Topping Stimulates Bitterbrush Twig Growth

Ferguson, R. Brian; Basile, Joseph V.

doi:10.2307/3798293

Cited by 24 publications

(12 citation statements)

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“…Although A. karroo has been shown to be very resistant to defoliation (Teague, 1987), except early in the season when TNC status was low, Stuart-Hill (unpublished data 1 ) has shown a sudden and substantial decline in vigour and an increase in mortality of A. karroo plants following 100% defoliation by hand at one, two or three times a year for four consecutive years. Other authors (Garrison, 1953;Cook & Goebell, 1962;Lay, 1965;Ferguson & Basile, 1966;Aucamp, 1979) have shown that for the first few seasons productivity is increased following moderate defoliation. After a few years this effect declines.…”

Section: Discussionmentioning

confidence: 94%

Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves inacacia karroohayne

Teague¹

1988

Journal of the Grassland Society of Southern Africa

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To cite this article: W.R. Teague (1988) Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves in acacia karroo hayne, Journal of the Grassland Society of Southern Africa, 5:4, 223-226, ABSTRACTA field study was conducted with Acacia karroo plants to determine changes in relative photosynthetic rates, the extent of carbohydrate reserve depletion and the rate reserves take to recover, following defoliation by goats at different intensities and phenophases, at a "wet" and a "dry" site.The rate of photosynthesis of fully expanded leaves increased markedly following defoliation. Light defoliation increased photosynthetic rate the most. Total non-structural carbohydrate levels dropped significantly after defoliation. The magnitude of decrease was directly related to the intensity of defoliation.Following the heavy defoliations, recovery of carbohydrate levels was much faster than after the light defoliations. Rates of recovery were also faster following defoliation in the second half of the growing season, than in the first half. However, the plants that had been heavily defoliated in the second half of the growing season had not fully recovered carbohydrate levels before leaf fall in late autumn.Moisture stress had very little effect on carbohydrate levels in comparison with the defoliation treatments. UITTREKSEL 'n Veldstudie is opAcacia karroo plante uitgevoer om verskille in relatiewe fotosintetiese tempo, die mate van koolhidraatreserwe vermindering en die tempo van herstel, na ontblaring teen verskillende intensiteite enfenofases, op 'n "nat" en 'n "droë" terrein, te bepaal. Na ontblaring, het die Fotosintese-tempo van volwasse blare, opvallend verhoog. Ligte ontblaring het die fotosintesetempo die meeste verhoog. Die totale nie-strukturele koolhidraat-vlakke het opvallend gedaal na ontblaring. Die grootte van dating is direk eweredig aan die intensiteit van ontblaring. Herstel van koolhidraatvlakke na strawwe ontblaring was baie vinniger as na ligte ontblaring. Die tempo van herstel van koolhidraatreserwes na ontblaring in die tweede helfte van die groeiseisoen was vinniger as gedurende die eerste helfte. Die koolhidraatreserwes van plante wat gedurende die tweede helfte van die groeiseisoen straf ontblaar is, het gedurende die daaropvolgende laat herfs nog nie volkome herstel nie. In vergelyking met die ontblaringsbehandetings, het vogstremming 'n minimale invloed op die koolhidraatvlakke gehad.

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Section: Discussionmentioning

confidence: 94%

Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves inacacia karroohayne

Teague¹

1988

Journal of the Grassland Society of Southern Africa

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“…Stuart-Hill, Dohne Research Centre, Private Bag X15, Stutterheim 4930, unpublished data) has shown a sudden and substantial decline in vigour and an increase in mortality of A. karroo plants following 100% defoliation by hand for four consecutive years at one, two or three times a year. Other authors (Garrison, 1971;Cook & Goebell, 1962;Lay, 1965;Ferguson & Basile, 1966;Aucamp, 1979) have shown that for the first few seasons productivity is increased following moderate defoliation. After a few years this effect declines.…”

Section: Discussionmentioning

confidence: 95%

Effect of intensity and frequency of defoliation on aerial growth and carbohydrate reserve levels inAcacia karrooplants

Teague¹

1989

Journal of the Grassland Society of Southern Africa

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Acacia karroo trees were defoliated by goats at two intensities and four frequencies; 2, 4, 8 and 12-weekly. Leaf accumulation and carbohydrate reserve levels were compared to a non-defoliated control, and to plants (defoliation controls) which were defoliated for the first time that season each time a frequency treatment was defoliated. These plants are activated by defoliation in such a manner that successive defoliations can result in this activation being additive. There is clearly a defoliation level below which they are not activated. Activation appears to be negated to a degree by defoliations at 2 and 4-weekly frequencies, relative to the 8-weekly defoliation frequency. The 12-weekly frequency at heavy defoliation produced less than the same defoliation at 8-weekly frequency. The 2-weekly frequency treatments produced as much leaf as the 4 and 12-weekly defoliations at the same defoliation intensity. The more frequently plants were defoliated, the more carbohydrate reserves dropped. However, plants adjusted to cope with very frequent defoliations. There was no connection between leaf accumulation and carbohydrate reserve levels following the different frequencies and intensities of defoliation.Acacia karroo borne is deur bokke benut teen twee vlakke van intensiteit en teen vier vlakke van frekwensie naamlik; 2, 4, 8 en 12-weekliks. Blaarakkumulasie is met 'n onbenutte kontrole en met plante ('benutte kontrole') wat vir die eerste keer in daardie seisoen teen elke vlak van frekwensie ontblaar is, vergelyk. Die plante word sodanig deur ontblaring geaktiveer, dat opeenvolgende ontblarings tot gevolg het dat hierdie aktivering kumulatief word. Daar is duidelik 'n vlak van ontblaring waaronder A. karroo plante nie geaktiveer word nie. Dit lyk of aktiveering tot 'n mate weerspreek word deur ontblaring teen frekwensies van 2 en 4-weekliks relatief tot die 8-weeklikse frekwensie se ontblaring. Die 12-weeklikse frekwensie, teen die hoe ontblaring, produseer minder as die 8-weeklikse frekwensie, teen dieselfde ontblaring. Die 2-weeklikse frekwensie behandelings het dieselfde hoeveelheid blare geakkumuleer as die 4 en 12-weeklikse frekwensie behandelings teen dieselfde ontblaringsintensiteit. Hoe meer dikwels die plante ontblaar is, hoe laer het die koolhidraatvlakke gedaal. Nogtans het die plante aangepas om tred te hou met veelvuldige ontblarings. Daar was geen ooreenkoms tussen blaarakkumulasie en koolhidraatreserwesvlakke, indien die verskillende frekwensies en ontblaringsintensiteite nagevolg is nie.

