, 1993 and Gilmore et al., 1996). Furthermore, recently conducted studies show that climate can also influences the hydraulic architecture and therefore the ratio of leaf area to sapwood area (Poyatos et al., 2007 and Martínez-Vilalta et al., 2009). And even within trees mTOR inhibitor the relationship between leaf area and sapwood area can vary with the position within
the tree (Mencuccini and Bonosi, 2001). Thus, for studies regarding the development of leaf area over time, other indirect methods for estimating leaf area should be found, preferably ones which are based on tree characteristics which can be collected easily and in a non-destructive way. The use of other crown characteristics to estimate leaf area, such as crown ratio, crown length, crown projection area, and crown surface area is rarely investigated (Pereira et al., 1997 and Kenefic and Seymore, 1999). Badoux (1945) and Assmann
(1970) used crown surface area as substitute for leaf area with the evident assumption that most of the growth influencing photosynthetically active leaves are at the crown surface. Assmann (1970) also described that therefore differences in efficiency Trichostatin A in vitro (there: growth per crown projection area) should lead to differences in the ratio of crown surface area to crown projection area and further, that trees with large crowns are less efficient than trees with smaller crowns due to their large inner crown volume (cubic content) bearing no leaves or needles. Therefore, this study aimed at the question if traditional forest crown measures, particularly
crown surface area (CSA) and crown projection area (CPA) are good measures for leaf area (LA), and if not, whether they can be improved by corrections through additional tree measures or stand measures. The study area was located near Bärnkopf, Lower Austria (15°00′20″ E, 48°23′24″ N) in the Bohemian Massif. Cediranib (AZD2171) On similar sites 8 even-aged Norway spruce (Picea abies L. Karst.) stands were investigated. The stands represented three different age classes and two thinning variants. We selected four pole stage stands, two premature, and two mature stands (ages of about 40, 80, and 125 years); two of the pole stage stands, and one of the premature and mature stands, respectively, were thinned 5 years ago (subsequently named “thinned”) and the other ones were not thinned for more than 10 years (subsequently named “un-thinned”). No other management, e.g., pruning or fertilization was performed in any of the investigated stands. Because of the relatively small size of the pole stage stands, for each thinning treatment two stands were selected. The fieldwork was conducted between April and September 2008. At first in each stand, the diameter at breast height (dbh), the tree height, the height to the crown base, and the coordinates of each tree were assessed.