Growth, herbivore distribution, and herbivore damage of timber trees in a tropical silvopastoral reforestation system
2013
Riedel, Judith | Dorn, Silvia | Plath, Mirco | Mody, Karsten
CONTEXT: The reforestation of degraded tropical pastures requires innovative tree planting systems that consider land user needs. AIM: We established a silvopastoral reforestation system and assessed the effects of companion trees on the native timber tree Tabebuia rosea in Panama. Timber tree individuals were established in (1) solitary plantings (TSol) or in companion plantings with (2) Guazuma ulmifolia (TGua) or (3) the nitrogen-fixing Gliricidia sepium (TGli). METHODS: We quantified growth characteristics and herbivory of T. rosea, and analyzed leaf chemistry (including the stable isotopes δ¹⁵N and δ¹³C) and structure (leaf mass per area). RESULTS: Companion trees significantly affected stem diameter growth of T. rosea. Stem diameter growth was as high in TGli trees as in TSol trees but was reduced in TGua trees. Furthermore, TGua trees had higher leaf water content, and lower δ¹³C and lower leaf mass-to-area ratio than TGli trees, suggesting there were effects of shading by G. ulmifolia on T. rosea. Herbivory was high but not affected by planting regimes. Leafing phenology did not differ between planting regimes and G. sepium did not increase nitrogen content in T. rosea leaves. CONCLUSION: Companion tree planting can support timber tree growth in silvopastoral reforestations, but adequate species selection is crucial for successful implementation of this planting system. Tree–tree interactions seem to be more relevant for timber tree growth than herbivory in the studied system.
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