Base Of Trunk Research Articles

Les formes sympatriques et allopatriques du genre Ravenala dans les forêts et les milieux ouverts de l'est de Madagascar

Four variants, or forms, in the currently monotypic Ravenala madagascariensis Sonn. (the “traveler’ s tree”) have been observed on the eastern slopes of Madagascar, from sea level up to an altitude of 1000 m in submontane forests : (1) the first form, locally called “malama”, is the most strikingly divergent variant, especially with respect to its juvenile phase. It grows in the understory of undisturbed submontane rainforest. The secondarily spiral arrangement of the leaves, the long decurrent blade, the absence of a leaf stalk and the arrangement of the leaf blades to form a torus, are very different from the usual growth habit of Ravenala. The adult stage of this “malama” is characterized by the classical fan-shaped leaf arrangement (2) the second forest form, locally called hiranirana is, according to our surveys, more abundant in forest gaps and more or less disturbed primary forest than in truly undisturbed forest. The juvenile phase of this second form is more similar to the usual fan-shaped ravenala, with a well developped leaf stalk and a relatively wide blade, but a slight and regularly alternate shift of the leaf blades, is characteristic of the “hiranirana”. It persists in the adult phase after the trunk has formed. (3) the third form, locally called “bemavo”, is the commonest form growing on the deforested slopes between 300 and 600 m elevation. This form constitutes the socalled “Ravenala forest s” . It is characterised by a well arranged fan-shape of the leaves at all stages of development, at least in these open areas, and the yellow color of its leaf sheaths. This is the form whose leaves are most used by local people to make roofs, and whose trunks are most used to make floors and walls. (4) the fourth form, locally called “horonorona”, grows mainly at elevations lower than 300 m It is common in the swampy areas along the coast, where it grows with Typhonodorum and species of Pandanus. This form usually presents a reduced leaf fan and an obliquely oriented trunk base. This last character is related to the multistemmed habit of this form. Indeed, “horonorona” differs strikingly from the other three recognized forms in its cespitose habit. This low elevation form is the one most commonly cultivated throughout the world despite the inconvenience of its suckering habit and low cold tolerance. From an evolutionary point of view, we suggest that the suckering habit and the perfect fan-shaped arrangement of the leaves, with the consecutive protecting self -shading of the blades, is the primitive condition. Thus the origin of Ravenala probably first evolved in more or less inundated lowland forests (which are today mostly destroyed), so the original Ravenala may have resembled the fourth form “horonorona” which now lives in deforested lowland sites, on either poorly or well drained soils. Afterwards, Ravenala presumably invaded steep slopes covered with originally quite open forest. Finally, forms similar to the extant “malama” (1), which is well adapted to the shade of the closed forest understory, invaded the more closed forests on less steep slopes. The establisment and persistance of Ravenala in open deforested areas may be a relatively recent event. The contractile roots, observed in all the forms, may be crucial for adaptation to the different habitats. Indeed, these contractile roots allow the stem apex to sink into the soil. This pattern of growth and establishment is responsible for the augmentation of the stem diameter through the initiation of numerous roots along the buried stem base. This growth habit stabilizes the plant on unstable inundated slois and steep slopes. II aslo protects the young stem apex against fire in the regularly burnt “savoka” and other savannah-like slopes of eastern Madasgascar. The “Malama” is most obviously divergent from the others. Thus future studies will probably lead us to begin by separating this form taxonomically. No matter what way these forms are classified, their different eco-morphological characters explain how Ravenala can grow in such strikingly different environments.

