An inventory of the mires of Hokkaido, Japan—their development, classification, decline, and conservation

Abstract

Hokkaido Island is located in the cool temperate zone, and its climate conditions facilitated the formation of a variety of wetland types, the majority of them peat-forming mires. Most of these remained in a natural state until the early 20th century. However, drainage and subsequent conversion mostly to agricultural land have since destroyed more than 70% of the original wetland ecosystems. This paper (1) provides an overview of mire types, (2) reviews the development process of mires in Hokkaido during the Holocene, (3) analyzes the causes of losses of wetland areas, and (4) gives a summary of the current conservation and management status. Basic mire types that have been described in other parts of the northern hemisphere can also be recognized in Hokkaido, although there are floristic differences, and the frequency and intensity of volcanic impact and tsunamis is higher than in most other regions with abundant mire formation. Mire formation started at various points during the postglacial period; a few mountain mires in southwest Hokkaido date back to the Lateglacial, but most mountain mires formed during the mid to late Holocene. Most lowland mires developed at altitudes below 20 m and were influenced by the Jomon transgression that peaked ca. 6,000 years BP. The largest lowland mires started forming after the sea retreated, and many are not older than ca. 3,000 years. In 1996, the total number of wetlands (including peat-forming mires, freshwater marshes, and saltmarshes) greater than 1 ha was 150, with a total area of 59,881 ha. In 1928, when many wetlands were yet undeveloped, their total area was 200,642 ha. Most losses occurred between the 1950s and 1970s, when post-war development economics promoted agriculture and large-scale reclamation projects. Currently, 90.7% of mountain wetlands are public land, while 81.3% of the lowland wetlands are private or in mixed ownership. The ownership condition affects the possibilities for the protection of complete mire complexes especially in the lowlands. For effective conservation of wetland ecosystems it is necessary to include the catchment area in the planning of protected areas.

Appendix

List of wetlands in Hokkaido (after Fujita et al. 1997). The wetland types are not necessarily equivalent to those used in Europe or North America as they are based on broadly defined physiognomic and floristic criteria rather than morphology and hydrology. A number of “bogs” would have to be placed in the poor fen category in a more rigorous classification system

Number	Wetland name	Area (ha)	Altitude (m)	Wetland type				Conservation status
				bog	poor fen	rich fen, marsh	salt marsh	National park	Quasi-national park	Prefectural park	Wildlife protection area	Nature conservation area	No protection
1	Orochigahara Mire	8	965–980	${\circledcirc}$				+
2	Nishioka Mire	7	130–140			${\circledcirc}$					+
