title: Use of two population metrics clarifies biodiversity dynamics in large-scale monitoring: the case of trees in Japanese old-growth forests: the need for multiple population metrics in large-scale monitoring.
abstract: Many indicators/indices provide information on whether the 2010 biodiversity target of reducing declines in biodiversity have been achieved. The strengths and limitations of the various measures used to assess the success of such measures are now being discussed. Biodiversity dynamics are often evaluated by a single biological population metric, such as the abundance of each species. Here we examined tree population dynamics of 52 families (192 species) at 11 research sites (three vegetation zones) of Japanese old-growth forests using two population metrics: number of stems and basal area. We calculated indices that track the rate of change in all species of tree by taking the geometric mean of changes in population metrics between the 1990s and the 2000s at the national level and at the levels of the vegetation zone and family. We specifically focused on whether indices based on these two metrics behaved similarly. The indices showed that (1) the number of stems declined, whereas basal area did not change at the national level and (2) the degree of change in the indices varied by vegetation zone and family. These results suggest that Japanese old-growth forests have not degraded and may even be developing in some vegetation zones, and indicate that the use of a single population metric (or indicator/index) may be insufficient to precisely understand the state of biodiversity. It is therefore important to incorporate more metrics into monitoring schemes to overcome the risk of misunderstanding or misrepresenting biodiversity dynamics.
authors.affiliation: Department of Forest Entomology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan. mifuyu@affrc.go.jp
authors.forename: Mifuyu
authors.initials: M
authors.lastname: Ogawa
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Yamaura
authors.forename: Shin
authors.initials: S
authors.lastname: Abe
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hoshino
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hoshizaki
authors.forename: Shigeo
authors.initials: S
authors.lastname: Iida
authors.forename: Toshio
authors.initials: T
authors.lastname: Katsuki
authors.forename: Takashi
authors.initials: T
authors.lastname: Masaki
authors.forename: Kaoru
authors.initials: K
authors.lastname: Niiyama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Saito
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakai
authors.forename: Hisashi
authors.initials: H
authors.lastname: Sugita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tanouchi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Amano
authors.forename: Hisatomo
authors.initials: H
authors.lastname: Taki
authors.forename: Kimiko
authors.initials: K
authors.lastname: Okabe
mesh_terms: D044822:Biodiversity; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D007564:Japan; D014197:Trees / Q000145:classification / Q000254:growth & development*