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The state of Open Data in Germany — Tree Register Data

Jan Degener
14 min readNov 18, 2022

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[German Version] Germany does not exactly have a reputation of being a thoroughly digitized society. Neither nationally nor internationally. There is some thing living within the soul of a German civil servant that makes it unexpectedly hard to make things — financed by the general public — directly available to that same general public.

Others have been doing it better for a long time. I remember an assignment in my studies in the late 2000s — a paper about the fresh water system of a big city. The specific city did not matter. Starting with the obligatory home bias, I quickly realized: there are hardly any sources on how Munich, Hamburg or Düsseldorf ensure their water supply. A few meaningless and very generic websites here and there. But concrete information or even live data?! Not in my backyard, fella!¹

The first English google search on “urban water supply data” brought up a long list of US cities. New York. Boston. San Diego. All with live data on flow rates, reservoir levels, maps, info, documentation, etc. that I, as a German living a few thousand miles away, could easily download and use. And we are not even talking about expensive or exclusive data like Landsat here— one of the longest continuous earth observation missions, paid by US taxpayers, and made freely available to me as an EU citizen for 20 years now.

But as soon as I am interested in data that I have paid for with my tax money, I almost feel bad to ask my own authorities if I could possibly maybe am allowed to borrow some little slice of that data. Please good sir, give me some data. Well, I said almost.

Since the topic is hardly present in the public, I thought it could not harm to write up on a few examples and anecdotes to the current state. Specifically on the topic of tree registers: where are the trees in the city, how old are they, what species do they belong to, etc.? Data that can be provided easily (if its available).

Many administrations are also making an effort. In many cases, the topic of Open Data is probably an additional task and often has to be done with inadequate equipment in addition to other tasks — and often in my experience, help was indeed provided quickly and without complications.

However, some administrations seem to have an easier time with the topic than others!

Current Open Data Situation in Germany

The site FragDenStaat.de (roughly translated to AskTheState), operated by the Open Knowledge Foundation, is in my opinion the best place in Germany to get information on this topic. Most information in this paragraph comes from here as well.

In general Germany has a Freedom of Information Act:

The Freedom of Information Act (IFG) was introduced at the federal level in Germany on January 1, 2006. It regulates access to government documents and files in a new way. Since then, public authorities have been required to release information upon request, thus de facto abolishing “official secrecy.” For example, minutes of internal deliberations and internal e-mails must be made public upon request. You can find more examples in our “Request Ideas” section. Since the federal Freedom of Information Act does not apply to state and local authorities, all federal states regulate the information laws themselves within their sphere of influence. In the process, a confusing “three-class society” has established itself over the last few years: Länder without IFG, Länder with IFG and Länder with transparency law. [source]

In my opinion, this three-tier society is actually a major problem in Germany. While Berlin or Schleswig-Holstein publish practically everything, in Bavaria or Lower Saxony you have to rely on the discretion of the respective authorities. The map from transparenzranking.de illustrates the patchwork quite well:

Degree of information transparency, https://transparenzranking.de/

Since some of the state governments have not enacted their own freedom of information laws, some municipalities have started to enact their own statutes. However, implementation is not always without problems, as the example of Nuremberg shows:

§ 1 Scope of application

(1) Every resident of the city shall be entitled to free access to official information held by the city administration, including the municipal undertakings, in accordance with the provisions of these Statutes.

If you are not a resident of the city, you have no right to the data! Which you can perhaps understand in a first reflex. But then: do I get upset every time someone from Hamburg uses my residential street to make a U-turn? How often does that happen, once in 3 years? The rest of the time the road is only used by residents. Similarly with data: I strongly believe that 99% of all requests for local data are made by local people and businesses either way. The last percentage point is at worst statistically insignificant and at best someone who actually does something useful with the data. Whereas in an ideal world, requests don’t even have to be made, since all data is freely available online.

And beyond that, Nuremberg is a good example for another point:

Metropolitan Region of Nuremberg (Google Maps)

If a non-native can locate the border between Fürth and Nuremberg, two distinct municipalities, here: respect. Do topics from the larger city of Nuremberg possibly affect the neighboring city? Topics like council resolutions? Traffic volume? Cloverleaf density at the Valznerweiher? I actually do think so! So why lock them out of requesting such data?

In my opinion, Open Data should be just that: Open. I guess many people don’t see the benefit in it yet. Code For Germany [https://www.codefor.de/] is leading the way with many good ideas and I hope that this will increase in the future. But as so often: without Data no applications, without applications no obvious need for Data!

Urbane tree registers in Germany

An estimated 20% of the adult population in Germany suffers from at least one allergy. A large part of the pollen allergy sufferers under birch pollen. Since I am one of the lucky ones, I wanted to have a deeper look for myself to find out, for example, where I could ideally move to in order to escape the pollen in the spring. Are other cities any better? Could I move in my own city to get farther away? Are there hotspots or are they distributed equally? I actually did not know an had never seen any information on the topic.