Effect of cutting height and frequency on Leucaena leucocephala forage and wood production

Leucaena leucocephala is a fast‐growing tree that can provide both high quality forage and firewood. The objective of this trial was to determine the optimum height and frequency of cutting for both wood and forage production. Cutting heights at 0.3 m, 0.6 m and 1.0 m were superimposed on 3‐month and 6‐month cutting frequencies on mature rows of L. leucocephala for three years. Effects of year or its interaction with the other factors were not significant (P≥0.10). There was an increase (P=0.07) in wood production but not forage production (P≥0.10) with the longer interval. Cutting height had an effect on forage (P<0.001) production, with 5.47 t ha−1 a−1 for the 0.3‐m height, 7.62 t ha−1 a−1 for the 0.7‐m height, and 8.71 t ha−1 a−1 for the 1.0‐m height. Cutting height also had an effect on wood production (P<0.001), with 7.22 t hd−1 a−1 for the 0.3‐m height, 9.33 t ha−1 a−1 for the 0.7‐mheight, and 11.55 t hd−1 a−1 for the 1.0‐m height. In this experiment, the six‐month interval produced more wood than the three‐month interval, but there were no differences in quantity of forage dry matter in L. leucocephala; there were advantages in both wood and forage production with the taller trunk base.

Epiphytic lichen diversity in old‐growth and managedPicea abiesstands in southern Finland

Abstract.Epiphytic and epixylic lichens were surveyed on 15 1‐ha plots in maturePiceaabies‐dominated boreal forests in southern Finland. The sample plots were classified into three groups according to the age of the dominant tree stand and recent signs of cutting: (1) early mature managed, ‘EM’ (95 ‐109 yr), (2) late mature managed, ‘LM’ (126 ‐ 145 yr) and (3) old‐growth, ‘OG’ (129 ‐ 198 yr). Two data sets on epiphytic and epixylic lichens were recorded from each plot: (1) species on basal trunks and branches ofPicea abiesand (2) species on all available woody substrates, including basal parts of all tree species, saplings, snags, logs and stumps.142 epiphytic and epixylic lichen species were found, of which 83 (58%) occurred onP. abies. Mean total numbers of species per sample plot were 69 in EM, 78 in LM and 88 in OG plots, species number onP. abieswere 47, 56, and 54 respectively. The LM plots had lower species numbers than OG plots, mainly due to the lack of oldPopulus tremulatrees, but they had higher species number than the EM plots mainly due to the higher age ofPicea abies. Differences in species composition, both within and between the three groups, were small. The results suggest that the epiphytic and epixylic lichen diversity in a managed stand can be increased by prolonging the rotation of the stand to &gt;120 yr and by increasing the diversity of habitats in the stand.

Early stages of podzolization under Corsican pine ( Pinus nigra Arn. ssp. laricio)

To assess the effects of the plants on pedogenesis, two arboreal species, Corsican pine ( Pinus nigra Arn. ssp. laricio) and silver fir ( Abies alba Mill.) were compared. We observed that at the base of the largest Corsican pines, patches of bleached soil occur on top of the A horizon. These eluviated areas lie at the outlet of wide bark channels through which the stemflow reaches the ground. In addition, an apparently less bleached material, in the shape of collars, is present around the big roots that collect and conduct the stemflow into the soil. On the contrary, patches and collars are absent in the soil under firs. To understand the role of the two species in the formation of the bleached material, throughfall, stemflow and forest floor solutions were collected for pine and fir. For pine, the stemflow moving along a wide bark channel was collected separately. All these solutions plus the rainfall were obtained and analysed seasonally for 1 year. Also, a number of profiles were excavated in the vicinity of the trunk base of pines and firs. Two profiles were selected for sampling and for the attendant analyses. The results indicate that under silver fir, the processes induce in the formation of an A horizon. The Corsican pine, on the other hand, in 50 years, has been able to produce, even if in small areas, a separate pedogenic process responsible for the bleaching of an existing A horizon. Because the bleaching process is at an initial stage, the chemical differences between the E material and the surrounding A horizon are small. Nevertheless, the E material is poorer in organic matter and in the most mobile inorganic elements than the A horizon. The presence of E material exclusively at the trunk base of the pines is due to the strong acidity of the stemflow — about 30-times higher than that of the fir. The most evident differences between the soils under pine and fir concern the features more directly related to the dynamics of the soil organic matter. Mineral assemblage, which needs longer time for its evolution, is very similar in the two soils; nonetheless a small amount of pedogenic smectite has been recognized in the E material.

