Seed dispersal
Male bellbirds perch on dead trees in order to attract mates, and often defecate seeds beneath these perches where the seeds have a high chance of survival because of high light conditions and escape from fungal pathogens.
Here, threshold means the minimum distance a plant can disperse its seeds and have it still count as LDD.
An example would be a rare or unique incident in which a normally-lemur-dependent deciduous tree of Madagascar was to have seeds transported to the coastline of South Africa via attachment to a mermaid purse (egg case) laid by a shark or skate.
However, it is still unclear today as to how specific traits, conditions and trade-offs (particularly within short seed dispersal) affect LDD evolution.
Fruits exhibiting this type of dispersal include apples, coconuts and passionfruit and those with harder shells (which often roll away from the plant to gain more distance).
An exceptional example of ballochory is Hura crepitans—this plant is commonly called the dynamite tree due to the sound of the fruit exploding.
[22] Witch hazel uses ballistic dispersal without explosive mechanisms by simply squeezing the seeds out at approx.
Wind dispersal can take on one of two primary forms: seeds or fruits can float on the breeze or, alternatively, they can flutter to the ground.
[24] The classic examples of these dispersal mechanisms, in the temperate northern hemisphere, include dandelions, which have a feathery pappus attached to their fruits (achenes) and can be dispersed long distances, and maples, which have winged fruits (samaras) that flutter to the ground.
Some wind-dispersed plants, such as the dandelion, can adjust their morphology in order to increase or decrease the rate of diaspore detachment.
[28] A typical example of an epizoochorous plant is Trifolium angustifolium, a species of Old World clover which adheres to animal fur by means of stiff hairs covering the seed.
This form of seed dispersal has been implicated in rapid plant migration and the spread of invasive species.
[29] Endozoochory is generally a coevolved mutualistic relationship in which a plant surrounds seeds with an edible, nutritious fruit as a good food resource for animals that consume it.
[31][32] The exact percentage of tree species dispersed by endozoochory varies between habitats, but can range to over 90% in some tropical rainforests.
[29] Seed dispersal by animals in tropical rainforests has received much attention, and this interaction is considered an important force shaping the ecology and evolution of vertebrate and tree populations.
[34][35] Seed dispersal through endozoochory can lead to quick spread of invasive species, such as in the case of prickly acacia in Australia.
[36] A variation of endozoochory is regurgitation of seeds rather than their passage in faeces after passing through the entire digestive tract.
[7] Seeds of myrmecochorous plants have a lipid-rich attachment called the elaiosome, which attracts ants.
[7] Myrmecochorous plants are most frequent in the fynbos vegetation of the Cape Floristic Region of South Africa, the kwongan vegetation and other dry habitat types of Australia, dry forests and grasslands of the Mediterranean region and northern temperate forests of western Eurasia and eastern North America, where up to 30–40% of understorey herbs are myrmecochorous.
[43] Other types of zoochory are chiropterochory (by bats), malacochory (by molluscs, mainly terrestrial snails), ornithochory (by birds) and saurochory (by non-bird sauropsids).
In this case, human societies form a long-term relationship with plant species, and create conditions for their growth.
[45] On the one hand, dispersal by humans also acts on smaller, regional scales and drives the dynamics of existing biological populations.
On the other hand, dispersal by humans may act on large geographical scales and lead to the spread of invasive species.
A study by Dunmail J. Hodkinson and Ken Thompson found that the most common seeds carried by vehicle were broadleaf plantain (Plantago major), Annual meadow grass (Poa annua), rough meadow grass (Poa trivialis), stinging nettle (Urtica dioica) and wild chamomile (Matricaria discoidea).
[52] Dispersal of seeds away from the parent organism has a central role in two major theories for how biodiversity is maintained in natural ecosystems, the Janzen-Connell hypothesis and recruitment limitation.
[54] In addition, the speed and direction of wind are highly influential in the dispersal process and in turn the deposition patterns of floating seeds in stagnant water bodies.
This affects colonization when it is situated on the banks of a river, or to wetlands adjacent to streams relative to the given wind directions.
The time period over which the dispersal occurs is essential when considering the consequences of wind on the ecological process.
