Temporal changes of an alfalfa succession and related soil physical properties on the Loess Plateau, China

Abstract

-The objective of this work was to investigate the relationship between changes in the plant community and changes in soil physical properties and water availability, during a succession from alfalfa (Medicago sativa L.) to natural vegetation on the Loess Plateau, China. Data from a succession sere spanning 32 years were collated, and vegetative indexes were compared to changes related to soil bulk density and soil water storage. The alfalfa yield increased for approximately 7 years, then it declined and the alfalfa was replaced by a natural community dominated by Stipa bungeana that began to thrive about 10 years after alfalfa seeding. Soil bulk density increased over time, but the deterioration of the alfalfa was mainly ascribed to a severe reduction in soil water storage, which was lowest around the time when degradation commenced. The results indicated that water consumption by alfalfa could be reduced by reducing plant density. The analysis of the data also suggested that soil water recharge could be facilitated by rotating the alfalfa with other crops, natural vegetation, or bare soil.Index terms: Medicago sativa, agropastoral transition zone, community characteristics, soil physical properties, soil water restoration. Variações temporais de uma sucessão de alfafa e de propriedades físicas do solo a elas relacionadas no Loess Plateau, ChinaResumo -O objetivo deste trabalho foi investigar a relação entre variações em uma comunidade de plantas e variações nas propriedades físicas do solo e na disponibilidade de água, durante uma sucessão de alfafa (Medicago sativa L.) por vegetação natural, no Platô Loess, na China. Dados de uma sucessão de 32 anos foram examinados e índices vegetativos foram comparados em relação às variações de densidade do solo e do armazenamento de água no solo. A produção de alfafa aumentou aproximadamente por sete anos, e então decresceu, e a alfafa foi substituída por uma comunidade natural dominada pela Stipa bungeana, que começou a crescer vigorosamente dez anos após a semeadura da alfafa. A densidade do solo aumentou com o tempo, e a deterioração da alfafa se deu principalmente em razão da redução severa da água armazenada no solo, que atingiu o mínimo quando a degradação da alfafa começou. Os resultados indicam que o consumo de água pela alfafa poderia ser reduzido pela redução na densidade de plantas e que a recarga de água no solo poderia ser facilitada pela rotação entre a alfafa e outras culturas, vegetação natural ou solo nu.Termos para indexação: Medicago sativa, zona de transição agropastoril, comunidades características, propriedades físicas do solo, recuperação da água no solo.

Estimating total net primary productivity of managed grasslands by a state-space modeling approach in a small catchment on the Loess Plateau, China

“…Understanding the spatial distribution of planted grassland NPP and the relationships with soil properties and other environmental variables has vital significance for grassland management and decreasing erosion. However, little is known about the interactions between soil properties and vegetation succession on the Loess Plateau (She et al, 2009), and the lack of knowledge on relationships between the spatial variability of NPP and other environmental factors (such as soil chemical and physical properties and topography) inhibits the progress of vegetation restoration. Because regression-and processbased models are usually used at relatively large scales and rarely involve available soils information (Lieth, 1975;Churkina and Running, 1998), in this study we applied a state-space analysis to identify underlying processes involved in planted grasslands NPP in a small catchment on the Loess Plateau of China.…”

Medicago sativa improves soil carbon sequestration following revegetation of degraded arable land in a semi-arid environment on the Loess Plateau, China

“…In this study, aboveground biomass peaked in year six after the experiment established, suggesting a degradation trend in the long term. Weed invasion and deep soil water deficit were considered to be the main causes for Medicago degradation (Jiang et al, 2006;She et al, 2009). Thus, appropriate field management should be undertaken to maintain Medicago production in the long run.…”

“…Highly erodible soil, low vegetation cover/biomass, gully terrain, and intensive human disturbance, such as overgrazing and intensive cultivation, are the main causes for serious soil erosion in this region (Chen et al, 2007;Wang et al, 2011a). Owing to high yields, the ability of fixing nitrogen, and adaptability to various environment conditions, legume pastures (e.g., Medicago sativa L. and Melilotus suaveolens L.) are widely used in the revegetation practices of "Grain for Green" on the Loess Plateau She et al, 2009;Deng et al, 2014a;Mu et al, 2014). Introduction of legume pastures exhibit high potential in sequestering C in soil because of the increased rates of organic matter addition and retention (Raiesi, 2012;Deng et al, 2014b;Dean et al, 2014;Guan et al, 2016).…”

Factors affecting the recovery of abandoned semi-arid fields after legume introduction on the Loess Plateau

“…On the Loess Plateau, returning degraded farmlands to grasslands has been a widely implemented policy since 1999 (Chen et al, 2007). Legume species such as M. sativa and M. suaveolens have been used in this process because of their rapid growth and the protection of the soil surface they provide (She et al, 2009). However, we do not know well how environmental factors drive the succession of plant communities after the introduction of legumes in this area.…”

“…Afforestation has been shown to contribute to environmental degradation (Cao, 2008;Cao et al, 2011), including low survival rate of trees , increased soil erosion (Normile, 2007;Wang et al, 2010), exacerbated water shortages (Cao et al, 2009) and deep soil desiccation (Chen et al, 2007). Consequently, some legume species have been used in restoration practices on the Loess Plateau (Zhang et al, 2000) because of their high yield, protection of the soil surface, fixation of nitrogen and adaptability to the semi-arid environment conditions She et al, 2009).…”