根域制限したブドウ「巨峰」樹の休眠期から開花期に至る炭水化物と窒素栄養の変化

Changes in carbohydrates and nitrogenous compounds in 'Kyoho' grapevines, grown under restricted rooting-zone conditions and in non-restricted conditions (control), were analysed during winter dormancy until full bloom. There were no significant differences in levels of sugars and starch, and total-N between the treated and control during winter dormancy. At bud-burst, however, vines with restricted rooting-zone contained more sugars in small roots but lower N level in the trunk and cane, compared to those with unrestricted rooting volume. Similar trends were observed in xylem sap collected from the trunk base at bud burst, young shoots disbudded 2 and 3 weeks after bud burst, and shoots and flower clusters at full bloom. Relationships between the nutritional status and retarded shoot growth, accompanied with improved berry set, in vines grown under restricted rooting-zone are discussed.

Chaenotheca olivaceorufa (Caliciales) New to North America

The lichen Chaenotheca olivaceorufa Vainio collected in California, Oregon, and Washington is here reported new for North America. The ecology of the species is discussed briefly and a map showing its known world distribution is provided. During a botanical excursion to California organized by the Department of Botany, University of Helsinki in 1992, the author collected Chaenotheca olivaceorufa Vainio, not earlier reported from North America. Since then the species has also been found from several localities in western Oregon and Washington. Chaenotheca olivaceorufa is a small species, but easily recognized even in the field by its flexuous, often grouped ascomata and a protruding mazaedium commonly extending as a column far beyond the edges of the apothecium (Fig. 1). The edges of the excipulum and the lower side of the capitulum are pruinose. The pruina is yellow in young apothecia and reddish brown in older ones. Ascospores are spheric, more or less smooth, and rather small (3.2)3.5-4.2(4.8) aim. The thallus is immersed, but may often give the substrate a greenish brown coloration. Chaenotheca olivaceorufa differs from most species of the genus in being lichenized with Trentepohlia. North American specimens agree well with previously described material, albeit having slightly larger spores. For a more detailed description, see Tibell (1983, 1987, 1996). Chaenotheca olivaceorufa occurs mainly on lignum and dead, rotten bark in shaded forests. All North American localities are from low elevations (50-260 m), from conifer forests and mixed hardwood-conifer forests. Large populations have been seen in decorticated basal crevices of old, living trees (Acer macrophyllum, Picea sitchensis, Taxus brevifolia) and on large snags (Pseudotsuga menziesii, Sequoia sempervirens). It has also been found on conifer bark, on the basal trunks of Abies grandis, Picea sitchensis, Pseudotsuga menziesii, Taxus brevifolia, and Tsuga heterophylla. Other species of Caliciales s.lat. (Tibell 1984) from the same microhabitats have included Calicium adspersum Pers., C. salicinum Pers., Chaenotheca brachypoda (Ach.) Tibell, C. chrysocephala (Ach.) Th. Fr., C. chlorella (Ach.) Mtill. Arg., C. ferruginea (Turner & Borrer) Mig., C. furfuracea (L.) Tibell, C. hispidula (Ach.) Zahlbr., C. hygrophila Tibell, C. stemonea (Ach.) Mtill. Arg., C. trichialis (Ach.) Th. Fr., Chaenothecopsis consociata (Nfidv.) A. E W. Schmidt, C. debilis (Sm.) Tibell, C. savonica (Raistinen) Tibell, C. ussuriensis Titov, Cybebe gracilenta (Ach.) Tibell, Cyphelium inquinans (Sm.) Trevis., Microcalicium disseminatum (Ach.) Vain., and Stenocybe clavata Tibell. Also branched groups of pycnidia, similar to those of Chaenothecopsis viridireagens (Nidv.) A. E W. Schmidt have been present in some specimens (Tibell 1993). Chaenotheca olivaceorufa and C. hispidula are among the few Chaenotheca species that are lichenized with Trentepohlia. In Oregon, they often occur in the same low elevation forests as Sclerophora farinacea (Chevall.) Chevall., S. peronella (Ach.) Tibell, and Chaenothecopsis rubescens Vainio, which also are associated with Trentepohlia. All of these species are characteristic of mature Pseudotsuga-Quercus woodlands and riparian hardwood stands in the Willamette Valley. The Trentepohlia photobionts of temperate and tropical Caliciales may be relatively sensitive to low temperatures. Thus, minimum temperatures could be important in explaining their restriction to low elevations and oceanic sites at higher latitudes (Rikkinen 1995). The total range of Chaenotheca olivaceorufa covers temperate, subtropical, and tropical regions (Tibell 1994). It has been collected from Australasia and the Neotropics, and seems to be particularly common on the North Island of New Zealand (Tibell 1983, 1987, 1996). In tropical South America its range also extends to the Atlantic Coast. In the Northern Hemisphere it has been reported from the southernmost Kuril Islands (Titov 1991) and now from western North America. As it seems to be widespread on both sides of the Pacific and also occurs in tropical lowlands, it may well have a circum-Pacific distribution (Fig. 2). Among other lichens, some taxa in Coccotrema, Placopsis, and Turgidosculum show such distribution patterns (Galloway 1991). Specimens examined.--U.S.A. CALIFORNIA. Mendocino Co., Rikkinen 92065. Humbolt Co., Rikkinen 98245. OREGON. Benton Co., Rikkinen 97124, 97125, 97207, 97215, 97341, 98367; Peterson 2805. Curry Co., Rikkinen 0007-2745/98/558-559$0.35/0 This content downloaded from 157.55.39.217 on Mon, 18 Apr 2016 08:40:04 UTC All use subject to http://about.jstor.org/terms 1998] RIKKINEN: CHAENOTHECA OLIVACEORUFA 559