3	Nakayama Mire	4	880–890	${\circledcirc}$				+
4	Makunbetsu Marsh	44	1			${\circledcirc}$							+
5	Echigo Numa	11	8			${\circledcirc}$							+
6	Okotanpe Mire	3	610–620			${\circledcirc}$		+			+
7	Kyu Osatsu Numa Mire	5	5–7.5			${\circledcirc}$							+
8	Shizukari Mire	34	5	${\circledcirc}$		${\circ}$							+
9	Onuma (including Higashi Onuma)	144	131			${\circledcirc}$			+		+
10	Yokotsudake Mire (Kumoi Numa Mire)	4	1,078–1,121	${\circledcirc}$									+
11	Hakamagoshidake Mire	5	740–750			${\circledcirc}$							+
12	Kitahiyama Ukishima Mire	34	0–40			${\circledcirc}$					+
13	Shinsen Numa Mire	4	770	${\circledcirc}$					+		+
14	Oyachi Mire	6	740			${\circledcirc}$			+		+
15	Nisekoannupuri Mire	1	920	${\circledcirc}$					+
16	Kagami Numa Mire	3	580	${\circledcirc}$									+
17	Tekagami Numa Mire	2	580	${\circledcirc}$									+
18	Nakadake Mire	3	1030	${\circledcirc}$ ?									+
19	Kyogoku Mire	20	860–870	${\circledcirc}$									+
20	Mekunnaidake Mire	5	890–910	${\circledcirc}$					+
21	Pankemekunnai Mire	4	940–960	${\circledcirc}$	${\circ}$				+
22	Yumoto Mire	1	550	${\circ}$	${\circledcirc}$				+
23	Shakunage Numa	1	980			${\circledcirc}$			+
24	Raidenyama Mire	1	1,140–1,160	${\circledcirc}$	${\circ}$				+
25	Utasai Mire	15	100	${\circledcirc}$									+
26	Yubaridake Mire (Maedake Mire)	2	1,380–1,450	${\circledcirc}$						+
27	Ashibetsudake North Slope Mire	1	1100	${\circledcirc}$						+
28	Tsukigaumi Mire	41	12	${\circledcirc}$		${\circ}$							+
29	Miyajima Numa	36	13			${\circledcirc}$					+
30	Bibai Mire	38	17	${\circledcirc}$									+
31	Ishikari River Oxbow Lakes	85	9–30			${\circledcirc}$							+
32	Uryu Numa Mire (incl. Etaibetsu & Toppu Mire)	176	750–990	${\circledcirc}$					+		+
33	Shumarinai Mire	10	280	${\circ}$		${\circledcirc}$				+
34	Horokanai Mire	3	700	${\circledcirc}$									+
35	Ukishima Mire	21	865–870	${\circledcirc}$							+
36	Kumoigahara Mire	1	1,060–1,070	${\circledcirc}$				+
37	Numanotaira Mire	45	1,270–1,560	${\circledcirc}$				+			+
38	Numanohara Mire	52	1,430–1,440	${\circledcirc}$				+			+
39	Tenningahara Mire	3	1,200–1,310	${\circledcirc}$				+			+
40	Tenninkyo Hyotan Numa	2	930	${\circledcirc}$		${\circ}$		+			+
41	Ichogahara Mire	232	1,400–1,750	${\circledcirc}$				+			+
42	Matsuyama Mire	18	790–805	${\circledcirc}$							+	+
43	Genshigahara Mire	115	1,000–1,300	${\circledcirc}$				+			+
44	Kanaura Mire	6	5–7	${\circ}$	${\circledcirc}$								+
45	Kutonbetsuyama Mire	5	650	${\circledcirc}$									+
46	Riparian Mire of Lower Teshio River	20	0–5			${\circledcirc}$							+
47	Kabuto Numa	247	5			${\circledcirc}$							+
48	Sarobetsu Mire	6,658	0–7	${\circledcirc}$	${\circ}$	${\circ}$		+			+
49	Naganuma Lakes	326	8–15			${\circledcirc}$		+			+
50	Nakaminenotaira Mire	12	400–490	${\circledcirc}$									+
51	Numaura Mire	29	5			${\circledcirc}$		+			+
52	Minamihama Mire	6	0–10	${\circledcirc}$							+
53	Lake Kushu	63	5			${\circledcirc}$		+			+
54	Koitoi Onuma	255	4			${\circledcirc}$					+
