Yearly fl uctuations of two most dominant moths, Hydrillodes morosa and Alcis angulifera in Mt. Jirisan (JNP). 

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... moth species was 14.4 individuals, while that of geometrids was 35.8 individuals. About 72.9% of noctuid species (247 species) were uncommon species (1 – 10 individuals per species). However, 61.4% of geometrid species (189 species) were uncommon. Meanwhile, the proportion of very abundant geometrid species ( ≥ 101 individuals per species) (21 species) was almost three times that of Noctuidae (7 species). In other words, noctuid moths were species rich but with fewer individuals of each species, while geometrid moths were species-rich with a relatively large number of individuals representing each species. Lindenmayer et al. (2012) listed several advantages of long-term ecological studies: (1) quantifying ecological responses to environmental change, (2) understanding complex ecosystem phenomena, (3) providing core ecological data for developing theoretical models, (4) providing platforms for collaborative studies, and (5) providing reliable data for ecosystem management and policy- or decision-making. By monitoring moths over a period of 7 years, we identi fi ed the total diversity of macromoths and patterns of changes in moth populations according to season and sampling locality. However, we were unable to answer several interesting questions. First, what factors cause spatial and temporal variation in macromoth populations in a forest ecosystem? Lepidopteran abundance has been shown to be affected by temperature and rainfall in both tropical and temperate areas (Holloway, 1977; Kato et al., 1995; Intachat et al., 2001; Brehm et al., 2007). During summer (July – August), species richness and abundance were high, while richness and abundance in spring (May) and autumn (October) were relatively low (Figs. 6a,b). A Mantel test showed that monthly changes were closely related with moth abundance and the overall peak in number of species and individuals was in June in JNP. The appearance of moths is likely to be time-constrained due to the availability of major resources such as food and reproductive partners, as well as avoidance of harmful weather conditions such as the high humidity as- sociated with monsoons. However, why overall moth diversity peaked in June is unclear. Hirao et al. (2006) argued the relationship between beta diversity and species rarity that relies on spatio-temporal scale. In their study, lepidopteran moths showed less rare species with high seasonal beta diversity while coleopteran beetles more rare species with low seasonal beta diversity. They reasoned that this difference was resulted from length of life span (Hirao et al., 2006). In the present study, we found that change of seasonal beta diversity was strong (Fig. 7a), but rarity varied along elevation, suggesting a rather weak relationship between beta diversity and rarity. Another Mantel test showed that geographic distance among sites was not related to moth abundance in JNP. Each site has different environment characteristics, such as plant species composition, elevation, and aspect, and we expected that these differences would result in different moth assemblages. However, geographic distance was not an ecological variable capable of explaining the observed pattern of moth diversity. Similarly, no relationship was found between geographic distance and moth assemblages in the southern part of Korea (Choi et al., 2009). Three groupings were resulted from the cluster analysis and the pattern corresponded with altitude (Fig. 5). Choi and An (2010) noted that altitude was one of the important environmental factors as- sociated with moth assemblages in JNP that showed a hump-shaped pattern. Distribution pattern of many organisms corresponds with altitudinal gradient since altitude is closely related with many abiotic conditions such as temperature, precipitation, relative humidity, solar radiation, wind and soil condition (Brehm and Fiedler, 2003; Körner, 2007; Fiedler and Beck, 2008; Fiedler et al., 2008; Chen et al., 2009). Therefore, we suggested that moth assemblage in JNP is strongly in fl uenced by altitudinal gradient and the close relationship between moth assemblage and altitude could be implied in the conservation research for the mountain top populations that are in danger of local ex- tinction risk from global warming. The second unanswered question is what is the causal factor re- sponsible for the appearance of different moth species? Moths as a major herbivore interact with diverse organisms at different trophic levels. They mostly feed on plants and are a major food source of ver- tebrates (e.g. birds and bats) and invertebrates (e.g. parasitoid wasps, fl ies, and spiders). We identi fi ed 10 dominant species with more than 300 individuals: Hydrillodes morosa , Alcis angulifera , Lemyra boghaika , Idaea biselata , Drymonia dodonides , Hermonassa arenosa , Heterothera postalbida , Orthocabera sericea , Telorta edentata, and Rikiosatoa grisea . Two notable outbreaks occurred during our 7-year monitoring period (Fig. 8). In 2006, 1117 individuals (22% of the total catch) of Hydrillodes morosa, a noctuid detritivore, were collected mostly from QM and AK, while in 2010, only 43 individuals (1.6% of the total catch) of this species were collected. A large number of individuals of another dominant species, Alcis angulifera , a geometrid polyphagous herbivore, were collected in 2010 (893 individuals, 33.9% of the total catch), mostly from CE and BS. However, our monitoring period was too short to determine if this was a periodic outbreak, the length of the periodic cycle, and what caused this periodic cycle in speci fi c years and at different sites. Many unknown factors, including trophic interactions, are likely involved. Trophic interaction studies are time-consuming and involve intensive research. However, research into biotic interactions is potentially very important for long-term ecological studies. Third, we were not able to determine why we found so many rare species. Rare species are very common in most areas (Preston, 1948; Kunin and Gaston, 1993; Miller et al., 2003). It was noted that high proportion of singletons is the re fl ection of true forest species that occupy special niches and occur at low densities or the presence of active colo- nists in early succession stage (Hilt and Fiedler, 2005). Among 948 species that we recorded, 275 moth species (29.0%) were observed at only one site and the proportion of singletons at each site was 50.1% (Table 1). These fi gures suggest that rare macromoth species are common in JNP. Miller et al. (2003) discussed why so many butter fl ies and moths are rare in forests. They listed six possible reasons: the rarity of food plants for caterpillars, narrow environmental tolerance levels, natural enemies, strong competition with other species, edge distributions of the whole range of species, and insuf fi cient sampling. Most moth populations function as herbivores during their larval stage and moths often have a narrow host plant range at the larval stage, i.e. they are mo- nophagous. The narrow host food range of moths could contribute to the high proportion of rare species. One low elevation site (CE) and two high elevation sites (AK and QM) had a relatively high proportion of rare species and high yearly turnover rate (Fig. 7b). Weather conditions at high elevation sites can be quite harsh and could be the causal factor of the relatively low species diversity and the high proportion of rare species observed at these sites. On the other hand, the relatively high turnover rate at the lowest elevation site (CE) was observed. This site was mainly dominant with conifers, Pinus densi fl ora and P. rigida and moth assemblage was characterized by high proportion of rare species (56.4%) and low dominance. Similarly, the moth diversity and abundance in conifer forests were low compared to hardwood forests in North America (Hammond and Miller, 1998). In the present study, we were not able to identify causal factors to explain the commonness of rare species in JNP. However, the six reasons listed above likely all play a role. Although we determined the diversity and temporal and spatial patterns of macromoths in JNP, we also raised many questions that need to be addressed in the future. As Lindenmayer et al. (2012) suggested, long-term ecological studies provide the data required to un- derstand ecological responses to environmental change and complex ecosystem phenomena. We hope to answer these questions by collaborative work and long time series. We are grateful to members of the environmental biology labora- tory at Mokpo National University for their help in collecting moths. The study was supported by the grant from Ministry of Environment (Korea Long Term Ecological Research Project) and from the Korea Research Foundation ...