Application of aerial survey for detecting a rare maple species and endangered wetland ecosystems

Abstract

Because aerial survey is a powerful tool to characterize landscape features, it is often applied to conserve biological diversity. I present such an example using aerial survey to locate new populations of the endangered maple species, Japanese red maple ( Acer pycnanthum K. Koch), and its supporting ecosystems. Japanese red maple is an endemic, obligate wetland species of central Honshu Island, Japan. Unlike its sister species, American red maple ( Acer rubrum L.), Japanese red maple has a restricted natural distribution and is listed as an endangered species. Despite its endangered status, information of the current occurrence is extremely limited. Therefore, plane flights were conducted in early spring of 2003 and 2004 when brilliant red flowers readily indicate the location of new populations and their wetland ecosystems. Sixteen sites with three or more clones were successfully located by this aerial survey approach, which increased the number of natural Japanese red maple sites of the database by 34% and the area of natural sites by 54%. Fifteen were new sites that are either unknown or not widely known to the public. Additional new sites in rugged terrain still require ground verification. The 16 sites identified by aerial survey are markedly larger in area and population size and less disturbed by silvicultural management than those of sites that were identified by conventional methods (i.e., literature search, ground search, and interviews with local residents). The new sites were all wetlands that have narrowly escaped from intensive human development near Nagoya, the third most highly populated area of Japan. Aerial survey not only increased the number of individuals and populations of Japanese red maple but more significantly it identified the endangered, near-natural wetland ecosystems characterized by this species. This remarkable discovery facilitates many new conservation initiatives such as educating landowners, characterizing ecosystem properties and biological diversity, and establishing new natural preserves. The aerial survey method is readily applicable to other species that also have distinctive crown features. Because the survey approach is easily applied, scientists, conservation groups, and managers of public and private forests are encouraged to apply this approach for management and conservation of suitable rare or endangered species and ecosystems that support them.