oak bases (mean = 21%). Percentage of crown scorch volume was the strongest predictor of oak crown dieback, but response was highly variable, especially when canopy scorch was ≥80%. Comparison of our results with FOFEM (First Order Fire Effects Model), a common fire effects model, revealed high model inaccuracy, likely due to lack of a species-specific equation for prediction of Oregon white oak mortality.ConclusionsThe results of this study indicate that Oregon white oak is highly resistant to mortality in restoration burns, even following long fire-free intervals. Prescribed fire is not contraindicated in areas with extant mature oaks, and may promote oak regeneration via basal sprouting.

Spatial variation in oak (Quercus spp.) radial growth responses to drought stress in eastern North America

Dendroecology provides a means to evaluate how mature trees have responded to climate stresses in the recent past and provides one approach for projecting how existing forests will respond to future climate change. This study documented spatial variation in the strength of growth–climate associations for six oak (Quercus) species at 284 sites in eastern North America that span substantial gradients of temperature and site water balance. Radial growth of oaks was more strongly related to growing-season precipitation and the ratio of precipitation to potential evapotranspiration at sites in the western part of the study region where drought conditions occur more frequently. Growth was more strongly related to growing-season mean maximum temperature in the warmer, southern part of the study region. Growth of oaks was not strongly related to site water balance or temperature in the northeastern part of the study region. These results indicate that if climate change results in increased growing-season drought stress, this will adversely affect mature oak trees growing in the southern and western parts of eastern North America, but oaks growing in northeastern North America have more safe space for change before they will suffer reduced growth and vigor.

The wood species of the historic gala berlines of the Palazzo Pitti in Florence

Abstract The wood species of 18th- and 19th-century Italian historic berlines (gala carriages mainly made of wood) housed in the Palazzo Pitti museum in Florence were investigated using non-destructive techniques based on the use of portable digital microscopes. Overall, thirteen wood taxa were identified. Among those, walnut (Juglans regia) was the most abundant species in berlines commissioned by noblemen of high rank, such as kings, princes and grand dukes, whereas in the other carriages of lower lineage, the walnut was replaced by elm (Ulmus sp.) wood, a species commonly used for carriages. Some species were typically present in specific parts of the structures, such as elm and ash (Fraxinus sp.) in the transoms and struts of the undercarriage, oak (Quercus sp.) in the wheel's spokes, poplar (Populus sp.) in the seats, panels and mouldings of the body and European beech (Fagus sylvatica) in the light frames. Species found only occasionally, including chestnut (Castanea sativa), fir (Abies alba) and spruce (Picea abies), may have been introduced in occasions of restoration or substitution. The results also showed a preference for the use of local species, which is different from carriages in other European countries where exotic species were already used.

Catocala Schrank species (Lepidoptera: Erebidae) in Iran with new distribution data

The holarctic moth genus Catocala Schrank (1802) (Erebidae: Erebinae, Catocalini) includes about 300 species that are often monophagous on oak (Quercus), willow (Salix) and poplar (Populus). In this research, we studied the moths of the genus Catocala in Iran that were collected by light traps in different Iranian provinces, mostly during 2010–2018. Our results revealed eight species and two subspecies of Catocala from the provinces of Kermanshah, Lorestan, Chaharmahal-va Bakhtiari, Ilam, Khuzestan, Kohgiluyeh-va Boyerahmad, Fars, Kerman, Khorasan-e Jonubi, Yazd and Khorasan-e Razavi. Among the records there are 14 new provincial records. Overall, we list 20 species and four subspecies of Catocala as occurring in Iran. This list is compiled from our own research and a review of existing literature.

Host Plant Effects on Winter Moth (Lepidoptera: Geometridae) Larval Development and Survival.

