Thesis subject

MSc thesis topic: The development of a KPI (key performance indicator) on tree vitality for street trees in the urban green area

Over the next 3 years, Wageningen Research will be laying the foundation for a new (KPI). The purpose of this KPI is to have a continuous understanding of the vitality of trees in the city. We want to achieve that this becomes an E-tool that gives a continuous insight (app) into the health of the tree stock in a city. Tree managers, arborists and policy makers can plan appropriate management and policies based on this.

Context
The value of green space is becoming increasingly better understood and its contribution can be called very broad. For example, trees contribute to cooling, biodiversity, health, CO2 storage, air purification and they limit water nuisance and heat stress. Consciously and unconsciously, quality greenery has a large number of positive effects on people and these effects are increasingly proven and recognized. Buffering climate change in the urban area is an important paragraph. Trees, as part of urban green space, can make an important contribution to this transition. The PBL/CBS prognosis 2019-2050 indicates that population growth in large cities will continue to be substantial. Over the next 30 years, a population growth of 1 million people is expected in the Netherlands, of which more than 50% will live in the urban environment. The quality of the urban environment therefore determines the quality of life of the majority of Dutch citizens.

Changing city climate
More and more applied urban trees have problems growing vitally. They are proving increasingly less climate resilient to the current and expected future inner-city environment. This leads, among other things, to poor growth, leaf and bark shedding, increased susceptibility to diseases and pests and, in general, to poor performance, which means that potential ecosystem services such as passive and active cooling of the air and water retention cannot be achieved. Much is demanded of the resilience of many tree species due to increasing abiotic stress factors, especially when it comes to bridging prolonged periods of drought and heat.

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To form an image of a tree's crown, satellite imagery is currently used a lot with the crown area. A better approach would be to know what the total amount of leaves is in the crown volume. This leaf biomass would be a much better indicator of the tree's vitality.

The assignment is to list the methods for remote vitality monitoring of urban trees at this time. Then to find the calculation rules how we can translate LA, LAI, crown area and crown volume to the total amount of leaves (mass) in the tree, knowing that it determines the maximum photosynthetic capacity, but also determines the retention of rainwater during downpours.

A factorial field trial is currently being prepared in Leeuwarden. In the next three years we will search there for the right factors with which we can develop a real-time measured dashboard.

Within this thesis we first aim to work on the use of terrestrial or mobile laser scanning, but we are open for other ideas.

Objectives

  • Identifying the parameters with predictive value for tree vitality
  • How to use remote sensing or LiDAR for KPI development for tree vitality

Literature

  • D.C. Stanley. (2021) Modern Urban Forestry for Modern Cities: Technology Chalanges and Oppertunities for remote sensing of urban forest. ARBORICULTURE & URBAN FORESTRY (and many more articles in this journal)

Requirements

  • The field trial will be conducted in Leeuwarden. There is also consultation with the municipal tree service man. Knowledge of the Dutch language and possession of a driving license is therefore preferred.

Theme(s): Sensing & measuring; Modelling & visualisation