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An example collection, so you can see what this page does. Nothing added here is kept: leaving deletes it.
Betula chichibuensis; photograph Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons CC BY-SAKrzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons

Betula chichibuensis H.Hara

Chichibu Birch

Betulaceae · Japan

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Betula chichibuensis, photograph Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia CommonsBetula chichibuensis, photograph Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia CommonsBetula chichibuensis, photograph Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons 4 photographs ›
Habitat figuresfrom few records
Cold floor (1 night in 100)
-13.1°C
Record low -18.1 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
24°C
Aug at the habitat CHELSA
Rain a year (median across the range)
1,773mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
16–33DLI
Lowest to highest month (DLI) CHELSA
The year in your months, northern hemisphere
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Wet summers: the rain comes May to October, read as a summer growing season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

From few records: 8 records in 7 grid cells. The records.

Summary

Betula chichibuensis, commonly known as Chichibu birch (Chichibu-Minebari in Japanese), is a species of birch native exclusively to limestone outcrops in the Okuchichibu and Kitakami Mountains of central and northeast Honshu, Japan. The tree is rated as Critically Endangered on the IUCN Red List due to its extreme rarity and limited range.

Quoted from Wikipedia, "Betula chichibuensis", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads a summer growing season: 70% of the median year's rain (1,387 mm of 1,781 mm) falls in May to October, warmer than the year (wet-season mean 16.6 °C against a yearly mean of 9.2 °C). Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: November to April.

Rain

1,781 mm in the median year at the habitat, 1,387 mm of it May to October. Wettest months (2 at 309 mm), driest month December at 36 mm. Across the grid cells of the range the year's total runs 1,566 mm to 1,922 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 1,773 mm, is the year's rain at the top of the page; the 1,781 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, northern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 16 to 33 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA; the lowest 10th-percentile month across the cells is 15, the highest 90th-percentile month 34).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -13.1 °C, the absolute minimum -18.1 °C, 6,632 frost nights in 44 years, 150.7 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 29.3 °C. Monthly means: the coldest month's mean nightly low -8.5 °C in January (across the grid cells of the range -10.6 °C to -5.6 °C), the warmest month's mean daily high 24.1 °C in August (median year across the grid cells of the range, CHELSA). Cold floor: -13.1 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).

Humidity

Relative humidity at the habitat: 56 to 70% across the year (monthly means, median year across the grid cells of the range, CHELSA). A figure about the air, saying nothing about how the plant takes water.

How this section is made

Each card states this species' habitat figures with their sources, and what two fixed rules read from them; nothing here says what the plant does, wants or tolerates. The rules · the terms.

Seasons. Read from the median year of CHELSA monthly rainfall and mean temperature across the grid cells of the range: the rain rule takes the smallest set of months carrying 70% of the rain and calls it winter when its mean is more than half a degree below the year's, summer when more than that above, and neither in between; the temperature rule, used only under 120 mm, names the cooler six months when they are at least a degree cooler than the other six. Months are shifted for the other hemisphere only where the temperature curve moves 4 °C or more and the habitat lies 10° or more from the equator. A reading of the curves, not an observation of the plant.

Rain. CHELSA monthly precipitation, median year across the grid cells of the range. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light. CHELSA shortwave radiation at each envelope cell, a daily-mean flux taken to a daily total and converted at 2.07 mol of PAR per MJ. The sky over the habitat, measured; what reaches a plant under a rock, a shrub or a shade cloth is not.

Temperature. NASA POWER daily minima and maxima over 44 years at a typical spot in the range, lapse-corrected +248 m to its elevation; CHELSA monthly means, median year across the grid cells of the range. The cold floor is the 1st-percentile night named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity. CHELSA relative humidity, median year across the grid cells of the range.

Climate across the habitat

From few records: this habitat climate is read from 8 records in 7 grid cells; a page says so under 12 records or 5 cells, and shows the figures as read.

