Ecology of subtropical grasses in temperate pastures: an overview

Abstract

<jats:p>Subtropical grasses can be a significant component of northern North Island pastures. Several annual and perennial types with different functional characteristics are widely established, allowing a range of different climatic, soil and moisture situations to be colonised. Many of the species have persistent seed banks or vegetative propagation facilitating long-term persistence. Biochemical types associated with moist conditions arc most common but types associated with arid conditions are also represented. Abundant rainfall at temperatures above 25"C, and factors which reduce temperate grass productivity (lowered soil fertility and winter/spring grazing damage) appear to favour higher proportions of both annual and perennial subtropical grasses such as summer grass and paspalum. Grazing pressure and timing, and level of fertiliser inputs appear important for species such as ratstail and carpet grass in less productive sites; The nature of competitive interactions between subtropical (C,) species and temperate (C,) species is poorly understood and invertebrate herbivory can be important in altering the balance between these species. An analysis of present subtropical grass species distributions in northern districts of New Zealand indicates that knowledge of the underlying species biological characteristics is useful in predi'cting subtropical grass abundance. To predict likely problem years and to develop management strategies to minimise problems, a better understanding is needed of the effects of climate on subtropical grass abundance in temperate pastures and competitive interactions. There may be scope for developing improved varieties for dry areas. Keywords: C,, C,, climate, competition, ecology, grazing, pasture, subtropical grasses, temperate</jats:p>

Plant Removals in Perennial Grassland: Vegetation Dynamics, Decomposers, Soil Biodiversity, and Ecosystem Properties

“…The strongest treatment responses by most components of the flora were to the removal of all C 3 grasses (occupying 22–53% of total biomass). Because removal of C 3 annual grasses (occupying 0–49% of biomass) alone did not exert much effect, we therefore conclude that C 3 perennial grasses, consisting almost entirely of Lolium perenne, were responsible for many of the treatment effects that we observed, consistent with previous investigations (, Campbell et al 1996). The data for the L. perenne × Trifolium repens interaction were, however, less consistent; there were periods during the winter when T. repens growth was strongly stimulated by L. perenne removal, and some periods in the summer when it was strongly inhibited by L. perenne removal (especially in early 1996).…”

“…Populations of the commonest curculionid species were generally smaller under the dicotyledonous weed removal treatment than the nonremoval treatments, consistent with literature suggesting that many of these species prefer dicotyledonous rather than monocotyledonous species (, , , Lanterni and Marvaldi 1995). The beneficial effects of removal of C 4 grasses for Naupactus leucoloma are consistent with the inferior resource quality provided by C 4 species, such as low nitrogen levels and high levels of recalcitrant structural carbohydrates (Campbell et al 1996, ). Further, the higher levels of Heteronychus arator under some of the treatments allowing dense grass cover is in agreement with the known preferences of this species for grass roots (Watson and Wrenn 1980, Watson and Marsden 1981).…”

“…This treatment was intended to correspond to treatment (2) by enabling comparison of C 3 and C 4 grass removal effects (cf. Wedin and Tilman 1993, Campbell et al 1996).…”

Climate‐change effects and adaptation options for temperate pasture‐based dairy farming systems: a review

“…This is an area that requires further research. Predictions are that in warmer, drier regions and areas prone to damage from diseases and insect attack, the proportion of perennial ryegrass (or other C 3 grasses) in pastures is likely to decrease, while the proportion of more heat ‐ and drought ‐ tolerant subtropical C 4 grasses and weed species increases (Campbell et al ., ). The proportion of legumes, such as white clover, may increase as they are more responsive to elevated CO 2 (Hebeisen et al ., ; Allard et al ., ); however, this will be dependent on the strength of the competition from other pasture species.…”

Regrowth Interval Influences Productivity, Botanical Composition, and Nutritive Value of Old World Bluestem and Perennial Ryegrass Swards

“…Maintaining monospecific stands of sown forages in pasture is difficult in the Appalachian region. Weather patterns, management, and competition among plants in the stand interact to create conditions allowing a range of native and naturalized forbs, grasses, and legumes to occupy gaps in the sward (Campbell et al, 1996). Fluctuations in botanical composition over years often were correlated with climatic conditions (Silvertown et al, 1994) and management.…”