Viikki Urban Tree Laboratorio Doc. Eero Nikinmaa, MSc Anu Riikonen

Aims of the study Improve knowledge base of urban tree management –How quickly tree recover from planting shock? what is suitable irrigation frequency? –Do the aereation tubes in soil have positive impact on street tree development? –How different surface material used on pavements impact on trees? To test the growing properties of load bearing soils –Can LBS be used to increase root growing space in northern environment (aereation, water holding capacity, heat capacity & transfer) –What soil substrate structure is optimal for aeration / water holding in street conditions –Can clay/ organic matter guarantee sufficiency of nutrients, when, how and what fertilizers are needed? To charecterise the growing environment of trees on streets –Air and soil temperature, light climate, evaporative demand

Experimental streets: Normal modern streets in Helsinki Narrow alleys Limited growing space High mechanical damage risk De-icing

Testing different technical solutions Aereation pipes Concrete and natural stones Different joint width

Load bearing soil 3 types Load bearing sceleton: (d 32-64mm) or (d mm) granite rocks % rocks and % soil + air (volumetric) Soil variation: –org. matter content (5- 20%) –variation in sand content (pF curves) –fertilized (N,P) and non- fertilized Load bearing properties passed laboratory tests

Soil nutrient analysis

Monitoring as a method By monitoring the growing conditions and the response of trees to them we gain rapidly information of the causal reasons for tree preformance in the urban environment.

Set up of monitoring 2 Streets 3 Load bearing soil types / street Alnus glutinosa & Tilia vulgaris ~5-6 trees/treatment /street 3 intensively monitored points/ street (High temporal resolution) 9 points of manual monitoring/ street (Spatial resolution) Manual measuring point Intensive monitoring Soil types Street II Street I

Monitoring -Intensive every 10 min - Manual every weeks Growing conditions Soil Profiles –Temperature –Volumetric –Gas concentrations Above ground –PAR –Air temperature Meteorological information from nearby weather station Tree Intensive –Sap flux (2 methods ) –Growth Manual –Gas exchange + fysiological measurements (Fluorosence) –Nutrients contents –Structure –Root sampling (sampling wells 4 distances from trees)

Installation of sensors

Soil Temperature Gas

Weather PAR Air Temp

Tree Sap-flux Heat dissipation Sap-flux Diam. variation

Datamanagement GSMGSM Office Street 2 Street 1

Manual measurements

Street as a growing site

Soil: Annual cycle of temperature, Sufficiency of water

Surface pavement material Concrete stone Granite”dice”

Impact of pavement on soil gas concentrations ?

Permeability to precipitation

Too much water can be a problem!

Aereation pipes are beneficial!

Soil organic matter reflects on gas concentrations!

Variation in factors influencing photosynthetic production

Differences in Photosynthetic production

Canopy conductance is linked to light and soil (example 2003)

Growth differences

Conclusions Irrigation after plantation was sufficiient Loosely positioned granite ”dices” allow air penetration, tight granite rock considerably less Aeration pipes improve situation Surplus water produced adverse conditions, draught problem not yet observed. Aereation of pores more critical than water holding capacity in the souther boreal city of Helsinki?Climate change scenarios suggest increasing storm water loads! Excees organic matter a risk factor, rapid decomposition eats O2 + soil properties change As O2 dropped below 18% (>2% CO2), tree physiology changed