Structure of the Nylsvley Savanna

Huntley, BJ; Morris, J. W.

doi:10.1007/978-3-642-68786-0_20

Cited by 20 publications

(13 citation statements)

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“…This was higher than values reported for woody species in studies on subtropical savannas, in western Africa (3-7%, Meneaut and Cesar, 1979), northern Australia (3-5%, Werner and Murphy, 2001), and South Africa (4%, Huntley and Morris, 1982;Rutherford, 1982). Our study included small plants, which had higher fractions of biomass as leaves than more mature individuals, and contributed to the higher range of values we noted.…”

Section: Article In Presscontrasting

confidence: 80%

Above-ground biomass and carbon and nitrogen content of woody species in a subtropical thornscrub parkland

Northup

Zitzer

Archer

et al. 2005

Journal of Arid Environments

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Section: Article In Presscontrasting

confidence: 80%

Above-ground biomass and carbon and nitrogen content of woody species in a subtropical thornscrub parkland

Northup

Zitzer

Archer

et al. 2005

Journal of Arid Environments

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Section: Study Areamentioning

confidence: 99%

“…Mean annual rainfall, based upon forty years of records from Mosdene (10 km north-east of the reserve) is 640 mm, of which 80% falls from November through March (Huntley & Morris 1982). Mean daily air temperature ranges from 12 to 20 ?C from April until August, 14 to 22 ?C from September to October and 20 to 25 ?C from November to March (Huntley & Morris 1982). Extreme maximum and extreme minimum temperatures at Nystroom (25 km south-west) were 38 9 ?C and -61 ?C, respectively, with ground frosts recorded on about 20 days between May and September (Huntley & Morris 1982).…”

Section: Study Areamentioning

confidence: 99%

Porcupines, Fires and the Dynamics of the Tree Layer of the Burkea Africana Savanna

Yeaton¹

1988

The Journal of Ecology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Ecology. SUMMARY (1) The tree layer of the Eragrostis pallens-Burkea africana savanna is composed primarily of Terminalia sericea and B. africana with other tree species occurring infrequently. Burkea africana is dominant on well drained soils at the upper portions of a soil catena, co-dominant with T. sericea at midslope and replaced on seasonally waterlogged soils at the base of the slope by T. sericea. (2) There is a successional process occurring within the tree layer. Terminalia sericea establishes only on open sites and never under itself or other members of the tree layer. Burkea africana establishes on open sites, under T. sericea and under itself. Dombeya rotundifolia, another common tree, establishes under B. africana but not under T. sericea or itself and never in the open. The other tree species establish either under the canopies of large individuals of B. africana or on termite mounds. (3) The general successional sequence is T. sericea followed by B. africana and later D. rotundifolia or other shade-tolerant tree species. The actual successional sequence varies over the slope. In the upper portions, where T. sericea is uncommon, B. africana initiates the sequence and is followed by more shade-tolerant species. At midslope, T. sericea generally establishes first, followed by B. africana and later by shade-tolerant species. At the base of the slope, T. sericea is dominant since it is able to withstand the seasonally waterlogged soils there. During long periods of drought B. africana may establish secondarily. Other tree species rarely establish in this zone and then usually upon termite mounds.(4) A mature, closed-canopy woodland does not develop due to the disturbance by porcupines and fire. Porcupines ringbark trees and expose the heartwood to fire. They preferentially attack D. rotundifolia and B. africana in that order and rarely scar T. sericea. The strong preference of porcupines for D. rotundifolia results in many coppiced shrubs and a reduction in the number of individuals reaching tree status. The secondary preference for B. africana, which is abundant over much of the slope, results in large individuals being removed by fire more frequently than T. sericea. Of the large, live trees that fell after a fire in September 1985, 57% were B. africana.(5) The Eragrostispallens-Burkea africana savanna is maintained by porcupines and fire as a mosaic of grassland and small woodland patches undergoing cyclical successions developing after the fall of large individuals of B. africana.

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“…The parameters treated in this way were maximum leaf area index laimax. coefficient of radiation absorption in the canopy k can , coefficient of precipitation interception by the canopy c-m, (CaldweU et al 1977, Whittaker and Niering 1975, Smith and Nowak 1990, S (Sims and Coupland 1979, Ripley and Redmann 1976, Numata 1979, h (Conant and Risser 1974, Sims and Coupland 1979, Ripley and Redmann 1976, Numata 1979), *Based on cover measurements of Ovington et al 1963, J(DeAngeUs et al 1981, Schulze 1982, Jarvis and Leverenz 1983, Mclntyre et al 1990, Burton et al 1991, Wang et al 1992), k (Schulze 1982, Jarvis and Leverenz 1983, MUler 1963a, Satoo 1983, ^Schulze 1982, Kummerow et al 1981, MiUer et al 1981, Mooney 1988, Ehleringer and Mooney 1983, m (Kinyamario and Imbamba 1992, Medina 1982, Huntley and Morris 1982, Misra 1983, Medina and KUnge 1983, n Murphy and Lugo 1986, °(Ramam 1975, DeAngeUs et al 1981, Schulze 1982, Medina and KUnge 1983, P (Schulze 1982, Medina and KUnge 1983, Edwards and Grubb 1977, Tann...…”

