On the combined effect of soil fertility and topography on tree growth in subtropical forest ecosystems - a study from SE China

Created at: 2016-11-03

Envisaged journal: Journal of Plant Ecology

Envisaged date: 2016-11-03

Rationale

Aims
The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning (BEF) experiment in subtropical SE China.
Methods
Geomorphometric terrain analyses were carried out at a spatial resolution of 5 x 5 m. Soil samples of different depth increments and data on tree height were collected from a total of 566 plots (667 m² each). The soils were analysed for carbon (SOC), nitrogen, acidity, cation exchange capacity (CEC), exchangeable cations (Na, K, Mg, Ca, Fe and Mn) and base saturation as soil fertility attributes. All plots were classified into geomorphological units. Analyses of variance and linear regressions were applied to all terrain, soil fertility and tree growth attributes. Important Findings In general, young and shallow soilslimited soil formation and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment. This explains the concurrently increasing CEC and SOC stocks downslope, in hollows and in valleys. However, colluvial, carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways. The results showed that soil fertility is mainly influenced by topography. Monte-Carlo flow accumulation (MCCA), curvature, slope and aspect significantly affected soil fertility. Furthermore, soil fertility wasattributes were affected by the different geomorphological positions onf the experimental sites with ridge and spur positions showing lower exchangeable base cation contents, especially potassium (K), due to leaching. This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50 cm depth. Few soil fertility attributes affect tree height after 1-2 years of growth, among which C stocks proved to be most important while pHKCl and CEC only played minor roles. Nevertheless, soil
acidity and a high proportion of Al on the exchange complex affected tree height even after only 1-2 years growth. Hence, our study showed that forest nutrition is coupled to a recycling of litter nutrients, and does not only depend on subsequent supply of nutrients from the mineral soil. Besides soil fertility, topography affected tree height. We found that especially MCCA as indicator of water availability affected tree growth at small-scale as well as aspect. Overall, our synthesis on the interrelation between fertility, topography and tree growth in a subtropical forest ecosystem in SE China showed that topographic heterogeneity lead to ecological gradients across geomorphological positions. In this respect, small-scale soil-plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility. In addition, it shows that terrain attributes should be accounted for in ecological research.

Datasets

No datasets are linked to this paperproposal.

Calculated Authors

Thomas Scholten Thorsten Assmann Jürgen Bauhus Helge Bruelheide, Prof. François Buscot David Eichenberg, Dr. Alexandra Erfmeier Markus Fischer Philipp Goebes Jin-Sheng He, Prof. Werner Härdtle, Prof. Peter Kühn Keping Ma, Prof. Pascal Niklaus, PD Dr. Michael Scherer-Lorenzen, Prof. Bernhard Schmid, Prof. Karsten Schmidt Steffen Seitz Xuezheng Shi Zhengshan Song Christian Wirth Tesfaye Wubet Goddert von Oheimb

Data request state

Preparation Project Board Finished