Comparison of transpiration of differently aged apple orchards on the Loess Plateau of China at multiple temporal scales

Accurately quantifying transpiration (T) in apple orchards and its proportion of precipitation (P) is important for comprehending hydrological and ecological processes. A field experiment was conducted during the growing seasons (May to September) of 2013-2016 on the Loess Plateau of China to investigate the characteristics of T in apple (Malus domestica, cv. Fuji) orchards of different ages at multiple temporal scales. The results indicated that tree age clearly influenced T for the young (8-year-old) and old (18-year-old) apple orchards. Transpiration was consistently higher in the old than the young orchard at the same time scales (p < 0.05). At the monthly scale, T was not significantly correlated with leaf area index (LAI) or soil relative extractable water (REW) for either orchard. Average ratios of T to P for the four years were 37.7% and 50.2% for the young and old orchards, respectively. These results identified that trees age should be considered when evaluating T and sustainably developing revegetation activities on the Loess Plateau and in other similar regions.