Appendix C. Estimated parameters for dispersal functions using different neighborhood search distances and functional forms of the dispersal kernel.
We estimated parameters for dispersal
functions using different neighborhood search distances and functional forms
of the dispersal kernel for a hypothetical data set generated from 1-km2
area of source trees and 200 1-m2 quadrats distributed in two transects
through a central 1-ha portion of the source area. Simulated seed rain
was generated as a Poisson process, with a lognormal dispersal function ("Logn")
and parameter values given in Table C1. The "Theoretical" curve
is the true, underlying lognormal dispersal function (see Appendix
A) used to generate the hypothetical data set. The exponential function
("Exp") allowed both B and
in Eq. 3 to vary. The "2Dt" curve was estimated using the dispersal
function presented by Clark et al. (1999). The
three sets of estimated parameters for the lognormal function used neighborhood
radii of 25, 50, and 100 m, respectively. We also used a 100-m radius and
examined the fit to the underlying lognormal data if an exponential or 2Dt function
was used.
TABLE C1. Estimated parameters for dispersal functions using different neighborhood search distances and functional forms of the dispersal kernel.
|
Theoretical |
Logn - 25 m |
Logn - 50 m |
Logn - 100 m |
Exp - 100 m |
2Dt - 100 m |
|
|
Search Radius |
25 |
50 |
100 |
100 |
100 |
|
|
No. quadrats |
200 |
200 |
200 |
200 |
200 |
|
|
Log-likelihood |
-528.8 |
-493.6 |
-492.5 |
-500.3 |
-499.1 |
|
|
r2 |
0.8283 |
0.8377 |
0.8394 |
0.8194 |
0.8214 |
|
|
Normalizer |
1941.4 |
3043.2 |
2539.6 |
2180.9 |
2199.4 |
0 |
|
A |
500 |
1449.5 |
487.3 |
462.8 |
411.5 |
426.2 |
|
|
2 |
1.6 |
2.2 |
2.1 |
2.2 |
2.2 |
|
B |
10 |
15.3 |
11.6 |
11.5 |
40.3 |
1458.1 |
|
|
0.6 |
0.50 |
0.59 |
0.56 |
1.70 |
2.27 |
The u parameter for the 2Dt model of Clark et al. (1999).
The p parameter for the 2Dt model of Clark et al. (1999).
Clark, J. S., M. Silman, R. Kern, E. Macklin, and J. HilleRisLambers. 1999. Seed dispersal near and far: patterns across temperate and tropical forests. Ecology 80:14751494.