Soils are formed by geochemical and biological processes that act upon the parent material. Climate and topography interact with biotic factors and cause heterogeneity of soil properties across space and time. Topography and hydrological and climatic processes can operate at large scales, while biotic factors act at fine-scales (less than 1 ha). 

Whether different soil nutrients maintain their patchy consistency (no change in ranking through sequential sampling) across seasonal fluctuations has rarely been investigated. Moreover, whether litterfall maintains soil nutrient patch consistency at fine spatial scales needs further exploration. 

Prof. CHEN Jin and his students at Xishuangbanna Tropical Botanical Garden (XTBG) of Chinese Academy of Sciences assessed topography, annual litterfall chemical fluxes, and the dynamics of fine-scale soil chemical properties in a 1-ha tropical seasonal rainforest within a 20-ha forest dynamics plot in Southwest China. They aimed to assess patch consistency of soil chemical properties and factors that contribute to it. 

The researchers measured soil pH, total N, NH₄–N, NO₃–N, and available P and K for four times and assessed the patch structure and their temporal consistency. They then tested how structure and consistency of chemical soil properties were affected by topography and chemical inputs from litterfall. 

Their study found significant spatial structures, a premise for patch consistency in all soil chemical properties in the study area and demonstrated that soil pH, total N, and available P and K showed patch consistency. This patch consistency was significantly related to topographic position index, litterfall chemical fluxes, and principal coordinates analysis of neighbor matrices variables. 

While topography and litterfall contributed to the fine-scale consistency of nutrient patches in soil pH, total N, and available P and K, their effect on soil NO₃–N and NH₄–N were weakened. 

The study entitled “Effect of topography and litterfall input on fine-scale patch consistency of soil chemical properties in a tropical rainforest” has been published in Plant and Soil.