Effects of mowing regimes and climate variability on hay production of Leymus chinensis (Trin.) Tzvelev grassland in northern China

Abstract

Abstract. Leymus chinensis (Trin.) Tzvelev grassland is the most widely distributed native steppe vegetation type suitable for haymaking in the semiarid pastoral regions of north-east Asia. The long-term effects of four mowing regimes (mowing once a year, twice a year, once every 2 years and twice every 3 years), and climatic variability on the hay production from L. chinensis grassland were investigated using permanent plots over 27 years. The results showed that (i) the overall cumulative annual herbage production over the 27 years was the highest under 'mowing once a year', and 'mowing twice a year' did not produce any significant change in the amount of harvested herbage; (ii) mowing induced a reduction in herbage production mostly in the first couple of years, and the reduction was larger under frequent than less frequent mowing. The annual herbage production in harvest years was higher under less frequent mowing (once every 2 years, or twice every 3 years) than that under annual mowing, but the higher herbage production in harvest years under less frequent mowing could not compensate for the herbage not made into hay in the years without harvest; (iii) annual herbage production generally increased with annual precipitation, but the response of annual herbage production to precipitation was best described by quadratic (instead of linear or logarithmic) equations, which suggested a decline in annual herbage production under the highest annual precipitation in the region, and the relationships stood under different mowing regimes; and (iv) an analysis of hay yield and quality, and costs of the mowing operation, showed that the haymaking from L. chinensis grassland was financially viable as long as the herbage production was not extremely low under drought. It is concluded that the best practice for haymaking from L. chinensis grassland should be based on the rule of 'mowing once a year' in high-production years and grazing in low-production years; and a light grazing early in the season may increase hay quality mowed in the autumn if the grassland grows well early in the season in high-production years.

Long-term effects of mowing on plasticity and allometry of Leymus chinensis in a temperate semi-arid grassland, China

“…Tzvel., widely distributed across eastern Eurasian temperate regions, is a dominant species of the grasslands of the Inner Mongolian steppe, which have been traditionally used as rangelands for both livestock grazing and haymaking (Wu, 1980;He et al, 2008). It is a normal practice in the semi-arid regions of Inner Mongolia in northern China to clip grassland every year without applying any fertilizer (Baoyin et al, 2014). A growing body of empirical evidence suggests that grassland ecosystems are affected to different extents by different mowing regimes (Han et al, 2007;Herrero-Jáuregui et al, 2014), but the differences have not been studied for L. chinensis.…”

“…Mowing in arid and semi-arid natural grasslands affects the properties and processes of ecosystems (Baoyin et al, 2014). Long-term mowing of plants can change the temperature and carbon content of the soil, which in turn change soil properties, such as respiration (Zhou et al, 2007;Baoyin et al, 2014).…”

Mowing succession of species composition is determined by plant growth forms, not photosynthetic pathways in Leymus chinensis grassland of Inner Mongolia

“…The precipitation has a large inter-annual variation ranging from 180 to 550 mm, and 60-80 % of which falls during the summer season of June to August. The climatic data recorded at the nearby meteorological observatory at the IMGERS/CAS shows that annual or plant growing-season (April-August) precipitation has no trend over the experimental period , while the annual mean temperature of plant growingseason shows a significant increasing trend (P = 0.001) by 0.06°C year -1 (Baoyin et al 2014). …”

“…Plant production in each plot was determined species by species by harvesting one quadrat of 1 9 1 m in the centre of each plot while all the area in the plot was cut to the same residual height. The intact grassland was monitored also using 6 quadrats of 1 9 1 m, but the quadrats were randomly placed around the area of the permanent mowing plots, and the placement of the quadrats were to avoid any identifiable previously-cut areas (Baoyin et al 2014). The harvested plant materials were oven-dried to constant at 60°C and weighted.…”

“…To explore the effects of mowing frequency on grassland production, we conducted a long-term mowing experiment on the L. chinensis grassland in the steppe region of Inner Mongolia. The primary results on the effects of mowing frequency on hay yield was reported (Baoyin et al 2014), so was the grassland dynamics for the early part of experimental period (Bao et al 2004), but not the long-term succession of grassland species composition and the underlying mechanisms in relation with plant growth forms and C-pathways. Here we present the succession trajectory of L. chinensis grassland over the 30-year period, emphasizing the changes in the relative abundance of plant growth-form groups (GFGs) and of C-pathway groups (C 3 /C 4 species).…”