The original idea was therefore to find out where my nearest pollen friends reside at my current and potentially next place of residence, but also at my past places of residence — mainly to have a general reference from past experiences. The quite interesting analysis with all the data described below can be found here.

Initial birch mapping from 2021 with Open Data from tree registral data. A deep dive to the new evaluation of 2022/11 can be found here

This was further followed by the question of how this looks like for other German cities. So the plan was, build it once, download data from other cities, plug & play the analysis part and everything is peachy. Can’t be that hard, can it?

The actual planned steps were: first find and collect all the data that is freely available and then request the missing data from the authorities. At least from the larger cities in Germany. So here comes the tale of what happened:

Open TreeData “Good Guys”

These are the cities and municipalities that follow the ideal route: making their data freely and easily available online. And not only as flat maps, but actually downloadable raw data!

Since this is only tree register data, a governments performance here is of course not a complete assessment of their entire open data strategy. But in my experience: it is a good indicator.

The list was compiled until 2022/11 and will probably be incomplete. Rough orientation were the top 50 largest cities in Germany, as well as cities that were found by chance during the search for tree registers (except for Vienna and Zurich, no cities outside Germany were checked). Especially smaller municipalities or data provided via private or public associations I probably missed.

Open BaumData “Good Effort Guys”

In addition, there are cities that provide their data… but in a form with which one can either not really work locally, or provide it with unnecessary hurdles:

  • Braunschweig has a nice map on which you can view the tree register and filter by certain tree types, but a download of the data is not possible. According to the metadata, there is an access restriction due to copyright. An Open Data request could of course be successful.
  • Karlsruhe has a tree register and also offers the data for download as geojson. However, only individually for each district. The URL query behind it can possibly be adjusted so that everything is still pulled, but this is not what I would call optimal:
    https://geoportal.karlsruhe.de/server/rest/services/Fachplaene/Baumkataster/MapServer/1/query?where=STADTTEIL='Innenstadt-West'&outFields=ARTDEUT,ARTLAT,BAUMART_ALLGEMEIN,BAUMGRUPPE,AUFNAHMEART,GENUTZT,ZUORDNUNG,STADTTEIL,X_KOORD_UTM,Y_KOORD_UTM&returnGeometry=true&f=geojson
  • The GeoPortal Niederrhein contains tree data for Krefeld (see above) as well as data of some smaller places (like Schwalmtal). Unfortunately, officially only in the form of a map or WMS layers and without the possibility to download them directly. Unofficially however, you can find a WFS server that provides the tree data for Issum, Schwalmtal, Viersen and Xanten: https://geoservices.krzn.de/security-proxy/services/wfs_verb_baum
  • The Geoportal-mv.de contains some entries for tree cadastres of smaller communities (Treptower Tollensewinkel, Rostocker Heide, Zingst…), which can also be opened as WFS. However a test with Treptower data returned only tree coordinates without further information like the tree species. However, the official WFS service of the Vorpommern-Rügen district can also be found via the page, whose data includes species designations, but only contains trees for selected streets.
  • The GeoPortal Niederrhein also contains tree data for the district of Wesel, some of which also includes trees in the urban area of Wesel itself. The data provided by the city of Wesel, however, does not contain this data, probably because the area is run by the district. Oh small municipality jurisdiction hell.
Tree data from the Open Data Portal of the city of Wesel (pink-ish) does not cover all trees in the city area. Green dots are from the Geoportal Niederrhein and appear to be from the district of Wesel.

Open Data Anfragen (FragDenStaat.de)

For some cities that do not make data openly available, an Open Data request was eventually made via FragDenStaat.de. The great thing about the site is that you are given a most formulations and laws as possibly needed and at the same time all the answers of the administrations are published for everyone to see or download. So in the end hopefully everyone can benefit from the data :)

In the following you will find all requests made with their respective links (also some requests that were made by other people and are marked accordingly) how long it took until the first or final answer and what the outcome was:

