Mesic Hardwood Forests Research Articles

Stimulus selection (light) in four subspecies of deermice(Peromyscus maniculatus)

Abstract Four subspecies of deermice (Peromyscus maniculatus) were selected from habitats along a gradient from mesic hardwood forests (gracilis), tall grass prairie (bairdi), short grass prairie (nebrascensis), to desert grassland (labecula) in effort to relate the light preferences of the mice to the habitat of their origin. Six individuals of each subspecies were maintained in dark chambers for 25 days, during which they could turn on a dim light for 30 seconds on ten of these days. Mice from the mesic habitats turned the lights on more frequently (light reinforcement) than mice from xeric habitats. The same subspecies that exhibited light reinforcement when raised in laboratory light conditions failed to show light reinforcement when raised in total darkness. The circadian periodicities also differed significantly among the subspecies. Conclusions drawn from the results were: (1) selection for light is genetically influenced as indicated by subspecific differences, (2) some genotypes are readily modif...

Biomasa i ciężary atomowe pierwiastków w zespole drobnych ssaków

Na dwóch powierzchniach polskiej metody Standard Minimum założonych w nizinnym, mezotroficznym lesie liściastym (Południowa Karolina, USA) łowiono osobników Blarina brevicauda, Peromyscus gossypinus i Ochrotomys nuttalli. Analizowano zawartość wapnia, potasu, sodu, magnezu, żelaza i cynku w ciele zwierząt. Stwierdzono, że zawartość tych pierwiastków (Tabela 1) oraz ich ciężary atomowe (Tabela 2) z wyjątkiem żelaza, były zasadniczo jednakowe dla każdego gatunku (zawartość w ppm suchej masy: Ca-37100; K-16700; Na-3690; Mg-1324; Fe-220-500; Zn-120) (Tabela 1).

A Pollen Diagram from Mud Lake, Marion County, North-Central Florida

Six pollen zones are described from a 1360-cm profile of sediments from a lake in north-central Florida. Zone Ml, at the top, has pollen predominantly of Pinus (pine) with some Quercus (oak) and other broad-leaved trees. It extends from the present back to 5070 ± 150B.P., and it represents a vegetation of sand-pine scrub, as today. Zone M2 has high Quercus percentages with much pollen of herbs, shrubs, and aquatics. It represents a sclerophyllous oak scrub or dry forest; it is dated at 8260 ± 200 B.P. at its base. Beneath zone M2 is a sand layer that marks a major hiatus, for the sediment immediately beneath it is over 35,000 years old. At this time the lake was dry, probably because the water table was lowered as a result of eustatic depression ofsea level during Wisconsin glaciation. Zone M3 below the sand layer resembles zone M2, so it must also reflect a warm-temperate climate, presumably of Sangamon age. Zone M4, with dominantly pine pollen, is also assigned t o the Sangamon. Zone M5 has abundant Quercus, Carya (hickory), and Liquidambar (sweet gum), and zone M6 has predominant Pinus with a trace of Picea (spruce). Both zones include Acer saccharum type (sugar maple), Fagus (beech), Tilia (basswood), and Carpinus type (hornbeam); they represent mesic hardwood forest, tentatively assigned to the time of the Illinoian glaciation.