Locating Birches in German Cities

12 min readNov 18, 2022

[German Version] All pollen allergy sufferers are looking forward to spring. All of them. It is absolutely the most beautiful time of the year! However, surprisingly little information can be found about where in Germany you can best avoid the birch (German “Birke”) fun… be it for living, working or vacationing.

Actually, this should have only been a short project, in which I wanted to compare my own place of residence and the places where I had lived before. In the sense of whether my personal experience corresponds with the actual data.

This turned out to be a somewhat more extensive undertaking… including a detour into the big wide world of German Open Data portals and requests. Why this was indeed very interesting and partly surprising can be read separately here. There you can also find the explanation why some cities are missing here on this page, or why exactly the cities below were selected.

TL;DR

Stay away from cemeteries!
Do NOT go to Rostock!! (at least during spring time ;)
Leipzig, Münster and Vienna on the other hand are relatively safe

Birches / km² per city. See below for details. Freiburg and Wesel are not included, as it is somewhat questionable to what extent the data are comparable.

Caveats:

Ideally, birch trees are filtered from the Latin name Betula. If no Latin names are available in the data sets, all tree names containing the word “Birke”(German for birch) are used.
It is often only “street trees” that are mapped. That is, birch trees in parks, cemeteries, and especially private gardens are not included, depending on the source. Since the overall data quality varies and often could not be independently verified, the figures below should be taken as a rough guide rather than an absolute truth.
Furthermore, trees in urban forests are not included. To mark these areas as potential birch sites, they are shaded red in the maps (Berlin is an exception, because better data exists).
The birch trees / km² always refer to the hexagons (each approx. 0.3 km²), which were more or less arbitrarily placed over the respective cities, so selectively higher concentrations may exist than indicated.

Berlin

Berlin (even provides data on forest composition dating from 2014: all forest areas in which the birch is among the top 5 main stands are included in the map above. However, these are not included in the calculations below). Green areas are apparently included in the data (see Tiergarten), cemeteries partially. Of the 801,214 individual tree sites, 3,990 species designations are marked as Unknown or NULL in the original data
Ø 36.2 birches / km² (32,298 birches / 892 km²)¹
Highest concentration¹: Parkfriedhof Marzahn ~1920 birches / km²
Hypothetical number of birches in cemeteries²: 2,120, equivalent to 34,418 birches (or 38.6 birches / km²)
Only built-up area³: 530 km² ≙ 64.9 birches / km²

Bielefeld

Mainly street trees, some green areas included (Sudbrack clay pit). No cemeteries included. Of the 88,072 tree locations, approx. 80 are NULL, post-capture or forest-like stands
Ø 14.6 birches / km² (3,788 birches / 259 km²)¹
Highest concentration¹: Hasselbachaue along Gasselstr. ~279 birches / km².
Hypothetical number of birches in cemeteries²: 792 equivalent to 4,580 birches (or 17.7 birches / km²)
Only built-up area³: 98 km² ≙ 46.7 birches / km²

Bochum

Includes street, plant, and cemetery trees. Of the 62,677 individual sites, 2,142 tree genera are identified as ZERO, tree, tree clump, tree stand area or forest-like stand
Ø 35.4 birches / km² (5,126 birches / 145 km²)
Highest concentration: Langendreer cemetery ~321 birches / km²
Built-up area only³: 96 km² ≙ 53.4 birches / km²

Bonn

Cemeteries and green spaces included in the data. Approx. 110 of 65,200 tree sites as NULL in the data set
Ø 15.5 birches / km² (2,201 birches / 142 km²).
Highest concentration: central cemetery ~417 birches / km².
Built-up area only³: 70 km² ≙ 31.4 birches / km²

