Water plants to preserve dry tropical forest species

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

Study locations

Key messages

  • One replicated, controlled study in Hawaii found that watering plants increased the abundance and biomass of forest plants.


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, controlled study in 1998-2000 in tropical dry forest in Hawaii, USA (Cabin et al. 2002) found that irrigation increased the abundance and biomass of most forest plants. Average biomass and density were higher in watered than in control plots for: all species (watered: 355 g/m2, 28 individuals/m2; control: 28 g/m2, 23 individuals/m2), for native species (watered: 129 g/m2, 16 individuals/m2; control: 7 g/m2, 11 individuals/m2) and for seeded species (watered: 34 g/m2, 7 individuals/m2; control: 1 g/m2, <1 individuals/m2). For non-seeded species average biomass was higher in watered (95 g/m2) than in control plots (6 g/m2), while density was lower in watered plots (watered: 9; control: 11 individuals/m2). Thirty two plots (1 m2) of each treatment: watered (20 litre/plot, three times a week for the first six months, once a week thereafter) and control (not-watered) were established in 1998. Each plot was sown with 60 seeds of shrubs and trees. Plants biomass and density was measured 21 months after treatment.

    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

What Works 2021 cover

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