Nut Yield Model for Ancient Torreya grandis cv. Merrillii

Investigations were implemented on each ancient Torreya grandis cv. Merrillii trees from July to September, 2015, at Xiaokun village,Changle town, Shengzhou, Zhejiang province. The nut yield model was developed by adopting the variable parameter modeling method. By modelvalidation，the coefficient of determination (R2 ) was 0.6413, the estimation accuracy (EA) was 97.32%, the total relative error (TRE) was 0.0191%,the mean relative error (MRE) was 0.425%. The yield model can estimate the output of a given DBH, tree height and crown diameter under averagemanagement level. The estimated results can estimate individual management level and forest resources assets of the nut value.