Spatial, temporal, and scale mismatches
Authors: Gabriela Torchio, Poliana Mendes, Yiyi Zhang, Amanda Schwantes
Introduction
Sometimes, the need for an ecosystem service (demand) and the ability of the environment to provide that service (supply) don’t match up. No-overlap between supply and demand can occur either in different places (spatial mismatch), at different times (temporal mismatch) or at different scales (scale mismatch).
For example, some insects, small mammals, and birds contribute to fertilization of plants (that is, to pollination) while they are feeding and moving among flowers. Where pollinators originate from in the landscape is the area of pollination supply. On the other side, demand for pollination occurs where there are plants that need pollination. For pollination to occur, pollinators have to move from their nesting places to their feeding sites. When there is a large separation between where pollinators originate from (supply) and where they feed and pollinate (demand), supply and demand do not match in space.
Case study
We’ll explore some examples of when demand and supply don’t line up using the ecosystem service of pollination as an example. This mismatch can happen in three main ways:
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Spatial mismatch: Let’s think of bees, as an example of pollinators. Bees fly from their nests to flowering crops, which are a good source of pollen or nectar. In the process of feeding, bees pollinate crops by transporting pollen among flowers. In this example, bees can be regarded as the “supply” of pollination, whereas the crops that are pollinated represent the “demand” for pollination. Empirical studies in crop fields show that the abundance of pollinators tends to be higher in smaller crop fields (e.g., 2 ha) than in large ones (e.g., 100 ha). Why is that? One explanation is that if bees’ nesting habitat is located relatively close to crop fields (including plants located in the center of the field), then they will find it easier to fly and pollinate all plants present in the field. In that case, there is a spatial match between the supply of pollination (bees) and the demand (crops). Now imagine a very large crop, where plants located in the middle of the field are far from bees’ nesting habitat, so far that bees won’t fly there. In that case, there is a spatial mismatch between pollination supply and demand.
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Temporal mismatch: Not all pollinators are active at the same time nor during all seasons of crop blooming. Crops may bloom at times that do not always coincide with all pollinators’ periods of high activity. This represents a temporal mismatch between pollination supply (insect pollinators) and demand (crops). As the climate changes, the periods of time when crops bloom and the periods of time when pollinators have high activity may no longer align, which may result in greater temporal mismatches.
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Scale mismatch: Now let’s move from a single farm to a whole agricultural region (many farms). Securing pollination supply for the whole region implies a specific arrangement of pollinators’ habitat around crop fields. For instance, one farmer might not have enough land to establish a nice hedgerow or a flower strip to support the pollinators or arrange it in the best way for them. Or maybe the farmer can create one nice habitat for bees, but if the field is too big, it might not be enough (because of the spatial mismatch!). However, if many farmers work together, they might be able to create a network of habitat with the right conditions for pollinators. This means that encouraging cooperation between farmers might be more successful than asking one farmer alone to increase pollinator-friendly habitats. In this example, the difference between one farm versus many farms represents a case of scale mismatch.
Researchers from ResNet are investigating the mismatches between supply and demand of pollination in the agricultural fields of the county of La Vallée-du-Richelieu (map at the right), and how restoration of wild-bee habitat could enhance crop pollination (Torchio et al. Submitted) [6].
Best practices and opportunities
- Understand the ecosystem service area: Think about the whole area that benefits from the ecosystem service, like pollination, and identify who or what benefits from it.
- Compare across beneficiaries: Look at different groups or areas that benefit from the service and compare them. This can help identify different needs and how they might be met.
- Identify the benefit gap: Try to figure out where the mismatches between supply and demand are. Where are the needs not being met? Understanding this gap can help in planning how to fix it.
- Think about the arrangement and size of habitat areas: It’s not just about how much habitat there is for the pollinators, but also about how this habitat is arranged. The layout and size of the land can influence how well it supports the pollinators and provides the needed service.
By considering these points, we can better understand how to manage and support many ecosystem services like pollination. It helps in creating a plan that fits the specific needs of the area and the people who depend on these services.