2019 ೧Ͷ͕͜Ζ੤೯ౣ͹৪෼ʀ৪ਫ਼ʀౖৗୖᲄ 㝯ᚿ 1*ࠊᘅ⏣ ඘ 1ࠊᕝୖ ࿴ே 2

Plant, vegetation and soil on Nishinoshima in 2019
Takashi KAMIJO1*, Mitsuru HIROTA1 & Kazuto KAWAKAMI2
1. ⟃Ἴ኱Ꮫ⏕࿨⎔ቃ⣔㸦ࠛ305-8572 Ⲉᇛ┴ࡘࡃࡤᕷኳ⋤ྎ 1-1-1㸧
Tennodai 1-1-1, Tsukuba, Ibaraki 305-8572, Japan.
2. ᳃ᯘ⥲ྜ◊✲ᡤ㫽⋇⏕ែ◊✲ᐊ㸦ࠛ305-8687 Ⲉᇛ┴ࡘࡃࡤᕷᯇࡢ㔛 1㸧
Matsunosato 1, Tsukuba, Ibaraki 305-8684, Japan.
* kamijo.takashi.fw@u.tsukuba.ac.jp (author for correspondence)
せ᪨ ᑠ➟ཎㅖᓥࡢすஅᓥࡣࠊ2013 ᖺ࠿ࡽࡢⅆᒣάື࡟ࡼࡗ࡚኱ࡁࡃ㠃✚ࡀᣑ኱ࡋࡓࠋ2013 ᖺ௨๓࠿ࡽᏑᅾࡋ࡚࠸ࡓᓥࡢ኱㒊ศࡣࠊ᪂ࡓ࡞⁐ᒾὶࡸࢫࢥࣜ࢔࡟そࢃࢀࠊ࡯ࡰ᪂ᓥ࡟㏆࠸≧ែ࡜࡞ࡗࡓࠋᮏㄪᰝࡣࠊすஅᓥࡢ᳜≀ࠊ᳜⏕ࠊᅵተࡢ⌧ἣࢆ᫂ࡽ࠿࡟ࡍࡿࡇ࡜ࢆ┠ⓗ࡜ࡋ࡚ࠊ2019 ᖺ 9 ᭶࡟⌧ᆅㄪᰝࢆ⾜ࡗࡓࠋ⌧ᆅㄪᰝࡢ⤖ᯝࠊ⥔⟶᮰᳜≀࡜ࡋ࡚ࠊ࢜ࣄࢩࣂࠊ࢖ࢾࣅ࢚ࠊ
ࢫ࣋ࣜࣄࣘࡢ 3 ✀ࢆ☜ㄆࡋࡓࠋࡇࢀࡲ࡛ࡢグ㘓ࢆᇶ࡟᳨ウࡍࡿ࡜ࠊࡇࢀࡽ 3 ✀ࡣ 2013 ᖺᄇⅆ௨๓࠿ࡽ⏕⫱ࡋ࡚࠸ࡓಶయ⩌⏤᮶࡜⪃࠼ࡽࢀࡓࠋᅵተ࡟ࡘ࠸࡚ࡣࠊ⾲ᒙᅵተࢆ᥇ྲྀࡋࠊ඲Ⅳ⣲㔞ࠊ඲❅⣲ྵ㔞ࢆ ᐃࡋࡓࠋࡉࡽ࡟ࠊ௒ᚋࡢࣔࢽࢱࣜࣥࢢࡢࡓࡵ࡟ࠊ5 ᆅⅬ࡟࠾࠸࡚᪉ᙧ༊
㸦10 m × 10 m㸧ࢆタ⨨ࡋࠊ᪉ᙧ༊ෆࡢ᳜⏕ㄪᰝࢆ⾜ࡗࡓࠋ࣮࣮࢟࣡ࢻ ୍ḟ㑄⛣ࠊᾏ㫽ࠊᾏὒᓥࠊࣔࢽࢱࣜࣥࢢࠊ⁐ᒾὶ㸯㸬ࡣࡌࡵ࡟ ᑠ➟ཎㅖᓥࡢすஅᓥࡣࠊ∗ᓥࡢす᪉⣙ 130 km ࡟఩⨨ࡋࠊ2013 ᖺ࠿ࡽ⌧ᅾ࡟⮳ࡿࡲ࡛άⓎ࡞ⅆᒣάືࢆ⾜ࡗ࡚࠸ࡿ (୰㔝࡯࠿ࠊ ๓㔝࣭ྜྷᮏࠊ2020)ࠋすஅᓥࡢⅆᒣᓥ࡜ࡋ࡚ࡢ≉ᚩࡣࠊᏙ❧ᛶࡀ㧗࠸ࡇ࡜ࠊᑠᆺࡔࡗࡓᓥࡀᄇⅆάື࡟ࡼࡗ࡚኱ᆺ໬ࡋ࡚ࡁࡓࡇ࡜ࠊࡑࡢ኱㒊ศ
ࡀ 2013 ᖺ௨㝆ࡢⅆᒣᄇฟ≀࡟そࢃࢀࡓࡇ࡜࡞࡝ࡀᣲࡆࡽࢀࡿࠋࡇࡢࡼ࠺࡟すஅᓥࡣࠊᓥࡢ࡯
ࡰ඲యࡀᄇⅆᚋ࠿ࡽ 6 ᖺ࡟‶ࡓ࡞࠸ᡂ❧ࡋࡓࡤ࠿ࡾࡢ㝣ୖ⏕ែ⣔࡜ࡋ࡚఩⨨௜ࡅࡽࢀࠊ⏕≀ࡢ㛗㊥㞳ศᩓ࡜ᐃ╔ࠊ⏕≀࡟ࡼࡿ⎔ቃᙧᡂస⏝࡜࠸ࡗࡓ⏕ែ⣔ࡢᇶᮏⓗ࡞ᙧᡂ࣓࢝ࢽࢬ࣒࡟ࡘ࠸᳨࡚ド࡛ࡁࡿ⮬↛ࡢᐇ㦂ሙ࡜࡞ࡗ࡚࠸ࡿࠋẚ㍑ⓗ኱ᆺࡢ᪂ᓥࡢᡂ❧౛࡜ࡋ࡚ࡣࠊ࢔࢖ࢫ

