Mixed Deciduous Woodland Research Articles

Research note. Effects of stand structure, composition and treatment on bark-stripping of beech by grey squirrels

Beech (Fagus sylvatica L.) is particularly vulnerable to bark-stripping by grey squirrels (Sciurus carolinensis Gmelin), especially when it is medium-sized and growing rapidly with a high average phloem volume. Patterns of bark-stripping are best explained as a consequence of agonistic behaviour, food-seeking or learning, which is amplified by tree-growth factors, including phloem volume and bark-structure (Shorten, 1954; Taylor, 1966, 1969; Mackinnon, 1976; Kenward, 1982, 1983; Rowe, 1984; Rowe and Gill, 1985; Kenward and Parish, 1986; Gurnell, 1987; Kenward et al., 1988a, b, 1996; Kenward, 1989; Gill, 1992; Kenward and Dutton, 1996; Mountford, 1997). Bark-stripping seems more intense in stands that have been silviculturally thinned, i.e. where growth rate and phloem volume have increased, and accordingly modified patterns of stand treatment have been proposed (Kenward et al., 1988a; Kenward and Dutton, 1996). This note records supporting evidence for the influence of thinning on the intensity of barkstripping. It relates to Lady Park Wood, a mixed deciduous woodland growing on and above steep slopes on Carboniferous limestone overlooking the river Wye (UK), where stand dynamics and the growth rate of individual trees have been closely observed for over 50 years (Peterken and Jones, 1987, 1989; Mountford, 1994, 1997; Peterken and Mountford, 1995, 1996, 1998). The reserve comprises a non-intervention area containing both old-growth and young-growth stands, and an adjacent compartment which had a similar composition and treatment history until a part was thinned in 1982.

Evaporative cooling of mushrooms

Temperature measurements from the spore-producing gills, spines, and tubes underneath fruit-body caps revealed cooling in 18 basidiomycete species growing in mixed deciduous woodland. The temperature of cultured fruit bodies of Lentinula edodes and Pleurotus ostreatus fell upon exposure to low velocity airflow, consistent with an evaporative mechanism of cooling. The mechanism of ballistospore discharge characteristic of basidiomycete fungi is dependent on condensation of water from the air surrounding the spores onto the spore surface. The current model for this process predicts that condensation, and therefore spore discharge, is enhanced by cooling of the fruit body.

Glechoma hederaceaL. (Nepeta glechomaBenth.,N. hederacea(L.) Trev.)

A polycarpic, aromatic, often purplish, softly hairy or nearly glabrous perennial herb. Flowering shoots 10–30 (–60) cm long, square in section and ascending or erect. Non-flowering stems also square in section, creeping and rooting at many, but not all, nodes. Leaf laminae 4–35 (–80) × 6–40 (–80) mm, reniform to ovate–cordate, obtuse or subacute and coarsely crenate. Petioles highly variable in length from 10 mm in grassland to over 200 mm in woodland with dense canopy cover and dense ground vegetation. Bracteoles 1–1.5 mm, shortly hispid or pubescent. Flowers zygomorphic and hypogynous, borne in few (2–5)-flowered secund axillary whorls, the bracts not differing from the foliage leaves. Calyx tubular or tubular-campanulate, 15-veined, not gibbous at base, and somewhat two-lipped. Upper lip of the corolla flat with three triangular acuminate teeth that are 0.2–0.3 times as long as the tube. Lower lip with two teeth. Corolla tube narrowly obconical, straight and hairy within at the base of lower lip. Corolla (6–) 15–22 (–25) mm, usually blue–violet with purple spots on the lower lip; rarely pink or white. Stamens four, two long and two short, borne on corolla tube and lying below upper lip; anther cells at right angles to each other, each opening by a separate slit. Ovary four-celled and deeply four-lobed, each cell with one ovule. Style gynobasic, its branches equal. Hermaphrodite and male-sterile forms of flowers occur, the latter usually with smaller corollas than hermaphrodite flowers, and much-reduced, pollen-less stamens that are often included in the corolla tube. Clones usually bear either only hermaphrodite or only male-sterile flowers, but in rare cases both types are found on the same individual (Price 1991). Each flower produces a maximum of four obovoid, slightly angled, smooth nutlets with a mean air-dry mass of 0.69 mg (n = 100). Each is slightly angled owing to pressure exerted by the adjacent developing nutlets before dispersal, and each bears a grey protuberance which may be an elaiosome. The dimensions of the seed are 1.9 × 1.1 mm. Glechoma serbica Halacsy & Wettst., which has been recorded in former Jugoslavia, is probably an ecological modification of G. hederacea (Fl. Eur. 3). The southern counterpart of G. hederacea in Europe is ssp. hirsuta (Waldst. & Kit.) F. Hermann, sometimes referred to as G. hirsuta (Elias 1979, 1983). This has denser and longer hairs and longer calyx teeth than G. hederacea, and the corolla is pale blue. It has been recorded in Albania, Austria, Bulgaria, the Czech Republic, Greece, Hungary, Italy, former Jugoslavia, Poland, Rumania, central and south-west Russia, Sardinia and Sicily (Fl. Eur. 3). Intermediates, which are presumably hybrids between G. hederacea and G. hirsuta, sometimes occur (Fl. Eur. 3). In eastern Asia a more or less distinct, short-pubescent race occurs that is called ssp. grandis (A. Gray) Hara [also var. grandis A. Gray and var. longituba (Nakai) Kuprian] (Hulten 1971). In North America the variety micrantha Moricand [or var. parviflora (Benth.) House] is distinguished (Hulten 1971).

