Sampling methods for titica vine (Heteropsis spp.) inventory in a tropical forest

Abstract

Key message: Titica vine provides useful raw fiber material. Using sampling schemes that reduce sampling error can provide direction for sustainable forest management of this vine. Sampling systematically with rectangular plots (10 × 25 m) promoted lower error and greater accuracy in the inventory of titica vines in tropical rainforest Context: The titica vine (Heteropsis spp.) is an important raw material for native communities located in the Amazon tropical rainforest. However, variability and spatial distribution of this species are some factors that hinder the assessment of accurate productivity prediction, and thus, inventory methods for management plan must be defined. Aims: The aim of this study was to develop and compare accuracy of different sampling approaches for the inventory of titica vines (roots ha−1) using simulations based on field data. Methods: Eighty-eight treatments were defined by the combination of the process (random or systematic), sampling intensity (5, 10, 15, and 20 % of 18 ha), plot size (250 to 3000 m2) and shapes (square, rectangle, and transect). Production estimate, sampling error, and relative efficiency were used to compare treatments with each other and with the reference inventory. Results: The mean production estimates for the random and systematic processes were 570 and 597 vine roots ha−1, while the reference estimate was 500 vine roots ha−1. Among of the treatments evaluated, only 5.8 % of them provided a sampling error less than 15 %. Conclusion: The sampling procedure that combines systematic or random process, plots sizes of 250 or 300 m2 and sampling intensity greater than 15 % was the most efficient for inventory of titica vine in tropical forests.