− 69 −ࣛࣥࢻࡢࢫࣝࢶ࢙࢖ᓥ (Fridriksson, 1975) ࡸ࢖ࣥࢻࢿࢩ࢔ࡢ࢔ࢼࢡ࣭ࢡࣛ࢝ࢱ࢘ᓥ (Thornton,1997) ࡢ౛ࡀ࠶ࡿࠋ࡞࠾ࠊすஅᓥࡢሙྜࠊ୍㒊࡟ᑠ㠃✚ࡢᪧᓥ㒊ศࡀṧᏑࡋ࡚࠸ࡿ࡜࠸࠺Ⅼ࡛ࡇࢀࡽࡢ஦౛࡜ࡣⱝᖸ␗࡞ࡿࠋࢫࣝࢶ࢙࢖ᓥ࡞࡝࡟ẚ࡭すஅᓥࡣᏙ❧ᗘࡀ㧗ࡃࠊ⏕≀ࡢ㛗㊥㞳ࡢศᩓ࡜ᐃ╔㐣⛬࡟ࡼࡿ⏕ែ⣔ࡢⓎ㐩ไᚚࡀࡼࡾᙉࡃാࡃ࡜ண᝿ࡉࢀࡿࠋࡇࡢࡼ࠺࡞≉ᚩⓗ࡞⏕ែ⣔ࡢⓎ㐩ࣉࣟࢭࢫࢆ᫂ࡽ࠿࡟ࡍࡿࡓࡵ࡟ࡣࠊྍ⬟࡞㝈ࡾ᪩࠸ẁ㝵ࡢ≧ἣࢆᢕᥱࡋࠊࣔࢽࢱࣜࣥࢢྍ⬟࡞యไࢆᵓ⠏ࡍࡿᚲせࡀ࠶ࡿࠋ 2013 ᖺᄇⅆ௨๓ࡢすஅᓥࡢ᳜≀࡟ࡘ࠸࡚ࡣࠊὠᒣ࣭ὸぢ (1970)ࠊ኱ἑ࣭಴⏣ (1983)ࠊAbe(2006㸧ࡢሗ࿌ࡀ࠶ࡿࠋࡲࡓࠊᄇⅆ௨๓ࡢ⎔ቃ┬ࡢ⌧Ꮡ᳜⏕ᅗ (⎔ቃ┬⮬↛⎔ቃᒁࠊ2016) ࡟ࡼࡿ࡜ࠊࢢࣥࣂ࢖ࣄࣝ࢞࢜⩌ⴠ Ipomoea pes-caprae community ࡜࢜ࣄࢩࣂ㸫ࢫ࣋ࣜࣄࣘ⩌ⴠEleusine indica - Portulaca oleracea community ࡀศᕸࡋ࡚࠸ࡓࠋ2004 ᖺ࡟ᐇ᪋ࡉࢀࡓ⌧ᆅㄪᰝ
࡛ࡣ 6 ✀ࡢ⥔⟶᮰᳜≀ࡀ☜ㄆࡉࢀ (Abe, 2006)ࠊᄇⅆ㛤ጞᚋࡢ 2016 ᖺࡢୖ㝣ㄪᰝ࡛ࡣࠊ1973ᖺ௨๓࠿ࡽᏑᅾࡋ࡚࠸ࡓᪧᓥୖ࡟࢜ࣄࢩࣂ Eleusine indica (L.) Gaertn.ࠊ࢖ࢾࣅ࢚ Echinochloa
crus-galli (L.) P.Beauv.ࠊࢫ࣋ࣜࣄࣘ Portulaca oleracea L.ࡢ 3 ✀ࡢ⏕⫱ࡀ☜ㄆࡉࢀ࡚࠸ࡿ (ᕝୖࠊ ᕝୖࠊᮍⓎ⾲)ࠋࡋ࠿ࡋࠊ2016 ᖺࡢᚋࡶᄇⅆάືࡀ᩿⥆ⓗ࡟⥆ࡁࠊᮏㄪᰝ࡟⮳ࡿࡲ࡛ࠊࡑࡢᚋࡢୖ㝣ㄪᰝࡣ࡞ࡉࢀ࡚࠸࡞࠿ࡗࡓࠋ ᮏ◊✲࡛ࡣࠊ⏕ែ⣔ࡢ⏕⏘ᇶ┙࡜࡞ࡿ᳜≀࡜᳜⏕ࢆ୺࡞ᑐ㇟࡜ࡋ࡚ࠊ2013 ᖺ࠿ࡽ 