Long‐term change in an unmanaged population of wych elm subjected to Dutch elm disease

1 Changes in a population of Ulmus glabra in Lady Park Wood (UK), a mixed deciduous native woodland, were studied by means of permanent transects. All individuals reaching 1.3 m height were recorded at irregular intervals from 1945 to 1993. 2 Dutch elm disease struck this population in about 1972. Most of the canopy and subcanopy stems were killed, but a few, slow‐growing, subcanopy individuals survived unscathed. 3 Subsequent seedling regeneration and growth of sprouts from rootstocks of infected trees was substantial and vigorous. Twenty‐three years after the outbreak of disease the number of elm individuals had increased by about 40%. Disease has, however, continued to afflict vigorous, exposed individuals. 4 The large‐scale distribution of elm has been unaffected, but the small‐scale pattern has changed due to the concentration of seedling regeneration in gaps. 5 The elm population appears to be differentiating into (i) a large high‐turnover subpopulation of fast‐growing, but repeatedly diseased maiden individuals and sprouts, and (ii) a small, low‐turnover subpopulation of slow‐growing individuals rooted in suboptimally dry, secluded sites.

Biomass, growth, and secondary production of Arcitalitrus dorrieni (Crustacea: Amphipoda: Talitridae) at two sites in Co. Galway, IrelandS

Growth rates, podomere addition, and secondary production of Arcilalitrus dorrieni (Hunt, 1925) populations inhabiting two neighbouring woodland sites at Kylemore, Co. Galway, Ireland, were investigated. One site was a mixed deciduous woodland infested with Rhododendron ponticum. The other a pure coniferous stand of Pinus contorta var. latifolia S. Wats. Seasonal changes in biomass were recorded at the two sites. In both years of the study, maximum biomass was recorded in September. Females had a higher growth rate than males, but growth rates of both males and females were higher at the mixed deciduous site. The number of podomeres on the second antenna was correlated with the size of the animal. The average length of A. dorrieni at each podomere number appeared to change seasonally. Comparisons of mean spring values with mean summer values showed a statistically significant decrease in mean amphipod length for a given podomere number, though this was more marked at the mixed deciduous site. Annual secondary production rates ranged from 5.06 g dry wt m‐2 year‐1at the coniferous site to 14.55 g dry wt m‐2 year‐1 at the mixed deciduous site. P:B values ranged from 2.41 at the coniferous site to 3.01 at the mixed deciduous site. Results are compared between sites and with data from other relevant crustacean species.

