Pollination and seed dispersal
Description
By ensuring pollination, insects - mainly honeybees and bumblebees - provide essential ecosystem services in the cultivation of hard and soft fruit (such as apples, pears, cherries, strawberries), greenhouse vegetables (e.g. tomatoes, eggplant, peppers) and in seed cultivation (e.g. cabbage , lettuce, carrot, onion). Ecosystems can be important for pollination due to the presence of habitats suitable for pollinating insects. Typical monoculture crops are individually insufficiently suitable for maintaining pollination. The problem with monoculture crops (and also fruit cultivation, for example) is the massive, but often very temporary, availability of nectar and pollen for pollinating insects. Proximity to natural habitats with a sufficient diversity of vegetation can provide a solution to this.
Based on the existing information, we cannot draw up well-founded key figures for the quantitative and monetary valuation of specific projects. However, a qualitative valuation can be made of the pollination service. Analyzes do show the potential importance of pollination for fruit and vegetable cultivation in Flanders. This benefit is closely intertwined with agricultural production.
Required information:
- Number of hectares of low, medium and high crops requiring pollination in a radius of 1 km around the area (www.vlm.be)
- Number of hectares of low, medium and high insect-suitable habitats within the study area
Qualitative appreciation
The supply of the ecosystem service “pollination” is determined by the presence of habitats that are suitable for pollinating insects. The demand is due to the presence of crops that require pollination. The relationship between supply and demand is ambiguous for the ecosystem service “pollination”. After all, pollinating insects are also partly dependent on the crops they pollinate. Supply and demand are therefore intertwined.
The qualitative rating is therefore based on the suitability of the ecosystem for harboring insects and the presence of crops that require pollination.
To determine the suitability of the ecosystem for insects, several attempts have been made to provide scores based on the potential occurrence of pollinators. The greater the diversity/abundance, the higher the score. Burkhard et al. (2009) used a score from 0 to 5 and a similar method was also used in Broekx et al. 2013.
According to the NARA 2014 'pollination' sheet, such an approach has some shortcomings:
- Not all pollinators need nature reserves to thrive. Sometimes a hole in a brick wall is sufficient.
- They are generally affected on a fine scale of landscape: a piece of roadside or hollow tree may be enough.
- The potential pollinators for different agricultural crops can be very different and specific, so that a land use class with a large number of pollinators does not necessarily provide a large supply of ecosystem services.
NARA uses a simplified score: eligible or not. This simplified score is adopted in the Nature Value Explorer, on the one hand for the reasons mentioned above, and on the other hand because of the ease of use of the tool.
When assigning the land use classes, the following aspects were taken into account for assigning the scores:
- More open habitats (heathland, natural grasslands, bushes), flower-rich vegetation (e.g. heath, robinia, etc.) are suitable (score 5) - nutrient-rich ecosystems and paved surfaces are not suitable (score 1)
- The presence of edges, verges, small-scale landscape elements, low and high greenery in the city, on the other hand, are potentially suitable nesting places (score 5). In addition, the distance of the ecosystem to crops that require pollination is examined. Insects only pollinate crops within a certain distance from where they live. This distance depends on several factors. Because little data is known about this, we use a study by Dewenter & Tscharnkte, 1999, who found that the effect of pollinating insects on yellow mustard becomes negligible at a distance of 1000 m. Ricketts et al. 2008 found that for pollinators at 2 km, there is a 35% chance of reaching the crops.
The pollination needs of agricultural crops were assessed. Crops that do not require pollination receive a score of 1.
The combination of the suitability for insects and the pollination needs of agricultural crops within a radius of 1 km gives the score for the qualitative evaluation.
Assumptions
- We consider a distance-effect relationship of 1 km
- Pollination for seed production was not included in the analysis because it is very case specific.
Numbers to use
Table: score of crops requiring pollination in a radius of 1 km around the area (extensive score)
| cultivation codes | Description | Pollination requirement score* | |
|---|---|---|---|
| Low pollination requirement | 701, 702 | Grass clover | 2 |
| 745 | Mixture of grass and legumes | 2 | |
| 411, 44 | Oilseeds except summer rapeseed and rapeseed | 2 | |
| 9521 | Ornamental plants in open ground | 2 | |
| 721 | Annual clover | 2 | |
| 9201 | Hazelnuts | 2 | |
| Average pollination requirement | 931, 932, 51, 52 | Peas and beans | 3 |
| 83 | Other legumes (luminoses) except annual clover | 3 | |
| 412 | Summer rapeseed and rapeseed | 3 | |
| 9516 | Strawberries | 3 | |
| High pollination requirement | 972 | Annual fruit crops except strawberries | 4 |
| 42 | Sunflower seeds | 4 | |
| 973 | Perennial fruit crops (green cover) | 4 | |
| Very high pollination requirement | 971, 974 | Perennial fruit crops | 5 |
| 9541 | Zucchini/pumpkins | 5 |
* other crops get score 1
Table: ecosystem suitability score for insects (simple score)
| Land use class | Suitability score* |
|---|---|
| Forests, grasslands and tall herbs, heathland and shrubs, wet nature, small landscape elements | 5 |
| Urban land use outside, meadow, cropland, rivers and lakes, sparsely vegetated land | 1 |
* other land use classes get score 1
Table: ecosystem suitability score for insects (extensive score)
| Habitat types | Suitability score* |
|---|---|
| Very high suitability for insects (calcareous dune grassland, dry heath with blueberries (cv), k(cg), kt (cg), broom and gorse thickets, orchard, sunken roads, tree or flower nursery) | 5 |
| High suitability for insects (thorn shrubs; beech forest with hyacinth, or white rush, verges, field edges with grassland vegetation, hedge, row of trees, wood edge) | 4 |
| Average suitability for insects (shrubs on calcareous soil (sk), beech forest with sedges (vm), gale shrubs) | 3 |
| Low suitability for insects (dry acid dune grassland (had), heath vegetation, shrub heath vegetation, degraded winding smele (cd, ce, cg) or verges, field edges or slopes with this vegetation, other valley, wetland and peat forests; oak-hornbeam forest with wild hyacinth (qe); oak forest with white rush (ql), other beech forests, parks, moist grassland and scrub (hc, hfc, hft) sour brush grass vegetation (hn), rough grassland (hr), pioneer vegetation and tall herbs (ku), meadow complex with many ditches and/or relief; rough meadow) | 2 |
* other habitats receive score 1
To obtain the total score out of 10, you must add the score for suitability to the score for crops in need of pollination.
Translation to an indicator
The indicator is the number of hectares of crops that depend on pollination.
An example
For the example, we refer to the Dutch version of the manual.