Nearly one quarter of New Zealand’s unique vascular plant flora is threatened, and weed invasion is implicated in the decline of more than half of these threatened species. However, there is little experimental evidence showing that invasive weeds have a direct impact on threatened native plants. This study experimentally tested the hypothesis that competition with invasive weeds threatens the ...

Wissman, J. 2006. Grazing regimes and plant reproduction in semi–natural grasslands. The dominating grazing regime in semi-natural grasslands today is continuous grazing throughout the season, and a high grazing pressure is often advised in order to avoid litter accumulation. Traditional management, on the other hand, included late mowing and grazing, which favoured plant flowering and seed pro...

Seed mass in species-rich moist tropical forests often varies over six or more orders of magnitude (Foster, 1982; Foster and Janson, 1985; Hammond and Brown, 1995). Most of these species, including some with the minutest seeds (Metcalfe, 1996; Metcalfe and Grubb, 1997), can be classified as ‘shade-tolerant’ with the ability to establish beneath a closed canopy. Seeds of the shade-tolerators var...

The success of germination, growth and final yield of every crop depends to a large extent on the quality of the seeds used to grow the crop. Seed quality is defined as the viability and vigor attribute of a seed that enables the emergence and establishment of normal seedlings under a wide range of environments. We attempt to dissect the mechanisms involved in the acquisition of seed quality, t...

Mechanization and simplification are inevitable trends in agriculture production to decrease input demands and simultaneously improve resource use efficiency. Dry direct-seeded rice is a resource-saving cropping system and has been considered as a replacement for traditional transplanted rice. However, the poor establishment of dry direct-seeded early rice, primarily induced by chilling stress,...

Soldier fly, Inopus rubriceps (Macquart), larvae suck nutrients from the roots of ryegrass, ‘reducing root growth, tiller and foliage production, and probably plant survival. Accurate placement of insecticide with the seed killed larvae, and en’hanced establsishment of the seedlings. The use of minimum cultivation, paraquat, and fertilizer sown with the seed, ‘all made larvae move on to the row...

In grazed habitats is a tradeoff between competition (decreases with the grazing intensity) and disturbance (increases). This may give tradeoffs between plant life stages. The seed production can be assumed to decrease at high disturbance intensities because of herbivory of reproductive organs, but also at high levels of competition (low grazing intensity) because of resource limitation. The es...

Immigration rates of species into communities are widely understood to influence community diversity, which in turn is widely expected to influence the susceptibility of ecosystems to species invasion. For a given community, however, immigration processes may impact diversity by means of two separable components: the number of species represented in seed inputs and the density of seed per speci...