Estimating plot-level forest structural attributes using high spectral resolution ASTER satellite data in even-aged Eucalyptus plantations in southern KwaZulu-Natal,South Africa

This study assessed the suitability of both visible and shortwave infrared of ASTER reflectance bands and various vegetation indices for estimating forest structural attributes of Eucalyptus species. The study was conducted in even-aged monoculture plantations of E. grandis and E. nitens in the southern KwaZulu-Natal Midlands of South Africa. Empirical relationships between forest structural attributes, i.e. stems per hectare (SPHA), diameter at breast height (DBH), mean tree height (MTH), basal area and volume, and ASTER data were derived using correlation and canonical correlation analysis (CCA). The results indicated weak relationships between the studied forest structural attributes and ASTER data. In the younger plantation stands (4–6 years) the adjusted R ² values from CCA regression for SPHA, DBH, MTH, basal area and volume were 54.2, 63.5, 33.8, 25.4 and 30.3, respectively. The adjusted R ² values in the mature stands (7–9 years) were distinctly weaker with values of 50.7, 55.8, 25.1, 20.2 and 27.3 for SPHA, DBH, MTH, basal area and volume, respectively. The results imply that ASTER satellite data are not applicable to forest structural attribute estimation in commercially managed forest stands.     

Maximally selected two-sample statistics as a new tool for the identification and assessment of habitat factors with an application to breeding-bird communities in oak forests

Near-natural forest management is one of the major principles of modern forestry in central Europe. A measure commonly used for the assessment of logging is the occurrence and density of character species typical for the local biotope. Near-natural forest structures can be designed only when sufficient knowledge about the relationship between species and habitat factors is available. We suggest the use of simple cutpoint regression models for the derivation of statistically valid rules of thumb. The methodology is applied to bird and structure data of ancient and present oak coppices with standards to demonstrate its practical application. The cutpoints are derived from estimates of break points by means of maximally selected two-sample statistics, and their validity is judged by multiple test procedures. Detailed results are presented for character species and their relationships to the environment. We show that, for example, the tree pipit (Anthus trivialis) is missing in stands with more than 40% canopy overstorey, whereas this species can be regularly observed in more open stands. For the tree pipit, the analysis is illustrated by means of a free software package.