Multiple indirect effects of plant litter affect the establishment of woody seedlings in old fields

Published source details Facelli J. (1994) Multiple indirect effects of plant litter affect the establishment of woody seedlings in old fields. Ecology, 75, 1727-1735.
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This study is summarised as evidence for the following.

	Action	Category
	Add organic matter after tree planting Action Link
	Apply insecticide to protect seedlings from invertebrates Action Link
	Mechanically remove understory vegetation after tree planting Action Link

Add organic matter after tree planting

A randomized, replicated, controlled study in 1989–1990 in a former arable field in New Jersey, USA (Facelli 1994) found that adding leaf litter to plots reduced tree of heaven Ailanthus altissima seedling emergence and survival, but increased their biomass if competing herbs were present. Plots with added leaf litter had lower seedling emergence than those without (litter: approx. 6; no litter: approx. 9 seedlings/plot). Seedling mortality in plots with litter was higher (approx. 31%) than in plots without (approx. 7%). Where competing herbs were present, seedling biomass was higher in plots with litter (no data provided). Where competing herbs were absent, biomass was similar with and without litter (no data provided). Sixteen plots (0.8 × 1 m) received dried, cleaned leaf litter from white oak Quercus alba at 150 g/m², held in place by chicken wire mesh. The remaining 16 plots received no leaf litter. In all plots, 20 seeds had been planted to ensure regeneration.
Apply insecticide to protect seedlings from invertebrates

A randomized, replicated, controlled study in 1989–1990 in a former arable field, in New Jersey, USA (Facelli 1994) found that using insecticides increased the number of emerging tree of heaven Ailanthus altissima seedlings and seedling survival. Plots treated with insecticide had greater seedling emergence (approx. 13 seedlings/plot) than untreated plots (approx. 9 seedlings/plot). Additionally, seedling mortality was lower in plots treated with insecticide (approx. 3 %) than in untreated plots (approx. 7%). Sixteen plots (0.8 × 1 m) were treated with Carbaril dust 5%, dosed at 5 g active ingredient/m². The other 16 plots were not treated with insecticide. In all plots, 20 seeds had been planted to ensure sufficient regeneration.
Mechanically remove understory vegetation after tree planting

A randomized, replicated, controlled study in 1989–1990 in a former arable field, in New Jersey, USA (Facelli 1994) found that removing competing herbs from plots did not increase the emergence or survival of tree of heaven Ailanthus altissima seedlings, but did increase seedling biomass. Seedling emergence did not differ between removal and untreated plots (removal: approx. 10; untreated: approx. 9 seedlings/plot). Similarly, seedling mortality was similar between treatments (removal: approx. 10%; untreated: approx. 7%). However, seedling biomass was greater in plots where competing herbs were removed than in untreated plots (no data provided). In 16 plots (0.8 × 1 m), all herbs were clipped at surface level and root connections were severed by driving a spade 30cm in the ground, around the plot’s perimeter. The other 16 plots were not clipped. In all plots, 20 seeds had been planted to ensure regeneration.