  • Augsburg [5 days until first/final answer] Information refused, will only be issued to persons living in Augsburg
  • Bochum [by third party. 11 days to first, 18 days to final response] Data finally shared as a json file after referring to the webapp
  • Bremen [30 days to first/final answer] Data was provided directly as a shapefile. The answer included other useful information as well
  • Dortmund [Inquiry of 2022-07–15 unanswered so far] Does have a tree register, but only as a WMS map service
  • Duisburg I und II [First inquiry answered after 3 days. Second inquiry since 02.05.2022 unanswered] The first inquiry went to the city’s business enterprises. Here came promptly the info one should turn directly to the environmental office. Since May, including inquiries in June and October, no response from the Duisburg Environmental Office
  • Dresden [Initial request answered after 9 days] Answer included a reference to the city’s Open Data Portal. The entry can be found under the term “city trees”. Woops, my bad. I think I had not searched that specific phrase, but it doesn’t show up when only searching “tree”
  • Düsseldorf [6 days to first/final answer] Data was provided immediately as *.xlsx file and inquiries were answered directly in a friendly manner
  • Erlangen [42 days to initial response, 48 days to final response] Initial request was overlooked, but was answered directly upon request. Data should have been chargeable at first, but after the request had landed with the responsible person, they were provided directly free of charge as *.gpkg
  • Essen [29 days to first/final answer] Request was rejected. The rejection was a 4-page PDF that was also sent to me again through physical mail. The exact legal reasons why the data cannot be made available were broken down. In summary, the city of Essen seems to be still in the process of preparing the data or to make them available in the future via a web portal and therefore cannot share them as of now
  • Freiburg [21 days until first/final answer] Data was sent uncomplicated as *.xlsx file
  • Fürth (BY) [Inquiry from 2022–04–29 so far unanswered] also on a reminder on 2022–07–01 so far no answer
  • Göttingen [29–30 days to first/final response] Request denied because submitting data is a “significant effort” that could not be accomplished due to the current workload
  • Hannover [Inquiry of 2022–29–10 unanswered so far]
  • Ingolstadt [by third party. 32 days to first, 65 days to final response] From the successful request of 2021 it appears that only about 1/3 of the tree data is available in the sent register. Possibly a new request would be useful here at the beginning of 2023
  • Kiel [by third party. 2 days until first/final answer] The request could not be fulfilled, quote:
    “Since the data are stored in a special program, it is not possible to pass them on for you to read. However, during office hours you have the possibility to inspect the tree register in the green space office. If you are interested in this and have a specific question about Kiel’s trees, please make an appointment.”
  • München [by third party. 32 days to first/final response] Request denied on the grounds:
    “The building department does not maintain a tree register. Therefore, we are unfortunately unable to provide you with a systematic record of trees in public green spaces with coordinates and species of each tree.”
  • Nürnberg [4 days to first, 19 days to final response] Request was denied. A digital city map with the information is probably planned for 2023. No information whether the data can also be downloaded
  • Stuttgart [169 days to first/final reply] initially no reply even to a reminder after 103 days. Data were finally provided as shapefiles without further requests/reminders
  • Würzburg [4 days to first, 65 days to last response] the request is still open. After some back and forth, the request finally landed with the person responsible. Since it was probably the first request of this kind, “the procedure first had to be clarified internally with other responsible departments of the city administration”. The procedure was completed and the geodata department was asked to provide the data. Since then, despite further requests on 2022–08–11 and 2022–10–14, there has been no update or data.

In short: out of 19 requests, 8 were successful, 5 were rejected, 5 remained without a response, and Germany’s third largest and certainly richest major city has no tree register at all.

Other Cities

Other larger cities such as Aachen, Hamm, Heidelberg, Leverkusen, Lübeck, Ludwigshafen, Mannheim, Mönchengladbach, Mühlheim a.d. Ruhr, Oldenburg, Osnabrück, Saarbrücken, Tübingen or Wiesbaden have not made any data available online at first glance, but have at least been checked by me. Some of them also have dedicated contact persons for the topic of tree register, so inquiries on those may well be worthwhile.

Erfurt has just committed to building a publicly viewable tree register in the next 2 years in September 2022. The city of Oberhausen, on the other hand, seems to have been building a register since 2012, but is not yet finished or does not make any data available online.

In Wuppertal, the publication of the data seems to have been rejected so far, at least a discussion post on the city’s Open Data Portal indicates this.

In Potsdam, on the other hand, BUND demanded at the end of 2021 that a tree register finally be drawn up.

Conclusion

So, where do we stand in Germany when it comes to Open Data —or at least when it comes to tree registers?

Well, there is a patchwork of different opinions out there about what Open Data is, how and if the data is made available, in which format it is available, and when or if it will ever be updated. And even if the data was made available, it varied considerably in coordinate system, granularity, format etc.

Surprisingly, not all of the major cities have a tree register either, or are in the process of building one. Even more, the size of the city hardly seems to matter.

While cities like Munich stand absolutely empty, smaller cities like Rostock or even Wesel make everything available at the click of a button. And even the smallest of communities such as Issum: joined together with other communities in the Geoportal Niederrhein, they really make an effort to make all their data available to everyone, despite the fact that it is not yet optimal in its current form.

So everything is perfect, awesome and great? Well…

Of course we are not that far yet. But we are on the right track in Germany. I think many administrations are actually making an effort to get closer to the Open Data idea, and are certainly not always to blame themselves if it does not work fully. I actually did not expect to see so much data when I started out with this.

So while this has evolved into a small Bachelor thesis — which was not what I intended-it actually got me more curios what else could be done with the data we already have in Germany. We will see ;)

¹This has actually improved nowadays. Practically all municipalities now provide at least a certain basic amount of data, such as biotopes, geology/soil, water management maps, etc.

Last updated: 2022–12–01

Germany
Trees
Open Data
Data
Anecdotal Evidence

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Jan Degener

Written by Jan Degener

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