03820naa a2200229 a 450000100080000000500110000800800410001902400520006010000180011224501530013026000090028352030190029265000230331165300300333465300360336465300310340065300320343170000210346370000220348470000190350677300650352521570742024-02-15       2024    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1007/s10342-023-01608-22DOI1 aMULLER, M. D.  aEstimating volume of eucalyptus trees for small-scale silvopastoral systemsbdo we really need height for accurate estimates?h[electronic resource]  c2024  aDouble-entry volume equations require measurement of diameter and height variables, making forest inventory more expensive. This can be limiting for small farms. Then the single-entry volume equations, where diameter at breast height (DBH) is the independent variable, are a cost-efective option for these landowners because they optimize data collection due to the use of one readily available variable (the DBH) and require few resources. The objective of this study was to evaluate the efective contribution of the height in the estimation of eucalypt trees volume for small-scale silvopastoral systems. For this, four single-entry and fve double-entry volumetric models were ftted to the data for six diferent silvopastoral systems in Coronel Pacheco, Minas Gerais State, Brazil. The six strata consisted of combinations of three diferent Eucalyptus genetic material and three silvopastoral systems, and the models were compared aiming the selection of the best of each type in each system. Double-entry models, specifcally logarithmic Spurr and logarithmic Schumacher?Hall, ftted better than single-entry ones for all but one of the strata, where they were overcome by the Husch?s model. Although the superiority of the formers can have been easily verifed by diferent and complementary statistics, we found that the volume estimates provided by the best double-entry and the best single-entry model of each stratum difered by a quantity that can be considered irrisory, from both practical and monetary points of view. On a per tree basis, the sum of the diferences for each stratum, in absolute value, did not surpass 0.051 m3 , or only US$ 0.25, considering a market value of US$ 4.90/m3 . And when simulating a real scenario of batch sales for each stratum, by simple extrapolation of the mean volume and considering their efective tree stand, such diferences did not exceed±0.25 m3 /ha, or±US$ 1.20/ha. Following the same logic, even when comparing the best doubleentry model to the worst single-entry one for each stratum, we still observed only negligible diferences. Considering the sampled trees, these diferences amounted to a balance per stratum of only?0.015 to+0.032 m3 (or between?US$ 0.07 and+US$ 0.16). When extrapolated to the total trees in each stratum, the overall balance did not exceed an absolute value of 0.283 m3 (or US$1.39). These results suggest that the contribution of height may be negligible in estimating the volume of eucalyptus trees for small silvopastoral systems. Consequently, smallholders may not beneft from measuring tree heights. Rather, they may save money by foregoing a comprehensive forest inventory and instead using single-entry models, such as the Husch model, to estimate the wood volume of their forest stands. Another highlight or reinforcement of this work is that the use of the Furnival index was crucial for a reliable selection of the best models, once it allows for comparisons among models both with and without a log transformation of the volume.  aSistema de Cultivo  aAgrosilvopastoral systems  aCrop-livestock-forestry systems  aSistema agrossilvipastoril  aSustainable farming systems1 aBORGES, C. A. V.1 aRESENDE, L. de O.1 aMARTINS, C. E.  tEuropean Journal of Forest Researchgv. 143, p. 81-94, 2024.