Vegetational history of central Scotland

Summary The vegetation history of central Scotland has been summarized from information obtained primarily from pollen analysed sites in the region. Open ground taxa began to be replaced by a dwarf shrub community during the late-glacial period but this process was reversed by the Loch Lomond glacial readvance. Following this cold period dwarf shrubs again migrated into the area. These were gradually followed by the major tree taxa until, by the time of maximum woodland expansion, central Scotland was covered by mixed deciduous woodland with small amounts of Scots pine growing on drier areas of peat bog. The expansion of the human population led to increasing woodland clearance and by the Iron Age extensive clearance of the woodlands of central Scotland was underway. Over the last 2000 yr changes in population have resulted in corresponding changes in the wood-land cover of central Scotland and have led to the deforested landscape seen today.

Size At Maturity and Sex Ratio of Arcitalitrus Dorrieni (Hunt, 1925) (Amphipoda, Talitridae) At Two Sites in County Galway, Ireland

AbstractAnthropogenic dispersal has led to the introduction of several terrestrial amphipod species to the northern hemisphere. One such species, Arcitalitrus dorrieni (Hunt, 1925), a native of Australasia, is now found in several woodland sites in Ireland and Britain. Aspects of the biology of A. dorrieni were investigated in County Galway over a period of two years and compared between a "typical" mixed deciduous woodland habitat and a more "atypical" coniferous woodland habitat. At both sites, statistically significant differences were found between summer (Aug.-Sep.) size at maturity and winter (Jan.-Apr.) size at maturity, i.e., females were mature at smaller sizes in summer than in winter. Between-site comparisons of August-September data for both years showed that females were mature at a significantly smaller size at the mixed deciduous woodland site. A sex ratio biased in favour of females was recorded on all but one sampling date at each site, though on some dates this bias was not significant. The change in cohort sex ratio at both sites was quite distinct and exhibited the same general pattern. During the recruitment of each cohort, the ratio was biased towards males. As the cohort increased in length, however, the ratio changed to a bias in favour of females, so that by the time a particular cohort entered its breeding period the following year, it was biased firmly in favour of females. Possible reasons for the observed patterns are discussed.

Occurrence of larval Ixodes scapularis (Acari:Ixodidae) on tree trunks.

Host-seeking larvae of blacklegged ticks, Ixodes scapularis Say, were found on the trunks of 7 species of trees in a mixed deciduous woodland in Maryland. Where larvae were present around the bases of trees, larvae were found on 45.8% of the tree trucks. Almost 15% of the larvae found on tree trunks were approximately 1-2 m above the ground. Larger trees harbored larvae more often than smaller trees. Trees having a circumference at breast height of > or = 1 m (0.96 m diameter) averaged 3.19 larvae. Because white-footed mice, Peromyscus leucopus (Rafinesque), the principal hosts of I. scapularis larvae, frequently nest in trees, it may not be detrimental to host-seeking larvae to ascend and remain on tree trunks.

Long‐term scatterhoarding by Eurasian red squirrels (Sciurus vulgaris)

Hoarding behavious, seed species hoarded and hoarding intensity by red squirrels (Sclurus vulgaris L.) are described for two population; one in a coniferous woodland with few deciduous trees, the other in a mixed deciduous woodland with some conifers. Seasonal variation in the recovery of hoards and the importance of hoarded food with regard to a squirrel's annual energy demands are discussed. The importance of having hoards is compared among tree squirrel species.

Effects of drought on beech in Lady Park Wood, an unmanaged mixed deciduous woodland

The effects over 16 years of the 1976 drought on the beech (Fagus sylvatica L.) population in mature, mixed deciduous, semi-natural stands in Lady Park Wood are described. Individual trees were recorded within sample transects at intervals from 1945 onwards, so it was also possible to examine responses in relation to previous growth. Many mature beeches were killed immediately or severly damaged. Growth of survivors was negligible until about 1985 and never recovered to pre-drought rates. Damaged trees were still dying 15 years later from drought-induced damage. Sub-canopy beech in those parts of the wood which suffered most canopy mortality grew rapidly after 1983. Through its effects on beech, the drought had a marked impact on the structure and successional trajectory of the wood.

