Remove or disturb leaf litter to enhance germination

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
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How is the evidence assessed?

Effectiveness

40%
Certainty

25%
Harms

23%

Calculating overall effectiveness category

Background information and definitions

A thick litter layer on the forest floor can inhibit seed germination and the development of many forest species. Removing litter can increase germination and consequently biodiversity in forests.

Study locations

Key messages

One replicated, controlled study in Costa Rica found that leaf litter removal decreased the density of new tree seedlings. One replicated, controlled study in Poland found leaf litter removal increased understory plant species richness but decreased their cover.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, controlled study in 1983-1999 in temperate mixed woodland in Poland (1) found that annual removal of leaf litter increased species richness and cover of mosses after 12 years and temporarily increased vascular plant species richness after 10 years, but decreased vascular plant cover after 13 years. Species richness and cover of mosses was higher in leaf litter removal plots than in control plots after four years and remained higher until the end of the experiment (average 4-15 years of removal: 8 species, 35% cover; control: 0 species and 0% cover). Vascular plant cover was lower in leaf litter removal plots than in control plots after 13 years of treatment (average 13-15 years of removal: 55%; control: 85%). Vascular plant species richness was higher in leaf litter removal plots than in control plots after 10 years (average 10-13 years of removal: 17; control: 9 species) and then became similar between treatments after 14 years of treatment (average 14-15 years: 16; control: 11 species). Monitoring was in three pairs of 5 × 5 m plots for two treatments: leaf litter removed (litter raked and removed every year 1983-1998) and controls (litter not removed).
Study and other actions tested
Referenced paper
Dzwonko Z. & Gawroński S. (2002) Effect of litter removal on species richness and acidification of a mixed oak-pine woodland. Biological Conservation, 106, 389-398.
A replicated, controlled study in 1997-1999 in tropical forest in Costa Rica (2) found that removal of leaf litter decreased the density of new tree seedlings in forest areas, but not in artificial gaps. The density of new tree seedlings was higher in control (0.5/m²) than in litter removal plots (0.3/m²) in forest areas, and similar between treatments in artificial gaps (control: 3.0/m²; litter removal: 2.7/m²). In 1997, large gaps (320–540 m²) were created inside five 40 × 40 m plots (gap plots) by cutting and removing all tree stems ≥5 cm diameter at breast height. Five other similar size plots (non-gap plots) were unmanipulated with respect to canopy cover. Five blocks were established within each plot, each comprised of two 2 × 2 m quadrats one of each of litter removal and a control with no litter removal. Data were taken every two months for one year after treatments.
Study and other actions tested
Referenced paper
Dupuy J.M. & Chazdon R.L. (2008) Interacting effects of canopy gap, understory vegetation and leaf litter on tree seedling recruitment and composition in tropical secondary forests. Forest Ecology and Management, 255, 3716-3725.

Please cite as:

Agra, H., Schowanek, S., Carmel, Y., Smith, R.K. & Ne’eman, G. (2020) Forest Conservation. Pages 323-366 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Forest Conservation

Related Actions

	Actions	Effectiveness	Studies	Category
	Encourage leaf litter development in new planting Action Link	No evidence found (no assessment)	0	Synopsis Link
	Remove or disturb leaf litter to enhance germination Action Link	Unknown effectiveness (limited evidence)	2	Synopsis Link