55	Meguma Numa	197	1–3	${\circ}$		${\circledcirc}$					+
56	Sarukotsu Numa	121	3	${\circ}$		${\circledcirc}$							+
57	Kimoma Numa	33	5			${\circledcirc}$					+
58	Kamuito Numa	131	5			${\circledcirc}$				+
59	Sarufutsu River Mire	1,295	2–20	${\circ}$	${\circ}$	${\circledcirc}$							+
60	Hisago Numa	43	5			${\circledcirc}$				+
61	Mokeuni Numa	375	5	${\circ}$		${\circledcirc}$				+	+
62	Asajino Mire	9	5	${\circledcirc}$						+	+
63	Mokeuni Numa Higashi Mire	24	5			${\circledcirc}$				+
64	Poro Numa (incl. Karibetsu River Mire)	430	0–3	${\circ}$		${\circledcirc}$					+
65	Lake Kutcharo	687	1–2			${\circledcirc}$				+	+
66	Pon Numa	30	5			${\circledcirc}$				+	+
67	Riparian Mire of Lower Kitamihorobetsu River	18	0–5			${\circledcirc}$							+
68	Piyashiri Mire	10	920–930	${\circledcirc}$							+	+
69	Onishi Numa Mire	47	0–10			${\circledcirc}$					+
70	Omushari Numa	40	0–20			${\circledcirc}$							+
71	Komuke Numa	727	0–3			${\circledcirc}$					+
72	Yasoshi Numa	44	0–3			${\circledcirc}$					+
73	Lake Shibunotsunai	339	0–3			${\circledcirc}$							+
74	Lake Saroma	613	0–3			${\circ}$	${\circledcirc}$		+		+
75	Pon Numa (Yubetsu Pon Numa)	12	1–2			${\circledcirc}$							+
76	Lake Notoro	941	0–1				${\circledcirc}$		+		+
77	Lake Mokoto	47	1–2			${\circledcirc}$			+
78	Lake Abashiri (Memanbetsu Mire)	123	1–2			${\circledcirc}$			+		+
79	Lake Tofutsu	118	1			${\circledcirc}$			+		+
80	Nikuru Numa	10	3			${\circledcirc}$					+
81	Totsuru Numa	64	5			${\circledcirc}$			+
82	Gattanko Mire (Ikushina Coastal Mire)	2	1			${\circledcirc}$					+
83	Lake Utonai	605	0–10			${\circledcirc}$					+
84	Bibi Mire	169	0–10			${\circledcirc}$							+
85	Yufutsu River Mire (incl. Tokisatamappu, Otarumappu)	355	0–10			${\circledcirc}$							+
86	Kashiwabara Higashi Marsh	20	6–7		${\circledcirc}$	${\circ}$							+
87	Benten Numa	34	2			${\circledcirc}$							+
88	Yufutsu Mire	284	0–10			${\circledcirc}$							+
89	Horohoro Mire	15	840–850	${\circledcirc}$				+
90	Lake Poroto Mire	10	0–10			${\circledcirc}$					+
91	Yokosuto Mire	14	0–10		${\circ}$	${\circledcirc}$							+
92	Matsuno Numa	11	0–10			${\circledcirc}$							+
93	Hiraki Numa Lakes	28	0–10			${\circledcirc}$							+
94	Hyakuninhama Mire	56	10		${\circ}$	${\circledcirc}$			+
95	Meakan Onsen Mire	7	630–900	${\circ}$	${\circledcirc}$			+
96	Onneto Mire & Nishiki Numa	29	640–690			${\circledcirc}$		+			+
97	Kamirawan Mire	4	500–520			${\circledcirc}$		+
98	Lake Shinonome	3	810			${\circledcirc}$		+			+
99	Shimohorokametokkuyama Mire	28	865–1,290	${\circledcirc}$	${\circ}$			+
100	Tomuraushi South Slope Mire	38	1,140–1,280	${\circledcirc}$	${\circ}$			+
101	Sarabetsu Mire	3	165		${\circledcirc}$								+
102	River Mouse Mire of Tokachi River	805	0–10			${\circledcirc}$					+
103	Yoshino Mire	234	0–10			${\circledcirc}$							+
104	Lake Chobushi	154	0–5			${\circledcirc}$							+
105	Toyokoro Mire	33	0–10			${\circledcirc}$							+
106	Yudo Numa	235	0–5			${\circledcirc}$					+
107	Toberi Mire	224	0–5		${\circ}$	${\circledcirc}$							+
