DIWPA: DIVERSITAS in the Western Pacific and Asia

DIWPA News Letter
Office: Center for Ecological Research, Kyoto University, Otsu, Shiga, Japan

July2021

No. 45

president of Ecological Society of Japan (ESJ)
also took on the post of EAFES presidency.
This time, EAFES presidency has beensuccessfully transferred from Prof. Takakazu
Yumoto (Kyoto Univ.), the president of ESJ, toProf. Ouyang Zhiyun (Chinese Academy ofScience), ESC president.
According to the report by ESC, EAFES
Hohhot consisted of 8 parallel sessions with450 registered participants from 9 countries(China, South Korea, Japan, Mongolia, France,Pakistan, Russia, Sri Lanka and Thailand). The
number of abstracts was 249 (Chinese 150,foreign 99) including of 136 oral presentations(Chinese 84, foreign 52) and 82 posters(Chinese 42, foreign 40). I organized thesession “S-05: Future collaboration in aquatic
ecology to be initiated by East Asianleadership”, with Dr. Sung Ryong Kang(National Institute of Ecology, South Korea),Dr. Qin Boqiang (Nanjing Institute ofGeography & Limnology, Chinese Academy ofSciences, China, and Dr. Song Lirong (Instituteof Hydrobiology, Chinese Academy ofMessage from the Chairperson
Shin-ichi Nakano

The 9 th EAFES International Congressorganized by the East Asian Federation ofEcological Societies (EAFES) was held inHohhot, China from July 10 to 13, 2021. The
congress was conducted in a hybrid way, on-siteand online. Because of COVID-19 spreading,the participants attended the congress on-sitefrom China, and online from foreign countries.
EAFES is an organization, where ecologicalsocieties of China, Japan, and Korea
collaboratively established a federation topromote ecological science in East Asia. The
three Ecological Societies take turns organizing
the joint meeting (EAFES Congress) at least
once in 2 years. In this time, EAFES Hohhot
was hosted by Ecological Society of China(ESC) and the Inner Mongolia Academy ofAgricultural and Animal Husbandry Sciences. I
have been attending all the congresses in charge
of EAFES Secretary General since 2015. The
theme of the congress in 2021, is “Harmonizing
People and Nature for Better Asia”, which
focuses on harmonious and sustainable
development among people, nature, and society
in the context of Asia development.
According to EAFES’s rule, EAFES
presidency is elected in the host society for
EAFES Congress. Since the last EAFES
Congress was held in Nagoya, Japan, theThe 9th EAFES International Congress organized by the East AsianFederation of Ecological Societies (EAFES) in Hohhot, China from July
10 to 13, 2021

1DIWPA News Letter No.45

Sciences, China). Our session consisted of 19
oral presentations and 6 posters. Those oralpresentations were dominated by young
researchers such as graduate students, and we
had hot and fruitful discussions. In addition,
there were 8 plenary talks, and all of them wereso excellent and impressive. Thus, we finished
EAFES Hohhot with great success, and I would
like to express my greatest and deepest thanks
to ESC and the Inner Mongolia Academy ofAgricultural and Animal Husbandry Sciences.
The next EAFES Congress is going to beheld in 2023, in Jeju Island, South Korea. We
expect on-site congress in 2023, encouraging
possible participants not only from the three
countries but from all over the world.
Therefore, we shall get together in Jeju to enjoy
science and international friendship, and thiswill foster the next generation in science ofecology and biodiversity. Through EAFES, wewould like to facilitate information exchange
among international researchers for further
development in ecological and biodiversity
research all over the world.

Messagefrom the Secretary General

Atsushi Ishida
In Japan, we are still in COVID-19 pandemic.
Although the vaccination has started frommedical doctors, healthcare workers and seniorcitizen, the rate of immunization is not yet highin Japan. However, we can go to research sites
within Japan. Now I am in the Ogasawara(Bonin) Islands with my students and thecolleagues of my research project. The islands
are located approximately 1,000 km south ofTokyo, listed in the World Natural Heritage
sites since June in 2011. Many endemic species
are living in the islands, because of oceanicislands. The early summer is one of the best
seasons surrounding beautiful sea and sky withdeep blue. Today we can inform the other goodnews. A part of Ryukyu Islands (Iriomote
Island, the north of Okinawa Island, Tokunoshima Island and Anami Island) is newly listed
in the World Natural Heritage sites form July in2021. This is the 5th World Natural Heritagesite in Japan. Rich beautiful nature with many
endemic species remains in the Ryukyu Islands.
The anthropogenic history of the Ryukyuislands is far older than that of the Ogasawara
Islands. We can thus look unique culture in theRyukyu Islands. In the next volume of DIWPA
Newsletter I will try to invite a report from theresearchers of Ryukyu Islands, to inform moredetailed nature in the area of Ryukyu Islands.

