Native Windbreaks Support Greater Understory Plant Diversity in Monteverde, Costa Rica
Rows of trees bordering agricultural fields, commonly called windbreaks, primarily serve to protect livestock and crops. However, they may also increase biodiversity and serve as foci for regeneration in agricultural landscapes. The effects of windbreak design on restoration potential and conservation have yet to be examined. This study focuses on the differences in understory plant diversity of windbreaks composed of native trees versus exotic trees on a farm in Monteverde, Costa Rica. The following questions are being addressed in this study: Is understory plant diversity greater in exotic or native windbreaks? Is there a difference in soil quality and composition between native and non-native windbreaks, and if so, could this be affecting understory plant diversity? What are the implications of these differences in plant diversity, if any, for biodiversity and forest regeneration? Understory plant species richness and abundance were examined in windbreaks using a randomized plot design. Four windbreaks consisted of planted native trees Croton niveus and Montanoa guatemalensis, and another four windbreaks were comprised of planted exotic trees Cupressus lusitanica and Casuarina equisetifolia. The Shannon-Wiener diversity index, which is a measure of species richness and evenness, was significantly greater for native windbreak understories (Hutcheson t(df>50)=9.35, p<.01). There were significant differences in species composition ([χ2=181.98, df=36, p<.01] [t(df>50)=9.35, p<.01]). Windbreaks composed of exotic trees contained more invasive individuals. This stark contrast indicates that windbreaks composed of planted native trees could be beneficial for promoting native biodiversity and forest regeneration in agricultural landscapes.