High ecosystem service delivery potential of small woodlands in agricultural landscapes, Valdes 2020

Compendium Volume 4 Number 1 July 2020

This article assesses the ecological value of small woodlands relative to larger ones. The authors conclude that:

…smaller woodlands potentially deliver multiple services at higher performance levels on a per area basis than larger woodlands of a similar age, even if the larger woodlands harbor a higher biodiversity [Valdes 2020: 12].

Because of their high edge-to-core ratio, smaller woodlots get more sunlight and more nutrient input from surrounding farmland, resulting in denser vegetation cover and higher biomass production at edges.

This altered functioning in turn increases the delivery potential of some services, such as game production potential, due to an increased quantity of food available for game, and topsoil carbon storage, due to the faster incorporation of organic matter in the soil. Tick-borne disease risk is, however, lower, likely due to decreased larval densities in the unfavorable (e.g. hotter and drier) microclimatic conditions at the edge [Valdes 2020: 12].

While smaller woodlands were more apt to deliver “multiple services at higher levels of performance per area than larger woodlands of a similar age,” the greater biodiversity of larger woodlands increased certain individual ecosystem services.

The supply potential of several individual ecosystem services indirectly increased in larger and more ancient woodlands because it was dependent on higher levels of biodiversity. For example, abundance of usable plants and game production potential might have increased due to a positive correlation with vascular plant diversity, while pest control potential probably increased due to bottom-up effects through the trophic chain. On the contrary, tick-borne disease risk, topsoil carbon storage and stemwood volume were unrelated to multidiversity, probably because they depended on particular environmental conditions or on the presence and abundance of specific species rather than on species richness per se.

Finally, it should be noted that we focused on the service delivery potential on a per area basis and that the total amount of services provided by large patches might still be larger than that of small patches. Our findings should therefore not be interpreted as a trade-off between large, biodiverse patches versus small patches that have a higher potential to deliver services, but rather as an observation that small woodlands in agricultural landscapes have the potential to deliver a high flow of services relative to their size [Valdes 2020: 12].

For the full PDF version of the compendium issue where this article appears, visit Compendium Volume 4 Number 1 July 2020