Quantifying the Danger for Parnassius Nomion on Beijing Dongling Mountain

DISCRETE AND CONTINUOUS Website: http://aimSciences.org DYNAMICAL SYSTEMS–SERIES B Volume 4, Number 3, August 2004 pp. 679–686

QUANTIFYING THE DANGER FOR PARNASSIUS NOMION ON BEIJING DONGLING MOUNTAIN

Ma Zufei, Li Dianmo, Baoyu Xie The National Laboratory of Integrated Management of Insect and Rodent Pests in Agriculture Institute of Zoology, Chinese Academy of Sciences Beijing 100080, P.R.China

Abstract. It is the major task of the researches of conservation biology to explore species existing necessary conditions and endanger mechanism [1]. Presently, population viability analysis models mainly focus on a single species and few of them take into account the influence of inter-species effect to aimed species [2][3]. It is more difficult to apply traditional population viability analysis to insects, as compared to birds or mammals. First, insects have complex life histories, small body and various species. For animals that have body length between 10m and 1cm, the number of the species increases by 100 times with the body length shorten by 1/10 [4]. Biologists’ knowledge is far from completely understanding insect species, or even the number of insect, because it is very difficult to obtain the life parameters of wild insect populations. Second, biologists are accustomed to study the key species of the community, which are often the topmost taxa in biology chain or the dominant species in communities. These insect species are rare to be found playing a key role independently in ecosystem maintenance or community succession. Last, many insect species have become extinct before people know them well. The efficient and comprehensive approach is required to detect why the population of some insect specify is descending and what kind of protective strategies should be applied. In this paper, we have proposed the competition index of Parmassius Nomion species by combining the aimed species population dynamics with the diversity index. The results have shown that the alteration of competition index is able to detect the danger of shrinking population.

1. Introduction Studies on dangerous species’ biology and population ecology are very important subject in biodiversity and conservation research. However, there are few studies on relation between the protected species and the components of community, especially the synchronization of dangerous species population dynamics with fluctuation of concomitant species diversity. Caughley presented the common distinguish methods and procedures to protect descending population [3]. He reported that the study of a descending population should base on long time observation and thorough knowledge of the species. However, Caughley’s method is difficult to apply when the descending population is small since the population descends quickly and may become extinct before people notice their existence, and also it is difficult to estimate individual number and obtain the information about their mortality by random disturbance for small population. We have studies a local population of Parnassius Nomion and the other butterflies on the spot. Loss of habitat and increase of natural enemy are the two factors contributing to decreased population of Parnassius Nomion on Dongling Mountain peak from the year of 1998 through 2001. But these two factors play different roles at different times. In this paper we propose the competition index of the Parnassius Nomion population. The change of competition index can be used to determine major effect that causes the fluctuations of Parnassius Nomion population. From 1998 through 2000, competition index of Parnassius Nomion population had a small change with descending

AMS 2000 Subject Classification: 92D40. Key words and phrases: competition index, population dynamics, endanger mechanism, insect species, Parnassius nomion. 679 680 ZUFEI MA, DIANMO LI AND BAOYU XIE population density, therefore, the loss of habitat was the main factor. In the year of 2001, competition index decreased rapidly together with the population density, therefore, natural enemy is the main factor. The results of this paper show that competition index is a useful tool to reveal the major effect that causes small and descending population to be endangered. 2. Competition Index Biodiversity is the sum of all biotic variation from the level of genes to ecosystems. It has a multitude of facets and different facets of biodiversity can each be quantified [5]. Any attempt to measure biodiversity quickly runs into the problem that it is a fundamentally multidimensional concept: it cannot be reduced sensibly to a single numbers [6]. To evaluate the competition index of the endangered species, we not only calculate each species’ number of individual in all units, but also evaluate the reflecting affiliation of aimed species dynamics and biodiversity changed by competition index fluctuation. The value of competition index could be used to determine whether the population size of aimed species synchronizes with other species. If there are s species in the community, and the jth is the aimed species. The competition index of the jth species is

2 Dj = Pj /λ

Pj = Nj/N X λ = (Ni(Ni − 1)/N(N − 1))

