The nutrient status of grasslands and adjacent Pinus patula and Eucalyptus grandis plantations on the eastern escarpment of South Africa

Simple item page
dc.contributor.authorKathawaroo, Deshika
dc.date.accessioned2006-03-13T07:08:20Z
dc.date.available2006-03-13T07:08:20Z
dc.date.issued2006-03-13
dc.descriptionMaster of Science - Scienceen
dc.description.abstractThe replacement of indigenous grasslands by commercial forestry plantations on the mountainous eastern escarpment of South Africa, has inevitably led to alteration of nutrient cycling. The overall objective of this study was to determine the nutrient status (soil, litter and foliar nutrient concentrations) of Pinus patula and Eucalyptus grandis plantations and adjacent grasslands. The 2, 13 and 30 year old P. patula plantations and adjacent Driekop grassland were located relatively high up on the escarpment (altitudes ranging between 950–1610 m) and were underlain by dolomite while the 2, 8 and 13 year old E. grandis plantations and adjacent Brooklands grassland were located lower down (altitudes ranging between 900–1100 m) and were underlain by granite. It was assumed that the nutrient status of the soil under the plantations and the adjacent grasslands were similar prior to afforestation. Samples were collected once in winter (August 2002) and once in summer (January 2003). Soil samples were collected to a depth of 20 cm and litter material, to a maximum depth of 20cm. Lower canopy foliar samples were collected within the lowermost metre of the canopies and upper canopy foliar samples were collected within the uppermost metre of the canopies. The data were analysed in the laboratory for various elements and soil physical parameters. The soil pH was lower under the P. patula (pH 4.8-5.2) and E. grandis plantations (pH 4.6-5.3) when compared with the soil under the adjacent grasslands (pH 5.3-5.6). The soil under the P. patula plantations had lower exchangeable base cation concentrations (204-300 mg kg-1) compared with the adjacent Driekop grassland (452-645 mg kg-1), while there were no clear trends when comparing the exchangeable basic cation concentrations in the E. grandis plantations and the adjacent Brooklands grassland. The soil aluminium saturation was similar between the plantations, ranging between 39.7 and 63.3% in the P. patula plantations and 27.4 and 75.6% in the E. grandis plantations. The grasslands had lower soil aluminium saturations, ranging between 17.7 and 35.7% in the Driekop grassland and 17.5 and 39.1% in the Brooklands grassland. Exudates from mycorrhizal associations chelate iv acidic cations, rendering plantations more tolerant of acidic soils. Soil total nitrogen, phosphorus and carbon in the plantations were similar to the adjacent grasslands. Higher nitrogen mineralisation rates in the P. patula plantations corresponded with higher litter and foliar total N concentrations relative to the adjacent Driekop grassland, while there were no clear trends when comparing rates of N mineralisation in the E. grandis plantations and the Brooklands grassland. The concentrations of foliar amino acids and protein were significantly higher (p<0.01) in the plantation foliage, when compared the grassland foliage. The amino acid arginine, occurred in higher proportions relative to other amino acids in plantation foliage, when compared with the relative proportions found in the grasslands. Relative to nitrogen, foliar ratios indicated that phosphorus and potassium were the most limiting nutrients for the plantations, which possibly resulted in N storage in the form of protein and amino acids. The soil and foliage were the more sensitive indicators of the nutrients status than litter. Differences in nutrients concentrations between the lower and upper canopies in both plantations were minor and no major trends were found. Therefore the sub division of lower and upper canopies is not recommended for further foliar nutrient analyses. Age related trends were unclear as a result of higher soil clay contents found in the 13 year old P. patula plantation and the 8 year old E. grandis plantation as well as the various silvicultural practices implemented. In terms of the relative impacts of P. patula and E. grandis plantations, the results of this study imply that the upper 20cm of soil was more impacted under the P. patula plantations than under the E. grandis plantations, in terms of reduced base cation and increased acid cation concentrations. The P. patula plantations are shallow rooters and thus the base cation status of the upper soil horizons may affect the sustainability of the P. patula plantations.en
dc.format.extent26266 bytes
dc.format.extent25506 bytes
dc.format.extent24598 bytes
dc.format.extent23753 bytes
dc.format.extent30061 bytes
dc.format.extent28538 bytes
dc.format.extent28847 bytes
dc.format.extent28616 bytes
dc.format.extent26668 bytes
dc.format.extent25275 bytes
dc.format.extent37793 bytes
dc.format.extent31577 bytes
dc.format.extent80889 bytes
dc.format.extent79084 bytes
dc.format.extent72221 bytes
dc.format.extent82168 bytes
dc.format.extent70489 bytes
dc.format.extent79212 bytes
dc.format.extent82978 bytes
dc.format.extent84310 bytes
dc.format.extent81212 bytes
dc.format.extent93173 bytes
dc.format.extent77373 bytes
dc.format.extent65838 bytes
dc.format.extent60444 bytes
dc.format.extent2240322 bytes
dc.format.extent214604 bytes
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/10539/234
dc.language.isoen
dc.subjectsouth africaen
dc.subjectescarpmenten
dc.subjectgrasslandsen
dc.subjecteucalyptus grandisen
dc.subjectpinus patulaen
dc.titleThe nutrient status of grasslands and adjacent Pinus patula and Eucalyptus grandis plantations on the eastern escarpment of South Africaen
dc.typeThesisen
Files
Original bundle
Now showing 1 - 5 of 27
No Thumbnail Available
Name:
Abstract.pdf
Size:
209.57 KB
Format:
Adobe Portable Document Format
Description:
Download
No Thumbnail Available
Name:
Dissertation.pdf
Size:
2.14 MB
Format:
Adobe Portable Document Format
Description:
Download
No Thumbnail Available
Name:
Figure16.pdf
Size:
59.03 KB
Format:
Adobe Portable Document Format
Description:
Download
No Thumbnail Available
Name:
Figure17.pdf
Size:
64.29 KB
Format:
Adobe Portable Document Format
Description:
Download
No Thumbnail Available
Name:
Figure18.pdf
Size:
75.56 KB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.8 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
ETD Collection