Effects of early season defoliation on above-ground growth ofAnthyllis cytisoides, a Mediterranean browse species

Anthyllis cytisoidesL. is a traditional forage species, well adapted to grazing pressure, and so might be expected to respond positively to moderate grazing. We performed a hierarchical design analysis of variance with three levels of plant defoliation (10, 50 and 90%) and three of stem defoliation (10, 50 and 90% of shoots removed), in three age classes based on trunk base perimeter (≤11cm, 11–20cm and >20cm). Response to herbivory was measured as total vegetative length, inflorescence length, leaf number, flower number, and the ratio of the number of floral axes to the total number of axes.We found thatA. cytisoidescompensated for herbivory. That is, above-ground growth ofA. cytisoidesincreased with the percentage of plant defoliation, with respect to elongation of the stem and increase in the total flower and leaf number. In contrast, growth following stem defoliation declined in the target stem as stem defoliation increases. Stem defoliation effect was more evident in young plants than in older ones. The increase in plant growth with plant defoliation was seen both in the average growth per floral axes and the number of floral axes per stem. However, only the number of floral axis per stem was responsible for the reduction in stem productivity with experimental defoliation.Stem overcompensation (greater elongation in defoliated stems than control) occurred only in stems suffering 10% defoliation when plants were under medium and high experimental herbivore pressure, indicating the ability ofA. cytisoidesto produce a compensatory response to herbivory. The growth consequences of early season defoliation persist after two growing periods, increasing above-ground growth differences among treatment groups.

The lichen flora on Picea abies in a suboceanic spruce forest area in Central Norway with emphasis on the relationship to site and stand parameters

The lichen flora on 400 Picea abies trees (branches, trunks and trunk bases) in 100 patches of suboceanic spruce forest in Central Norway has been investigated. Relationships between occurrence of the species and a number of habitat and tree variables were analysed by detrended correspondence analysis (DCA). A total of 122 lichen species were recorded. Total species number was found to be about the same on branches and trunk bases (considerably lower on trunks), but with higher β‐diversity on trunk bases. Most species could be classified as branch specialists, generalists, trunk or trunk base specialists. Among the measured habitat variables, stand age, altitude and vegetation type were found to be the most important for explaining the patterns of species distributions. Alectoria sarmentosa, Mycoblastus sanguinarius and several dry bark species on trunks, including Caliciales species, were more or less confined to old forests, while Usnea spp. were more abundant in young form. Trentepohlia‐containing trunk base species like Arthonia vinosa, Dimerella pineti, Lecanactis abietina and Sclerophora coniophaea showed preference for vegetation types indicating nutrient‐rich substrates. The number of branch species was highest on lower altitudes while the opposite was true for trunk species. Larger trees with rough bark in older stands had a more species‐rich lichen flora, probably because of higher substratum area and availability of more diverse microsites.

