“…So, following the unit value based approach, one should value the 2011 ES using the 2011 unit values (Costanza et al, 2014), value the 2050 ES using the 2050 unit values (Kubiszewski et al, 2017), rather than value the 2011 ES using the 1997 unit values (Costanza et al, 2014), value the 2050 ES using the 2011 unit values (Kubiszewski et al, 2017). However, re-estimating all unit values is a heavy work, especially, considering the non-linearity in ecosystem services (Barbier et al, 2008; Koch et al, 2009) and the spatial heterogeneity of unit values (de Groot et al, 2012; Crossman et al, 2013; Drakou et al, 2015). In the primary data based approach, the difficulty for accurately valuing each individual ES is remained (Guo et al, 2001; Dai et al, 2016), although there are some technique innovations in recent years (Coscieme et al, 2014).…”