Ecological value of global terrestrial plants

As a crucial primary producer of the earth, terrestrial plants play important functions in energy flow and biogeochemical cycles of the planet. However, their real wealth contributions to human society are not properly evaluated because of their widespread distribution and limitations in evaluation methods. This study used the emergy methodology to evaluate the ecological economic value of global terrestrial plants. Terrestrial plants were divided into three groups of bryophytes, gymnosperms and angiosperms for the emergy evaluation. The area of the system boundary for terrestrial plants was 13.5 E+9 ha. Total annual emergy use of the terrestrial plants was 10.29 E + 24 sej yr(-1) which consisted of 9.19 E + 24 sej yr(-1) by angiosperms, 1.00 E + 24 sej yr(-1) used by gymnosperms, and 0.09 E + 24 sej yr(-1) by bryophytes. The total emergy stored in the terrestrial plants was 648.50 E + 24 sej, with 550.28 E + 24 sej stored in angiosperms, 91.64 E + 24 sej in gymnosperms, and 6.58E+24 sej in bryophytes. The Unit Emergy Values (UEVs) of the Net Primary Production (NPP) of terrestrial plants was calculated as 183.31 E + 6 sej gC(-1). For each plant group, UEVs were 189.00 E + 6 sej gC(-1) for angiosperms, 145.54 E + 6 sej J(-1) for gymnosperms, and 159.63 E + 06 sej gC(-1) for bryophytes. The emdollar values were calculated to determine approximate monetary values for production and storage of the terrestrial plants. The ecological values of the annual plant production were 5.14 trillion (em)$ for the all terrestrial plants with 4.59 trillion, 0.50 trillion, and 0.05 trillion (em)$ for angiosperm, gymnosperm, and bryophytes respectively. The ecological values stored in the plant biomasses were 324.25 trillion (em)$ for all the terrestrial plans, with 275.14 trillion, 45.82 trillion, and 3.29 trillion (em)$ for angiosperm, gymnosperm, and bryophytes respectively.