The winter moth, Operophtera brumata (L.) is an invasive forest and agricultural pest in North America that causes severe defoliation to a wide range of host species. This study examines the differential larval densities, development, and survival on seven host species in midcoast Maine: red oak (Quercus rubra L., Fagales: Fagaceae), apple (Malus domestica L., Rosales: Rosaceae) and crab apple (Malus sp. L., Rosales: Rosaceae), red maple (Acer rubrum L., Sapindales: Sapindaceae), pin cherry (Prunus pensylvanica L., Rosales: Rosaceae), white birch (Betula papyrifera L., Fagales: Betulaceae), wild lowbush blueberry (Vaccinium angustiflolium L., Ericales: Ericaceae), and highbush blueberry (Vaccinium corymbosum L., Ericales: Ericaceae). We also explore the degree of synchrony between selected host plants and larval hatch and its effect on survival. We found that densities, development, and survival were significantly greater on red oak (Quercus rubra) and apple (Malus sp.) than on all other target species and were lowest on pin cherry (Prunus pennsylvanica). We found low larval densities in open, wild lowbush blueberry fields; however, larvae successfully fed and developed on wild lowbush blueberry in a laboratory setting. This suggests that winter moth is a potential pest to wild lowbush blueberry in Maine if the outbreak expands to include areas with wild lowbush blueberry production.

Canopy gap regime as a function of woodland age in the Kansas Cross Timbers

Oaks (Quercus spp.) have low or intermediate shade-tolerances and forest canopy gaps can promote their regeneration. Current fire frequencies and/or intensities in eastern North America are less than they were historically, thus changing gap dynamics and allowing mesic, fire-intolerant, shade-tolerant species to fill canopy gaps on many sites. Hence, many oak forests are changing in tree species composition. By contrast, it has been hypothesized that oak ecosystems are stable on xeric, nutrient-poor sites despite fire regime changes. We characterized the canopy gap regime and investigated changes in tree species composition in woodlands at the xeric edge of North American eastern deciduous forest. We used the line-intersect method to quantify canopy gap frequency, size, cause, and identities of gap replacement species in four young and four old post oak (Quercus stellata) woodlands in the Cross Timbers ecosystem of Kansas, USA. Woodland age did not affect gap characteristics. Canopy gap regime in these xeric woodlands was characterized by infrequent, small gaps that primarily form from snags or snapped boles. Through gap formation and filling, gradual change in the canopy composition of Kansas Cross Timbers woodlands is likely. Post oak dominates the canopy and forms the largest proportion of gaps, but it is the canopy replacement species in far-fewer gaps. By contrast, species that are minor components of the canopy, including hickories (Carya sp.), eastern redcedar (Juniperus virginiana) and more mesic-associated oaks, fill more gaps than they form. These xeric oak woodlands appear to be unstable under the current regional disturbance regime.

Современное состояние полезащитной полосы с участием дуба

Shelterbelt forests are one of the most important factors of ecological optimization of agrolandscape. The research purpose is to analyse the current state of the forest belt with the involvement of English oak (Quercus robur L.) and Norway maple (Acer platanoides L.) in the vicinity of Zolotaryovka village (Stanichno-Luganskiy district of Lugansk region, Ukraine) and development of necessary measures for belt’s regeneration. Archival data on the time of planting and age of the studied object were not found out. Shelterbelts in Lugansk region were created in accordance with Stalin’s plan for the transformation of nature, which was designed for the period from 1949 till 1965. We laid out two permanent trial plots due to the branch standard OST 56-69–83 in the studied plantation. We determined the composition of the shelterbelt, the diameter and mean height of trees and their condition by Kraft using the results of the enumerative inventory. The vital status of trees was estimated based on the “Sanitary regulations in the forests of the Russian Federation”. Undergrowth of Norway maple, Tatarian maple and mahaleb cherry (Prunus mahaleb L.) is the most numerous under the canopy of parent plantations. These species originally were not in the stand composition of the shelterbelt. It has been found that in the stand there is a forest-forming process aimed at formation of a forest biocenosis with predominance of Norway maple. The decisive factor affecting the condition of oak trees in the shelterbelts is the condition of their last rows. The survival rate of oak depends on the fall of Norway maple with the natural formation of forest stand in the plantation created by the corridor or ordinary way. It was revealed that it is necessary to carry out increment felling in the rows of Norway maple in order to improve the conditions for growth and development of English oak in the studied plantation. If a set of measures for promotion of tree regeneration in the shelterbelt is not carried out, then in the future there may be a change of English oak to Norway maple and Tatarian maple trees.For citation: Gribacheva O.V. The Current State of the Shelterbelt Featuring English Oak (Quercus robur L.) and Norway Maple (Acer platanoides L.). Lesnoy Zhurnal [Forestry Journal], 2019, no. 4, pp. 34–44. DOI: 10.17238/issn0536-1036.2019.4.34

Last Glacial Maximum, early Holocene and modern environments of the northern South China Sea region: Insight from SEM analysis of Oak (Quercus) pollen.