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“…This is thought to slow the extraction of limited moisture and nutrients from the soil leaving more resources available for the shrubs (Garrison 1953, Hubbard 1957, Ferguson and Basile 1966, McConnel and Smith 1977, Neal 1981, Reiner and Unless 1982 This was probably the mechanism that stimulated shrub growth in our light -grazing treatment, as light cattle grazing had little if any direct effect on bitterbrush dimensions. Bitterbrush responded favorably over the growing season to the partial removal of the herbaceous component and were wider, taller, and supported longer twigs (P < 0.05) in the fall than shrubs in the ungrazed controls.…”

Section: Discussionmentioning

confidence: 99%

Can spring cattle grazing among young bitterbrush stimulate shrub growth?

Ganskopp¹,

Svejcar²,

Taylor³

2004

REM

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Due to its palatability and forage quality, antelope bitterbrush (Purshia tridentata Pursh DC) is a desirable shrub across western US rangelands. Because little information is available regarding grazing management of young bitterbrush, a study was undertaken to explore stocking pressure thresholds and quantify effects of light and heavy spring cattle grazing on shrub growth. Rates of browsing and trampling and forage availability were monitored over 3 years in southeast Oregon. Across years, 29% of bitterbrush endured trampling in light-grazing treatments, and 55% experienced trampling under heavy grazing. Linear models relating time and cattle density successfully explained (r2 = 0.84 -0.86) probabilities of bitterbrush being trampled. Forage utilization averaged 32% and 59% in lightly and heavily grazed units, and 14 and 62% of bitterbrush were browsed in lightly and heavily -grazed pastures, respectively. Cattle began browsing when herbaceous standing crop declined to 100 -150 kg ha -1.Browsing in heavily -grazed pastures reduced diameters of bitterbrush by 4.5 to 9.5 cm in 1998 and 1999, but shrub height was unaffected. Lightly -grazed stands exhibited a 50% greater increase in bitterbrush diameter, 30% greater height increment, and 8% longer twigs than shrubs in ungrazed pastures. At the end of the 1997 and 1998 growing seasons, bitterbrush in heavilygrazed pastures were 11 cm greater in diameter than ungrazed controls and equal to shrubs in lightly -grazed pastures. To stimulate bitterbrush growth, young stands can be lightly -grazed (30 to 40% utilization of herbaceous forage) by cattle when bitterbrush is flowering and accompanying grasses are in vegetative to late -boot stages of phenology.Key Words: Purshia tridentata, livestock, big game, winter range, wildlife, habitat, browse Antelope bitterbrush (Purshia tridentata Pursh DC) is an important shrub for mule deer (Odocoileus hemionus hemionus), pronghorn (Antilocarpa americana), and livestock on western North America rangelands (Kufeld et al. 1973, Vavra and Sneva 1978, Neal 1981, Urness 1981, Kinuthia et al. 1992. With a sustained crude protein content above 8.0% (Hickman 1975 andKituku et al. 1992), bitterbrush can substantially enhance late season diet quality of ruminants when nutritive value of herbaceous forages has declined to sub -maintenance levels (Ganskopp and Bohnert 2001 Manuscript accepted 1 Jul. 03. JOURNAL OF RANGE MANAGEMENT 57(2) March 2004Resumen Debido a su gustocidad y calidad de forraje el "Antelope bitterbrush" (Purshia tridentata Pursh DC) es un arbusto deseable en los pastizales del oeste de U.S.A. Debido a que hay poca información disponible respecto al manejo del apacentamiento de plantas jóvenes de "Bitterbrush ", se condujo un estudio para explorar los umbrales de la presión de apacentamiento y cuantificar los efectos del apacentamiento ligero y fuerte de ganado en primavera sobre el crecimiento del arbusto. Durante 3 años en el sudeste de Oregon se monitorearon las tasas de ramoneo y pisoteo y la disponibilidad d...

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Topping Stimulates Bitterbrush Twig Growth

Cited by 24 publications

References 6 publications

Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves inacacia karroohayne

Effect of the intensity and phenophase of defoliation and water stress on the rate of photosynthesis and the recovery of carbohydrate reserves inacacia karroohayne

Effect of intensity and frequency of defoliation on aerial growth and carbohydrate reserve levels inAcacia karrooplants

Can spring cattle grazing among young bitterbrush stimulate shrub growth?

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