108	Horokayanto Numa	11	0–5			${\circledcirc}$					+
109	Oikamanai Numa	326	0–10			${\circledcirc}$							+
110	Kimonto Numa	232	10–20	${\circ}$	${\circ}$	${\circledcirc}$					+
111	Koitoi Numa	73	0–10			${\circledcirc}$							+
112	Pashukuru Numa	358	0–10			${\circledcirc}$					+
113	Chokubetsu Mire (Kinashibetsu Mire)	115	0–10			${\circledcirc}$							+
114	Hyotan Numa	4	430–450			${\circledcirc}$		+			+
115	Yukawa Mire	20	120–130	${\circledcirc}$		${\circ}$		+
116	Kushiro Mire	17,675	0–20	${\circ}$	${\circ}$	${\circledcirc}$		+			+
do.	Takkobu Numa	106	0–20			${\circledcirc}$		+			+
do.	Lake Toro	691	0–20			${\circledcirc}$		+			+
do.	Lake Shirarutoro	820	0–20			${\circledcirc}$		+			+
117	Bekanbeushi Mire	8,320	0–30	${\circ}$		${\circledcirc}$	${\circ}$			+	+
118	Lake Akkeshi	957	0–10			${\circ}$	${\circledcirc}$			+	+
119	Kiritappu Mire	2,909	0–10	${\circ}$	${\circledcirc}$	${\circ}$				+	+
120	Hichirippu Numa	257	0–10			${\circledcirc}$				+	+
121	Mochirippu Numa	183	0–10			${\circledcirc}$				+	+
122	Poroto Mire	184	0–10			${\circledcirc}$							+
123	Esato Numa	8	0–10			${\circledcirc}$							+
124	Mire Complex of Nemuro Peninsula	154	0–20	${\circ}$	${\circ}$	${\circledcirc}$							+
125	Horonitai & Fureshima Mire	121	0–10			${\circledcirc}$							+
126	Cape Ochiishi Mire	61	40–50	${\circledcirc}$								+
127	Ochiishi Mire	63	40–50	${\circledcirc}$									+
128	Ochiishi Nishi Mire	39	60–65	${\circledcirc}$									+
129	Yururi Island Mire	53	30–40	${\circ}$	${\circledcirc}$						+	+
130	Onne To	197	0–10			${\circledcirc}$	${\circ}$			+	+
131	Lake Choboshi	12	0–10			${\circledcirc}$				+	+
132	Tanne To, Onne To, Nanbu Numa	174	0–40			${\circledcirc}$					+
133	Shunkunitai	242	0–10	${\circ}$		${\circ}$	${\circledcirc}$			+	+
134	Tobai River Mire	79	0–10			${\circledcirc}$	${\circ}$			+	+
135	Bettoga River Mire	155	0–10			${\circledcirc}$	${\circ}$			+	+
136	Attoko River Mire	230	0–10			${\circledcirc}$	${\circ}$			+	+
137	Yarimukashi Mire	105	0–10			${\circledcirc}$	${\circ}$			+	+
138	Furen Mire	2,314	0–10			${\circledcirc}$	${\circ}$			+	+
139	Yaushubetsu River Mire	339	0–10			${\circledcirc}$	${\circ}$			+
140	Hashirikotan Mire	512	0–10			${\circledcirc}$	${\circ}$			+	+
141	Kanekin To & Nishibetsu Konuma	669	0–10			${\circledcirc}$							+
142	Barasan To	453	0–10	${\circ}$		${\circledcirc}$					+
143	Nishibetsu River Mire	20	30–40		${\circledcirc}$								+
144	Tokotan River Mire	82	0–10			${\circledcirc}$							+
145	Shunbetsu River Mire	150	0–10			${\circledcirc}$				+	+
146	Notsuke Peninsula Mire	621	0–10			${\circledcirc}$	${\circ}$			+
147	Tohoro River Mire	591	0–20			${\circledcirc}$	${\circ}$			+
148	Shibetsu Mire	371	0–10	${\circledcirc}$	${\circ}$						+
149	Lake Rausu	21	700–800	${\circledcirc}$				+			+
150	Futatsu Ike	1	1,320–1,330	${\circledcirc}$				+			+

1. ${\circledcirc}$: Two concentric circles indicate the dominant wetland type for each wetland; ${\circ}$: Single circles indicate the nonnegligible wetland type in each wetland