Abundance, vegetation, and environment of four patch types in a northern mixed prairie

1992 ◽  
Vol 70 (2) ◽  
pp. 277-284 ◽  
Author(s):  
Charles E. Umbanhowar Jr.

The importance of concurrent disturbances to the maintenance of plant species diversity in grasslands has been emphasized by several authors, but there are few studies comparing different disturbances at the same site. In this study the size, abundance, vegetation, and environment of thatching ant mounds, earthen mammal mounds, bison wallows, and openings in dry marshes are compared in a northern mixed prairie in north central South Dakota. Patch size and abundance varied considerably between patch types. Ant and earthen mammal mounds were the smallest but most abundant patch types. Bison wallows and dry marshes were larger and occurred less frequently than ant and earthen mounds. Different patch types occupied a similar amount of area. Ordination of patch vegetation revealed marked between-type compositional differences; ant and earthen mounds were dominated by vegetatively reproducing perennials, while annuals occurred more abundantly in bison wallows and dry marshes. Many species were restricted to either wallows or marshes. Levels of nitrate, phosphorus, soil organic matter, and other environmental factors varied significantly between patch types. Different patch types supported different groups of species, and patch vegetation was a product of mechanism of patch creation, patch environment, and location. Key words: ant mounds, disturbance, earthen mounds, northern mixed prairie, patches, potholes, wallows.

1997 ◽  
Vol 22 (1) ◽  
pp. 324-324
Author(s):  
M. A. Boetel ◽  
B. W. Fuller ◽  
R. J. Braun

Abstract A commercial sunflower field near Mina, in north-central South Dakota, was selected foi our trial of several insecticide treatments at standard and reduced rates for management of SB larvae. The experiment was arranged in a RCBD with 4 replications, and individual treatment plots were 25 ft long by 10 rows (38 inch spacing) wide. In addition, each plot was bordered by two buffer rows to prevent drift. Pre-application evaluations were carried out using whole-plant visual counts of the number of live SB larvae per plant. Twenty plants were examined from each treatment plot and these counts indicated an average of 11 SB larvae per plant within the test area. Treatments were applied on 11 Ju’ using a CO2-propelled backpack sprayer system with a hand-held 6.7-ft long boom. The boom was equipped with 4 TeeJet 8001 nozzles spaced 20 inches apart, and was calibrated to deliver a spray volume of 15 gpa while traveling at 3 mph. Insecticide efficacy was evaluated at 6 DAT using the same count ing technique and number of samples described for pre-application sampling. Data were analyzed with SAS’ s General Linear Models procedure and means were compared using DMRT.


Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 595-601 ◽  
Author(s):  
L C R Pessenda ◽  
S E M Gouveia ◽  
R Aravena

During the last decade radiocarbon dating has been used extensively in distinct regions of Brazil to provide information about soil chronology in paleoenvironmental studies. This paper presents 14C data of soil organic matter (SOM), humin fraction, and charcoal in several soil profiles under natural vegetation from different Brazil locations (north, central, and southeast regions). The main objective is to compare the obtained 14C dating of total SOM with humin, the oldest fraction of SOM. In order to validate the humin ages these data are compared with the age of charcoal collected at similar depths. The 14C ages obtained on charcoal were, in most of the cases, in agreement with the humin fraction considering the experimental errors, or 20% older in average. The dates obtained from total SOM showed significantly younger ages than the humin fraction indicating contamination by younger carbon. These results show the humin fraction is considered a reliable material for 14C dating in soils. However, the humin fraction ages could be assumed as the minimum ages for carbon in soils.


1997 ◽  
Vol 22 (1) ◽  
pp. 323-323
Author(s):  
M. A. Boetel ◽  
B. W. Fuller ◽  
R. J. Braun

Abstract A grower-established sunflower field (planted on 25 May with a seeding rate of 23,300 per acre) was found to have sufficient SB larvae (5 per plant) to conduct our insecticide evaluations. This site in north-central South Dakota (Ipswich) was used to evaluate 3 pyrethroid insecticides at standard and reduced rates for management of SB larvae. Plots were 25 ft long by 8 rows (36 inch spacing) wide and the study was arranged in a RCBD with 4 replications. Treatment plots were buffered by 2 untreated rows to prevent cross-contamination between plots due to insecticide drift. Pre-application evaluations used whole-plant counts which were carried out on 20 plants per plot. Treatments were applied to plots on 2 Jul at V-8 stage of sunflower physiological development. Applications were made using a CO2-propelled backpack sprayer system equipped with a 6.7 ft long, 4-nozzle (TeeJet 8001 flat fan; spaced 20 inches apart) boom. The system was calibrated to deliver a spray volume of 15 gpa while traveling at 3 mph. Efficacy was evaluated at 7 and 24 DAT using the same counting technique and number of plants sampled as pre-application sampling. Data were analyzed with SAS’s General Linear Models procedure and means were compared using DMRT.


1991 ◽  
Vol 44 (1) ◽  
pp. 7 ◽  
Author(s):  
M. A. Naeth ◽  
A. W. Bailey ◽  
D. J. Pluth ◽  
D. S. Chanasyk ◽  
R. T. Hardin

1999 ◽  
Vol 13 (4) ◽  
pp. 835-839 ◽  
Author(s):  
Mark A. Brinkman ◽  
Sharon A. Clay ◽  
Robert J. Kremer

Rhizobacteria have been shown to be phytotoxic to leafy spurge in laboratory assays. This field study investigated the influence of two strains ofPseudomonas fluorescens[Trevisan, (Migula)], deleterious rhizobacteria (DRB), on root weight, root bud number, and root carbohydrate content of leafy spurge at three sites located in northeast and north-central South Dakota. Soils were inoculated with 2 g of starch-based granules containing no bacteria or starch granules containing 108colony-forming units (cfu)/g of either bacterial strain LS102 (Montana origin) or LS174 (South Dakota origin). Bacterial strains were detected on root samples from treated areas. Root weight and root carbohydrate content were reduced about 20% compared to roots from control plots.


2007 ◽  
Vol 55 (2) ◽  
pp. 110 ◽  
Author(s):  
Chang Ting Wang ◽  
Rui Jun Long ◽  
Qi Ji Wang ◽  
Lu Ming Ding ◽  
Mei Ping Wang

During the growing seasons of 2002 and 2003, biomass productivity and diversity were examined along an altitudinal transect on the south-western slope of Beishan Mountain, Maqin County (33°43′–35°16′N, 98°48′–100°55′E), Qinghai–Tibetan Plateau. Six altitudes were selected, between 3840 and 4435 m. Soil organic matter, soil available N and P and environmental factors significantly affected plant-species diversity and productivity of the alpine meadows. Aboveground biomass declined significantly with increasing altitude (P < 0.05) and it was positively and linearly related to late summer soil-surface temperature. Belowground biomass (0–10-cm depth) was significantly greater at the lowest and highest altitudes than at intermediate locations, associated with water and nutrient availabilities. At each site, the maximum belowground biomass values occurred at the beginning and the end of the growing seasons (P < 0.05). Soil organic matter content, and available N and P were negatively and closely related to plant diversity (species richness, Shannon–Wiener diversity index, and Pielou evenness index).


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