Notes on Some Ohio Lizards

Author Institution: Dayton Museum of Natural History, Dayton, Ohi

Arthropod Faunas of Monocultures and Polycultures in Reseeded Rangelands

Sap-feeding and predaceous arthropod faunas of forage bunchgrasses in reseeded rangeland vegetation were examined. Four major species of sap feeders were found; the major predators were spiders. Grass monoculture had very high densities of sap feeders compared with grass biculture, shrub-grass, tree-grass, and native areas; this was reflective of the large contribution from the mirids Irbisia brachycera Uhler and Conostethus americanus (Knight). They were present during the leaf stages of crested wheatgrass when it had its lowest carbohydrate root reserves. Homoptera and predator densities were not significantly related to the pattern of vegetation. The lowest number of sap-feeder species occurred in the grass monoculture, and sap-feeder faunas in this plot were dissimilar to those of all other plots. One-season dispersal experiments did not support the hypothesis that grass density caused the differences between arthropod faunas in different vegetation, whereas big sagebrush, common in reseeded pastures, repelled I. brachycera during short-term dispersal. The data indicate that reseeding to monocultures may result in high densities of Miridae during the leaf stages compared with moderate densities of Homoptera during the flower and seed stages in bicultures. The implications for pest management are discusse

Spider Community Organization : Seasonal Variation and the Role of Vegetation Architecture

The relationship between vegetation architecture and spider community attributes were examined in a big sage community. Spiders were separated into guilds using similarities of species\u27 hunting behavior. Shrub architecture was experimentally manipulated in the field by either clippings 50% of the shrub\u27s foliage to decrease foliage density or tying together a shrub\u27s branches to increase foliage density. Shrub perturbations resulted in changes in the number of spider species, spider guilds and guild importance values. The number on spider species and guilds in the tied shrubs were significantly higher than those in the clipped or control shrubs sampled. Spider species diversity and the number of species and guilds were positively correlated with indicators of shrub volume and shrub foliage diversity. This suggests that structurally more complex tier shrubs can support a higher number of spider species and species diversity. Temporal patterns of the number of spider species, and species diversity showed midsummer peaks in both 1974 and 1975. Evenness remained relatively constant through both seasons. The data suggest that architectural properties of habitat may be an important determinant of the distribution and species diversity of predatory invertebrates

Herbivorous mammals along a montane sere: Community structure and energetics

All common herbivorous mammals were censused along a successional gradient in northern Utah in order to assess some of the changes in ecosystem attributes predicted to occur by Odum (1969). Biomass (B) and energy flow [Production (P), Respiration (R), and P + R (E)] through each of nine species in each of four seral stages (montane meadow, Populus-dominated forest, Abies-dominated forest, and Picea-dominated forest) were estimated. Tests of eight predicted trends were supportwe in five cases (P/R ratio, P/B ratio, B/E ratio, net community production, and species richness), inconsistent in two cases (total organic matter and species evenness/general diversity) and ambiguous in one (size of organism). Community stability, as measured by changes in average community biomass between years of relatively normal and extremely low precipitation, increased with ecosystem maturity. Individual species, however, fluctuated greatly in biomass between the 2 years. Our results are consistent with the hypothesis that mammals are determinants of successional patterns only insofar as they affect plant colonization. However, a continuum probably exists between completely passive species and those that strongly influence successional patterns in plant communities through their effects on plant recruitment and/or mortality. Changes in the plant community in turn affect the composition of the herbivorous mammal community