Maliau drip tips project (proposal)

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Role of the drip-tips in Tropical Rain Forests: Association of Leaf drip-tips with other leaf morphological characters to reduce the growth of epiphylls and fungi.

Douwe Yntema, Mohd Ridwan A. Rahman and Imesh Nuwan Bandara



We plan to study drip tips and their relation to epiphyll and fungal growth. Drip tips, or long narrow apices of leaves, are common in wet lowland rain forests (Leigh 1975) but thier function is yet to be understood properly. A long standing hypothesis is that they both hasten the drying time of leaves (Stahl 1893; Dean and Smith 1978; Ivey and De Silva 2001) and thus prevent easy colonization by epiphylls and fungi (Ivey and Desilva 2001). However, uncertainty remains as to the true importance of this morphological characteristic and definitive evidence of their function has yet to be discovered. Considering their frequent occurrence and uncertainty of function, we believe drip tips merit further study.

Research question

Does drip tip size in relation to leaf length influence the growth of epiphylls, fungi, and other leaf covering? We believe this is important to understand considering the possible trade-offs of varying leaf morphology to trees.


Leaves with proportionally larger drip tips will reduce the occurrence of fungi and epiphylls.


In order to test this, we will:

  • Conduct random sampling of trees on 50 meter transects in different primary forest (gap/non gap).
  • Collect one branch sample every 5 meters.
  • Observe leaf morphology: leaf arrangement, leaf shape, apex, leaf margin, leaf lamina, leaf length, and drip tip length (measured from inflexion point).
  • Measure leaf size using a 5 mm X 5 mm grid sheet.
  • Measure the percentage cover of fungi, and epiphylls (algae, lichen or moss).
  • Observe lichen species alpha diversity.


Our statistical hypothesis is that we will find a strong relationship between proportional drip tip size and percentage cover of epiphyll and fungi. Our null hypothesis is that there will be a random distribution.


  • Dean, J.M., and Smith, A.P. (1978), ‘Behavioral and morphological adaptations of a tropical plant to high rainfall’, BIOTROPICA 10:152-154.
  • Ivey, C. T. and DeSilva, N. (2001), ‘A Test of the Function of Drip Tips’, BIOTROPICA 33(1), 188-191.
  • Leigh, E.G. (1975), 'Structure and climate in tropical rain forests. Ann. Rev. Ecol. Syst. 6:66-68.
  • Stahl, E. (1893), ‘Regenfall and Blattestalt. Ann. Jard. Bot. Buitenz. 11: 98-182.