Echocardiographic assessment of pulmonary blood supply in patients with pulmonary atresia and ventricular septal defect

The purpose of this study was to determine the role of high resolution two-dimensional echocardiographic imaging and color flow Doppler study in assessing the pulmonary blood supply in patients with pulmonary atresia and ventricular septal defect (VSD). Although echocardiography is a well established technique for assessing central pulmonary arteries in pulmonary atresia VSD and for determining the presence or absence of a patent arterial duct, few data are available on its role in patients whose source of blood supply is from collateral vessels. Forty-two patients aged a few hours to 19 months (mean 29 days) were prospectively assessed by high resolution echocardiography, including color flow Doppler study, during a 4-year period ending in 1994, before any intervention other than intravenous administration of prostaglandins. Angiographic confirmation was available in 29 patients, including 18 (95%) of 19 with aortopulmonary collateral channels. A patent arterial duct was correctly identified as the sole source of pulmonary blood supply in 23 patients, whereas aortopulmonary collateral channels were detected in 19, with one of these having a small patent arterial duct and collateral channels. The patent arterial duct originated from the undersurface of the aorta in 16 (67%) of 24 patients and from the base of the brachiocephalic trunk in 7 (33%) of 24. All patients with a patent ductus as the sole source of pulmonary blood supply had confluent pulmonary arteries. Nonconfluent pulmonary arteries were present in six patients, with all but one having aortopulmonary collateral channels as the sole source of pulmonary flow. Aortopulmonary collateral channels were direct in 17 (89%) of 19 patients, whereas in 2 (11%) of 19, both direct and indirect collateral channels were present. Color flow Doppler study was accurate in determining the presence or absence, the side and the origin of the collateral channels in all patients, with the correct number being determined in 12 (67%) of 18. "Wash-in" to the hilar pulmonary arteries (retrograde color flow) was seen in 12 (92%) of 13 patients with collateral channels and confluent pulmonary arteries. Failure to identify a tiny central pulmonary artery occurred in one patient. High resolution imaging and color flow Doppler study provide good appreciation of the source of pulmonary blood supply in neonates and young infants with pulmonary atresia VSD.

Epiphyte Flora and Diversity on Basal Trunks of Six Old-Growth Forest Tree Species in Southern and Middle Boreal Finland

Epiphytic lichen and bryophyte species composition, richness and diversity were surveyed on basal trunks of six common old-growth forest tree species, Picea abies, Pinus sylvestris, Betula pendula, Alnus incana, Salix caprea and Populus tremula, in two old-growth forest areas, one in southern and one in middle boreal Finland. The average species numbers per tree ranged from 18 (Picea) to 27 (Salix) in the southern and from 20 (Populus) to 31 (Salix) in the middle boreal area. A few widespread habitat-generalist species, such as the foliose lichens Hypogymnia physodes and Platismatia glauca, were most abundant on all the tree species, except Populus. Most other epiphyte species showed at least a slight preference for one or two tree species. Populus proved to have the most distinct flora characterized by the abundance of certain, rather specialized crustose lichens and bryophytes. The number of species that occurred on only one tree species was highest on Populus (9) in the southern and on Alnus (18) in the middle boreal area. Differences in bark acidity and structure were the most likely explanations for the differences between tree species in the epiphytic flora and diversity. Salix and Populus were the most important of the tree species studied for the conservation of epiphyte diversity in the boreal forests of Finland.

