Rethinking assessment of biodiversity in northern New Zealand forests: Incorporating lichens, a neglected but important group, in vegetation monitoring
A project undertaken at the Unitec Institute of Technology and supervised by Dan Blanchon
Dan Blanchon, Andrew Marshall, Glenn Aguilar, Peter de Lange (Unitec Institute of Technology)
Approximately 85% of the New Zealand lichen mycobiota has been described, however information about the distribution, population size and ecology of most of these species is lacking (1108 of 2026 taxa are listed as `data deficient' in New Zealand's 2018 threat listing). Biodiversity surveys of vegetation in New Zealand routinely ignore lichens, perhaps assuming that lichen diversity will be reflected in diversity data collected for vascular plants, i.e. biodiversity surrogacy. There is a lack of research into the effectiveness of biodiversity surrogates in New Zealand. Results are often unclear as they are usually dependent on the taxonomic groups in question and the type of forest sampled. With the exception of one Australian study, most studies of biodiversity surrogates have taken place in the northern hemisphere. In Auckland the Council maintains 20 x 20m permanent plots from which it collects a range of data, however they do not currently assess lichens. Little is known of lichen assemblages in mainland forested areas and only limited, out of date information is available for Auckland's Waitakere Ranges. There is also a lack of literature on lichen assemblages in particular ecosystem types, such as kauri forest (threatened by kauri dieback), or on regenerating forest such as Kunzea/ Leptospermum `scrub', which is often considered to be of “low value” ecologically. This makes it difficult for biodiversity staff to consider lichens when making recommendations on applications to clear forest for development and for restoration initiatives.
This project utilized 50 existing 20 x 20m permanent plant monitoring plots across the Auckland Region (Figure 1) incorporating a variety of forest types in regional parks and urban forest remnants to provide baseline data on lichen diversity in different vegetation types and assess if lichen diversity is "implied" using current monitoring methods. Six hundred individual trees from 48 different tree species were surveyed, with four vertical quadrats (relevés) per tree (2400 relevés), (Figure 2). Opportunistic sampling within the plots was done for a further 14 tree species (Figure 3) and from tree canopies, roots and the forest floor. Over 2700 voucher specimens have been collected, with around 60% already accessioned into Unitec’s herbarium.
Thirteen new species records for New Zealand were identified, the presence of one of which (Pertusaria endoxantha) has already been published (Figure 5). We are working on a series of papers recording the other species currently (for submission in 2019). Three species new to science have also been identified and the first of these will be named in a paper being written currently.
In addition, this project aims to produce lists for particular sites in the Auckland Region (identification of sites of ecological importance); produce lichen species lists for specific vegetation types (identification of important ecosystems, provision of reference ecosystem data, information for ecological restoration, vegetation covenant audits); produce suitability maps for rare lichen species may aid in the discovery of other populations.