AbstractPlanting trees is suggested as a measure to sequester carbon (C), but might conflict with agricultural land use. C-sequestration can act as a climate engineering measure to mitigate increasing CO2 emissions to the atmosphere. Changing grass- and cropland into nut orchards might increase C-sequestration, without encroaching on agricultural land use. Nut orchards can easily be transformed into an agroforestry system by combining nut production with another agricultural activity. Data on the impact of land use change from agriculture to agroforestry systems based on nut orchards in the temperate zone are scarce.
C-sequestration dynamics in soil organic carbon (SOC) and in the above- and belowground biomass of trees and grasses in nut orchards have been analyzed. The object of study were nut orchards, aged between 8 and 124 years old, located on a sandy soil in the temperate zone of the Netherlands. Field measurements on trees and lab results on soil data from chronosequences from grass- and cropland to stands of Corylus avellana (Hazelnut) and Juglans regia (Walnut) trees were combined with modelling future pathways of C-sequestration at the level of parcels. All results pertain the top 60 cm of the soil and include carbon stored in harvested wood. Data on belowground biomass of grasses and trees were based on allometric equations.
Total C-sequestration ranges from 0.8 to 3.4 Mg C ha-1 yr-1 (mean 1.72 Mg C ha-1 yr-1). Compared to control parcels, C-sequestration in SOC ranges from -/-0.1 to 2.2 Mg C ha-1 yr-1, in aboveground biomass from 0.3 to 1.2 Mg C ha-1 yr-1 and in belowground biomass from 0.02 to 0.4 Mg C ha-1 yr-1. Overall, these results confirm the C-sequestration potential of changing grass- and cropland into nut orchards in the temperate zone to mitigate global CO2 emissions.
|Date of Award||3 Jul 2020|
|Supervisor||Angelique Lansu (Examiner) & Stefan Dekker (Co-assessor)|