Bremen

Added 2022–12–01. Contains street, plant and cemetery trees. Quote from the Umweltbetrieb Bremen: “The trees in the dataset are exclusively the digitized tree population of urban areas that are in our maintenance. For areas which are not in our maintenance, such as nature reserves, we have no data.”
Only 30 of 230,760 individual sites are listed as unknown in the data set.
Ø 25.6 birches / km² (8,136 birches / 318 km²)
Highest concentration¹: north of Atlantic Hotel Universum ~ 988 birches / km².
Built-up area only³: 166 km² ≙ 49.0 birches / km²

Chemnitz

Street trees only, no plant or cemetery trees included. 429 of 49,999 individual sites entered as NULL, dead or different in the dataset. The number 49,999 may look like an error (export of max 50,000 or such), but an older dataset from 2021 had 49,314 entries. So the number is quite plausible
Ø 10.4 birches / km² (2,311 birches / 222 km²)¹
Highest concentration¹: Markersdorf along Volgograd Street ~ 349 birches / km²
Hypothetical number of birches in cemeteries²: 288 equivalent to 2,599 birches (or 11.7 birches / km²)
Only built-up area³: 85 km² ≙ 30.6 birches / km²

Dresden

Street trees only, no plant or cemetery trees included. 15 of 109,880 individual sites listed as “(not yet) known”, unknown conifer or deciduous tree
Ø 8.5 birches / km² (2,785 birches / 328 km²)
Highest concentration: Zschernitz along Südhöhe ~259 birches / km²
Hypothetical number of birches in cemeteries²: 500, equivalent to 3,285 birches (or 10.0 birches / km²)
Built-up area only³: 130 km² ≙ 25.2 birches / km²

Düsseldorf

Extreme concentration in the city’s cemeteries. Of the 166,688 individual sites, 6,443 are marked as Unknown or NULL
Ø 22.0 birches / km² (4,794 birch trees / 218 km²)
Highest concentration: Gerresheimer Waldfriedhof ~1017 birches / km²
Built-up area only³: 113 km² ≙ 42.4 birches / km²

Elmshorn

Includes Elmshorn and Kölln-Reisiek, as tree data are available for both parts. Street trees, some greenery and the municipal cemetery are included. Cemetery are included, but not the Protestant Cemetery. Of the 11,786 individual sites only 20 are described as unknown.
Ø 18.9 birches / km² (532 birches / 28.2 km²)
Highest concentration: Städt. Friedhof ~115 birches / km²
Hypothetical number of birches in cemeteries (only Protestant cemetery)²: 66, equivalent to 597 birches (or 21.1 birches / km²)
Only built-up area³: 15.8 km² ≙ 37.8 birches / km²

Erlangen

Includes street and plant trees (incl. cemeteries). Compared to other cities, Erlangen’s cemeteries have only a very small proportion of birch trees. Of the 22,325 individual sites, 669 of the species data are marked as Unknown or NULL
Ø 7.1 birches / km² (553 birches / 78 km²)
Highest concentration: central cemetery ~71 birches / km²
Built-up area only³: 28 km² ≙ 19.8 birches / km²

Frankfurt (Main)

Includes plants and cemetery trees in addition to street trees, with an extreme agglomeration of birch trees visible in cemeteries. Of the 158,559 individual sites, 527 are marked as unknown, forest-like stand or X
Ø 16.9 birches / km² (4,186 birch trees / 248 km²)
Highest concentration: main cemetery ~803 birches / km²
Built-up area only³: 123 km² ≙ 34.0 birches / km²

Freiburg (Breisgau)

approx. 10,800 trees (out of 43,331) are still listed as “unknown”, which means that the figures can be considered of little significance and therefore no further calculations are made. Cemetery and green space locations are included
Ø 0.78 birches / km² (121 birches / 155 km²)¹
Highest concentration¹: along Ferdinand-Weiß-Strasse ~46 birches / km²
Only built-up area³: 39 km²

Gelsenkirchen

Figures from 2017 and apparently not updated since. The sites also include cemeteries and green spaces. Of the 60,0057 individual sites, 9 sites are entered as NULL
Ø 21.7 birches / km² (2,282 birches / 105 km²).
Highest concentration: Städt. Hauptfriedhof ~376 birches / km²
Built-up area only³: 63 km² ≙ 36.2 birches / km²