2018 ᖺࡢᄇⅆᚋࡢ⌧≧ࢆ᫂ࡽ࠿࡟ࡍࡿࠋࡉࡽ࡟ࠊ௒ᚋࡢࣔࢽࢱࣜࣥࢢㄪᰝࡢࡓࡵࡢᅛᐃㄪᰝ༊ࡢタ⨨≧ἣ࡜ࠊ⾲ᒙᅵተࡢ඲Ⅳ⣲㔞࡜඲❅⣲ྵ㔞࡟㛵ࡍࡿศᯒ⤖ᯝࡢ୍㒊࡟ࡘ࠸࡚ሗ࿌ࡍࡿࠋ㸰㸬ᮦᩱ࡜᪉ἲ ୖ㝣ㄪᰝࡣࠊ2019 ᖺ 9 ᭶ 3㹼5 ᪥࡟⾜ࡗࡓࠋୖ㝣ࡣすഃࡢ὾࠿ࡽ 2 ᅇࠊ༡すࡢ὾࠿ࡽ 1 ᅇ⾜ࡗࡓࠋ᳜≀┦࡟ࡘ࠸࡚ࡣࠊୖ㝣ࡋࡓ὾࡜ࡑࡢ࿘㎶ࡢ⁐ᒾୖ࠾ࡼࡧᪧᓥୖࢆ㋃ᰝࡍࡿࡇ࡜࡛⏕⫱ࢆ☜ㄆࡋࡓࠋ௒ᚋࡢࣔࢽࢱࣜࣥࢢㄪᰝࡢࡓࡵ࡟ࠊ10 m × 10 m ࡢ᪉ᙧ༊ࢆ 5 ᆅⅬタ⨨ࡋࡓ㸦ᅗ 1㸧ࠋྠ᫬࡟ࠊ⥅⥆ⓗ࠿ࡘ⡆౽࡞ࣔࢽࢱࣜࣥࢢࡀᐇ᪋࡛ࡁࡿࡼ࠺࡟↓ே⯟✵ᶵࢆ⏝࠸ࡓ᧜ᙳࡶ⾜ࢃࢀࡓࠋ5 ᆅⅬࡢෆヂࡣࠊ
1973 ᖺ௨๓࠿ࡽᏑᅾࡋ࡚࠸ࡓᪧᓥୖࡀ 2 ᆅⅬࠊ2017 ᖺ⁐ᒾୖࡀ 2 ᆅⅬ (QD1,QD5)ࠊ2014-2015 ᖺ⁐ᒾୖࡀ 1 ᆅⅬ (QD4) ࡛࠶ࡿࠋᪧᓥୖࡢ 2 ᆅⅬ࡟ࡘ࠸࡚ࡣࠊ᳜⏕ࡀ↓࠸㒊ศ (QD2) ࡜᳜⏕ࡀከ࠸㒊ศ (QD3) ࢆࡑࢀࡒࢀ㑅ᐃࡋࡓࠋ࡞࠾ࠊ5 ᆅⅬࡢෆࠊQD4 ࡀ᭱ࡶᾏᓊ࡟㞄᥋ࡋ࡚࠸ࡿࠋ᳜≀ࡀ⏕⫱ࡍࡿ QD3 ࡟ࡘ࠸࡚ࡣࠊ᳜≀♫఍Ꮫⓗ᪉ἲ࡟ࡼࡿ᳜⏕ㄪᰝ(Braun-Blanquet, 1964) ࢆ⾜ࡗࡓࠋ ⾲ᒙᅵተ࡟ࡘ࠸࡚ࡣࠊྛ᪉ᙧ༊ࡢ࿘㎶࡛᥇ྲྀࢆ⾜ࡗࡓࠋᅵተ᥇ྲྀ⏝ࡢ 100 ml ෇⟄⟶ࢆ⏝࠸࡚ࠊ῝ࡉ 5 cm ࡲ࡛᥇ྲྀࡋࡓࠋᮏ◊✲࡛ࡣࠊணഛⓗ࡟ศᯒࡋࡓ 2014-2015 ᖺ⁐ᒾୖࡢ 5 ᆅⅬ
㸦QD4 ࿘㎶㸧ࠊ2017 ᖺ⁐ᒾୖࡢ 5 ᆅⅬ (QD1, QD5 ࿘㎶) ࡢศᯒ⤖ᯝࢆࡲ࡜ࡵࡓࡶࡢࢆ♧ࡍࠋ௒ᅇ♧ࡍࠊ஝ᅵᙜࡓࡾࡢ඲Ⅳ⣲㔞࡜඲❅⣲ྵ㔞࡟ࡘ࠸࡚ࡣࠊ⟃Ἴ኱Ꮫᡤ᭷ࡢ NC ࢔ࢼࣛ࢖ࢨ࣮ (SUMIGRAPH NC-220F) ࢆ⏝࠸࡚ᐃ㔞ࡋࡓࠋ௒ᚋࠊศᯒヨᩱࢆቑࡸࡍ࡜࡜ࡶ࡟ศᯒ㡯┠ࢆ㏣ຍࡍࡿணᐃ࡛࠶ࡿࠋ