Pj is the proportion of number of individual of the aimed species (Nj) in the total individual number (N) in the community. λ is Simpson index and is the measurement of the concentration (inverse to diversity) [7]. Some of the most popular diversity measures have been formulated as decreasing functions of the concentration index λ [8]. For example, ecologists uses 1−λ as one of the most frequently used diversity measures [6][9][10]. Besides possessing a number of interesting mathematical properties, this diversity index also has an intuitively appealing interpretation: it is the probability that two individuals selected at random (with replacement) from the sample will belong to different species.However, the diversity index is not describing the competition ability of the aim species in community. This ability is decided by the proportions of individuals belong to the aim species and the other species.If the proportion of individuals belong to the aimed species is higher, than the competition ability of the species is higher too. On the other hand, when the proportion of individuals belong to the aimed species is fixed, with the proportions of individuals belong to the other species in the community are lower, what means a lower concentration of species in community, the competition ability of the aimed species is higher. Then this ability should be formulated not only as decreasing 2 function of the concentration index, but also as increasing function of Pj , where Pj is the proportion of individuals belong to the jth species. The competition index of jth species is Dj = Pj/λ. Competition index (Dj) has characters described as follows:1)0 ≤ Dj ≤ 1. When the jth species is extinct, Dj = 0. When only the jth species exists, Dj = 1. 2) Changes of Dj’s value is also decided by the syn- chronous of aimed species and the surrounding species. The more synchronization, the smaller the changes of D value will be. 3) When the proportion of the aimed species individuals in the total individuals is constant, Dj value will be larger with a higher diversity of community. 3.Material and Method Parnassius Nomion is on the list of endangered animals in China. Until present this butterfly was found in Korea, Japan, Russia and China. QUANTIFYING THE DANGER FOR PARNASSIUS NOMION 681

There are records of catch in Beijing, Heilongjiang, Jilin, Xinjiang and Qinhai in China [11]-[14]. Dongling Mountain lies in southwest of Beijing, north latitude 40 degree 1 cent and east longitude 115 degree 27 cent, where the annual average tem- perature is 2-8 and annual average precipitation is more than 700mm. Vegetation of Dongling Mountain is distinctly delaminating with the change of altitudes, and butterfly diversity is high. Since the last two decades of 20 century, Dongling Mountain has been a natural conservative region in Beijing . This Mountain includes three hills. The first hill is about above sea level 1700-1950 meters, the second is about 1900-2150 meters and the third is about 2100-2300 meters. The plant community in the third hill has clearly divided into three typical vegetation types such as defoliate- broadleaf forest (Betula dahurica forest), defoliate-broadleaf shrubland (Caragana jubata shrubland) and subalpine meadow (Saussurea iodostegia and Carex capillaris meadow). In the meadow region, we have found four butterfly species such as Melanargia montana, Brenthis ino, Gen sp. and Parnassius Nomion. Through the observation from the year of 1998 to 2001, a population of Parnassius Nomion habitating were found on the south sloping field of the highest peak, whichis about 2200-2300 meters above sea level. Its area is about 5,000 square meters. The vegetation type is meadow community with dominance species as Saussurea iodostegia, Carex capillaris, Scabiosa tschiliensis, Carum carui and Potentilla freyniana. The habitat is encircled with shrublands and forests. The Parnassius Nomion population is isolated because the species live only above altitude of 1,800 meters. The nearest attainable fitting habitat is more than 5,000 meters away, and is separated by forests and shrublands. We have observed and noted butterflies population size in the habitat from the year of 1998 to 2001. It was separated to two periods. The first was from May 25 through September 22 in 1998, each two observations had a ten days interval, and began at 10:00 and ended at 17:00 for each day. The butterfly populations were estimated and recorded in every hour to grapple the imagoes annual activity rule and day activity rhythm. The second is from July 14 to August 3 in 1999 year to 2001 year, the observation began at 12:00 and ended at 13:00 for each day. We investigated and ascertained the activity cycles of Parnassius Nomion in a year and in a day. Three observations in the zeniths of the year activity period and the day activity period were recorded, and the average value of data is dealt with as the Parnassius Nomion population size in the year. All valid observations are only recorded during sunshine. Observations and estimates to the other butterflies were made simultaneously as to Parnassius Nomion.

4.Results Parnassius Nomion’s life span is one year. In Dongling mountain region, the annual appearance of adults begins at June and ends in September (Fig.1). From July through August is the peak period of Parnassius Nomion adult activities(Fig.1), thus observations in this period are suitable to estimate the population size. In the peak period of Parnassius Nomion imago in a year, the imago begins flying and feeding from 10:00 o’clock, peaks at noon and declines from 15:00 o’clock. From 1998 through 2001, the Parnassius Nomion population had two biggest dropping periods(Fig.3). The first is in the year of1999 and the second is in the year of 2001. In 1999, the other butterflies were also declining, but in 2001, they had very different dynamics to that of Parnassius Nomion population. In the habitat there are four butterflies as Melanargia montana, Brenthis ino, Gen sp. and Par- nassius Nomion. We estimated the competition indexes for these four species. The changes of competition index explains different mechanisms of Parnassius Nomion 682 ZUFEI MA, DIANMO LI AND BAOYU XIE population declining (Fig.3).

