Aboveground litter quality changes may drive soil organic carbon increase after shrub encroachment into mountain grasslands

• Published in: Plant and soil Vol. 337; no. 1/2; pp. 151 - 165
• Main Authors: Montané, Francesc, Romanyà, Joan, Rovira, Pere, Casals, Pere
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.12.2010; Springer Netherlands; Springer Nature B.V
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Beans; Biological and medical sciences; Biomedical and Life Sciences; Botany; Carbon; Carbon content; Chemical, physicochemical, biochemical and biological properties; Conifers; Ecology; Encroachment; Festuca; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Grasses; Grassland soils; Grasslands; Juniperus communis; Legumes; Life Sciences; Mimosaceae; Mineral soils; Mountains; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant litter; Plant Physiology; Plant roots; Plant Sciences; Plants; Regular Article; Shrubs; Soil science; Soil Science & Conservation; Soil sciences; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; Root decomposition; Conifer shrub; Litter production; Root production; Ingrowth cores; Litter quality; Legume shrub; Litter decomposition; C sequestration; Grassland; Organic carbon; Organic matter; Growth; Rhizogenesis; Decomposition; Physical environment; Mountain; Gymnospermae; Production; Ingrowth core technique; Litter; Root; Shrub; Shrub encroachment; Vegetation dynamics; Woody plant; Carbon sequestration; Organogenesis; Cores; Soils; Penetration; Measurement technique; Vegetative apparatus; Spermatophyta; Coniferales; Soil plant relation
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-010-0512-1

Shrub encroachment into grasslands is ubiquitous but its impact on soil organic C (SOC) remains unclear. In previous work we had observed that shrub encroachment into mesic mountain grasslands increased SOC content. Here we sought the mechanisms of this increase. To this end, we assessed aboveground and belowground production for a conifer shrub (Juniperus communis L), a legume shmb (Cytisus balansae ssp. europaeus (G. López & Jarvis) Muñoz Garmendia) and grass (Festuca eskia Ramond ex DC), together with decomposition rates for both aboveground litter and roots. Belowground C net inputs do not clearly explain SOC increase: grass root production was higher than that of either shrub and the decomposition rate of grass roots was the lowest. Aboveground C net inputs were only slightly greater in shrubs than in grass, but the decomposition rate of litter of both shrubs was much lower than that of grass. The decomposition of conifer litter was N-limited, whereas that of legume shrub litter was P-limited. Thus we conclude that the SOC increases after shrub encroachment into mesic grasslands probably as a result of higher recalcitrance of shrub aboveground litter relative to grass litter.