− 70 −ᅗ  すஅᓥ  ᖺㄪᰝ࡟࠾ࡅࡿ㋃ᰝᆅᇦ࿘㎶ࡢⅆᒣ⾲ᒙᆅ㉁ᅗ࡜ᅛᐃㄪᰝ༊ࡢ఩⨨ ɫ๓㔝࣭ྜྷᮏ   ࢆ୍㒊⡆␎໬ࡋ࡚సᡂࡋࡓࠋ)LJXUH9ROFDQLFVXEVXUIDFHJHRORJLFDOPDSRI1LVKLQRVKLPDLQFOXGLQJVXUYH\DUHDVLQDQGORFDWLRQRITXDGUDWHV ɫ
7KHVLPSOLILHGPDSRI0DHQR <RVKLPRWR  㸱㸬⤖ᯝ ㋃ᰝࡢ⤖ᯝࠊ࢜ࣄࢩࣂ(OHXVLQHLQGLFD / *DHUWQࠊ࢖ࢾࣅ࢚(FKLQRFKORDFUXVJDOOL / 3%HDXYࠊࢫ࣋ࣜࣄࣘ 3RUWXODFDROHUDFHD/ࡢ  ✀ࢆ☜ㄆࡋࡓ ᅗ  ࠋᪧᓥ㒊ศ࡟ࡣࡇࢀࡽ  ✀࡜ࡶ⏕⫱ࡋ࡚࠸ࡓࠋᄇⅆᚋࡢἼᾉస⏝࡟ࡼࡗ࡚ᙧᡂࡉࢀࡓ὾ࡢෆࠊᪧᓥ࡟㞄᥋ࡍࡿすഃࡢ὾࡛ࡣࠊ࢜ࣄࢩࣂ࡜ࢫ࣋ࣜࣄࣘࡢ⏕⫱ࢆ☜ㄆ࡛ࡁࡓ ᅗ  ࠋ࢜ࣄࢩࣂ࡜ࢫ࣋ࣜࣄࣘࡣಶయᩘࡶከࡃࠊᄇⅆ๓࡟☜ㄆࡉࢀ࡚࠸ࡓ࢜ࣄࢩࣂ㸫ࢫ࣋ࣜࣄࣘ⩌ⴠ ⎔ቃ┬⮬↛⎔ቃᒁࠊ  ࢆᙧᡂࡋ࡚࠸ࡓ㸦ᅗ 㸧ࠋ୍᪉ࠊ⁐ᒾୖ࡟ࡘ࠸࡚ࡣࠊᪧᓥࡢ㞄᥋ᆅ࡛࠶ࡿすഃࡢ⁐ᒾୖࠊ༡すഃࡢ⁐ᒾୖ࡜ࡶࠊ⥔⟶᮰᳜≀ࠊᆅ⾰⹊ⱏ㢮ࡢ⏕⫱ࡣ☜ㄆ࡛ࡁ࡞࠿ࡗࡓࠋ࡞࠾ࠊᾏ࡟㠃ࡋࡓ⁐ᒾୖ࡛ࡣࠊ ᆅⅬ࡛⸴㢮࡞࡝࡜ᛮࢃࢀࡿ⥳Ⰽࡢ⿕そࡀほᐹࡉࢀࠊᒾࡈ࡜᥇ྲྀࡋࡓࠋ௒ᚋࠊྠᐃࡢࡓࡵࡢศᯒࢆࡍࡿணᐃ࡛࠶ࡿࠋ ⾲ᒙᅵተ࡟ࡘ࠸࡚ぢ࡚ࡳࡿ࡜ࠊ ᖺ⁐ᒾୖ࡛ࡣᅵተ୰ࡢ඲Ⅳ⣲㔞ࡣ࡯ࡰࢮࣟ࡟㏆ࡃࠊࡴࡋࢁ඲❅⣲㔞ࡢ᪉ࡀከ࠿ࡗࡓ ᅗ  ࠋ୍᪉ࠊᾏᓊ࡟㞄᥋ࡋࡓ  ᖺ⁐ᒾୖ࡛ࡣࠊ୧⪅࡜ࡶ๓⪅ࡼࡾ್ࡀ㧗ࡃ ᅗ ࠊᖹᆒ್࡛ぢࡿ࡜඲❅⣲ࡣ⣙ ಸࠊ඲Ⅳ⣲ࡣ⣙ ಸ࡟࡞ࡗ࡚࠸ࡓࠋ ࣔࢽࢱࣜࣥࢢࡢࡓࡵ࡟タ⨨ࡋࡓ᪉ᙧ༊ࡢ⌧ἣ࡟ࡘ࠸࡚ᅗ  ࡜⾲  ࡟♧ࡍࠋ࡞࠾ࠊ᳜⏕ࢆྵࡴ᪉ᙧ༊ࡣᪧᓥୖࡢ 4' ࡢࡳ࡛࠶ࡿࠋ4' ࡢ᳜⿕⋡ࡣ 㸣࡛࠶ࡾࠊ࢜ࣄࢩࣂ  ✀ࡀ⏕⫱ࡋ࡚࠸ࡓࠋࡲࡓࠊ࠸ࡎࢀࡢㄪᰝ༊࡟࠾࠸࡚ࡶ⣅࡞࡝ࡢᾏ㫽ࡢ⑞㊧ࡀ☜ㄆࡉࢀࡓࠋ≉࡟ࠊᪧᓥୖࡢㄪᰝ༊࡜ᾏ࡟㠃ࡋࡓ  ᖺ⁐ᒾୖࡢㄪᰝ༊ 4'  ࡛ࡣࠊከࡃࡢᾏ㫽ࡢ⣅ࡀ☜ㄆࡉࢀࡓࠋ− 71 −EDFᅗ  ⏕⫱ࡀ☜ㄆࡉࢀࡓ⥔⟶᮰᳜≀  ✀D  ࢜ࣄࢩࣂࠊ E  ࢖ࢾࣅ࢚ࠊ F  ࢫ࣋ࣜࣄࣘࠋ)LJXUH2EVHUYHGWKUHHYDVFXODUSODQWVSHFLHV
D (OHXVLQHLQGLFD E (FKLQRFKORDFUXVJDOOL F 3RUWXODFDROHUDFHD D                  Eᅗ  ࢜ࣄࢩࣂ࡜ࢫ࣋ࣜࣄࣘ࠿ࡽ࡞ࡿ᳜⏕ࡢᴫほD  ᪧᓥࠊ E  ᪧᓥ࡟㞄᥋ࡋࡓᾏ὾ࠋ୰ኸࡣ࢝ࢶ࢜ࢻࣜࠋ)LJXUH9HJHWDWLRQFRPSRVHGRI(OHXVLQHLQGLFDDQG3RUWXODFDROHUDFHD
D 2OGLVODQG E EHDFKDGMDFHQWWRWKHROGLVODQG7KHELUGLQWKHPLGGOHRIWKLVSLFWXUHLV6XODOHXFRJDVWHU− 72 − D Eᅗ  ᖺ⁐ᒾୖ࡜  ᖺ⁐ᒾୖ㸦ᾏᓊ࡟㞄᥋㸧࡟࠾ࡅࡿ D  ඲❅⣲ྵ᭷⋡࡜ E  ඲Ⅳ⣲ྵ᭷⋡஝ᅵᙜࡓࡾࡢ࡛♧ࡉࢀ࡚࠸ࡿࠋ)LJXUH6RLOWRWDOQLWURJHQDQGFDUERQRQ D ODYDIORZDQG E ODYDIORZIDFLQJVHDVKRUH
