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Pollination

Pollination is the interaction between plants and (1) biotic vectors (e.g. insects, birds and mammals) and (2) abiotoic vectors (e.g. wind and water) in the movement of male gametes for plant production. Pollination and seed dispersal are linked.

 

ecosystem FUNCTION CATEGORY

Regulating Functions

  

How does pollination contribute to ecosystem service provision?

Insects are the most common pollinators of plant species and vital to the natural regeneration of ecosystems.

Pollination is the sexual process for gene exchange between angiosperm (flowering) plants. Pollination occurs when pollen grains (male gametes) are transferred by pollinators (animals, wind or water) from the anther of one flower to the stigma of another flower of the same species. A pollen tube then grows down towards the ovary, which contains the ovules (female gametes), whereby fertilisation occurs if a pollen tube reaches an ovule. Plants may either be cross-fertilised (i.e. require pollen from another plant of the same species), self-fertilised (i.e. can pollinate using self pollen or pollen from another plant of the same species), or preferentially outcrossed, whereby they can successfully pollinate from self pollen, but "prefer" (i.e. have greater success rates) from outcrossed pollen.

A fundamental expectation of pollination is that the most attractive plants will have greater potential male and/or female reproductive success (increased pollinator visits) and hence fitness (i.e. Darwinian Fitness). Moreover, selection should favour plant and floral traits that attract the most efficient pollinators, thus maximising the deposition of viable pollen and reducing competition for pollination. However, attracting pollinators is not the result of a single plant characteristic, but rather a combination of characteristics (e.g. floral display, plant size). Evidence suggests plant characteristics most effective at increasing plant attractiveness, and therefore competitive ability, are floral display and nectar production, however, pollen production is also recognised as an important floral reward.

As Table 1 below shows, relative to other ecosystem functions pollination contributes to the provision of many ecosystem services, especially to provisioning services such as food products, genetic resources for cultivated products, potential biochemical, medicinal and pharmaceutical and ornamental resources. The pollination of agricultural crops is also vitally important to people. Pollination contributes to crop production (and therefore food products) when successful pollen transfer allows for seed germination and the growth of new plants which may be fed upon by herbivores (e.g. cows and sheep); or through seed germination which produces plants and fruit for consumption by humans.  

Pollination of outcrossed plant species contributes to increasing the mixing of genes from two different plants of the same species. This increase in genetic variation increases the genetic resources available for cultivated, medicinal and pharmaceutical products; and may also give the new plants a greater chance of surviving disease and disturbance. Pollination contributes to the provision of ornamental resources by facilitating fertilisation, which allows for seed and fruit production and the growth of new plants and thereby, plant based products which may be harvested. 

 

 

What is the temporal and geographic scale pollination operates at and services are delivered?

 

Without flying fox the pollination and natural regeneration of native trees would be limited.

Possums transfer pollen carried in their fur from flower to flower as they feed.

SEQ has many colourful lorrikeets and parrots that eat seeds and scatter them in and outside the region in their faeces.

Links to other publications and websites

SEQ Catchments - Flying Foxes
Dept. Enviro. & Herit. - Flying Foxes
Aust. Museum - Pollinators
Aust. Plants and Geology
Role of Animal Pollinators

 

Pollination can occur within minutes, such as the time it takes a bird, insect or mammal to visit and pollinate flowers on the same plant; or the time it takes to travel from one plant in one location to another plant in another location. Pollination occurs throughout the year, in response to the flowering times of plants. Climate change is likely to alter plant flowering times, which may in turn disrupt pollination of some plant species. Whereby there are changes in the time of year that plants flower and this may result in decreased reproductive output due to changes in the abundance or diversity of available pollinators. Pollinators may also change their distribution in the landscape in response to temperature increases, thereby moving away from traditional nectar sources.

Pollination can occur at a very localised scale (i.e. within a single plant or within a small population of ten plants) or a very large geographic scale (i.e. across plants kilometres apart).The ecosystem function pollination has two geographical flow types, omni-directional and in-situ. With reference to abiotic pollination (i.e. pollination by wind and water), pollination is considered omni-directional because although pollination occurs in a particular location (i.e. within a plant or group of plants) the service and benefit is provided to the surrounding area (i.e. plants in the surrounding area may be pollinated and therefore set seed and produce fruit aiding regeneration of native species or important commercial food crops). The most important bias in this scenario is the course of a water way or direction the wind is blowing which influences where the pollen travels and therefore, whether it lands on a plant of the same species (allowing for pollination) or lands on a different species (failing to pollinate).

With reference to biotic pollination (i.e. pollination by birds, insects and mammals), pollination will generally be omni-directional or occur in-situ. It is omni-directional when pollen is carried by birds, insects or mammals from one location to another, providing potential services and benefits to the surrounding area (this is dependent upon the distribution of plants and habitats thoughtout the landscape). The issues to consider with reference to omni-directional flows include habitat fragmentation, whereby gaps in vegetation may prevent pollinators from travelling to other populations; interference from other flowering plants (i.e. mixing of pollen); spraying of insecticides from nearby agricultural land; and pollen/nectar thieving, whereby (primarily) European Honeybees visit native plants and successfully remove nectar (and sometimes pollen) without pollinating the flower (e.g. in some banksia, grevillea, hakea and other Proteaceae species). Biotic pollination may also occur and provide services and benefits in-situ. This occurs where there are small or isolated populations of plants, especially where plants are self-compatible (i.e. seeds can be germinated by self-pollination), are pollinated by specialist pollinators, the plant is rare or threatened or the population is highly fragmented.

The map to the right shows areas where the function pollination is expected to occur across SEQ. Data sets supporting the map can be found in the Quick Index. By clicking on the link below the map it will provide a more detailed view.  

  

How do we know if we are degrading, maintaining or improving pollination in SEQ?

Pollination is a difficult ecosystem function to quantify. The only way to directly know if pollination is being degraded, maintained or improved is by changes in the presence, abundance or diversity of known pollinators and by changes in the abundance (i.e. population size) of flowering plants. In coastal and terrestrial species monitoring plots would need to be established of indicator species from different plant families where the following plant and pollinator traits could be documented:

-         Population size;

-         Number of flowers per plant;

-         Number of seed/fruit per plant;

-         Number of different pollinators per population/plant;

-         Number of different plants an individual pollinator visits within a monitoring plot;

-         How frequently pollinators visit monitoring plots within a day. 

Genetic analysis of seed would also provide information on whether a seed was self produced or outcrossed. If it was outcrossed further analysis of all plants within a population would allow for an assessment of what plant provided outsourced pollen. Tagging of bird and mammal pollinators or of pollen (using dye) would allow for some assessment of distance travelled by pollen/pollinators.

 

How do we manage this ecosystem function in SEQ?

Pollination is one of the most important ecological processes on earth, ensuring the reproduction of angiosperm plants and the natural regeneration of ecosystems. We should be conserving and monitoring the native ecosystems that support and facilitate this service as an urgent priority. If the ecosystems are protected and conserved then pollination will occur of its own accord (not withstanding the impacts of climate change), without our intervention. The issue is that so many ecosystems are under threat and require some level of management or protection to ensure pollination continues.   

Under the Department of Agriculture, Fisheries and Forestry, Biosecurity Queensland have an important role to play in maintaining border control with respect to the prevention and spread of competing introduced species (e.g. Veroa mite) that can lead to colony collapse. Federal and state agencies also have a role to play in conserving and protecting natural ecosystems and preventing habitat degradation and removal. In SEQ the local government, the Department of Environment and Heritage Protection, SEQ Catchments, universities and community groups all have a role to play in ensuring this function continues.