Saproxylic Invertebrates

The Medieval Park, with its history of continuous woodland, and its trees of varying ages from young to veteran, and the estate’s policy of leaving as much decaying wood down on the ground, rather than removing it for aesthetic value, has proved extremely beneficial to some of the most threatened species in the UK, the Saproxylic invertebrates.

Saproxylic invertebrates are dependent on the microhabitats associated with the processes of decay or damage in the bark and wood of trees and make up 7% of the 2000 different invertebrate species found within Britain.

Dead or decaying wood is important to these creatures as it provides them a home and ideal conditions for egg laying and larval development, and a food supply, as most other invertebrates do not possess the necessary gut enzymes to break down the principal components of wood – cellulose and lignin.

Saproxylic invertebrates are important to us, as they play a critical role in the overall health of the ecosystem. They contribute to biodiversity by providing food for birds, mammals and other invertebrates.

But they are also vital for the natural regeneration of the woodlands as they provide the mechanical breakdown of woody material by tunnelling and feeding in living trees that are decaying.

One of the most important by-products of the saproxylic invertebrates’ work is the formation of humus created through their symbiotic relationship with fungi and microorganisms that humify wood.

Humus is a dark, organic material that forms in soil when plant and animal matter decays. It is the original material decomposed to its most basic chemical elements. Many of these chemicals, particularly nitrogen, are important nutrients for the soil and organisms that depend on soil for life, such as plants.

Humus is a magical thing and has many important roles to play, including the prevention of plant disease, but also when humus is mixed in the soil, the soil will crumble, allowing air and water to move through it more easily, allowing oxygen easier access to the roots, whilst also assisting in water management.

With this understanding in mind, it is of no surprise that Saproxylic invertebrates are considered bioindicators and are used to assess the overall health of the ecosystem.

In 2018, Haddon commissioned Conops Entomology Ltd to make its first assessment of the Saproxylic Invertebrates within the Medieval Park. Despite a rather late start, July not April, and even though the summer of 2018 was exceptionally hot and dry, the results were hugely encouraging. Within a short period over 290 species were found, with 16 of conservation importance, all indicating that Haddon’s Medieval Park is a high quality mature habitat.

Due to the importance and the current threat to these species, Haddon will continue to monitor the Saproxylic invertebrates within the park closely.