9DOXHVDUHVKRZQE\SHUFHQWDJHLQGU\VRLOZHLJKW㸲㸬⪃ᐹ ⌧ᅾࡳࡽࢀࡿ⥔⟶᮰᳜≀ࡣ࠸ࡎࢀࡶᄇⅆ๓ࡢ᳜≀ࣜࢫࢺ࡟⾲グࡉࢀ࡚࠸ࡿࡶࡢ࡛࠶ࡾࠊ ᖺ௨㝆ࡢᄇⅆࢆ⏕ࡁᘏࡧࡓಶయ⩌⏤᮶࡜⪃࠼ࡽࢀࡿࠋ୍᪉ࠊ ᖺ࡟☜ㄆࡉࢀ࡚࠸ࡓࢢࣥࣂ࢖ࣄࣝ࢞࢜ ,SRPRHDSHVFDSUDH / 6ZHHWࠊࣁ࣐ࢦ࢘ 9LWH[URWXQGLIROLD/Iࠊࢶࣝࢼ 7HWUDJRQLDWHWUDJRQRLGHV 3DOO .XQW]H ࡢ  ✀ࡣ☜ㄆ࡛ࡁ࡞࠿ࡗࡓࠋᮏ◊✲࡛ࡢୖ㝣⠊ᅖࡣ㝈ࡽࢀ࡚࠸ࡓࡶࡢࡢࠊᪧᓥ࡜ࡑࡢ࿘㎶㒊ࡢ㋃ᰝࡣᐇ᪋࡛ࡁ࡚࠾ࡾࠊࡇࢀࡽࡢ✀ࡣ⤯⁛ࡋࡓࡶࡢ࡜⪃࠼ࡽࢀࡿࠋ☜ㄆࡉࢀࡓ  ✀ࡣࠊᇶᮏⓗ࡟ᪧᓥୖ࡟ศᕸࡍࡿࡀࠊ࢜ࣄࢩࣂ࡜ࢫ࣋ࣜࣄࣘ࡟ࡘ࠸࡚ࡣ᪂ࡓ࡟ᙧᡂࡉࢀࡓすഃࡢ὾ୖ࡛ࡶ⏕⫱ࡀ☜ㄆࡉࢀࡓࠋࡇࡢࡇ࡜ࡣࠊἼᾉ࡛ᙧᡂࡉࢀࡿ὾࡟ࡘ࠸࡚ࡣࠊ᳜≀ࡢᐃ╔ࡀ⁐ᒾୖ࡟ẚ࡭ࡼࡾ᪩࠸ࡇ࡜ࢆ♧ࡋ࡚࠸ࡿࠋ᪂ࡋ࠸⁐ᒾୖ࡟ࡣᇶᮏⓗ࡟᳜≀ࡣࡳࡽࢀ࡞࠿ࡗࡓࡀࠊᾏ㫽ࡢ⣅ࡸṚయࡀㄪᰝ༊ෆ࠶ࡿ࠸ࡣ
ࡑࡢ࿘㎶࡛ぢࡽࢀࡓࠋすஅᓥࡣ࢝ࢶ࢜ࢻࣜ 6XOD OHXFRJDVWHU ࡞࡝ࡢᾏ㫽ࡢ⦾Ṫᆅ࡜ࡋ࡚▱ࡽࢀᕝୖ࡯࠿ࠊ ᕝୖࠊ ࠊ ᖺࡢᄇⅆ௨㝆ࡶᾏ㫽ࡢ⦾Ṫࡀ☜ㄆࡉࢀ࡚ࡁࡓ ᕝୖ  ࠋᾏ㫽ࡢ⦾Ṫᆅ࡛ࡣࠊᾏ㫽ࢆ⏤᮶࡜ࡍࡿ᭷ᶵ≀ࡸᰤ㣴ሷࡀࠊ᳜⏕㑄⛣࡟ᙉ࠸ᙳ㡪ࢆ୚࠼ࡿࡇ࡜
ࡀࢫࣝࢶ࢙࢖ᓥ࡞࡝࡛ᣦ᦬ࡉࢀ࡚࠸ࡿ /HEODQVHWDO0DJQ~VVRQHWDO ࠋᮏ◊✲࡟࠾࠸࡚ࡶࠊᾏ࡟㠃ࡋࡓ  ᖺ⁐ᒾୖ࡛ࡣࠊᾏ㫽ࡢ⣅ࡀከࡃࠊᅵተࡢ඲❅⣲ྵ᭷⋡ࡶ㧗࠿ࡗࡓࠋࡇࢀࡽࡢࡇ࡜ࡣࠊ௒ᚋࡢすஅᓥ࡟࠾࠸࡚ࠊᾏ㫽ࡢႠᕢ࠶ࡿ࠸ࡣఇᜥࡍࡿሙᡤ࡛ࡣ⊂⮬ࡢ⏕ែ⣔Ⓨ㐩㐣⛬ࡀほ ࡉࢀࡿྍ⬟ᛶࡀ࠶ࡿࡇ࡜ࢆ♧ࡋ࡚࠸ࡿࠋ ᮏ◊✲࡟ࡼࡾࠊすஅᓥࡢᄇⅆᚋࡢ᳜≀࡜᳜⏕ࡢึᮇ≧ែࢆグ㘓ࡍࡿࡇ࡜ࡀ࡛ࡁࡓࠋ௒ᚋ㐍⾜ࡍࡿᓥ࡬ࡢ᳜≀ࡢ౵ධ㐣⛬࡜㑄⛣㐣⛬ࢆ⌮ゎࡍࡿࡓࡵ࡟ࡶࠊࣔࢽࢱࣜࣥࢢࢆ⥆ࡅࡿࡇ࡜ࡀᚲせ୙ྍḞ࡛࠶ࡿࠋ

