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Volume 53 (2011)
- Issue 2 Pages 41-
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Volume 53, Issue 2
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Akihiro Tani, Eriko Ito, Masahiro Tsujino, Makoto Araki, Mamoru Kanzak ...Article type: Article
2011 Volume 53 Issue 2 Pages 41-52
Published: December 25, 2011
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSThe hemispherical photography method is widely used to estimate the leaf area index (LAI) of forest stands. Both photographic exposure and threshold determination in producing binary images critically affect LAI estimates. To remedy LAI estimation error, we propose a series of protocols that we term the Open-sky Reference Method (ORM). ORM uses reference photographs of an open-sky area and photographs within the canopy at one-stop overexposure, relative to the reference photos. In threshold determination, the reference photograph is used as the maximum digital number classifying the open-sky area into white. In total, 14 stands of multi- or single-layered broad-leaved forests and sparse conifer forests located in the Japanese temperate zone were used to investigate the effects of photographic exposure error (or shift from an optimum value) on LAI estimated using ORM. We also compared our LAI estimates with those obtained using other photographic protocols that are more sensitive to exposure error because LAI estimates change largely in proportion to exposure shifts. ORM stabilized LAI estimates regardless of exposure shifts, indicating that ORM is tolerant of unpredictable field measurement errors and is, thus, a more practical LAI estimation method.View full abstractDownload PDF (1668K) -
Masato Shibuya, Tsutomu Urata, Hiroyuki Torita, Hayato IijimaArticle type: Article
2011 Volume 53 Issue 2 Pages 53-59
Published: December 25, 2011
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSWe investigated the relationship between windthrow damage and tree shape in coniferous plantations that had suffered windthrow in 2004 in central Hokkaido, northern Japan, to examine the effect of tree shape on the resistance of trees and stands to windthrow. We investigated the following tree-shape parameters in damaged and undamaged plantations of Larix kaempferi, Abies sachalinensis, and Picea jezoensis, major plantation species in Hokkaido, 2-4 years after the windthrow: slenderness ratio (H/D ratio), crown length/tree height ratio (C_L ratio), and the height of the center of gravity of the wind load/tree height ratio (H_W ratio). In L. kaempferi and A. sachalinensis plantations, mean H/D ratios were distinct between damaged and undamaged plantations; the mean H/D ratio was lower in undamaged plantations than in damaged plantations. Based on differences in C_L and H_W ratios, the crown size of L. kaempferi and A. sachalinensis trees was larger in undamaged plantations than in damaged plantations. In P. jezoensis plantations, similar tendencies in H/D, C_L, and H_W ratios were observed. These data suggest a definite relationship between tree shape and resistance to windthrow, whereby trees with small slenderness ratios and large crowns are more resistant to windthrow. It is also suggested that vulnerability of coniferous plantations to windthrow changes drastically at thresholds in H/D and C_L ratios. Therefore, coniferous plantations should be managed to reduce windthrow risk. Because tree shape is heavily influenced by stand density, risk management on plantations should include density control initiatives.View full abstractDownload PDF (1073K) -
Xiaoqiang Lu, Hiroto Toda, Fangjun Ding, Dongsu Choi, Shengzuo FangArticle type: Article
2011 Volume 53 Issue 2 Pages 61-71
Published: December 25, 2011
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSBulk precipitation, throughfall, stemflow, and stream water were collected and the concentrations of major ions were determined from samples collected from a subtropical natural evergreen and deciduous broadleaf mixed forest in Maolan, a karst area in southwest China, in order to quantify the input-output budgets of major dissolved nutrients and to examine changes in the chemical composition of precipitation after passing through the canopy. Calcium ion and Mg^<2+> derived predominantly from carbonate weathering were the major contributors to the hydrologic system's compartments. Low ion concentrations and a high pH value characterized bulk precipitation quality that was influenced by natural rather than anthropogenic sources in Maolan. Calcium ion and Mg^<2+> had negative annual input-output budgets in contrast to K^+, Na^+, Cl^-, SO_4^<2->-S, and dissolved inorganic nitrogen (DIN) that had annual positive input-output budgets. We used a canopy budget model (Na^+ tracer) to estimate amounts of dry deposition and canopy exchange of ions in throughfall. Calcium ion had the largest annual dry deposition, followed by SO_4^<2-> and NH_4^+. Annual atmospheric deposition of DIN amounted to 12.3kgha^<-1>yr^<-1>. Eighty-six percent of DIN input in the forest was retained in the plant-soil system, indicating effective immobilization by vegetation and/or soil microflora.View full abstractDownload PDF (1981K) -
Tatsuyuki SeinoArticle type: Article
2011 Volume 53 Issue 2 Pages 73-78
Published: December 25, 2011
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSThe spatial-temporal shifting of Kalopanax septemlobus population was examined in a cool-temperate coniferous-hardwood mixed forest, northern Japan. Saplings distributed far from the conspecific adult trees indicated clumped distribution by a small cohort. There were no specific relationships between distance from conspecific adult trees and growth traits of saplings. The saplings distributed around the conspecific adults at their early stage of regeneration, and shifted to far from the conspecific adults at late stage of regeneration. The establishment of offspring in K. septemlobus was determined early in distribution, survived only on a preferred site, and endured until the occurrence of an unpredictable event such as a change in the canopy gap.View full abstractDownload PDF (787K)
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