Plant a mixture of tree species to enhance diversity
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
Background information and definitions
Direct planting of new trees can be used to restore degraded tree communities. This can also affect the abundance of other plant species and consequently the composition of the whole forest.
Supporting evidence from individual studies
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
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