EPIPHYTE FLORA AND DIVERSITY ON BASAL TRUNKS OF SIX OLD-GROWTH FOREST TREE SPECIES IN SOUTHERN AND MIDDLE BOREAL FINLAND

Epiphytic lichen and bryophyte species composition, richness and diversity were surveyed on basal trunks of six common old-growth forest tree species, Picea abies, Pinus sylvestris, Betula pendula, Alnus incana, Salix capreaand Populus tremula, in two old-growth forest areas, one in southern and one in middle boreal Finland. The average species numbers per tree ranged from 18 ( Picea) to 27 ( Salix) in the southern and from 20 ( Populus) to 31 ( Salix) in the middle boreal area. A few widespread habitat-generalist species, such as the foliose lichens Hypogymnia physodesand Platismatia glauca, were most abundant on all the tree species, except Populus. Most other epiphyte species showed at least a slight preference for one or two tree species. Populusproved to have the most distinct flora characterized by the abundance of certain, rather specialized crustose lichens and bryophytes. The number of species that occurred on only one tree species was highest on Populus(9) in the southern and on Alnus(18) in the middle boreal area. Differences in bark acidity and structure were the most likely explanations for the differences between tree species in the epiphytic flora and diversity. Salixand Populuswere the most important of the tree species studied for the conservation of epiphyte diversity in the boreal forests of Finland.

Life History Comparisons of Ground‐ and Canopy‐Nesting Populations of Ochrogaster lunifer Herrich‐Schaffer (Lepidoptera: Thaumetopoeidae): Evidence for Two Species?

ABSTRACTPopulations of Ochrogaster lunifer Herrich‐Schaffer display different larval behaviours (ground‐nesting and canopy‐nesting), suggesting the existence of two or more species. Here, the behaviour and biology of ground‐nesting populations are described from extensive surveys in southeastern Queensland. Females oviposit at the base of the host tree, covering the eggs with scales from the anal tuft. The larvae are processionary and pass through eight instars. First instars do not feed, remaining at the base of the tree trunk within the scale mass. Second instars ascend the tree in single file in the morning to feed in the canopy each day, returning to the scale mass after several hours. Later instars feed only at night. Six new host plants are recorded: five species of Acacia, and one species of Casuarina. Predators and parasitoids recorded on 0. lunifer included chalcidoids, dermestids, tachinids and a predatory pyrrhocorid bug. The results of the study highlight a number of major differences between ground‐nesting and canopy‐nesting populations. Differences include habitat and geographical distribution; host plant range; number of instars; size and colour of final instar; size of adult female; oviposition site and larval behaviour. These differences provide further evidence for the existence of two species.

Importance of spruce swamp‐forests for epiphyte diversity and flora on Picea abies in southern and middle boreal Finland

The epiphyte (lichens and bryophytes) species richness, diversity and composition on basal trunks of Picea abies in spruce swamp‐forests were compared to adjacent mesic forests on mineral soil in two southern and two middle boreal sites in old‐growth forest patches in Finland. The sampling was carried out along four line transects parallel to swamp‐forest margin: 1) in the spruce swamp‐forest, 2) at the swamp‐forest margin, 3) on mineral soil c. 10–20 m off the swamp‐forest margin and 4) on mineral soil at least 50 m off the swamp‐forest margin. In the two southern boreal sites there was a decreasing trend in the average species number per tree from the trees in swamp‐forests (21–25 species) to the trees on mineral soil (17–18 species), whereas in the two more humid and virgin middle boreal sites a similar trend was not detected (25–28 species on all trees). There were no major differences in the epiphyte flora between the locations or study sites; the dominant species occurred on nearly all sample trees. The crustose lichens Cliostomum leprosum, Arthonia leucopellaea and Lecanactis abietina were the most common species that were mainly confined to the swamp‐forests in the southern boreal sites, C. leprosum also in the middle boreal sites. In addition, several rare species occurred exclusively on the swamp‐forest trees. Lecanactis abietina extended significantly higher on the swamp‐forest trees than on the trees on mineral soil in the southern boreal sites. The spruce swamp‐forests proved to be one of the most important habitats for maintaining the epiphyte diversity in the boreal forest landscape.

