Growth dynamics and leaf quality of the stinging trees Dendrocnide moroides and Dendrocnide cordifolia (Family Urticaceae) in Australian tropical rainforest: implications for herbivores

Leaf growth dynamics and leaf quality of Dendrocnide moroides (Wedd.) and D endrocnide cordifolia (L.S.Sm.) Jackes and Hurley varied widely with age, s eason, plant height and habitat. Although leaves were produced continuously , growth rates varied seasonally. Leaf moisture and nitrogen content increa sed in spring and summer and decreased with age, while toughness increased with age. All leaf growth attributes varied with height, with the majority of activity occurring on mid-sized plants. Leaf growth rates and proportion s of different leaf age classes were similar for both species. Leaves were larger and lived longer in shade. Size and longevity responded rapidly to c hanging light conditions, reflecting their ability to survive in small rain forest gaps. Leaves of all ages were highly nutritious and the exceptionall y nutritious young leaves were abundant throughout the year making them sus ceptible to herbivore attack. However, immature stinging tree leaves were d ensely covered with painful stinging hairs and hair density decreased with age. Further to causing pain, stinging hairs of D. moroides and D. cordifol ia are shed continuously and may deter mammalian herbivores by causing alle rgic reactions. However, the leaves of stinging trees appeared better suite d to the rapid colonisation of rainforest gaps, than in fending off or avoi ding herbivore damage.