The ecology and harvest potential of titica vine roots (Heteropsis flexuosa: Araceae) in the eastern Brazilian Amazon

Aerial roots from hemiepiphytic Heteropsis (Araceae) vines have long been used in Amazonia as a strong flexible material in construction and making handicrafts. Commercial demand for this product known in Brazil as "titica" has increased in recent decades for making wicker furniture. We conducted inventories, harvests and experimental root cutting in the Alto Rio Guamá Indigenous Reserve in the eastern Brazilian Amazon to investigate several aspects of titica ecology, root biology, and harvest impact to estimate root harvest potential in a range of intact and disturbed forest areas. The average density of host trees with titica roots in relatively undisturbed upland "terra firme" plots with light to moderate forest use was 371 trees/ha with 115 of these having commercially harvestable roots. These areas had an average of 0.9 commercially harvestable roots and 2.4 non-harvestable roots per host tree generating a titica root density of 1332 roots/ha with 26% of these being commercially harvestable. Titica plants did not show a positive preference for particular types of host trees, but the number of titica roots per host tree did increase with host tree size. The vines were virtually absent from forest areas subject to periodic flooding, a common palm tree found near small streams, and on pioneer tree species in patches of secondary forest recovering from a fire that occurred almost 20 years ago. Experimental cutting of mature titica roots showed that harvesting can have a severe impact on root survival. In the two treatments, where at least half of mature titica roots per host tree were cut 4 m above the ground, an average of 63% cut roots died and only 16% showed some regrowth after 7 months. The roots that did start to grow back had an average of 1.7 new roots arising from them, but each cut root had only one commercial quality root to replace it. These commercial quality roots were growing at an average of 220 cm per host tree per year. The high mortality and slow regrowth following root harvest indicate that many decades will be needed in between intensive titica harvests in one area. Options for managing titica harvests include reducing the percentage of roots removed per plant, setting up blocks of forest that would be harvested in succession, and in some cases integrating titica harvests into long-term timber cutting cycles.