Leaf Contamination by Atmospheric Pollutants as Assessed by Elemental Analysis of Leaf Tissue, Leaf Surface Deposit and Soil

In order to evaluate the influence of air pollutants influx on leaf elemental composition, the concentration of N, S, Cu, Fe and Pb were analyzed in the surface deposit and tissue of Quercus ilex L. leaves from 8 sites of the urban area of Naples. The soil from the trunk base area of Q. ilex trees in the same sites was also analyzed for total contents of N and S and for available contents of Cu, Fe and Pb. In the leaf surface deposit S content was high though significantly (P < 0.001) lower than in the leaf tissue, whilst N was not detectable. Cu, Pb and Fe contents in leaf surface deposit were conspicuous. The Pb content was higher in the leaf surface deposit than in the leaf tissue. No correlation between leaf tissue and surface deposit contents was found for S or for Fe. By contrast, positive and significant correlations (P < 0.01) were found between leaf deposit and leaf tissue for both Cu and Pb. N and S contents in the leaves were not correlated to the respective contents in the soil and the same was also found for Cu and Fe. In contrast with the presence of limiting concentrations in the soil, N, S and Fe leaf contents were significantly higher than in the leaves from remote sites. The data suggest that direct uptake of airborne pollutants, in addition to root absorption, may influence leaf elemental composition of Q. ilex L. leaves.

Trace metal biomonitoring in the soil and the leaves of Quercus ilex in the urban area of Naples.

The concentrations of Pb, Cu, Fe, and Mn were analyzed in surface deposit and tissue of Quercus ilex leaves from several sites of the urban area of Naples, exposed to different degrees of air pollution. These included some major roads with heavy traffic loads, squares, and three urban parks. The soil from the trunk base area of Q. ilex trees in the same sites was also analyzed for total and available metal contents. Pb, Cu, and Fe contents in the surface deposit and leaf tissue were significantly higher (p < 0.01) in leaves from roadside sites than in leaves from parks; significant correlations were found between deposit- and tissue-contents of Pb, Cu, and Fe. Mn content in leaves from roadside sites and in leaves from parks were similar and Mn content in the leaf deposit was irrelevant. Significant differences (p < 0.001) in both total and available Pb and Cu soil content were found between sampling sites. Also for available Fe and Mn soil content differences among sites were relevant, although the highest values were measured in soil from urban parks. A positive correlation between leaf and soil metal content was found only for Pb, thus suggesting that trace metal contents of leaves directly depend on atmospheric depositions. Seasonal variations of Pb, Cu, and Fe were pronounced at a polluted site, whereas no relevant seasonal variation was observed at a control site; moreover, metal accumulation was high at the polluted site. Mn content and seasonal dynamics were comparable at control and polluted sites.

Fossil Arbuscular Mycorrhizae from the Early Devonian

The 400 million-year-old Rhynie chert has provided a wealth of information not only of early land plants, but also of the fungi that inhabited this paleoecosystem. In this paper we report the first unequivocal evidence of arbuscules in an endomycorrhizal symbiosis. A new genus, Glomites, is characterized by extraradical, aseptate hyphae with a two-parted wall, and an intraradical, highly branched network of thin-walled hyphae. Hyphal branches produce terminal, elongate-globose multilayered spores that lack a basal septum. Other hyphae penetrate cell walls and form arbuscules. Arbuscules are morphologically identical to those of living arbuscular mycorrhizae (AM) in consisting of a basal trunk and highly dichotomous distal branches that form a bush-like tuft. Arbuscules are confined to a narrow band of specialized thin-walled cells in the outer cortex that continue to be meristematic. Features of the fossil biotroph are compared with those of extant arbuscular mycorrhizae. Although interpretations regarding the evolution of mycorrhizal mutualisms continue to be speculative, the demonstration of arbuscules in the Early Devonian indicates that nutrient transfer is an ancient phenomenon that may have been in existence when plants invaded the land.

