scholarly journals Alien tree invasion into a South African montane grassland ecosystem: impact of Acacia species on rangeland condition and livestock carrying capacity

Author(s):  
Thozamile Steve Yapi ◽  
Patrick J. O’Farrell ◽  
Luthando E. Dziba ◽  
Karen J. Esler
2006 ◽  
Vol 44 (3) ◽  
pp. 417-419 ◽  
Author(s):  
Edmund C. February ◽  
Andre D. Mader ◽  
William J. Bond

2011 ◽  
Vol 365 ◽  
pp. 110-114 ◽  
Author(s):  
Rui Jie Wang ◽  
Lian Wei Yang

Due to population pressure and over-grazing, ecological degradation of the rangeland in HulunBuir becomes more and more serious in past decades. To balance pasture grazing activities and ecosystem sustainability, monitoring grass productivity of the rangelands and livestock carrying capacity are very necessary. Grassland yield is the basis of developing livestock, net primary production (NPP) is an important parameters in determining carrying capacity. Using MODIS remote sensing data, we estimated the NPP of grassland ecosystem of HulunBuir in 2006. The total NPP of grassland ecosystem in HulunBuir was 2.9×1013 gC/a in 2006, with an average of 261.01gC/m2•a. Then we based on the estimated NPP to calculate the optimal carrying capacity which was 765.41 ten thousands sheep units. The actual carrying capacity was 1838.45 ten thousands sheep units, total overloading was 1073.04 ten thousands sheep units. The serious regions of overloading were Arong Banner with 325.45 ten thousands sheep units, Zlantun City with 270.72 ten thousands sheep units, Molidawadahanr Autonomous Banner with 254.71 ten thousands sheep units. The carrying capacity of Oroqin Autonomous Banner, Genhe City and Erguna City were scarcity, there were great potential to excavate in livestock.


Bothalia ◽  
1975 ◽  
Vol 11 (4) ◽  
pp. 481-489 ◽  
Author(s):  
P. J. Robbertse

The external morphology and the anatomy of the pods all the South African Acacia specoes are discussed. It was found that the South African Acacia species can grouped into a number of distinct categories on the basis of the anatomy of their pods. There is quite a marked difference in anatomy odfthe pod of the series Vulgares and that of the series Gummiferae.


Bothalia ◽  
1975 ◽  
Vol 11 (4) ◽  
pp. 473-479 ◽  
Author(s):  
P. J. Robbertse

A large number of seedlings and young twigs of South African  Acacia species was sectioned and the vascularization of the nodes and internodes studied. The nodes of all the species examined are trilacunate and the vascular tissue of the stipules originates from the lateral leaf traces. The Gummiferae species all have spinescent stipules, while stipules of the Vulgares species are membranous. Prickles containing no vascular tissue are found on the nodes and in some species also on the internodes of the Vulgares species. These prickles always occur on the ridges formed on the stem by leaf traces.


Author(s):  
N. H. Olson ◽  
T. S. Baker ◽  
Wu Bo Mu ◽  
J. E. Johnson ◽  
D. A. Hendry

Nudaurelia capensis β virus (NβV) is an RNA virus of the South African Pine Emperor moth, Nudaurelia cytherea capensis (Lepidoptera: Saturniidae). The NβV capsid is a T = 4 icosahedron that contains 60T = 240 subunits of the coat protein (Mr = 61,000). A three-dimensional reconstruction of the NβV capsid was previously computed from visions embedded in negative stain suspended over holes in a carbon film. We have re-examined the three-dimensional structure of NβV, using cryo-microscopy to examine the native, unstained structure of the virion and to provide a initial phasing model for high-resolution x-ray crystallographic studiesNβV was purified and prepared for cryo-microscopy as described. Micrographs were recorded ∼1 - 2 μm underfocus at a magnification of 49,000X with a total electron dose of about 1800 e-/nm2.


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