Fine-scale spatiotemporal influences of salmon on growth and nitrogen signatures of Sitka spruce tree rings

BMC Ecology

Table 1 Top ten most highly ranked models of indexed annual Sitka spruce growth and δ ¹⁵ N isotopic enrichment

Response variable	Model rank	Model predictors	AICc	Δ AICc	ω_i
Growth index
	1	salmon, temperature, salmontemperature, salmonforest	4367.54	0	0.60
	2	salmon, temperature, salmon*temperature	4368.34	0.80	0.40
	3	salmon, temperature, precipitation, salmontemperature, salmonprecipitation	4379.01	11.47	0.00
	4	salmon, temperature, salmontemperature, salmonupstream	4381.63	14.09	0.00
	5	null (intercept only)	4390.26	22.73	0.00
	6	temperature, precipitation, temperature*precipitation	4390.94	23.41	0.00
	7	salmon, salmon*forest	4391.44	23.90	0.00
	8	salmon	4392.14	24.61	0.00
	9	temperature	4394.52	26.98	0.00
	10	salmon, salmon*upstream	4394.98	27.44	0.00
δ¹⁵N
	1	forest, upstream, forest*upstream	281.20	0.00	0.77
	2	growth index, forest, upstream, forest*upstream	284.53	3.23	0.15
	3	forest, upstream, salmon, forest*upstream	286.89	5.68	0.05
	4	growth index, forest, upstream	287.40	6.20	0.03
	5	forest	294.03	12.83	0.00
	6	growth index, forest, upstream, forestupstream, salmongrowth index	296.70	15.49	0.00
	7	forest, upstream	297.28	16.09	0.00
	8	growth index, forest	297.28	16.09	0.00
	9	upstream	298.82	17.61	0.00
	10	salmon, forest	299.66	18.46	0.00

Model predictors are annual salmon abundance (salmon), mean maximum temperature (ºC) for the biological year (temperature), distance from stream (forest), distance upstream (upstream), total precipitation for the biological year (precipitation) and derived annual tree ring width (growth index; see methods). Models were ranked using AICc values. For predictors of the growth index, the top two models were averaged. * interaction effect.

ISSN: 1472-6785