Size-dependent Allometry of Tree Height, Diameter and Trunk-taper

The allometry of tree height with respect to trunk diameter and the allometry of trunk diameter with respect to distance from the top of the tree (i.e. trunk taper) were determined for 27 Robinia pseudoacacia trees differing in age and size growing in an open field. The allometric (scaling) exponent for height was > 1 for small and young trees and decreased to 2/3 and then 1/2 as tree size and age increased. Similarly, the exponent for taper was > 1 near the tips of young and old trunks and converged onto values of 2/3 and 1/2 toward the base of mature tree trunks. These observations indicate that a single 'optimal mechanical design principle' (i.e. elastic, stress or geometric self-similarity) neither holds true throughout the lifetime of R. pseudoacacia trees, nor does a single design principle govern the taper of a trunk throughout its entire length. Rather, over the course of growth and development, the allometry of R. pseudoacacia tree height and trunk taper progressively changes, complying with geometric self-similarity for young plants (and young portions of old plants) and subsequently giving the appearance of elastic or stress self-similarity as plants (or portions of plants) get older and therefore larger. Analyses of published (and new) data suggest that the conclusions drawn for R. pseudoacacia trees are likely to hold true for other tree species because stem growth in diameter is 'indeterminate' whereas growth in overall tree height is asymptotic and therefore essentially 'determinate'.

Four hundred-million-year-old vesicular arbuscular mycorrhizae.

The discovery of arbuscules in Aglaophyton major, an Early Devonian land plant, provides unequivocal evidence that mycorrhizae were established >400 million years ago. Nonseptate hyphac and arbuscules occur in a specialized meristematic region of the cortex that continually provided new cells for fungal infection. Arbuscules are morphologically identical to those of living arbuscular mycorrhizae in consisting of a basal trunk and repeatedly branched bush-like tuft within the plant cell. Although interpretations of the evolution of mycorrhizal mutualisms continue to be speculative, the existence of arbuscules in the Early Devonian indicates that nutrient transfer mutualism may have been in existence when plants invaded the land.

Foraging behavior of Black-backed and Three-toed woodpeckers during spring and summer in a Canadian boreal forest

During one spring to summer study in a Canadian boreal forest, Black-backed Woodpeckers (Picoides arcticus) were found to excavate mainly on logs and at the base of large-diameter tree trunks. In contrast, Three-toed Woodpeckers (Picoides tridactylus) preferred higher strata and smaller diameter trunks. The predominant foraging technique used by Three-toed Woodpeckers was bark scaling. Canadian Three-toed Woodpeckers showed foraging behavior similar to that found in European woodpeckers, but in the Nearctic range they have not fully developed the sap-licking behavior that is typical of the Three-toed Woodpeckers of the western Palearctic range.

Reproductive Ecology of Magnolia schiedeana (Magnoliaceae), a Threatened Cloud Forest Tree Species in Veracruz, Mexico

DIERINGER, G. AND J. E. ESPINOSA S. (Instituto de Ecologia, A.C., Apartado Postal No. 63, KM. 2.5 Antigua Carretera a Coatepec, 9 1000 Xalapa, Veracruz, Mexico). Reproductive ecology of Magnolia schiedeana (Magnoliaceae): a threatened cloud forest tree species in Veracruz, Mexico. Bull. Torrey Bot. Club 121: 154-159. 1994.-Flowering among three study populations of Magnolia schiedeana Schlecht. (Magnoliaceae) varied considerably, beginning in January or February and continuing for 2 to 4 months. The variability in time of flowering led to very low fruit production in some populations when not coincident with pollinator emergence. Flowers produced a strong fruity fragrance, were functional for one day, protogynous (opening in the morning and becoming male the same afternoon), and self-compatible. Pollinators were beetles, Stenagria sp. (Staphylinidae) and Cyclocephala jalapensis (Scarabaeidae), that entered flowers at night and remained throughout the next day engaged in a variety of behaviors (copulation and feeding on pollen and petal tissue). Cyclocephala jalapensis, a regional endemic, is closely associated with cloud forest habitat and appears dependent on M. schiedeana for adult nutrition. Magnolia schiedeana therefore seems to possess a more specialized pollination system than temperate Magnolia species. All three populations experienced some degree of previous disturbance (cutting) and exhibited very low fertility. The average tree produced 1 flower per day, 2-4 flowers during the season, and 1 fruit. Regeneration of populations was primarily by resprouting of roots and trunk bases and not seedling recruitment. Future existence of M. schiedeana within Veracruz is jeopardized by deforestation brought about by a large human population struggling for basic necessities.