“…Due to the above-mentioned drawbacks of estimating LAI from space-borne data and crop growth models, this study obtains LAI in forests from meteorological data via employing the GEP technique. In the recent years, GEP has been applied to many hydrological problems such as estimation of solar radiation (Landeras et al, 2012), air temperature (Kisi et al, 2013a;Kisi and Shiri, 2014;Shiri et al, 2014a), pan evaporation (Kisi et al, 2012;Pour Alibaba et al, 2013;Kisi, 2015;Kim et al, 2015), forest carbon fluxes (Dou and Yang, 2018), crop evapotranspiration (Torres et al, 2011;Shiri et al, 2014b, c;Shrestha and Shukla, 2015;Karimi et al, 2016), soil parameters (Shiri et al, 2017a, b), river flows (Liu et al, 2014;Karimi et al, 2017) and river qualitative parameters (Kisi et al, 2013b). Recently, Karimi et al (2018) utilized GEP and random forest to estimate LAI in croplands and grasslands from in-situ meteorological data.…”