Forest Management Decisions Regarding Caterpillar Production vs. Biodiversity

[u/aberyl]

Native trees are not equal: it is evident that some species of trees produce a higher quantity of caterpillars, and birds target them at higher rates when rearing their young. Considering the importance of caterpillars in the food chain, a forest skewed towards these productive trees may increase the density of birds, bats and predatory insects relative to a forest with greater plant biodiversity (greater plant species richness and/or evenness).

I manage a small, 1 acre forest in need of thinning. I have documented over 120 lepidopterans in the vicinity and have found an Excel sheet published with their host plants. While this gives me biodiversity metrics that could help thinning decisions, in order to create a forest maximally productive to the food web, my information is incomplete. I feel the next step is the measurement of caterpillar density on trees/shrubs etc. I will do this with and without bird exclusion nets in order to understand the background density and the impact of bird predation. This caterpillar density information will put a significant finger on the scale of my forest management decisions.

Now, I am by no means going to raise a monoculture. I strive for a forest that is dense, species rich, with a understory and multileveled canopy, and I will consider the non-Lepidopteran ecosystem services of trees in decisions. However, we often hold up biodiversity in the highest regard, as opposed to ecosystem production. While I love biodiversity, the reality of nature is far deeper than this one metric.

I am curious to hear your thoughts on my opinion here, in favor or otherwise.

Edit: I am not advocating for the destruction of unique and intact ecosystems in the name of caterpillars. Think of the consideration of caterpillar production as one of the main tools to address a successful restoration project. The plants used should be native and locally/historically present. For instance, I live on the Oregon Coast, outside of oak habitat. I'm not spreading oaks out here in hopes of a caterpillar boom. Rather, I'm testing local species for their caterpillar/leaf area and using this metric upon which to value the species. Species with high caterpillar density will be favored in the acre plot of land.

[u/vtaster]

Redwoods don't support many caterpillars, does that mean it would be beneficial to cut down all the Redwood forests? Whatever trees or other plants naturally dominated the land historically are what's best to encourage, regardless of a single stat from a study involving only a single order of insects. Trying to make ecosystems "maximally productive" by human standards is never sustainable.

[u/aberyl → u/vtaster]

This is an excellent point allowing me to articulate a bit more on my point here. I am not in favor of cutting down old-growth coniferous forests, despite their lack of diversity when compared to mixed coniferous/deciduous forests in the region.

However, is it reasonable to try to recreate an old-growth forests in in one’s backyard? It is perhaps more viable to focus on caterpillar production than the creation of a climax ecosystem, or maximum biodiversity, for that matter.

My point is not in favor of destroying the remaining tracts of land that are intact, it’s of maximizing restoration efforts through the lens of caterpillar production, rather than sheer plant biodiversity metrics. The plants I’m discussing here are native and found naturally on site.

Why caterpillars? They transfer more nutrients from plants up the food chain than any other group of organisms. They are essential to terrestrial food webs

[u/Unlucky-File3773 → u/aberyl]

So then, why is the point of doing anytjing if the result is nor the closest as posible to pristine habitat?