Fig.1. The Parnassius nomionimago annual behavior rhythm, date from 1998 and 1999 year, and the population size is the max individual number in one hour the day.

Fig.2. The Parnassius nomionimago diurnal behavior rhythm, date from 1998 QUANTIFYING THE DANGER FOR PARNASSIUS NOMION 683 year. (Fig.2). We use the observation records from 12:00 to 13:00 that is the peak period of activities of the imago as the data of imago in a day (Fig.2).

5.Analyses Our investigations from the year of 1998 through 2001 have shown that the Parnassius Nomion population in Dongling Mountain is declining . The factors contributing to the decrease excessive preying, destroyed habitat, endangering from introducing species and extinct chain [15]-[19]. Beijing City Government has opened and supervised the travel industry in Dongling Mountain since the year of 1990. There are some yaks introduced into the mountain in 1995. Yet the yaks has not disturbed the Parnassius Nomion species since their grazing regions is more than 5 kms away from the habitat of Parnassius Nomion and the yaks number have not been more than 100. Forestation had processed in Dongling Mountain from the 1950s to the 1980s, which had made a larger area of primal meadow vanished. The habitat of the butterﬂy had rapidly deteriorated in that period. Fortunately, the forestation has gradually stopped since the 1990s. The aggrandized forests were not the cause of the ﬂuctuations in the four years we observed. With the development of the tour industry the meadow vegetation is destroyed by the grazing of the horses

Fig.3.The fluctuations of competition index and population size of Parnassius nomion and total individuals number of butterflies Dj for competition index of Parnassius nomion, N for total individuals number of butterflies after standardization, Nj for population size of Parnassius nomion after standardization. offered to tourists. The meadow community trampled and grazed by horses has a fast succession to be Caragana jubata shrubland. The business sells firecrackers to tourists to make a profit, and the tourists fired lots of firecrackers on the peak from May to October of the year of 2001. The enormous noises emerged by firecrackers frightened and dispelled birds on the peak. Finally, the government clamped down firecracker sale in 2001 and bird has begun to come back to the habitat since then. We were not able to observer any birds on the habitat from the year of 1998 through 684 ZUFEI MA, DIANMO LI AND BAOYU XIE

2000. However, there were flocks of Pyrrhocorax pyrrhocorax appearing in the habitat in 2001. Habitat destroyed and augmented natural enemy are two major factors that endanger Parnassius Nomion local population in Dongling Mountain from the year of 1998 through 2001. But these two factors had different effects during different time period. The change of competition index can be used to determine the types of disturbances for population fluctuations. From 1998 to 2000, competition index of the Parnassius Nomion is rather stable with the descending population, which indicates that all butterflies species had similarly fluctuations by the same threat from the deteriorated habitat. In the year of 2001, the competition index had a swiftly drop together with declining Parnassius Nomion population. The key factor was natural enemy, which had a strong prey selection of butterflies in 2001. The prey selection had major effect on Parnassius Nomion since it had a bigger body than the other species and its body color is white, thus it is easier to be found in the habitat by birds; besides, Parnassius Nomion flies more slowly than the other species.

