Although numerous studies concerning the vegetation management of Horqin Steppe have been conducted, there are few documented reports on the relationship between vegetation management and phenological aspects, especially flowering and fruiting phenology. This paper reports relationships between the flowering and fruiting phenology of perennial species and their frequency and abundance under two utilizations, mowing and grazing, in the Horqin Steppe of northern China. The objectives are to find out how the plant phenological aspects of perennials, such as flowering and fruit-maturating relate to their frequency and abundance in meadow and to make suggestions on vegetation management in the study area.
The study sites were located at the Wulanaodu region (119°39′～120°02′E, 42°29′～43°06′N, 480 m a.s.l.) The climate of the region is semiarid with a mean annual precipitation of around 340 mm and a mean annual temperature of 6.3℃. The investigation was conducted along four transects, each 10m apart, on each kind of grassland. One hundred and sixty quadrats of 1 m×1 m, each at 10 m interval, were selected on the transects. Species composition and abundance were recorded in each quadrat.
Phenological investigation was conducted in the years 2003 and 2004. Quadrats of 2m×2 m were selected in the mowing meadow, and the date of flowering and fruiting of all species in the quadrats was recorded every three days in 2003 and every five days in 2004. Meanwhile, the date of flowering and fruiting of plants outside the quadrats was also recorded in 2004. The starting date of flowering and the fruit-maturating of 34 perennials were investigated. In analyzing the data, the species abundance, days of starting date to bloom from April 19, to have mature fruits from May 9 were logarithmically transformed.n the 34 perennials, 3 species started to bloom in April, 13 in May, 10 in June, 7 in July and only one in August. In the 34 perennials, 3 species started to have mature fruits in May, 14 in June, 11 in July, 5 in August and only one in September.Compared with the mowing, the frequency and the abundance of the species in the grazing declined more sharply, indicating that excessive grazing is more likely to eliminate the species with late flowering and fruit-maturating than is continuous mowing.
When the species with vegetative regeneration excluded, the frequency and the abundance of the species in the meadow grazing tended to decline more sharply compared with the meadow mowing, indicating that vegetative regeneration plays a critical rule in alleviating the extinction of species with late onset of flowering and fruit- maturating in the grazing grassland. eproductive phenology of species should be taken into consideration in the vegetation management of grassland. Suggestions for the effective management of grassland ecosystem were given that mowing should be done at the end of seeding period, and that mowing should be conducted rotatively, to allow plant species to finish seeding. Grazing should be started at the tillering stage, ended at the bud period and started again at the late seeding period.