Fertiliser addition is important for tree growth on cut-over peatlands in eastern Canada

Published source details Caisse G., Boudreau S., Munson A.D. & Rochefort L. (2008) Fertiliser addition is important for tree growth on cut-over peatlands in eastern Canada. Mires and Peat, 3, 11.
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This study is summarised as evidence for the following.

	Action	Category
	Directly plant peatland trees/shrubs Action Link
	Add inorganic fertilizer (before/after planting) Action Link
	Add inorganic fertilizer (before/after planting) Action Link

Directly plant peatland trees/shrubs

A replicated study in 2004–2005 in a historically mined bog in Quebec, Canada (Caisse et al. 2008) reported that 81% of planted tamarack Larix laricina seedlings and 55% of planted black spruce Picea mariana seedlings survived over 16 months. Additional fertilized seedlings had higher survival: 92–98% for tamarack and 58–87% for black spruce. In June 2004, seedlings were planted 3 m apart into drained, bare peat. For each species, three plots of 50 seedlings were fertilized, but three plots of 900 seedlings were not. Survival was checked after two growing seasons in October 2005.

(Summarised by: Nigel Taylor)
Add inorganic fertilizer (before/after planting)

A replicated, randomized, paired, controlled study in 2004–2005 in a historically mined bog in Quebec, Canada (Caisse et al. 2008) reported that fertilization increased survival and growth rate of two planted tree species. These results were not tested for statistical significance. After two growing seasons, survival of fertilized tamarack Larix laricina was 92–98% (unfertilized: 81%) and of fertilized black spruce Picea mariana 58–87% (unfertilized: 55%). As a measure of growth rate, shoot length of fertilized tamarack was 9–33 cm (unfertilized: 1 cm) and of fertilized spruce 4–6 cm (unfertilized: 3 cm). In early June 2004, seedlings of the two tree species were planted into drained bare peat. There were three blocks/species. Within each block, six plots of 150 trees immediately received a random fertilization treatment (commercial or custom-made; see original paper). Three additional plots of 50 trees were not fertilized. In October 2005, seedling survival was assessed. Terminal shoot length was measured for 15 trees (across five randomly placed quadrats) in each plot.

(Summarised by: Nigel Taylor)
Add inorganic fertilizer (before/after planting)

A replicated, randomized, controlled study in 2005–2006 in two historically mined bogs in New Brunswick, Canada (Caisse et al. 2008) reported that fertilization increased growth of planted trees in 8 of 14 combinations: only when the fertilizer included phosphorous. These results are not based on tests of statistical significance. After two growing seasons, trees fertilized with phosphorous had longer shoots (black spruce Picea mariana: 13–23 cm; tamarack Larix laricina: 46–65 cm) than unfertilized trees (spruce: 7 cm; tamarack: 2 cm). Trees fertilized only with nitrogen or potassium had similar-length shoots to unfertilized trees (spruce: 4–6 cm; tamarack: 2–3 cm). Saplings were originally planted into bare peat in spring 2001. In spring 2005, four plots of each tree species (one random plot in each of four blocks) received each fertilization treatment: no fertilizer, N (40 g/plant), P (9 g/plant), K (15 g/plant), N+P, N+K, P+K or N+P+K. In October 2006, terminal shoot length of eight trees was measured in each plot.

(Summarised by: Nigel Taylor)