EAFES Hohhot Congress on-site

2DIWPA News Letter No.45

Nakado-jima, an oceanic island ofOgasawara Islands, in the northern Pacific

New Site

Kenji Hata
Nihon University, College of Commerce (Japan)
Department of Biological Sciences, Graduate School of Science,Tokyo Metropolitan University (Japan)

Introduction

History of ecosystem degradation by disturbancesof feral goats

Nakodo-jima (27º37′–27º38′N, 142º10′–142º11′E,
1.37 km2 in area) is a subtropical oceanic island
belonging to the Ogasawara Islands, in the northern
Pacific (Fig. 1). The mean precipitation and annual
temperature on Chichi-jima, the largest island in theislands, were 1,014 mm and 23.4 °C, respectively,
during 1995–2020 (Japan Meteorological Agency,Tokyo, Japan).
Ogasawara Islands have unique ecosystems
containing many endemic species, which is thecharacteristic of oceanic islands (Shimizu 2003).
Therefore, the islands were certified as a World
Natural Heritage by UNESCO in 2011. On the other
hand, loss of biodiversity and alternation of native
ecosystems have been caused by several invasive
species (Kawakami 2010). For conservation andrestoration of theisland ecosystems,controls andmanagements ofsome invasive
species have been
conducted (Sato2019).

Ecosystems of Nakodo-jima had been disturbed bygoat (Capra hircus), which is one of the mostinvasive mammals in the world, especially inoceanic islands (Loope et al. 1988). It is assumed
that people introduced domestic goats as livestock
into Nakodo-jima since 1912 (Shimizu 1993). Thegoats became naturalized on Nakodo-jima when all
people left from the island after 1945 (JapanWildlife Research Center 1992).
It is likely that Nakodo-jima was covered withnative forests before the introduction of goats(Shimizu 1993). Details of the species compositionof the forests in Nakodojima before goat
introduction are not clear, but the forests remaining
after goat eradication would be similar to the forests
present before the introduction (Shimizu 1993). The
native forests are dominated by Pisonia umbellifera,Pandanus boninensis, Livistona chinensis,
Neisosperma nakaianum and Ardisia sieboldii.
The number of feral goats had drasticallyincreased since 1945, and the number in 1991 wasapproximately 500 (317/km2) (Japan Wildlife
Research Center 1992). Feral goats in the islands
caused vegetation degradation. Goats destroyed
native vegetation, which led about 90% of theoriginal forest to shift into grassland and bareground. Goats grazed seedlings of trees and shrubs,
which prevented the regeneration of native forests
after the death of canopy trees (Shimizu 1993). As aFig. 1 Location of Nakodo-jima in the Ogasawara Islands

3DIWPA News Letter No.45

(c) The eroded soil flowed into the sea

result, forests shifted to grasslands. Thereafter,grazing and trampling of the goats to herbaceous
species resulted in loss of vegetation cover in someof the grasslands and exposure of surface soils (Fig.
2a). The exposure of surface soils resulted in theerosion (Fig. 2b). The eroded soil flowed into thesea (Fig. 2c), which affected the coastal
communities such as coral and fishes (JapanWildlife Research Center 2002).
Changes of ecosystems after eradication offeral goats
For the first step of restoration of the island
ecosystems, all goats on the island were eradicatedbetween 1997 and 1999 (Japan Wildlife ResearchCenter 2002). After goat eradication, vegetation,
especially grassland vegetation, recovered.
According to aerial photographs in 1991, 2003 and2012, areas of grassland increased and those of bareground decreased after goat eradication (Osawa etal. 2016), which would be likely to releases fromgrazing and trampling by feral goats.
In some areas of the grasslands, an invasive
shrub, Leucaena leucocephala, aggressively
invaded after the eradication (Fig. 3, Hata et al.
2010a; Osawa et al. 2016), which may be related toreleases from herbivory of goats. L. leucocephalacan prevent subsequent establishment of native tree
species by limiting seed germination and seedling
growth (Hata et al. 2010b). Therefore, it is likelythat there would be no replacement of native treesof mid- or late-successional species in the forests
dominated by L. leucocephala, which is also
observed in other islands in Ogasawara Islands(Yoshida and Oka 2000). For effective control of L.
leucocephala, it is necessary to set priorities byclassifying target areas based on propagule supply
and habit suitability of L. leucocephala (Osawa etal. 2020).
On the other hand, vegetation recovery did notoccur at some sites even after goat eradication. The
substantial variation in extent of vegetation
recovery within the island indicated that degraded
vegetation does not always recover, even after goat
eradication.
The soil erosion would prevent vegetation
recovery after goat eradication through limitation ofFig. 2 Alternation of ecosystems in Nakodo-jima disturbed byferal goats.

