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ECOLOGICAL AND ECONOMICAL IMPORTANCE OF OSTRYA CARPINIFOLIA IN SLOVENIA. The paper treats of the spread of Ostrya carpinifolia Scop., its appearance in various phytocenoses, its ecology, and its forestry problems in Slovenia.

OSTRYA CARPINIFOLIA - ASSOCIATIONS IN SOUTH TYROL. The article describes the floristic variation of Ostrya-stands in South Tyrol, in relation with soil types and human action.

THE OSTRYA-ASSOCIATIONS IN THE SUBMEDITERRANEAN VEGETATION COMPLEXES. In Italy and in the neighbouring countries, a dozen landscape systems have been described. Several of them including wood-associations with dominating Ostrya carpinifolia. The ecological optimum of Ostrya can be identified with the areas where Ostrya is most frequent i.e. SE-Alps and N-Apennines. Ostrya also appears in Southern Italy, but it is rare and segregated in marginal habitats. It may be assumed that Ostrya associations are primary only in these last habitats, while the diffused Ostrya formations of SE-Alps and N-Apennines can be regarded as secondary.

Three pollen spectra from lake sediments stratigraphically well below mid-Kansan fauna indicate plant associations for the Sonoran desert, Arizona, approximating those found now at elevations of 1500 ft and more above the desert floor. The presence of Ostrya, Betula, and Artemisia may indicate some invasion by northern species as well. A climate cooler or wetter, or both cooler and wetter, than the present climate is inferred from paleobotanical and sedimentary evidence. Correlation with the Nebraskan glacial stage is tentatively suggested.

PEET, R. K. (Dept. Biol., Univ. N. Carolina, Chapel Hill, NC 27514). Twenty-six years of change in a Pinus strobus, Acer saccharum forest, Lake Itasca, Minnesota. Bull. Torrey Bot. Club 111: 61-68. 1984.-A 0.48 ha permanent plot located in a mesic Pinus strobus dominated forest was remapped after 26 years. Pinus remained the dominant species in basal area and had the lowest mortality rate of any major tree species. The understory was dominated by Acer saccharum, Tilia americana, and Ostrya virginiana, all of which had high mortality rates. Establishment of numerous new stems resulted in a net gain in Ostrya and Tilia density whereas Acer declined substantially. Populations of the shade intolerant Populus tremuloides, P. grandidentata, and Betula papyrifera, which appear to have become established following mild surface fires in the late 1800's, all had high mortality. The shiort-term prognosis is a stable Pinus strobus canopy, loss of Populus and Betula, and a steady enrichment of the understory with Ostrya and Tilia. Acer should remain important but continue to decline in relative density. The long-term outlook is uncertain owing to the increasing probability of catastrophic breakup of the pine canopy.

Scanning electron microscopy was used to examine foliar surface features such as cuticular patterns, epicuticular wax, and trichome types in species ofAlnus, Betula, Carpinus, Corylus, andOstrya. Six trichome types are recognized in this survey, four non-glandular (acicular, filiform, aduncate, subulate) and two glandular (stipitate gland and peltate scale). The distribution of these trichomes among the genera supports the recognition of two tribes, Betuleae (Alnus andBetula) and Coryleae (Carpinus, Corylus, andOstrya). Trichome morphology can be an important supportive taxonomic character in determining evolutionary relationships.

Slashing for the production of browse is today a standard game management practice. In New England and New York, much of the best game range is on lands formerly in agriculture now reverting to forest. Some areas are stocked with stands in which the proportion of inferior hardwoods is undesirably high. They may result from the pioneer forest community invading grassland or from excessive cutting. Of the Northern Hardwoods, aspen, grey birch, and red maple are persistent and aggressive sprouters. When clear-cut, vigorous stumps of these species produce an abundance of coarse sprouts of low palatability. The sprouts often are 3 feet tall at the end of the first season and in 3 to 5 years grow to such size as to furnish little browse. Slashings in such stands are costly to maintain and the effect of frequently repeated cuttings upon plant succession and upon the soil is not well understood. A tract of second-growth hardwood on the writer's forest at Stephentown, New York, was marked for improvement in the fall of 1935. This area is a spring to early winter range for deer, the animals remaining until the first deep snow. The stand was 20-30 years old, with 1,000 stems per acre ranging from 2 inches to 9 inches d.b.h. By number, 35 per cent were better hardwoods (ash, red oak, sugar maple, black cherry, yellow birch) and 65 per cent were inferior hardwoods (Ostrya, soft maple, aspen, grey birch), with abundant advance reproduction of sugar maple and a scattering of small hemlock. A crown thinning, aimed to free all satisfactory trees, removed 25 per cent of the stems, chiefly grey birch and soft maple. The effect of this winter thinning upon browse production was astonishing. The additional light stimulated the growth of herbs and ferns without encouraging coarse annuals or grasses. The stumps sprouted much less vigorously than did those exposed to full sunlight. Sprouts were mostly less than 18 inches tall and much slimmer than

