Plant a mixture of tree species to enhance diversity

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One replicated, randomized, controlled study in Brazil found that planting various tree species increased species richness, but had no effect on the density of new trees.
  • One replicated, controlled study in Greece found that planting native tree species increased total plant species richness, diversity and 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

  1. A replicated, randomized, controlled before-and-after study in 2004-2005 in subtropical forest in Brazil (1) found that planting increased species richness, but had no effect on the density of new trees. The change (after minus before) in number of species was higher in planted plots (planted: 10; unplanted: 0/plot), while the change in stem density was similar between treatments (planted: 1,000; unplanted: 1,000/ha). Data were collected immediately before (January 2004) and one year after treatment (March 2005) in four replicates of adjacent unplanted control and planted (42 seedlings of 18 tree species) plots (10 × 10 m).

    Study and other actions tested
  2. A replicated, controlled study in 1998-2003 in a degraded Mediterranean kermes oak Quercus coccifera shrubland in Greece (2) found that planting native pine species increased plant species richness, diversity and cover five years later. The total number of species (planted: 47; unplanted: 42/plot), number of woody species (planted: 9; unplanted: 7/plot), species diversity (Shannon’s index planted: 3.0; unplanted: 2.6) and the total plant cover (planted: 81%; unplanted: 76%) were higher in planted areas. Cover of kermes oak was lower in planted (17%) than in unplanted areas (26%), while the cover of all woody species was similar between treatments (planted: 41%; unplanted: 39%). Planting were in winter 1998. Data was collected five years after planting in one 50 m2 plot within each 200 m2 treatment unit. Eighteen units were planted with 30 plants of native Aleppo pine Pinus halepensis or stone pine Pinus Pinea and 15 were control plots in unplanted areas.

    Study and other actions tested
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

Forest Conservation

This Action forms part of the Action Synopsis:

Forest Conservation
Forest Conservation

Forest Conservation - Published 2016

Forest synopsis

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What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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