Phosphorus translocation by saprotrophic basidiomycete mycelial cord systems on the floor of a mixed deciduous woodland

Translocation of 32 P was examined in seven mycelial cord systems of Hypholoma fasciculare, Phanerochaete velutina and Phallus impudicus which had developed from wood block inocula placed on the floor of a mixed deciduous woodland. Five days after addition of radiotracer to the central inoculum activity was detected at the margins of cord systems, demonstrating translocation 32 P over distances up to 75 cm. Destructive sampling showed that radioactivity was present in cords and a range of wood and leaf litter components colonized by cord systems. Radioactivity was also detected in live Fragaria vesca plants and shoots of the moss Hypnum cupressiforme .

Holocene vegetation history and human impact at Bryn y Castell, Snowdonia, north Wales

summaryThree radiocarbon‐dated pollen diagrams are presented from Holocene peat and lake deposits in Snowdonia, close to the Late Iron Age/Romano‐British ironworking hill‐tort of Bryn y Castell, Gwynedd, in upland north Wales. This paper discusses pollen, charcoal and peat‐stratigraphic evidence for major local vegetation changes and for the development of the surrounding cultural landscape during the last 10000 radiocarbon yr. Pollen data from one of the sites (BYC 2) provided a vegetational record for most of the Holocene. The early part of the sequence suggests an oligotrophic lake in a landscape that is being colonized by birch‐pine woodland; later, mixed deciduous woodland surrounds an infilling lake basin. Dating of peat deposits at two of the sites (BYC, BYC H) indicated that their pollen records commenced between 5500 and 5000 yr BP. By this time, the lake basin was fringed by alder carr. There followed a gradual and then, c. 2700 yr BP, a more abrupt decline in woodland, such that, by the end of the Bronze Age and with the basin largely terrestrialized, the local landscape became dominated by mire vegetation communities, which have persisted to the present. Human activity seems to have been a major factor in the loss of woodland cover. Although there is some circumstantial evidence for earlier phases of human disturbance at BYC 2, human activity becomes increasingly apparent from c. 5000 yr BP. During the mid Holocene, the impact of Neolithic and early‐ to mid‐Bronze Age cultures appears to be characterized by temporary woodland clearances, for arable and pastoral agriculture. By c. 2700 yr BP the majority of woodland cover seems to have been permanently removed from the landscape, but as there is scant archaeological evidence for late Bronze Age cultures in this part of Snowdonia, other factors, especially climate change, could be implicated. During the late Holocene, especially during part of the late Iron Age and Romano‐British period, remaining local stands of woodland seem to have been exploited for iron smelting, although the overall impact of ironworking was limited.

Woodland history of northern Greece from the mid Holocene to recent time based on evidence from peat pollen profiles

The woodland history of the northern mountainous parts of Greece is considered in the context of pollen profiles from bogs in Rhodopes, Lailias-Vrontou, Paiko, Voras and Pieria. In the time period covered by these diagrams (only those from Voras and Lailias extend back to the 7th millennium B.P.) the overall trends in the woodland history at the particular sites are comparable but there are also substantial differences that are attributed to the effects of human influence which varied in time, intensify and extent. The earlier phase, which corresponds to the Atlantic period of Firbas, is characterized by mixed deciduous woodlands with Quercus or Tilia the main components. This is followed by the phase (Subboreal) in which coniferous woodlands, which consisted of Abies and Pinus, dominated. In this time, Fagus gradually expanded. In the final phase (Subatlantic), Abies becomes more or less extinct and Fagus has a dominant role. These developments broadly correspond with those recorded in pollen profiles from Central Europe.

Soil chemistry change in a lowland english deciduous Woodland 1974?1991

This study outlines the results of analysis of soil samples collected from fixed quadrats located in a regular pattern across Wytham Wood. Oxfordshire, England. The site contains plots of mixed deciduous ancient woodland and more recent plantations. A previous soil study was undertaken in 1974 and samples archived. Soils were resampled in 1991 and some re-analysis of the 1974 samples was undertaken. Soils were of a wide range in types from sands to gravels with a pH range of 3.0–7.0. Results showed some decline in pH in lower horizons, but most striking was a large increase in soil nitrogen for all horizons and soil types.

