Xochimilco is a 700-year-old commons governance system that is failing in real time — not because people stopped caring, but because there is no layer that can tell the difference between a budget decision and a living result. That gap is what this node addresses.
Xochimilco — "place of the flowers" in Nahuatl — is the last surviving fragment of the vast lake system that once surrounded the Aztec capital. The chinampas, human-made agricultural islands built by layering mud, plants, and branches on shallow lake beds, have been farmed continuously since the fourteenth century. They are a UNESCO World Heritage Site, a Ramsar wetland of international importance, and an FAO-recognised Site of Agricultural Importance.
They are also collapsing.
Of 20,922 documented chinampas, only 17% were still being actively cultivated as of the last systematic survey. The rest have been converted to sports fields, restaurants, party venues, or simply abandoned. The canals are fed by treated wastewater from four treatment plants — a consequence of the natural springs being overdrawn decades ago to supply the city. Invasive carp and tilapia, introduced by the government in the 1970s, have destroyed habitat and preyed on native species at every life stage.
The axolotl (Ambystoma mexicanum) is endemic to Lake Xochimilco. It exists nowhere else on Earth in the wild. In 1998, there were approximately 6,000 individuals per square kilometre. By 2014, there were 36. Current estimates: between 50 and 1,000 remain in the wild.
The axolotl is not just a charismatic species — it is a precision indicator of water quality, habitat health, and ecosystem function. It retains its larval form throughout life, making it extraordinarily sensitive to changes in temperature, salinity, and pollution. When the axolotl disappears, the system it inhabited has already been failing for years. It is, in the language of the PG Ledger, the ultimate succession signal.
If we can restore the axolotl's population and habitat in a city of more than 20 million people, I feel that we have hope for humanity. — Luis Zambrano, UNAM ecologist, lead researcher on axolotl conservation
The conservation work that is actually working is not technological. UNAM researchers and local chinamperos have built 21 chinampa-refuges — protected canal sections with biofilters made from wood, gravel, and native plants. Water quality has improved, invasive species have declined, crop yields have increased, and native fish have returned. The axolotl is still present, detected by environmental DNA even in areas where direct observation failed. Captive-bred individuals released into restored chinampas in 2025 survived, foraged, and gained weight.
The lesson is precise: when stewardship governance is restored at the pixel scale — when a named person holds a named piece of water and documents what lives there — the system begins to recover. This is what Spiralweb calls an active node.
Arturo holds a PhD in Politics from the University of York and has spent his career at the intersection of citizen participation, accountability, and urban governance innovation in Mexico City. He is Co-Chair of the International Committee of the Urban Affairs Association, editor of the Journal of Urban Affairs, and Director of the Anahuac Global Research Center.
He is one of Latin America's most published researchers on participatory budgeting. Mexico City introduced PB in 2011 — one of the first major metropolitan systems in Latin America. Arturo has documented it systematically since the beginning, written the foundational chapter on Mexico City's PB in The Participatory City (2016), and led the ESRC/Newton Fund-financed ECOSCIM project on citizen-oriented smart city innovation in collaboration with the University of Bristol.
His central research finding: in most smart city and participatory governance systems, citizens are positioned as users rather than participants with genuine influence. And PB's structural weakness — there is no mechanism to monitor whether what was decided is actually working — remains unresolved.
This is where participatory budgeting and the PG Ledger meet.
The missing link in PB systems globally is not more participation at the decision stage — it is honest, steward-held, field-level documentation of what actually happens after the decision. That is what the PG Ledger provides.
In Xochimilco, this convergence is not abstract. Between 2007 and 2018, Mexico City's Community Program for Neighbourhood Improvement funded 2,127 projects benefitting nearly two million residents. Participatory processes allocated significant public resources to Xochimilco's conservation. And yet the axolotl population continued to collapse, the chinampas continued to be abandoned, and the water quality continued to deteriorate. The decisions were made. The money was spent. There was no governance layer that could document whether the biological conditions were improving or worsening at the scale of a named steward, a named chinampa, a named canal.
The Mexico City node is developing in two parallel directions that Arturo holds together.
The first is fieldwork: an orientation toward integrating PG Ledger observation into one or more of the existing chinampa-refuge projects in Xochimilco. Monthly steward observation of the eight categories — soil cover, water behaviour, succession signals, biodiversity presence, human rhythm — would produce the first systematic governance documentation of what is actually changing in these restored sites over time. The axolotl's return, or absence, becomes a verifiable succession signal in the ledger.
The second is institutional: Arturo's position in the urban governance research community gives Spiralweb a voice in the conversations where PB reform, smart city governance, and urban biodiversity policy are being shaped. The argument — that participatory budgeting needs a living-systems evidence layer to fulfil its democratic promise — is publishable, presentable, and institutionally legible in a way that field evidence alone cannot be.
Together, these two directions demonstrate something important: the PG Ledger is not only a tool for rural food forest stewards. It is a governance instrument for any commons — urban or rural, land or water — where decisions need to be held accountable to living conditions over time.
All three protocol domains are active in Xochimilco: land (chinampa restoration), water (canal quality, axolotl habitat), air (320 documented bird species including several endemic and threatened). This makes Mexico City the only current Spiralweb node where all three kernel protocol domains converge in one site.