(a) By grazing and trampling of goats, forests shifted tograsslands, and grasslands shifted to bare ground(b) Exposure of surface soil with loss of vegetation covercaused soil erosion(c) Eroded soils followed into sea

4

DIWPA News Letter No.45

References

primary production with alternation of soil chemical
properties (Hata et al. 2019). Deeper soil horizons
with exposure of the loss of surface soil often haveextremely low nutrient levels and pH on the island(Hiradate et al. 2015). The soils with low nutrients
can limit plant growth because of deficiency ofnutrients. Also, the soils with low pH can cause
immobilization of labile and inorganic phosphorus
in soils, which is unavailable for plants (Bardgett2005). Therefore, it is necessary for ecosystem
restoration to prevent further erosion of the surface
soil by anthropogenic efforts such sandbag dams. In
addition, facilitation plant establishment on erodedsoil via fertilizer application, and seed andtransplant should be also necessary.

Bardgett R. 2005. The biology of soil: a community and ecosystemapproach. Oxford University Press, Oxford, UK.
Hata K., Suzuki J.I. and Kachi N. 2010a. Fine-scale spatial distribution ofseedling establishment of the invasive plant, Leucaena
leucocephala, on an oceanic island after feral goat extermination.
Weed Research 50: 472–480.
Hata K., Suzuki J.I. and Kachi N. 2010b. Effects of an alien shrub species,
Leucaena leucocephala, on establishment of native midsuccessional tree species after disturbance in the national park in
the Chichijima island, a subtropical oceanic island. In Restoring theOceanic Island Ecosystem (Kawakami K. and Okochi I. Eds.),PP103-110. Springer, Tokyo.
Hata K., Osawa T., Hiradate S. and Kachi N. 2019. Soil erosion alters soil
chemical properties and limits grassland plant establishment on anoceanic island even after goat eradication. Restoration Ecology 27:333–342.
Hiradate S., Morita S., Hata K., Osawa T., Sugai K. and Kachi N. 2015.
Effects of soil erosion and seabird activities on chemical properties
of surface soils on an oceanic island in Ogasawara Islands, Japan.
Catena 133: 495–502.
Japan Wildlife Research Center. 1992. Report on the urgent research
about damage of feral goats on plants and animals in theOgasawara Islands. Japan Wildlife Research Center, Tokyo, Japan.
(In Japanese)
Japan Wildlife Research Center. 2002. Report on the research ofvegetation recovery in the Ogasawara National Park. Ogasawara
branch of Tokyo Metropolitan Government, Tokyo, Japan. (inJapanese)
Kawakami K. 2010. What’s the Bonin Islands? In Restoring the Oceanic
Island Ecosystem (Kawakami K. and Okochi I. Eds.), PP3-7. Springer,Tokyo.
Loope L.L., Hamman O. and Stone C.P. 1988. Comparative conservation
biology of oceanic archipelagoes. Bioscience 38: 272–282.
Osawa T., Hata K. and Kachi N. 2016. Eradication of feral goats enhances
expansion of the invasive shrub Leucaena leucocephala on
Nakoudo-jima, an oceanic island. Weed Research 56: 168–178.
Osawa T., Akasaka M. and Kachi N. 2020. Facilitation of management
plan development via spatial classi cation of areas invaded by alien
invasive plant. Biological Invasions 21: 2067-2080.
Sato N. 2019. Recent control of invasive alien animals in the Bonin
Islands. Global Environmental Research 23: 9-19.
Shimizu Y. 1993. Vegetation of Mukojima Island Group in the Bonin
Ogasawara Islands with reference to the ecology of Ardisiadominant forest and the in uence of feral goats. Komazawa
Geography 29: 9–58 (In Japanese)
Shimizu Y. 2003. The nature of Ogasawara and its conservation. Global
Environmental Research 7: 3-14.
Yoshida K. and Oka S. 2000. Impact of biological invasion of Leucaena
leucocephala on successional pathway and species diversity ofsecondary forest on Hahajima Island, Ogasawara (Bonin) Island,northwestern Paci c. Japanese Journal of Ecology 50: 111−119. (inJapanese with English abstract)

Fig. 3 Forests dominated by L. leucocephala in Nakodo-jima(a) 2003(b) 2005

fiflfi5DIWPA News Letter No.45

from DIWPA Of ce
Due to concerns over the spread of Coronavirus, we regretfully announce thecancellation of 2021 DIWPA IFBC. We believe that 2022 DIWPA IFBC will beheld.
DIWPA website has been redesigned.
Enjoy our new website!
https://diwpa.ecology.kyoto-u.ac.jp

DIWPA New Letter is published in PDF format only on our website to promote
paperless. Thank you very much for your understanding.

DIWPA OFFICE
Chairperson

Shin-ichi Nakano

Secretary General

Atsushi Ishida

SecretaryHiroshi Kudo

Center for Ecological Research
Kyoto University509-3, 2-chome, Hirano, Otsu, Shiga 520-2113, JAPANTel : +81-77-549-8238
E-mail : diwpa@ecology.kyoto-u.ac.jp

Shoko Sakai

http://diwpa.ecology.kyoto-u.ac.jp/

Shigeo Yachi
Assistant Secretary Akiko Sekifi6

DIWPA News Letter No.45