Chemical changes in decomposing forest litter in response to atmospheric sulphur dioxide

SUMMARYDecomposing needle and leaf litter, from a pine (Pinus sylvestris L.) stand and a mixed deciduous woodland, respectively, were exposed to arithmetic mean SO, concentrations of up to 50 nl l−3 (mm3 m−3) in controlled field‐based experiments lasting up to 215 d. The objectives of the study were: (1) to evaluate whether SO, concentrations, known to occur in parts of Europe, could alter the chemical composition of forest litter and leachates, and (2) to use such information to complement results obtained during microbiological studies (Wookey et al., 1991).Dry deposition of SO, on the litter resulted in the production of sulphate during damp conditions or when the litter was moist. The formation of SO2−4 and associated H+ ions led to cation exchange processes whereby Mg2+ and Ca2+ in particular were leached from the litter. This resulted in significant (P<0.01) depletion of magnesium and calcium in both litter types, even at the lowest SO2 concentrations tested (15 nl l−1). Incomplete buffering by base cations resulted in acidification of leachates.The magnitude of cation leaching and depletion within the litter was not always linearly related to SO, or leachate SO2−4 concentrations, and the role of microbial processes and litter quality as modifiers of such responses is considered.

Effects of atmospheric sulphur dioxide on microbial activity in decomposing forest litter

At extremely high concentrations, relative to those occurring in the atmosphere, sulphur dioxide (SO 2) has known antimicrobial properties. There is also circumstantial evidence, based on field surveys, to indicate that the occurrence and activities of a number of phylloplane fungi and soil microorganisms are correlated with atmospheric concentrations of SO 2 occurring in parts of Europe and North America. The results of these studies need to be corroborated by controlled fumigation experiments applying realistic concentrations of SO 2. Unfortunately such experiments have been rare. The suggestion that SO 2 may be affecting soil microorganisms merits serious consideration because of the fundamental role of these organisms in maintaining soil fertility, especially in forests. Events in the forest litter layer are considered to be particularly important because it forms an interface between the atmosphere and the soil system. The research described in this paper involved exposing leaf litter (from a Pinus sylvestris L. stand and a mixed deciduous woodland) to arithmetic mean concentrations of SO 2 of ⩽0.050 μl 1 −1 in controlled field-based experiments lasting up to 215 days. Fungal cultures, isolated from the pine litter, were also fumigated with ⩽0.053 μl 1 −1 SO 2 in laboratory-based studies. Results showed that arithmetic mean concentrations of SO 2 as low as 0.015 μl 1 −1 significantly reduced microbial activity (respiration) in both pine and deciduous litter in the open-air fumigation experiment. Results should also be interpreted in relation to the peak SO 2 concentrations (often considerably higher than arithmetic means) to which the litter was exposed. Pure cultures of Cladosporium cladosporioides (Fres.) de Vries and Coniothyrium olivaceum Bonord, isolated from the litter, were shown to be sensitive to SO 2 concentrations of ⩽0.053 μl 1 t-1 in laboratory-based fumigations. It is concluded that the dry deposition of SO 2 to forest soils may have important implications for nutrient cycling processes and therefore forest productivity and community structure.

Territorial behaviour of the Robin Erithacus rubecula: the importance of vegetation density

Robin Erithacus rubecula territories were mapped in an isolated copse of mixed deciduous woodland. An index of vegetation density, measured at numerous randomly chosen sites within the copse, was found to be higher in areas occupied by Robins. Both vegetation density and territory area were compared with measures of breeding success. In all cases vegetation density was correlated with breeding success and territory area was not. Possible evolutionary advantages to defending areas with dense vegetation are discussed.

