Climatic and Altitudinal Criteria for Commercial Afforestation with Special Reference to Natal

Although foliar analysis is commonly used to diagnose the nutritional status of trees and their ability to respond to fertilising, it is also a measure of site type and quality. The availability of nutrients in the soil varies with climatic and biotic as well as edaphic factors, while uptake by the plant may depend on more than the nutrient status of the soil. This paper examines the foliar nutrient concentrations of Eucalyptus grandis as expressions of climatic and edaphic factors for a wide range of sites, in order to test and quantify these relationships. Preliminary results show foliar nutrients to be strongly correlated to topsoil organic carbon, extractable P, exchangeable Ca, Mg, K, exchangeable acidity and pH. Highly significant multiple regressions accounted for 78 to 96 % of the variation in foliar nutrients. Climatic factors were correlated with fewer foliar nutrients, the most important variable being temperature, which in turn was correlated with topsoil organic carbon. There is a need to stratify sites for relational site factor studies possibly on the basis of organic carbon content and exchangeable acidity and develop separate foliar norms for E. grandis on different site types.

Section: Methodsmentioning

confidence: 99%

The Influence of Site Factors on the Foliar Nutrient Content ofEucalyptus grandisin Natal

Herbert

1991

“…It is obvious that such limits increase with a decrease in latitude. According to the author the upper limit of 1 200 m applies to a latitude of 27°S (Piet Retief) and it is suggested that this altitude limit increase by 50 m for each degree decrease in latitude or vice versa (Schonau and Schulze, 1984). Because of the sensitivity to frost, cognisance should be taken of the microtopography at higher altitudes.…”

Section: Climatementioning

confidence: 98%

“…In general this map concurred closely with the actual situation and practical experience. Improvements were suggested by Schonau and Schulze (1984) and the slightly improved criteria are given in Table 1 below. They conform closely with those given in "Eucalypts for planting" (FAD, 1979).…”

Section: Climatementioning

confidence: 99%

Basic Silviculture for the Establishment of Eucalypt Plantation with Special Reference toEucalyptus grandis

Schönau¹

1985

Self Cite

SYNOPSISThe importance of site preparation, fertilising and site requirements for afforestation with Eucalyptus grandis is indicated. The site requirements for this species in respect of climate, soil and topography are given and the optimum silvicultural techniques described. The basic principles apply equally to other eucalypts. More attention should be given to planting these species when conditions are not optimal for E. grandis.

“…This was applied for five different species in Natal where optimum growing areas were established using appropriate climatic criteria and a computerbased data set of climatic parameters (Schonau and Schulze, 1984). Within these areas further assessment of site quality was then able to take place on the basis of soil types which express nutrient availability, moisture regime and topography (soil catenas).…”

Section: Use Of Soil Classification In Determination Of Site Qualitymentioning

confidence: 99%

7. Problems in Using Vegetation or Soil Classification in Determining Site Quality

Schönau

1987

Self Cite

SYNOPSISThis paper discusses the concepts of site and site quality and reviews briefly the determination of the latter. Site quality is viewed primarily as productive capacity of forest land, although other aspects are considered also. It is concluded that nowadays site index, or the top height of a stand at a certain reference age, is used more frequently than any other indicator. The various methods of determination of site quality, i.e. stand parameters, site factor analysis and classification are discussed. Main emphasis is given to vegetation or soil classification as determinant. The main problems in using vegetation are that it does not work well where it has been significantly altered or when the abundance of species increases. Soil classification also gives rather poor results since these systems are developed mainly for agricultural use. The trend is to include factors important for tree growth in the classification systems thereby improving determination. Better results are achieved with broader ecological methods which are always dependent on the condition of the ecosystem. South African approaches are reviewed.