Reduction in throughfall reduces soil aggregate stability in two subtropical plantations

• Published in: European journal of soil science 2019-03, Vol.70 (2), p.301-310
• Main Authors: Yang, Y. J., Liu, S. R., Wang, H., Chen, L., Lu, L. H., Cai, D. X.
• Format: Article
• Language: English
• Subjects: Aggregates; Aggregation; Bulk density; Carbon sequestration; Climate change; Control; Control stability; Distribution; Drought; Forest soils; Forests; Herbivores; Iron; Moisture content; Oxides; Pine trees; Plantations; Porosity; Precipitation; Reduction; Slaking; Soil; Soil aggregates; Soil density; Soil depth; Soil moisture; Soil porosity; Soil properties; Soil stability; Soil temperature; Soil texture; Stability analysis; Texture; Throughfall; Water content; Weight
• ISSN: 1351-0754; 1365-2389
• DOI: 10.1111/ejss.12734

Summary Climate change has altered global precipitation regimes in terms of intensity and frequency of drought stress and, consequently, it is likely to affect soil moisture and soil aggregation. However, we know little about the effects of drought on soil aggregate size, distribution and stability, and how that affects carbon sequestration. A drought manipulation experiment was conducted by throughfall exclusion treatment (TET) of 50% in two planted forests (Pinus massoniana Lamb. and Castanopsis hystrix A.DC.) in subtropical China. The aim was to investigate the effects of a reduction in throughfall on aggregate size, distribution and stability. The results from the 4‐year experiment show that the TET affected soil moisture content significantly (with 14.5 and 20.4% decreases in the P. massoniana and C. hystrix plantations, respectively) compared with the control. Soil temperature at 0–5‐cm soil depth and soil texture were not affected significantly. Soil porosity in the TET plots was greater than that of the control, whereas soil bulk density and free Al oxide content were less. The mass fractions of macroaggregates (> 0.25 mm) and mean weight diameter (MWD) of aggregates, an indicator of aggregate stability, decreased in the TET compared with the control. Variation in aggregate size, distribution and stability can be caused by Fe and Al oxides, soil texture, bulk density and porosity. Our results indicated that TET reduced soil aggregate stability in subtropical plantations because of a decrease in free Al oxide and an increase in porosity. Slaking effects from variation in soil moisture were also possible for the decreased MWD. This study suggests disturbance of forest soils should be minimized in the context of a decline in precipitation. Highlights Size, distribution and stability of forest soil aggregates were evaluated under throughfall exclusion. TET reduced free Al oxide content but increased soil porosity, leading to breakdown of macroaggregates. Soil aggregate stability was reduced by TET. Fe and Al oxides and soil texture contributed more than SOC to aggregate size and stability.