Clematis vitalbain a New Zealand native forest remnant: does seed germination explain distribution?

Abstract

The pattern of distribution of the invasive vine Clematis vitalba in a typical New Zealand native forest remnant and the influence of chilling duration (chilling), nitrate (NO3-), and light on germination of C. vitalba were investigated. In the forest remnant, C. vitalba was not established in undisturbed forest where light levels were <3% full sunlight and rarely established where light levels were <5%. Clematis vitalba was, however, established in forest gaps and margins where light levels exceeded 5%, particularly when these areas were associated with recent soil disturbance. Under controlled environment conditions, germination in the absence of chilling, NO3-, or light was low (3%). When applied alone, chilling and NO 3-increased germination. Light, however, only increased germination when applied with one or both other factors. In the pres- B97006Received 27 January 1997; accepted 27 May 1997 ence of light, germination increased up to c. 80% with increased chilling (0-12 weeks), and increased up to c. 50% with increased applied NO 3-in the range 0.1-2.5 mol/m 3 but then changed little with additional NO3-up to 50.0 mol/m 3. In general, germination in the presence of two or three factors was greater than when either factor was applied alone.In the field, seeds remaining on vines over winter retained a high degree of dormancy and viability. We suggest that sporadic release of this seed effectively produces a seed bank. By comparing the levels of chilling, NO3-, and light that can be expected in the field with the levels that influence germination under controlled environment conditions, and considering a seed bank, we argue that C. vitalba is likely to rapidly establish following soil disturbance. We suggest that rapid establishment may account for the distribution of C. vitalba in recently disturbed, high light sites and, to some extent, the success of C. vitalba in New Zealand native forest remnants.

Can alternating temperature, moist chilling, and gibberellin interchangeably promote the completion of germination in Clematis vitalba seeds?

“…In particular, untreated (0) and DAR seeds needed 72 days to reach 50% germination (T 50 . This indicates that a certain degree of dormancy could be found in the study species, which is consistent with previous reports (Bungard et al 1997;Rudolf 1974;Van Gardingen 1986;West 1992). Moreover, it is widely reported that cold, moist incubation and/or GA 3 treatment promote completion of germination in dormant seeds (e.g., Baskin and Baskin 2014; Finch-Savage and Leubner-Metzger 2006), especially in temperate species, for which moist chilling is considered to be an effective mechanism that delays seed germination until after winter when conditions are more favourable for plant establishment (Bewley and Black 1985).…”

Effects of irradiance and nitrogen onClematis vitalbaestablishment in a New Zealand lowland podocarp forest remnant

“…In New Zealand, the introduced vine Clematis vitalba is a major weed in native forest remnants. In these remnants, C. vitalba does not establish within Downloaded by [162.244.26.76] at 11:36 06 June 2016 undisturbed forest but instead tends to establish in forest gaps and forest margins, particularly when these areas have been subject to recent disturbance (Atkinson 1984;Bungard et al 1997a). Compared with the understory of undisturbed forest, forest gaps and margins have elevated irradiance, and soils that have been subject to recent disturbance often have elevated levels of soil NO3- (Haynes 1986;McDonald & Norton 1993;Bungard et al 1997a).…”

“…In these remnants, C. vitalba does not establish within Downloaded by [162.244.26.76] at 11:36 06 June 2016 undisturbed forest but instead tends to establish in forest gaps and forest margins, particularly when these areas have been subject to recent disturbance (Atkinson 1984;Bungard et al 1997a). Compared with the understory of undisturbed forest, forest gaps and margins have elevated irradiance, and soils that have been subject to recent disturbance often have elevated levels of soil NO3- (Haynes 1986;McDonald & Norton 1993;Bungard et al 1997a). Establishment of C. vitalba in forest gaps and margins, rather than in undisturbed forest, is consistent with reports suggesting that C. vitalba is adapted to high irradiance environments and that low irradiance may be a major factor limiting the distribution in forest remnants (Atkinson 1984;Van Gardingen 1986;West 1992).…”

“…Similarly, with regard to nutrients, plants capable of rapid growth in high fertility environments often have a greater potential for nutrient uptake and assimilation compared with plants adapted to low fertility environments (Andrews et al 1992;Lee et al 1986). Bungard et al (1997a) showed that dormancy of C. vitalba seed was reduced by light and soil NO 3 , and argued that germination in response to these factors meant that seedlings were likely to establish rapidly following disturbance and, therefore, were likely to establish into a favourable environment for growth. They suggested that these germination characteristics could, to some extent, explain the distribution of C. vitalba in recently disturbed forest gaps and margins.…”

Germination studies on three critically endangered endemic angiosperm species of the Kashmir Himalaya, India

“…However, many studies that have examined the influence of different treatments, such as gibberellins (McDonough 1970), scarification (Pelton 1956), stratifications (Cavieres and Arroyo 2000) on seed germination of such alpine species, have pointed towards important role of dormancy in reproductive success of plants. For example, a chilling requirement can effectively regulate the timing of seed germination (Bungard et al 1997) and germination response to NO 3 -and/or light may be important as a gap or disturbance detection mechanism (Pons 1992). Thus, the study of dormancy mechanisms and germination requirements of alpine endemic species offers the prospect of understanding the survival advantages of dormant over-wintering seeds and also the role of seed germination in augmentation of restoration efforts urgently required for salvaging the critically endangered endemic species from extirpation and extinction.…”