Section: Comparison Of Terra and Daytransmentioning

confidence: 99%

“…, ° (Grier and Logan 1977, Harlow and Harrar 1969), P(CaldweU et al 1977, Vasek and Barbour 1988, Burk 1988, Shreve and Wiggins 1964, Munz and Keck 1963, <l (Risser et al 1981, McGregor et al 1986), r (Ovington et al 1963, McGregor et al 1986), s (Bowden et al 1991, Harlow and Harrar 1969), *(McGuire et al 1992, Harlow and Harrar 1969), u (MUler 1963, Moore and Irwin 1978, v (Steward and Webber 1981, Hanes 1988, Munz and Keck 1963, W (Huntley and Morris 1982, Gibbs-RusseU 1990, Pooley 1993, Keay 1989, X (Lugo et al 1978, Long andLakela 1971), Y (Ramam 1975, Hooker 1875, z (Prance 1990, Gentry 1993, Maas and Westra 1993 98 …”

mentioning

confidence: 99%

Description, calibration and sensitivity analysis of the local ecosystem submodel of a global model of carbon and nitrogen cycling and the water balance in the terrestrial biosphere

Kercher

Chambers

1995

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We have developed a geographically-distributed ecosystem model for the carbon, nitrogen, and water dynamics of the terrestrial biosphere TERRA. The local ecosystem model of TERRA consists of coupled, modified versions of TEM and DAYTRANS. The ecosystem model in each grid cell calculates water fluxes of evaporation, transpiration, and runoff; carbon fluxes of gross primary productivity, litterfall, and plant and sou* respiration; and nitrogen fluxes of vegetation uptake, litterfall, mineralization, immobilization, and system loss. The state variables are soil water content; carbon in live vegetation; carbon in soil; nitrogen in live vegetation; organic nitrogen in soil and litter; available inorganic nitrogen aggregating nitrites, nitrates, and ammonia; and a variable for allocation. Carbon and nitrogen dynamics are calibrated to specific sites in 17 vegetation types. Eight parameters are determined during calibration for each of the 17 vegetation types. At calibration, the annual average values of carbon in vegetationC v show site differences that derive from the vegetation-type specific parameters and intersite variation in climate and soils. From calibration, we recover the average C v of forests, woodlands, savannas, grasslands, shrublands, and tundra that were used to develop the model initially. The timing of the phases of the annual variation is driven by temperature and light in the high latitude and moist temperate zones. The dry temperate zones are driven by temperature, precipitation, and light In the tropics, precipitation is the key variable in annual variation. The seasonal responses are even more clearly demonstrated in net primary production and show the same controlling factors.We have found the sensitivities of the total ecosystem, total carbon storage, and net primary production to changes in model parameters. With only a few exceptions, the systems are ultra sensitive to the parameters controlling the effect of soil moisture on soil decomposition and soil respiration from the tundra to the tropics. The calibration parameters are important in all 17 vegetation types in determining the total system sensitivity; of these, usually Kd (parameter for soil respiration) is the most important and K r (parameter for plant respiration), the least The most common ordering in total system sensitivity for the eight calibration parameters is K& Nio SS (loss of nitrogen from soil), Kf a u (rate of carbon transfer by litterfall), Nmax (rate of nitrogen uptake by vegetation), Cmax (gross primary productivity), Lnc (nitrogen transfer by litterfall), N up (immobilization of nitrogen by bacteria in litter), and K r , from the most sensitive to the least. This suggests that immobilization and plant respiration are less important on a relative basis for the total system, and soil respiration and nitrogen losses from soils are the most important processes. The parameter that controls the respiration response to temperature <2io is a key parameter in total system sensitivity, total carbon sequestration and net...

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Structure of the Nylsvley Savanna

Cited by 20 publications

References 1 publication

Above-ground biomass and carbon and nitrogen content of woody species in a subtropical thornscrub parkland

Above-ground biomass and carbon and nitrogen content of woody species in a subtropical thornscrub parkland

Porcupines, Fires and the Dynamics of the Tree Layer of the Burkea Africana Savanna

Description, calibration and sensitivity analysis of the local ecosystem submodel of a global model of carbon and nitrogen cycling and the water balance in the terrestrial biosphere

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