Habitat months, northern hemisphere

Habitat climate of Betula chichibuensis through the yearWarmest month August, mean daily high 24 °C; coldest month January, mean nightly low -8.5 °C; 1,781 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA; the extremes at the edge from NASA POWER. Habitat months, northern hemisphere.-20°-10°0°10°20°30°40°frost29.3° 99th-percentile day, NASA POWER-18.1° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0100200300400mm rainDLI 16–33RH 56–70%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 7 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low extremes over 44 years at a typical spot in the range, from NASA POWER, marked at the edge, in no month DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C1 / -1–42 / 0–56 / 4–812 / 10–1517 / 15–1920 / 18–2223 / 21–2524 / 22–2720 / 18–2315 / 13–1710 / 8–125 / 3–7
Night °C-9 / -11–-6-8 / -10–-5-4 / -6–-22 / 0–58 / 6–1012 / 10–1516 / 15–1917 / 15–2014 / 12–167 / 5–101 / -1–4-4 / -6–-2
Rain mm43 / 39–5547 / 44–5789 / 82–108109 / 100–125145 / 133–157201 / 179–212232 / 201–243309 / 254–322309 / 261–323191 / 173–22670 / 62–8736 / 31–50
DLI18 / 17–1924 / 22–2529 / 26–3033 / 30–3333 / 31–3428 / 26–3029 / 27–3029 / 28–3022 / 21–2319 / 18–2017 / 16–1716 / 15–17
RH %56 / 54–5656 / 55–575859 / 58–6062 / 61–6368 / 66–6969 / 68–7069 / 68–7070 / 68–7065 / 64–666056 / 55–56
How this section is made
Each figure is the median across the 7 grid cells holding the 8 in-range records, with the 10th–90th percentile span across those cells after the slash where it differs. A dash is a month one or more of those cells has no figure for in the grid (a variable CHELSA does not carry there), so no median is taken rather than one over fewer cells. Extremes and elevation were read at a typical spot in the range, cell 1080:6376 (35.975, 138.825). Over 44 years there: absolute minimum -18.1 °C, 1st-percentile night -13.1 °C, 99th-percentile day 29.3 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Across the range: median and 10th–90th percentile of each month across the 7 distinct grid cells holding 8 of the 8 in-range records; extremes and elevation at the typical cell 1080:6376 (its coldest month's mean nightly low nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 36.00_138.750, lapse-corrected +248 m at 6.5 °C/km. Elevation: ETOPO 2022, 1080 m (cell mean).

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing: the climate was read across the cells of the in-range records placed well enough to read one, not at the marker.
Openly licensed records inside the range, framed on where they fall.
NativeJapan · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker36, 138.8 · in the densest population, 11 records (100% of those in range)
Kew's description“tree” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 11 georeferenced records inside the native range; the climate across the range on the 8 of them placed to within 10 km; the map shows only the 10 openly licensed ones, which alone would put the marker in the same place. Under a dozen records behind the map and the climate. 3 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population of the 11 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Betula chichibuensis, photograph 1did not loadBetula chichibuensis, photograph 2did not loadBetula chichibuensis, photograph 3did not load

Photographs: Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons (3).

Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.

Picea maximowiczii Picea maximowiczii Maximowicz's Spruce Photo: CC BY-SA, Inti-solWeigela maximowiczii Weigela maximowiczii Caprifoliaceae Photo: CC BY-SA, Qwert1234Silene miqueliana Silene miqueliana Caryophyllaceae Photo: CC BY, Yoshihiro TokueEnkianthus subsessilis Enkianthus subsessilis Ericaceae Photo: CC BY-SA, Qwert1234Salvia koyamae Salvia koyamae Shinano Autumn Sage Photo: CC BY-SA, peganum from Henfield, EnglandRhododendron wadanum Rhododendron wadanum Ericaceae Photo: CC BY, Marco Mussita

Other Betula 47 in the reference

Betula alleghaniensis Betula alleghaniensis Yellow birch Photo: CC BY, naturalist charlieBetula alnoides Betula alnoides Indian birch Photo: CC BY, Ramnarayan KBetula × aurata Betula × aurata Betulaceae Photo: CC0, Stephen James McWilliam Betula bomiensis Betulaceae Betula × caerulea Betula × caerulea Blue birch Photo: CC0, author not stated Betula calcicola Betulaceae Betula celtiberica Betula celtiberica Betulaceae Photo: CC BY, Jose CastroBetula chinensis Betula chinensis China birch Photo: CC0, author not statedBetula cordifolia Betula cordifolia Mountain paper birch Photo: CC BY, Tyler Ekholm Betula corylifolia Hazel-leaf Birch Betula costata Betula costata Korean birch Photo: CC BY, Jane CharlenBetula davurica Betula davurica Black birch Photo: CC BY, Tatyana Petrenko all 48 ›

Names & registers

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Betulaceae
Described by
H.Hara
Native to
Japan
Wild records
11 in range · 10 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-21
GBIF species record gbif.species answeredasked 2026-10-21
GBIF synonyms gbif.synonyms answeredasked 2026-10-21
GBIF common names gbif.vernacular answeredasked 2026-10-21names fetched 2026-10-21
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21
Habitat climate climate answeredasked 2026-10-21
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-21NASA POWER (MERRA-2) daily 1981–2024, cell 36.00_138.750, lapse-corrected +248 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-21
Wikipedia wikipedia answeredasked 2026-10-21
iNaturalist photographs, wild inat.photos.wild nothing to reportasked 2026-10-22from iNaturalist's open data of 2026-09-27: research-grade observations with an open-licence photograph, the 24 whose photographs iNaturalist received last (the open data holds no votes); filled 2026-10-22
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media nothing to reportasked 2026-10-21
Wikimedia Commons commons answeredasked 2026-10-21
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 5 datasets via GBIF.org; each carries its own licence.

Cultifolio

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