Table 3 summarized the selected independent variables 
and their statistics of three remotely sensed images 
from individual band data. Taking the airborne 
multispectral scanning data as an example, in the crown 
closure estimation equation, the selected individual 
were MSSs - MSSg ^ and MSSg. Their R^ and F- 
value were 0.532 and 25.79 respectively. The probability 
was 0.0001. The values under the independent 
variable in tables were their F-value and probability. 
For instance, the F-value of of MSSs was 10.44, 
probability was 0.0019. Studying Table 3 briefly, a 
primary conclusion was that the crown closure 
estimation equations were effectively but the volume 
equations were not. 
Table 4 ^ The Selected Five Independent Variables and Their Statisties of 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Individual Band Data 
sensor  |dependent independent variable 
variable n? F-value |prob 
multi- [crown MSSs MSSg MSSg MSSo MSS10 
spectral |closure 2.76 0.0101 0.18] 0.6706 3.98, 0.0501 1.56, 0.0166 0.431 0.5143 0.539| 15.44| 0.0001 
scanner |volume MSS; MSS6 MSSg MSSg MSS10 
5.951 0.0407 3.11| 0.0824 378, 0.0562 L77 0.1889 4.36 0.0403| 0.198| 1.58] 0.1771 
crown TM1 TM3 TM3 TM4 TMs 
Landsat- |closure 22.62 0.0001 1.09 0..3005 6.84] 0.0108 6.411 0.0135 5.01 0.0283 0.910| 148.84| 0.0001 
TM volume TM, TM3 TM3 TM4 TM7 
2.60] 0.1112 1.73| 0.1920 3.62] 0.0612 6.16 0.1054 2.08| 0.1536| 0.099|  1.61| 0.1689 
  
  
  
  
  
  
General speaking, the more independent variables in a 
equation give more information about the dependent 
variable. What happened if more than three independent 
varialales contained in a multiple regression equation ? 
Table 4 was the results of five independent variables 
selected from the individual band of the airborne 
multispectral scanning data and the Landsat-TM data. By 
their R and F-value. A conclusion were made that the five 
independent variable equations in Table 4 were not more 
effectively on crown elosure and stand volume estimation 
than the equations with three independent variables in 
Table 3. In another words, three independent variables 
were enough in the crown closure and stand volume 
127 
equation establishment, no more variables were needed. 
2. Vegetation Index 
As mentioned previously, the vegetation indices used in this 
study were IND ]^NIR-R, IND2=(NIR-R)(NIR+R), 
IND3=(IND2+0.5) ', IND4-NIR-G, IND5=(NIR-G)/(NIR+G) 
and INDg=(IND5+0.5) ^. These vegetation indices computed 
by the digital number of three remotely sensed data 
respectively were used as the independent variables in the 
regression equations and the crown closure and stand volume 
as the dependent variables The results were shown in Table 5. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996