− 73 −

4'  ᖺ⁐ᒾ  ODYDIORZ              4' ᪧᓥ  ROGLVODQG4' ᪧᓥ  ROGLVODQG                        4'  ᖺ⁐ᒾ  ODYDIORZ

4'  ᖺ⁐ᒾ  ODYDIORZ

ᅗ  ᅛᐃㄪᰝ༊ࡢ෗┿)LJXUH3KRWRJUDSKVRIHDFKRIWKHTXDGUDWHV− 74 −⾲ 1. ᅛᐃㄪᰝ༊ࡢ᝟ሗ࡜᳜⏕ㄪᰝ⤖ᯝTable 1. Plots data and results of vegetation survey
QD

QD1

QD2QD3QD4QD5タ⨨᪥
Date of installation

2019/9/3

2019/9/4

2019/9/4

2019/9/4

2019/9/5❧ᆅSite2017ᖺ⁐ᒾ2017 lava flowᪧᓥOld islandᪧᓥ
Old island

2014-2015ᖺ⁐ᒾ2014-2015 lava flow2017ᖺ⁐ᒾ2017 lava flow

㠃✚Area10 m × 10 m

10 m × 10 m

10 m × 10 m

10 m × 10 m

10 m × 10 m⦋ᗘ
LatitudeN27°14.723

N27°14.748

N27°14.765

N27°14.875

N27°14.486⤒ᗘLongitude

E140°52.399

E140°52.400

E140°52.382

E140°52.310

E140°52.350

ഴᩳ
Slope degree

0°

3°

0°

3°

7°

᪉఩
Direction

䠉

N80W

䠉

N80W

S45W

ᆅ⾲㠃䛾ᒾ䛾๭ྜProportion of rocks

100%

15%0%

40%100%ᒾ䛾㧗పᕪ
Difference of elevation of rocks

2m

0.3 m

0m

1m3m

ᆅୖ䛻䛔䜛ᾏ㫽
Seabirds on ground䠉䜹䝒䜸䝗䝸䛾
୍✀
Sula spp.

䜹䝒䜸䝗䝸䛾
୍✀
Sula spp.

䜹䝒䜸䝗䝸䛾
୍✀
Sula spp.

䠉ᾏ㫽䛾⣅Seabird's droppingᑡ䛺䛔*littleከ䛔
manyከ䛔
many

ከ䛔
many

ᑡ䛺䛔**littleᾏ㫽䛾ᕢSeabird's nest0ᕢ2ಶ
Two nests

ᕢ✰8ಶ
8 burrows

00᳜⿕⋡
Vegetation cover

0%0%

20%0%0%᳜⏕㧗Vegetation height䠉䠉

75 cm䠉

䠉䜸䝠䝅䝞Eleusine indica䠉䠉3䡡2***䠉䠉ᯤ䜜䛶䛔䜛ⴥ䛜ከ䛔䚹Many dead leaves෇♟䛜ከ䛔䚹㫽䛾Ṛయ䛜࿘㎶䛻ぢ䜙䜜䜛䚹Many round gravel
Dead body ofseabirds were foundaround the QD

䠉ഛ⪃Remarks䠉䠉*⾲ᒙ䛾0.2-0.3%䚸**⾲ᒙ䛾0.䠍%௨ୗ䚸
*0.2-0.3% of surface, **less than 0.䠍% of surface***Braun-Blanquet (1964) 䛾ඃ༨ᗘ䞉⩌ᗘ㝵⣭***Cover-Abundance value of Braun-Blanquet (1964)