Kirchner Marsh and Lake Carlson are located 3 miles apart in Dakota County about 15 miles south of Minneapolis in the St. Croix moraine, which was formed by the Superior lobe during the Cary phase of the Wisconsin glaciation. During the Mankato phase that followed, the Des Moines lobe advanced to within a few miles of the sites. The region today is in a mixed-oak forest, with a maple-basswood forest 15 miles to the west and a re-entrant of the prairie on the sand plain south of the moraine. The general limit of coniferous trees is about 50 miles northeast of the sites, although outliers, especially of Pinus strobus, may be found along the Mississippi Valley a few miles to the east. One sediment core 12–13 m long from each site was analyzed for pollen content at 5–25-cm intervals. Diagrams based on percentage of total pollen (trees, shrubs, wind-pollinated herbs) show essentially identical sequences at the two sites, starting with the late-glacial phase of ice retreat. The diagrams have been subdivided into pollen zones according to the A-B-C sequence introduced by Deevey for New England. The late-glacial pollen record starts at Kirchner Marsh with a short Picea-Cyperaceae-Gramineae phase (Zone K), believed to represent a spruce parkland. Its C-14 date of 13,270 BP and the stratigraphy indicate a pre-Two Creeks and post-Cary correlation. Apparently the Kirchner site did not become established as a lake until this time owing to persistence of dead ice in the moraine. The absence of pollen of specific tundra indicators and the presence of pollen of such thermophilous plants as Fraxinus, Quercus, Corylus, Ambrosia, Humulus, and Typha latifolia imply that the climate was cool rather than cold. Zone A-a, which follows, correlates with the Two Creeks interstade. It is marked by the dominance of Picea, with appreciable percentages of Fraxinus and Ambrosia and with minor amounts of other thermophilous plants and the normal boreal associates of spruce like Betula, Larix, and Salix. Zone A-b, starting 12,050 C-14 years ago, correlates with the Valders ice advance. It is represented at both Kirchner and Carlson and shows the withdrawal of Fraxinus and Ambrosia and the slight rise of Artemisia. Except for the absence of pine in the late-glacial assemblage the vegetation implied by these three zones seems to have its closest modern counterpart in the southern fringe of the Boreal Forest of the Riding Mountain region of southwest Manitoba. It is concluded that pine did not migrate southward with the spruce during the Wisconsin glaciation, at least in the western Great Lakes region, and was thus eliminated from this region. During the late-glacial phases of ice retreat, herbs and spruce pioneered on the deglaciated terrain; pine did not follow until the destruction of the spruce forest at the end of the late-glacial phase. Zone B introduces postglacial time. It represents the time of rapid vegetational succession following the deterioration of the spruce forest. Simultaneous maxima of Betula, Alnus, Fraxinus, and Abies occurred 10,230 years ago at Kirchner Marsh. These were followed rapidly by a Pinus maximum and then a rise of Ulmus, Quercus, and other deciduous types, dated as 9300 years ago at the correlative site of Madelia. This succession may represent differential rates of migration from refuges south and east of Minnesota. Deciduous trees dominate the C Zones. Zone C-a shows Ulmus and Ostrya/Carpinus followed by Quercus; it probably represents principally a mesic maple-basswood forest changing to oak. Zone C-b represents the advance of prairie into the region at the expense of the oak woodland or savanna. The large and abrupt fluctuations in the curves for Ambrosia-type and Chenopodiineae, especially at the Carlson site, may record encroachment of annual weeds onto intermittently dried lake bottoms. C-14 dates place Zone C-b between 7100 and 5100 years ago. In Zone C-c the Quercus again dominates until the abrupt increase in Ambrosia-type and Chenopodiineae that marks the time of forest clearance and land settlement 50–75 years ago.