Season and rainfall gradient effects on condensed tannin concentrations of woody rangeland species

Abstract

Shrubs and trees in warm climate rangelands play multiple roles including providing ruminants with forage. Condensed tannins (CT) in these species can have negative and positive effects on those ruminants so quantifying them is crucial to their management. The objective of this study was to measure CT concentrations of key woody perennials during distinct seasons in Pernambuco, Brazil. The species were collected along a 432 to 607 to 1200-mm rainfall gradient. When season differences were identified, CT concentration declined (P ? 0.05) during the dry season compared to the rainy season. There was distinct correlation in CT concentration and aridity with dissimilarity cluster formation. Myracrodruon urundeuva Allemão [62.3 ± 8.5 g kg-1 dry matter (DM)] and Schinopsis brasiliensis Engl. (61.53 ± 14.8 g kg-1 DM) had the greatest (P ? 0.05) concentration of CT while Cordia leucocephala Moric (10.9 ± 10.9 g kg-1 DM) and Oxalis insipid St. Hil. (19.3 ± 8.2 g kg-1 DM) had the least. Conservation or reseeding these species in rangeland may depend on whether their CT concentrations are beneficial to wildlife or domesticated livestock.