Journal of Range Management, Volume 57, Number 5 (September 2004)
http://hdl.handle.net/10150/635440
2024-03-28T19:08:53ZBook Review: Origins of the Organic Agriculture Debate, Thomas R. DeGregori
http://hdl.handle.net/10150/643583
Book Review: Origins of the Organic Agriculture Debate, Thomas R. DeGregori
Metzger, C. W.
Book Review: Origins of the Organic Agriculture Debate, Thomas R. DeGregori, Iowa State Press, Ames, Iowa (2004).
2004-09-01T00:00:00ZBook Review: Natural Enemies: An Introduction to Biological Control, Ann Hajek
http://hdl.handle.net/10150/643582
Book Review: Natural Enemies: An Introduction to Biological Control, Ann Hajek
Metzger, C. W.
Book Review: Natural Enemies: An Introduction to Biological Control, Ann Hajek. Cambridge University Press, New York (2004).
2004-09-01T00:00:00ZCanopy spectra of giant reed and associated vegetation
http://hdl.handle.net/10150/643581
Canopy spectra of giant reed and associated vegetation
Everitt, J. H.; Yang, C.; Alaniz, M. A.; Davis, M. R.; Nibling, F. L.; Deloach, C. J.
This paper describes the spectral light reflectance characteristics of giant reed (Arundo donax L.) and the application of aerial color-infrared photography and videography for distinguishing infestations of this invasive plant species in Texas riparian areas. Airborne videography was integrated with global positioning system (GPS) and geographic information system (GIS) technologies for mapping the distribution of giant reed. Field spectral measurements showed that giant reed had higher near-infrared reflectance than associated plant species in summer and fall. Giant reed had a conspicuous pink image response on the color-infrared photography and videography. This allowed infestations to be quantified using computer analysis of the photographic and videographic images. Accuracy assessments performed on the classified images had user's and producer's accuracies for giant reed that ranged from 78% to 100%. Integration of the GPS with the video imagery permitted latitude-longitude coordinates of giant reed infestations to be recorded on each image. A long stretch of the Rio Grande in southwest and west Texas was flown with the photographic and video systems to detect giant reed infestations. The GPS coordinates on the color-infrared video scenes depicting giant reed infestations were entered into a GIS to map the distribution of this invasive weed along the Rio Grande.
2004-09-01T00:00:00ZStocking rate and grazing frequency effects on Nebraska Sandhills meadows
http://hdl.handle.net/10150/643580
Stocking rate and grazing frequency effects on Nebraska Sandhills meadows
Voleski, Jerry D.; Schacht, Walter H.; Richardson, Devyn M.
Nearly one-half million ha of the Nebraska Sandhills is comprised of highly productive wet meadows. A study was conducted from 1998 to 2001 to evaluate the effects of stocking rate and grazing frequency on herbage dynamics, disappearance, and composition of a wet meadow dominated by cool-season vegetation. Defoliation characteristics were measured on 2 key species. Stocking rates were 148, 296, and 444 AUD ha-1 combined with a grazing frequency of 3 (F3) or 5 (F5) times. Cumulative standing crop disappearance and height reduction increased linearly with increasing stocking rate. Disappearance was 1,920, 2,700, and 3,090 kg ha-1 for the 148, 296, and 444 AUD ha-1 stocking rates, respectively. Greater disappearance at the highest stocking rate was expected based on calculated intake estimates for that stocking rate. Percentage of tillers grazed and percentage height reduction increased with stocking rate for both key species. Percentage of tillers grazed was greater under F3 compared to F5. This likely was caused by higher grazing pressures under the F3 treatment at each grazing period. Frequency of occurrence of the primary plant species or groups was not affected by stocking rate or grazing frequency during any year of the study (P > 0.05); however, frequency of occurrence of legumes and Kentucky bluegrass (Poa pratensis L.) was higher in grazed pastures compared to the control. The abundance of soil moisture in these meadows appeared to mitigate the effects of heavier defoliation associated with higher stocking rates. However, defoliation of the taller grasses and sedges resulted in a more open canopy allowing shorter-statured species to increase. Overall, stocking rate affected more response variables than grazing frequency and the productivity of our wet meadow site would potentially support a stocking rate of 296 AUD ha-1.
2004-09-01T00:00:00Z