Countries of Occurrence:
Portugal - Azores
Facilitators / Compilers/s:
Trechus terrabravensis is a single island endemic species restricted to Terceira (Azores). It has a very small extent of occurrence (EOO = 32 km²) and reduced area of occupancy (AOO = 32 km²). There is a continuing decline in the EOO, AOO, extent and quality of habitat as well as the number of mature individuals as a result of the invasions of non-native plants. The species is particularly restricted to some still pristine locations. In the past, the species has probably strongly declined due to changes in habitat size. Therefore, we suggest as future measures of conservation: (1) regular monitoring of the species; and (2) control of invasive species namely Hedychium gardnerianum. The species is assessed as Critically Endangered (CR).
Trechus terrabravensis is a single island endemic species restricted to Terceira (Azores, Portugal) (Borges et al. 2010), known from the Natural Forest Reserves of Biscoito da Ferraria e Pico Alto, Pico do Galhardo, Terra Brava and Caldeira Sta. Bárbara e Mistérios Negros. The extent of occurrence (EOO) is 32 km² and the maximum estimated area of occupancy (AOO) is 32 km².
The species is particularly restricted but abundant in some of the locations (Gaston et al.2006). A continuing decline in the number of mature individuals is inferred from monitoring schemes and from the ongoing habitat degradation due to invasions of alien plants.
This species occurs deep inside very humid laurel forests (native forests dominated byLaurus azorica, Ilex perado subsp. azorica and Juniperus azorica) on Terceira, with an altitudinal range between 500 and 1000 m. Several specimens were collected in leaf litter, suggesting that this is a litter species. In both Terra-Brava and Caldeira da Serra de Santa Bárbara, the terrain is basaltic with a system of cracks and deep holes and the forest floor is covered by a dense carpet of mosses and ferns with little light reaching the ground (Borges et al. 2004). It is a predator that lives in in the soil.
In the past, the species has probably strongly declined due to changes in habitat size and quality and lack of resources due to its large body size (Terzopoulou et al. 2015). Currently, Cryptomeria japonica wood & pulp plantations management and invasive plant species spreading (e.g. Hedychium gardnerianum) are changing the structure of the forest and the cover of bryophytes and ferns in the soil with impacts on the species. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts and habitat shifting & alteration).
The species is not protected by regional law. Its habitat is in a regionally protected area (Natural Park of Terceira). The Terceira Natural Park administration is currently starting control measures of the invasive plants. Degraded habitats should be restored and a strategy needs to be developed to address the future threat by climate change. A habitat management plan is needed and anticipated to be developed during the coming years. Further research is needed into its ecology and life history in order to obtain information on population size, distribution and trends. It is also necessary to create an area-based management plan and a monitoring plan for the invertebrate community in the habitat in order to contribute to perform a species potential recovery plan as a consequence of invasive plant species spread in two native forest fragments (Biscoito da Ferraria e Pico Alto and Pico do Galhardo). Monitoring every ten years using the BALA protocol will inform about habitat quality (see e.g. Gaspar et al. 2011).