6.Discussion There are different methods to measure animal populations’ size which can be expressed as a density per unit area of the ground of the habitat. Population size used to calculate diversity index may be the absolute number of population such as number of individuals per unit area, or population density such as the number of individuals per leaf, per plant, per shoot or per host. And population size could also be relative number of population. Generally, data from field work are estimated relatively to population size such as catch per unit effort. There are population indices that the animals themselves are not counted, but their products (e.g. frass, webs, exuviae, nest) or impacts (especially plant damage) are counted [20]. Because there are no fitting products and impacts of the Parnassius Nomion, absolute population size has to be applied to estimate Parnassius Nomion population. Collecting is a generally-used method to measure relative number of insects. For butterflies, collecting methods usually include net sweeping and trap collecting, etc. However, a major drawback of these methods is that a few individuals have to be removed from habitat on each trapping or net sweeping occasion. Therefore, the following restriction has to be enforced to collecting methods[21]: 1) the population must remain stable during the trapping or catching period; 2) the population must not be so small that the catching of one member interferes with the catching of another. Therefore, collecting method is inappropriate for endangered insect species. They are regularly with small local population size, to which collecting bring potential danger. Therefore, visual observation appears to be a feasible alter- native. The observer counts in situ all the animals one can see in a fixed time and distance. Within a given habitat this method could provide a reasonable estima- tion of the population size. Visual observation has no effect on population size and avoids deflection of trapping, thus is an appropriate method applied to monitoring of endangered populations and community. Its flaw is high variations in availability under various weather conditions and at various time of a day. To overcome these flaws, we investigated and ascertained the activity cycles of Parnassius Nomion in a year and in a day. Three observations in the zeniths of the year activity period and the day activity period were recorded, and the average value is computed as the Parnassius Nomion population size. Exploring the extinction precession and clarifying succession conditions of species are core subjects in conservation biology [1]. Population viability analysis (PVA) is applied for assessing extinction risk and exploring the consequence of potential management strategies need [2]. Testing QUANTIFYING THE DANGER FOR PARNASSIUS NOMION 685 procedures are typically used to assess quantitative predictions, but the quality of PVA models can also be assessed according to their usefulness for management, the ecological insights that they provide, and /or their simplicity,generality, robustness (insensitivity to assumptions), and efficiency. However, for any given species or sys- tem, little replication is possible and extinction may be rare, so it is difficult to test the risk of extinction, which is the primary prediction of PVA models . No model can be a perfect replication of the reality. Attempts to prove that the predictions of models are ”true” or ”false” are misguided .No amount of model testing can prove a model true because its predictions will always be inadequate in at least some respects . Double dipping may be most confounding in complex models that use generic PVA software packages to simulate a large number of threatening factors, and least confounding in simple models that collapse these factors into a few key parameters ). It is therefore important to seek new methods to illuminate the threats that can affect the growth and persistence of small populations. On the other hand, PVA models are still objected to single species [2][3], and interaction in species is neglected. Diversity index is an important parameter of complex interspecies, especially to a huge number of insect species. The most commonly considered facet of biodiversity is species richness—the number of species in a site, habitat or clade [5]. There are about 1,750,000 scientifically described species on the earth, and the insect species is about 950,000. Estimating to the total number on earth is 13,000,000 to 14,000,000 species, and insect species about 8,000,000 [22]. The ab- sence of insects and mites, along with the nematodes could comprise more than 95% of species diversity , would reverberate through food webs, changing soil faunas and fertility, exterminating most species of birds and much of the remainder of Earth’s terrestrial vertebrate fauna [23]. Protective biology study on insects greatly lags behind that on ”hot-spot species” such as mammals, birds or amphibians. There are some difficulties that make it almost impossible to apply generic PVA model to insects. First of all, insects have a complex life style, a small body size and a huge number of species. Taxologists found that number of species will aggrandize to 100 times if their body length reduce to 1/10 for animals with a body length from 10 meters to 1 cm [24]. Biologists have obtained far from enough knowledge on insects. And therefore, it is very difficult to estimate the life parameters of insects in wild, especially to estimate the competition between species[25]. What’s more, biologists are accustomed to focus on the key species in community. These species are usually according to the topmost taxa in biology chain or the dominant species.There are always many concomitant insects inside of a community. For most insects,they are not keystone to maintain ecosystem . Insects altogether connect complex food net, but the impacts of a single insect species on the community are difficult to measure. A great deal of insects would be extinct before we have gained a fair amount of knowledge of them. Celerity and general method is necessary to endangered insects to judge and determine the reason of population descending and to establish protective policy. Relation of aimed population dynamics and coexisting species diversity index changes shed much light on understanding various factors causing population descending. When aimed species population descends, if competition index is stable, the cause of population decrease are weak selectivity factors such as climate change, habitat destroy and natural catastrophes that make coexist species declined simultaneity; if competition index ascends swiftly, the cause of population decrease are strong selectivity factors such as enemy, special food or diseases are dominating. Competition index is reactivity to the aimed species ratio in community.The change of competition index shows the synchronization of aimed species 686 ZUFEI MA, DIANMO LI AND BAOYU XIE and other coexisting species. Acknowledgements. This work is supported by Chinese National Science Foundation 39893360; Chinese Academy of Sciences Program KSCX2-SW-103 and KSCX2-1-02; Chinese Academy of Sciences Innovation Program KSCX3-IOZ-04.

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