Halle (Saale)

Trees in green spaces do not seem to be consistently recorded, cemeteries not at all. According to the administration’s website, “not all locations have been completely digitized yet.” In the data set 327 of 39015 entries are without tree species
Ø 7.2 birches / km² (973 birches / 135 km²)¹
Highest concentration¹: south of Pestalozzipark ~377 birches / km²
Hypothetical number of birches in cemeteries²: 392, equivalent to 1,365 birches (or 10.1 birches / km²)
Built-up area only³: 57 km² ≙ 23.9 birches / km²

Hamburg

Includes only street trees and no green spaces or cemeteries etc. 1604 of 230,620 entries are without tree species
Ø 12.7 birches / km² (9,278 birches / 731 km²)¹
Highest concentration¹: Hollkoppelweg / Am Mühlenbach ~382 birches / km²
Hypothetical number of birches in cemeteries²: 1,612, equivalent to 10,890 birches (or 14.9 birches / km²)
Built-up area only³: 370 km² ≙ 29.4 birches / km²

Karlsruhe

Street trees and cemetery trees are included in the data set. However, the species designations are missing for the cemetery trees in particular. In total, 38,878 of 131,803 individual sites are without species designation, which limits the informative value and potentially underestimates birch concentrations
Ø 8.7 birches / km² (1,509 birches / 173 km²)¹
Highest concentration¹: Frankenthaler Straße ~204 birches / km²
Only built-up area³: 67 km² ≙ 22.5 birches / km²

Köln

Contains only street trees and no green spaces. Cemeteries do not seem to be consistently recorded (e.g. Melaten cemetery included, Deutz cemetery not). 2,562 of 153,095 entries in the cadastre are listed as “unknown genus” but further information (year of planting or similar). Another 43,639 entries show a location, but all other fields are NULL
Ø 8.7 birches / km² (3,523 birches / 405 km²)¹
Highest concentration¹: Cologne Kalk along Donarstr. ~374 birches / km²
Hypothetical number of birches in cemeteries²: 824, equivalent to 4,347 birches (or 10.7 birches / km²)
Built-up area only³: 206 km² ≙ 21.1 birches / km²

Krefeld

The dataset includes 80,522 entries of which 3,234 are listed as NULL, various or fort and includes street trees, green spaces and cemetery trees.
Ø 25.4 birches / km² (3,472 birch trees / 137 km²)
Highest concentration: west of Tiergartenstraße ~337 birches / km²
Built-up area only³: 65 km² ≙ 53.4 birches / km²

Leipzig

Contains only street trees and no green spaces or cemeteries, etc. The cadastre contains a total of 60,415 entries
Ø 3.0 birches / km² (912 birches / 304 km²)¹.
Highest concentration¹: Liebertwolkwitz, along “Auf dem Colmberg” ~133 birches / km²
Hypothetical number of birches in cemeteries²: 580, equivalent to 1,492 birches (or 4.9 birches / km²)
Only built-up area³: 130 km² ≙ 11.4 birches / km²

Magdeburg

Includes only street and green space trees, but not cemetery trees. Of the 89,766 individual sites, 223 are marked as unknown, forest-like stand or NULL
Ø 5.7 birches / km² (1,150 birches / 202 km²)¹
Highest concentration¹: Alt Olvenstedt, along “Birkenallee”🤗 ~276 birches / km².
Hypothetical number of birches in cemeteries²: 548, equivalent to 1,698 birches (or 8.4 birches / km²)
Only built-up area³: 74 km² ≙ 22.9 birches / km²

Münster

Includes only street trees and no green spaces or cemeteries, etc. 518 of 43,114 entries are either labeled as NULL, unknown, or generically labeled as “group of trees”
Ø 3.6 birches / km² (1,084 birches / 301 km²)¹
Highest concentration¹: Gremmendorf, along “Gremmendorfer Weg” ~206 birches / km².
Hypothetical number of birches in cemeteries²: 240, equivalent to 1,324 birches (or 4.4 birches / km²)
Only built-up area³: 76 km² ≙ 17.4 birches / km²