− 75 −㸳㸬ㅰ㎡ ᮏ◊✲ࡣࠊ⎔ቃ┬ࡀ୺ദࡋࡓ௧࿴ඖᖺᗘすஅᓥ⥲ྜᏛ⾡ㄪᰝ࡟ࡼࡗ࡚⾜ࢃࢀࡓࠋㄪᰝࢆᐇ᪋ࡍࡿ࡟࠶ࡓࡾࠊᶓᒣ┤ேẶ࡜Ⳣ㔝ᗣ♸Ặࢆࡣࡌࡵ࡜ࡍࡿ⎔ቃ┬ࡢⓙᵝࠊ᳃ⱥ❶Ặࠊ 㝯୍Ặࠊᑎ⏣๛ẶࠊỌ㔝⿱Ặࠊ᪥㧘⿱⳹Ặ࡞ࡽࡧ࡟ᑠᒣ⏣భ㍜Ặࢆࡣࡌࡵ࡜ࡍࡿ⮬↛⎔ቃ◊✲ࢭࣥࢱ࣮ࡢⓙᵝࠊᰴᘧ఍♫ᾏὒ࢚ࣥࢪࢽ࢔ࣜࣥࢢࡢ኱ᮧᑑ᫂Ặࠊᰴᘧ఍♫࣊࢟ࢧ࣓ࢹ࢕࢔ࡢᒸᮧᘻᶞẶࠊᑠ➟ཎᮧᙺሙࠊᑠ➟ཎᮧࡢ㧗ᕊ᫓ኵẶࠊΏ㑓⠜Ặࠊ㏆⸨ὒẶࠊྥဴႹẶ࡞ࡽࡧ࡟ᕝཱྀ኱ᮁẶ࡟ࡣ኱ኚ࠾ୡヰ࡟࡞ࡗࡓࠋᮾி኱Ꮫࡢ๓㔝῝༤ኈ࠿ࡽࡣ⾲ᒙᆅ㉁ᅗ࡟ࡘ࠸࡚ࡈᩍ♧ࡋ࡚㡬࠸ࡓࠋᅵተศᯒ࡟ࡘ࠸࡚ࡣ⟃Ἴ኱Ꮫࡢᯈ㰯኱ᶞẶ࡟༠ຊࡋ࡚㡬࠸ࡓࠋୖ㝣ࡢࡓࡵࡢ஦๓カ⦎࡛ࡣࠊ᪥ᮏࢫࣀ࣮ࢣࣜࣥࢢ㐃┕ࡢᖹᕝ኱㍜Ặࠊ㤳㒔኱Ꮫᮾிࠊᮾி኱Ꮫࠊ୕Ꮿᓥࡢ㔝⏣༤அẶ࡟኱ኚ࠾ୡヰ࡟࡞ࡗࡓࠋࡇࡢሙࢆ೉ࡾ࡚ᚚ♩⏦ࡋୖࡆࡿࠋ
㸴㸬ᘬ⏝ᩥ⊩
Abe T (2006) Colonization of Nishino-shima Island by plants and arthropods 31 years after eruption.
Pacific Science 60: 355-365.
Braun-Blanquet J (1964) Pflanzensoziologie, 3Auf. Springer Verlag, 865p.
Fridriksson S (1975) Surtsey: Evolution of Life on a Volcanic Island. Butterworth, 288p.
⎔ቃ┬⮬↛⎔ቃᒁ (2016) ࠗ1/2.5 ୓⌧Ꮡ᳜⏕ᅗ࠘ ⎔ቃ┬⮬↛⎔ቃᒁ⏕≀ከᵝᛶࢭࣥࢱ࣮.
http://www.biodic.go.jp/kiso/vg/vg_kiso.html㸦᭱⤊㜀ぴ᪥: 2020 ᖺ 1 ᭶ 12 ᪥㸧ᕝୖ ࿴ே (2019) ⅏࠸㌿ࡌ࡚すஅᓥ. ⚾ࡓࡕࡢ⮬↛ 622: 9-11.
ᕝୖ ࿴ே࣭ᒣᮏ ⿱࣭ᇼ㉺ ࿴ኵ (2005) ᑠ➟ཎㅖᓥすஅᓥࡢ㫽㢮┦. Strix 23: 159-166.
Leblans NIW, Sigurdsson BD, Roefs P, Thuys R, Magnússon B & Janssens, IA (2014) Effects of seabird
nitrogen input on biomass and carbon accumulation after 50 years of primary succession on a young
volcanic island, Surtsey. Biogeosciences 11: 6237-6250.
๓㔝 ῝࣭ྜྷᮏ ඘ᏹ (2020) すஅᓥࡢᄇⅆ࡟ࡼࡿᆅᙧ࣭ᆅ㉁࣭ᄇฟ≀ࡢ≉ᚩ࡜ࡑࡢኚ໬. ᑠ➟ཎ◊✲ 46: 37-51.
Magnússon B, Magnússon SH, Ólafsson E & Sigurdsson BD (2014) Plant colonization, succession andecosystem development on Surtsey with reference to neighbouring islands. Biogeosciences 11: 55215537.
୰㔝 ಇ࣭๓㔝 ῝࣭ྜྷᮏ ඘ᏹ࣭኱‖ 㝯㞝࣭Ώ㑓 ⠜ᚿ࣭ᕝୖ ࿴ே࣭༓⏣ ᬛᇶ࣭Ṋᑿ ᐇ (2017)ᄇⅆࡀ⤊ࢃࡗࡓすஅᓥ࡟ึୖ㝣ㄪᰝ. GSJ ᆅ㉁ࢽ࣮ࣗࢫ 6 (1): 1-4.
኱ἑ 㞞ᙪ࣭಴⏣ ὒ஧ (1983) すஅᓥ᪂ᓥ࡬ࡢ᳜≀ࡢ౵ධ. ᥇㞟࡜㣫⫱ 45: 377-380.
Thornton IW (1997) Krakatau: the Destruction and Reassembly of an Island Ecosystem. Harvard
University Press, 346p.
ὠᒣ ᑦ࣭ὸᾏ 㔜ኵ⦅ⴭ (1970) ࠗᑠ➟ཎࡢ⮬↛࠘ᘅᕝ᭩ᗑ, 271p.

− 76 −

OGASAWARA RESEARCHSUMMARY

Plant, vegetation and soil on Nishinoshima in 2019
Takashi KAMIJO1*, Mitsuru HIROTA1 & Kazuto KAWAKAMI2
1. Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki
305-8572, Japan.
2. Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba, Ibaraki 305-8684, Japan.
* kamijo.takashi.fw@u.tsukuba.ac.jp (author for correspondence)
Nishinoshima Island is an active volcano in Ogasawara Islands. The island has erupted from 2013, its
area has expanded and almost all of old island were covered by new lava flows. Now, the island became
like a newborn island. In this study, we surveyed flora, vegetation and soils on Nishinoshima in September
2019. We recorded only three vascular plant species: Eleusine indica, Echinochloa crus-galli andPortulaca oleracea. Based on comparison of flora with the records before the 2013-2018 eruption, thesethree species seem to have survived during the eruption. Establishment of vegetation composed of E. indica
and P. oleracea was observed only on the old island and beach adjacent to it whereas no establishment ofvegetation on the new lava flows. We collected surface soils and measured total carbon and nitrogen inlaboratory. Soils on lava flow facing seashore showed relatively high total nitrogen content as young
volcanic substrate. This may be related to seabird’s activities, such as seabird’s dropping. In addition, tomonitor ecosystem development, we installed five 10 x 10 m quadrates.
Key words
Lava flow, Monitoring, Oceanic island, Primary succession, Seabird

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