Table 2. Mutual invasibility experiments testing the ability of native perennial grass seedlings to invade exotic annual communities and vice versa.

			Biomass response to treatment
			Perennials added to annual community				Annuals added to perennial community
			Resident annuals		Seeded perennials		Resident perennials		Seeded annuals
Experiment	Source	df	S.S.	P	S.S.	P	S.S.	P	S.S.	P
Water	Block	7	144.37	0.332	388.44	<0.001	122.43	0.087	205.11	0.033
	Seeding	1	48.46	0.104	86.05	0.002	22.60	0.113	3.84	0.553
	Water	1	56.22	0.082	137.92	<0.001	140.82	<0.001	8.45	0.381
	Seed with water	1	1.92	0.739	7.45	0.314	11.21	0.257	14.65	0.252
	Total	31	604.04		767.054		470.47		453.80
Nitrogen	Block	4	59.77	0.305	68.62	0.005	32.13	0.673	34.11	0.763
	Seeding	1	87.31	0.016	58.34	<0.001	3.48	0.622	4.26	0.641
	Nitrogen	1	1.33	0.734	1.73	0.438	1.56	0.740	16.96	0.361
	Seed with N	1	4.42	0.538	0.01	0.962	2.27	0.690	0.32	0.899
	Total	19	284.67		160.94		173.87		240.34
Fire	Block	3	47.46	0.041	20.41	0.193	15.54	0.136	37.53	0.292
	Seeding	1	17.06	0.063	91.35	<0.001	4.34	0.190	31.31	0.089
	Fire	1	2.34	0.452	2.30	0.430	0.83	0.551	0.65	0.790
	Seed with fire	1	3.31	0.374	0.02	0.946	2.90	0.277	17.53	0.189
	Total	15	104.19		145.68		43.07		164.56

Biomass of resident and seeded species are analyzed separately for two scenarios: perennials seeded into an annual community and annuals seeded into a perennial community.