Rostock

Data set contains 70,211 individual trees along roads and in green areas, incl. cemeteries. Rostock by far leads the data on birch concentrations. Probably do not come here for Kur in spring if you suffer from pollen allergies.
Ø 40.0 birches / km² (6,989 birches / 175 km²).
Highest concentration: New Cemetery South ~1,633 birches / km²
Built-up area only³: 54 km² ≙ 129.4 birches / km²

Schwalmtal

Coverage either incomplete or inconsistent. Does not include trees on green spaces or Waldniel cemetery, for example, but Amern cemetery is covered. 22 of 6,146 tree locations are shown as ZERO or shrubs.
Ø 3.3 birches / km² (161 birches / 49 km²)
Highest concentration: European School ~20 birches / km².
Hypothetical number of birches in cemeteries³: 24, equivalent to 185 birches (or 3.8 birches / km²)
Only built-up area³: 8.3 km² ≙ 22.3 birches / km²

Stuttgart

Added 2022–12–01. Includes trees on street, facility, and cemetery sites. 364 of 107,877 tree sites are identified as “N.n.” or “unknown”.
Ø 11.6 birches / km² (2,437 birches / 210 km²).
Highest concentration: northern Pragfriedhof ~258 birches / km².
Built-up area only³: 99 km² ≙ 24.6 birches / km²

Wesel (inkl. Kreis)

Trees in the district of Wesel (other data source) account for 6,945 trees, but all without information on tree species. The cadastre of the city of Wesel contains 14,380 entries, of which 462 are listed as unknown / various / empty / fruit trees / forest-like stand. Cemeteries in the city area are included in the dataset. The dataset seems a bit too sparse across the large area. The numbers are probably not very trustworthy overall.
Ø 0.2 birch trees / km² (226 birch trees / 1,130 km²)
Highest concentration: New cemetery ~117 birches / km²
Hypothetical number of birches in cemeteries²: 784, equivalent to 1,010 birches (or 0.9 birches / km²)
Built-up area only³: 156 km² ≙ 6.5 birches / km²

Wien

Contains only street trees, no cemetery data, but occasional greenery. Of the 214,243 individual sites, only 3 are listed as unknown species
Ø 6.7 birch trees / km² (2,784 birch trees / 415 km²)¹
Highest concentration¹: Southern Water Park ~315 birches / km².
Hypothetical number of birches in cemeteries²: 1,340, equivalent to 4,124 birches (or 9.9 birches / km²)
Built-up area only³: 235 km² ≙ 17.5 birches / km².

Zürich

Includes street, plant, and cemetery trees. Of the 77,026 individual sites, 121 are identified as fruit trees, deciduous trees or copses
Ø 36.0 birches / km² (3,312 birches / 92 km²).
Highest concentration: east of Bucheggplatz ~446 birches / km²
Built-up area only³: 56 km² ≙ 59.1 birches / km²

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Missing your own city?! An overview why it might be missing can be found here.

¹) Numbers are valid with restrictions, please note the resepective texts
²) With assumed 400 birches / km² on cemeteries. For Berlin and Cologne only 200 birches / km² were assumed, because here a part of the cemeteries was already available in their data.
The 400 birches / km² are an average estimate based on the cities with cemetery trees (in birches / km²): Bochum 402, Bonn 460, Düsseldorf 893, Erlangen 356, Frankfurt 769, Gelsenkirchen 345, Krefeld 369, Rostock 1,754.
³) Assumes as area reference only the built-up area according to CLC 2018. Birch number is the number corrected for cemeteries. For comparison of two cities, this number is probably most appropriate.

Sources: Tree Data, Cemeteries via OSM Overpass API, urban forest and built-up area from CLC 2018 data, level 2 boundaries from GADM and VG250 data for smaller municipalities boundaries

Last update: 2022–12–01