Abstract: To investigate the home-field effects of litter decomposition and the underlying mechanisms at the regional scale, we examined mass loss rate and nitrogen release rate of leaf litter from three dominant tree species of subtropical China (Pinus massoniana, Cunninghamia lanceolata, and Quercus variabilis) under interplanting conditions of different soils at specific temperatures. We collected soil and leaf litter samples in sites of the southern and northern subtropics and carried out a 126-day indoor decomposition experiment under different temperatures. The results showed that: (1) species identity and decomposition time significantly affected the mass loss rate and nitrogen release rate of leaf litter, with Q. variabilis showing the greatest mass loss rate and nitrogen release rate during the 126 days (32.43% and 33.51%), with C. lanceolata having a relatively low mass loss rate (15.35%); (2) Under the same-regional interplanting conditions, Q. variabilis showed home-field disadvantage of nitrogen release only on north subtropical soils (-28.35%), P. massoniana showed both home-field disadvantage of mass loss and nitrogen release on south subtropical soils (-3.20% and -17.65%), and C. lanceolata showed home-field advantage of mass loss on south subtropical soils (2.13%). Under the cross-regional interplanting conditions, Q. variabilis showed home-field disadvantage of mass loss and nitrogen release regardless of the northern and southern subtropics (-57.55% to -3.70%), while P. massoniana and C. lanceolata showed home-field disadvantage of mass loss or nitrogen release in the northern subtropics (-31.76% to -4.40%), and home-field advantage in the southern subtropics (3.78% to 58.43%); (3) The range of home-field advantage (additional decomposition at home, ADH) in leaf litter mass loss and nitrogen release and the frequency of their home-field effect increased under cross-regional interplanting conditions compared to the same-regional interplanting. Staged mass loss was positively correlated with microbial biomass nitrogen, whereas ADH of nitrogen release was negatively correlated with microbial biomass under same-regional interplanting conditions, and ADH of nitrogen release was positively correlated with temperature under cross-regional interplanting conditions. These results suggest that the home-field effects of leaf litter decomposition of the three tree species in the subtropics were affected by a combination of temperature, leaf litter species, decomposition time, and soil microorganisms. In contrast, temperature, in addition to substrate quality, can significantly constrain the home-field effects of leaf litter decomposition under cross-regional interplanting conditions.

Key words: leaf litter decomposition, soil microbial biomass, mass loss, nutrient release, home-field effect