Table 3.

Parameters and associated statistics of SADIE. I_a represents the index of aggregation, and a value greater than one represents an aggregated spatial pattern. P_a indicates the significance of the respective I_a value, where a value of less than 0.05 is significant. v_i and v_j are the indices of clustering.

Variable	Site	I a	P a	Mean vj *	Mean vi **	p (Mean vj)	p (Mean vi)
Buckthorn Index (BI)	1	5.18	0.0003	−5.065	4.579	<0.0001	<0.0001
	2	3.49	0.0003	−3.213	2.912	<0.0001	<0.0001
	3	1.74	0.0003	−1.649	1.746	0.0015	0.0005
	4	2.64	0.0003	−2.857	2.639	<0.0001	<0.0001
Presence (%)	1	2.40	0.0003	−2.405	2.422	<0.0001	<0.0001
	2	4.13	0.0003	−4.062	4.197	<0.0001	<0.0001
	3	1.91	0.0003	−1.832	1.944	0.0005	<0.0001
	4	1.83	0.0015	−1.904	1.740	0.0008	0.0023

* v_i = index of clustering for points in which the BI or presence value is above average for that site. ** v_j = index of clustering for points in which the BI or presence value is below average for that site.