Dispersal Spectra

Oudtshoorn, Karen van Rheede van; Rooyen, M.W. van

doi:10.1007/978-3-662-03561-0_9

Cited by 8 publications

(12 citation statements)

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“…Seeds with no obvious structures were classified as having no particular dispersal mode (none). Two types of multiple dispersal strategies were also accounted for: a combination of wind and animal, as well as wind and water (Plitmann, 1986; Burke, 1995; van Rheede van Oudtshoorn & van Rooyen, 1999). Growth forms were assigned according to a combination of structural, anatomical, life span and in some instances metabolic characteristics (Table 1).…”

Section: Methodsmentioning

confidence: 99%

Determinants of inselberg floras in arid Nama Karoo landscapes

Burke¹

2001

Journal of Biogeography

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Aim This study investigated the relationship between inselberg floras in floristic and functional terms and their correlation with environmental variables at macro‐scale and landscape level. Location Four inselberg landscapes in Namibia’s arid Nama Karoo in southern Africa were selected. Methods Plant surveys were undertaken over a 3‐year period and species composition, growth form and dispersal spectra were used as measures for floristic and functional composition. Canonical correspondence analysis (CCA) was employed as the main tool to explain the perceived patterns. Results Regarding floristic affinities, inselberg floras formed distinct groups per study area and thus geographical position, with strong correlations between inselbergs within a particular study area. Neither growth form nor dispersal spectra closely resembled the pattern that emerged in the ordination of floristic composition. The influence of geographical position lessened when functional rather than floristic measures were introduced in the analysis. Main conclusions (1) On landscape and macro‐scale, floristic composition of inselberg floras was largely determined by geographical position, geology, elevation, habitat diversity, rock outcrop in the surrounding and surface area of inselbergs. (2) Environmental variables operating at landscape level had greater influence on functional composition than on floristic composition. (3) Stochastic variables were more important in shaping the flora of these arid Nama Karoo inselbergs than deterministic processes such as niche relations and competition.

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Section: Methodsmentioning

confidence: 99%

Determinants of inselberg floras in arid Nama Karoo landscapes

Burke¹

2001

Journal of Biogeography

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“…In addition, seed structures and characters (seed mass and seed shape) affect the effectiveness of seed dispersal [ 8 , 9 ]. Hence, species with different structures form different dispersal syndromes, including anemochory [ 10 – 12 ], zoochory [ 13 – 23 ], autochory [ 24 , 25 ], ombrohydrochory [ 7 , 25 ], and barochory [ 26 ]. However, very little is known about the dispersal strategy in relation to dispersal syndromes in plant species of cold deserts.…”

Section: Introductionmentioning

confidence: 99%

Seed Dispersal and Germination Traits of 70 Plant Species Inhabiting the Gurbantunggut Desert in Northwest China

Liu

Zhang

Yang

et al. 2014

The Scientific World Journal

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Seed dispersal and germination were examined for 70 species from the cold Gurbantunggut Desert in northwest China. Mean and range (3 orders of magnitude) of seed mass were smaller and narrower than those in other floras (5–8 orders of magnitude), which implies that selection favors relatively smaller seeds in this desert. We identified five dispersal syndromes (anemochory, zoochory, autochory, barochory, and ombrohydrochory), and anemochorous species were most abundant. Seed mass (F = 3.50, P = 0.01), seed size (F = 8.31, P < 0.01), and seed shape (F = 2.62, P = 0.04) differed significantly among the five dispersal syndromes and barochorous species were significantly smaller and rounder than the others. There were no significant correlations between seed mass (seed weight) (P = 0.15), seed size (P = 0.38), or seed shape (variance) (P = 0.95) and germination percentage. However, germination percentages differed significantly among the dispersal syndromes (F = 3.64, P = 0.01) and seeds of ombrohydrochorous species had higher germination percentages than those of the other species. In the Gurbantunggut Desert, the percentage of species with seed dormancy was about 80%. In general, our studies suggest that adaptive strategies in seed dispersal and germination of plants in this area are closely related to the environment in which they live and that they are influenced by natural selection forces.

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“…Seeds from capsules and follicles are usually small and have no features to facilitate dispersal by specific vectors. These seeds could be indirectly dispersed by wind 12 , a process that has been defined as anemoballism by van der Pijl 1 , jactitation by Ridley 18 and the censer mechanism by Bansal and Sen 19 . Although the mechanism of this dispersal type has received quite limited attention, van der Pijl 1 noted that “ … Many Campanulaceae are comparable (to papaver) and also have pores at the top of erect capsules and at the base of hanging ones, preventing the seeds from simply falling out ”.…”

Section: Discussionmentioning

confidence: 99%

“…However, this mechanism may not be widely applicable to other plants that show similar phenomenon. For most plants, it is plausible to speculate that this phenomenon may be a mechanism for improving seed dispersal 1 11 12 , given that erecting the stalks may raise fruits to a position suitable for dispersal. Surprisingly, however, we have found no study testing this hypothesis to date.…”

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confidence: 99%

“…Furthermore, fruit orientation may also correlates to other fruit characters, such as fruit type and dispersal mechanisms. Erecting the stalks after flowering had been more frequently reported in capsule- and follicle-bearing taxa 1 12 , but a more rigorous investigation is needed to get a more comprehensive understanding of the distribution pattern of this phenomenon.…”

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Post-floral Erection of Stalks Provides Insight into the Evolution of Fruit Orientation and Its Effects on Seed Dispersal

Yang

Zhou

Wen

et al. 2016

Sci Rep

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That stalks reorient after flowering to face upwards is a common phenomenon in many flowering plants, indicating the potential importance of fruit orientation on seed dispersal. But this idea has not been subject to an empirical test. We examined this hypothesis by analysing the evolutionary correlation between fruit orientation and other characters and by investigating the effects of fruit orientation on seed dispersal. We found that 1) in a sub-alpine plant community, upward fruit orientation strongly correlates with fruits that act as seed containers, which are often of dry type and are dispersed by non-animal vectors; 2) as exemplified by the Campanulaceae s. str., fruit orientation strongly correlates with dehiscence position. Upwardly-oriented capsules dehisce at the apex, whereas pendent ones dehisce at the base, in both cases ensuring that seeds are released from an upright position; 3) in manipulation experiments on Silene chungtienensis, upward fruits (the natural state) exhibit much greater dispersal distances and more dispersive pattern than pendent ones, and have a more even distribution of dispersal direction than horizontal ones. Our results suggest that fruit orientation may have important function in seed dispersal, which may be the reason why the phenomenon that stalk erection after flowering occurs widely.

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Dispersal Spectra

Cited by 8 publications

References 0 publications

Determinants of inselberg floras in arid Nama Karoo landscapes

Determinants of inselberg floras in arid Nama Karoo landscapes

Seed Dispersal and Germination Traits of 70 Plant Species Inhabiting the Gurbantunggut Desert in Northwest China

Post-floral Erection of Stalks Provides Insight into the Evolution of Fruit Orientation and Its Effects on Seed Dispersal

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