Oak (Quercus) pollen was identified at the infra-generic (i.e. sub-genus to species) utilizing Scanning Electron Microscope (SEM) images of modern (i.e. 18 species from southern China) and fossil pollen grains from northern South China Sea (SCS) marine and terrestrial sediments. Key morphological characteristics of Quercus exine sculpture were used to separate the pollen into evergreen and deciduous groups, with this distinction applied to the fossil oak pollen from the Last Glacial Maximum (LGM) and early Holocene periods. The presence of Quercus pollen from the modern Pearl River and northern SCS suggests long distance transport from inland temperate to tropical regions surrounding the SCS. Fossil oak pollen from terrestrial and marine sediments from the northern SCS region suggests different pollen representation between these two sedimentary environments, with the terrestrial site dominated by evergreen Quercus types and the marine location showing greater representation of deciduous oak species. The presence of both evergreen and deciduous oak pollen in the LGM age marine sediments suggests only moderate cooling during this time period, while the dramatic increase of deciduous Quercus pollen in the marine core, as well as generally higher pollen influx values, reflects greater fluvial discharge, which in turn is linked to increased precipitation in the region during the early Holocene period.

The Legacy of Pre–Columbian Fire on the Pine–Oak Forests of Upland Guatemala

Mountain tropical forests of the Southern Maya Area (Pacific Chiapas and Guatemala, El Salvador and Northern Honduras) predominantly comprise pine and oak formations, which form intricate mosaics and complex successional interactions following large–scale fire. These forests have been transformed by the peoples of the Maya civilization through practices of horticulture, agriculture and architectural developments over thousands of years. Anthropogenic impacts and the extent of early human interaction with these upland forests is currently poorly understood. In this study we identify: (i) the natural baseline vegetation of the region; (ii) when human impact and agrarian practices began in the Maya uplands; and (iii) what impacts the Maya had on forest structure, composition, and successional regeneration. Past vegetation, anthropogenic use of fire, and faunal abundance were reconstructed using proxy analysis of fossil pollen, macroscopic charcoal, microscopic charcoal, and dung fungal spores (Sporormiella). Three phases of forest succession were identified from 4000B.C.E. to 1522CE that broadly overlap with the well–defined archaeological periods of (i) the Archaic (10,000–2000B.C.E.); (ii) Pre–Classic (2000B.C.E. –100C.E.); (iii) Terminal Pre–Classic (100–250C.E.); (iv) Classic (250–950C.E.); and (v) Post–Classic (950–1522C.E.). These results also include the earliest evidence for agriculture within the Southern Maya Area through presence of peppers (Capsicum) from 3850B.C.E. and the rise of maize cultivation (Zea mays) from 970B.C.E. Persistent high intensity burning driven by agricultural practices and lime production during the Late–Pre-Classic (400–100B.C.E.) to Classic Period resulted in a compositional change of forest structure c.150B.C.E. from oak (Quercus) dominated forests to pine (Pinus) dominated forests. The legacy of Pre–Columbian anthropogenically driven fire in these mountain tropical forests demonstrates the resilience and thresholds for fire driven succession. These findings are particularly relevant for addressing current land use and management strategies involving agriculture, fire, and forest management in the mountain tropical forests of the Southern Maya Area.

Growth and morphological features of common oak (Quercus robur L.) in the comparative experiment in the Karczma Borowa Forest District

Growth and morphological features of common oak (Quercus robur L.) in the comparative experiment in the Karczma Borowa Forest District