A SIMPLE FIELD METHOD FOR MEASURING LIGHT QUALITY: SEASONAL CHANGES IN A TEMPERATE DECIDUOUS WOOD*

Abstract— Light was measured at 5 m intervals along a ground level transect through a mixed deciduous woodland in SE England. A simple method was developed to characterise the light environment, using measurements of photon fluence rate in the blue, photosynthetically active radiation (PAR) and near infrared regions of the spectrum. It was demonstrated that the two parameters, required to describe the state of the photoreceptor phytochrome the photostationary proportion of Pfr and the cycling rate, can be calculated from the quantities of PAR and IR light. These parameters as well as the amount of blue light were followed throughout the year along the woodland transect. The main seasonal changes are the fall and rise in the proportion of light which is PAR (and hence in the proportion of phytochrome as Pfr) associated with the appearance and disappearance of the green leaf canopy.

FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS: I. ESTABLISHMENT VIA THE AERIAL CUT SURFACE.

More than 450 beech (Fagus sylvatica L.) logs, 10 to 20 cm in diameter and 30 to 40 cm long, were cut from freshly felled trees and placed upright 1 m apart with their bases buried up to 10 cm deep in the ground in a plot of about 600 m2 in a mixed deciduous woodland in the Forest of Dean, Gloucestershire, UK. Fungal colonization via the aerial and buried cut surfaces was studied - in some cases following inoculation of basidiospores - using a combination of direct and indirect techniques. A wide variety of ascomycetes, basidiomycetes and fungi imperfecti were identified, by direct observation or following direct incubation of wood samples, from the vicinity of the aerial cut surface within the first six months after cutting. Some such as Coriolus versicolor (L. ex Fr.) Quél. subsequently increased in occurrence, whereas others, including Chondrostereum purpureum (Fr.) Pouz. declined. Isolation onto malt agar from thin sections of wood revealed the presence of some fungi, notably a Fusarium sp., not detected by direct means. In addition, homokaryons of the basidiomycetes Bjerkandera adusta (Willd, ex Fr.) Karst. and C. versicolor were isolated from near the aerial cut surface up to two years after cutting, and, lower down, mostly up until six months after cutting (thereafter heterokaryons predominated). Moreover, evidence was obtained that small volumes of discoloured, but not strongly decayed wood, sometimes contained large numbers of mutually antagonistic individuals (up to 30 per cm3 ) of the decay species B. adusta, C. versicolor and Stereum hirsutum (Willd. ex Fr.) S. F. Gray. Vertical penetration from the aerial cut surface showed a marked lag phase, such that for the first six weeks after cutting, overt colonization was restricted to about 3 mm depth. Thereafter the depth occupied increased rapidly.

FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS: II. ESTABLISHMENT VIA THE BURIED CUT SURFACE.

Patterns of fungal colonization from the base of cut beech logs placed upright and partly buried in the ground at a mixed deciduous woodland site were fundamentally different from those from the aerial cut surface. Principal colonists resulting in decay, and mostly arriving within three months, were the ascomycete Xylaria hypoxylon (L. ex Hooker) Greville and various rhizomorph/mycelial cord-forming basidiomycetes, including Armillaria bulbosa (Barla) Kile & Watling, Phallus impudicus (L.) Pers., Phanerochaete velutina (DC ex Pers.) Parmasto and Tricholomopsis platyphylla (Pers. ex Fr.) Sing. Apart from A. bulbosa, these generally readily formed mycelial mats on the basal surface, between which somatic incompatibility reactions were often observed. Most frequent reactions occurred with X. hypoxylon which almost invariably produced numerous individuals in discrete decay columns. By contrast, lack of somatic incompatibility reactions between isolates of A. bulbosa indicated that a single extensive mycelial type occurred throughout the site. The occurrence of somatic incompatibility between isolates off. velutina from different logs indicated independent establishment, presumably via basidiospores, and this was consistent with the unusually late arrival of this species at the site. In no cases were numerous somatically incompatible individuals isolated from small volumes of wood lacking demarcation into discrete columns, as had been observed near the aerial cut surface. Vertical penetration from the base was more rapid than from the aerial cut surface, with X. hypoxylon a major pioneer species, and there was no pronounced lag phase.