1. Ecological Indicators 18(2012) 559-566
Circular distributions of fallen logs as an indicator of forest disturbance regime
Toshihiro Abe, Yasuhiro Kubota, Kenichiro Shimatani, Tuomas Aakala, Timo Kuuluvainen
Ecological Indicators 18(2012)

2. どんな内容か・・・？ やること 倒木の方向をはかります しりたいこと 倒木の方向は、過去の森林撹乱体制の指標に用いることができるのか？
Measuring directions of fallen logs
しりたいこと
倒木の方向は、過去の森林撹乱体制の指標に用いることができるのか？
Can Directional distributions of fallen logs be an indicator of past forest disturbance regimes？

3. 背景 windthrow is important component of natural disturbance regime.
(in the absence of severe disturbances...)
senescene-related mortality of individual trees
or small groups make small-scale gap dynamics.
the functioning and role of wind as a disturbance factor may vary from case to case

4. 背景
Forest structural attributes (tree species, size, spatial pattern…) are affected by the occurrence of wind-induced disturbances.
to understand the mechanisms of forest dynamics...evaluate the vulnerability of forests against wind, and the magnitude and the ecological impact of windthrows.

5. 背景
the vulnerability of forests against wind, and the magnitude and the ecological impact of windthrows.
This information is also essential for developing ecosystem-based forest management (Natural Disturbance Emulation)

6. 背景
Forest monitoring and wind damage monitoring can provide direct information of wind-caused disturbance.
Retrospective studies using dendroecology may be used to infer longer-term disturbance regimes.

7. 背景 Use of another type of data…
The directions of fallen logs as an indicator of forest disturbance regimes, with special emphasis on the role of wind.
Using measurements of log start and end points, or directions.

8. 研究の意図
Examine the use of directional distributions of fallen logs as an indicator of past forest disturbance regimes.
To do this we used data from three areas of primeval Picea abies-dominated boreal forests with contrasting disturbance histories.

9. 調査地
Area 1: in the Pallas-Ylläs National Park Area 2: in the Kazkim river valley Area 3: in the Dvina-Pinega area 40m×400m plots Area 1: Plots 1-5 Area 2: Plots 7-11 Area 3: Plots 12-16

10. 調査地

11. 調査項目 all living and dead tree(DBH:10cm≦) ⇒mapped
Tree species, DBH, Height
dead tree⇒based decay classes
The directions of fallen logs ⇒every 5°

12. 調査項目

13. 統計手法 circular statistics
The unit is radian, 0=east, π/2=north, π=west, 3/2π=south

14. 統計手法 VM WC SSVM SSWC Symmetric circular distribution
If the symmetry is rejected
Skewed circular distribution
SSVM
SSWC

15. 結果
Plot 7-11
in area 2
Plot 1-5
in area 1
Plot 12-17
in area 3

16. 結果

17. 考察

18. 考察
Five curves of distributions of log directions within each are were similar
Whereas, there appeared significant contrasts between the areas
Between study areas> within study areas

19. 考察
The results from the analyses of fall directions support the hypothesized differences in the role of wind in the disturbance regimes of the three areas.
Area1: heart-rot fungi in combination with wind were the main causes of tree death
Area2: single events can then have strong impact over the entire area
Area3:tree mortality and intermediate disturbances

20. 結論
Differences in the circular distribution patterns of fallen logs can be meaningfully related to essential characteristics of forest disturbance regimes.
Directions of fallen logs can provide a new approach for making retrospective inferences about past forest disturbance regimes.