, 2013). A LI-7000 fast response
gas analyzer (LiCor, Lincoln, USA) was used to continuously measure latent heat from air samples at the eddy covariance mast from June 2010 onwards. Latent heat flux was converted into evapotranspiration using air temperature and latent heat of vaporization. Precipitation was monitored from June 2010 onwards using a tipping bucket rain gauge (model 3665R, Spectrum Technologies Inc., Planfield, USA) installed next to the eddy covariance mast. The soil water balance was calculated as the difference between the monthly cumulative precipitation minus the monthly evapotranspiration, considering positive values as water excess and leaching (Fig. 2). The samples for the present study were collected during the single-stem system of the first rotation (2010–2011) and the multi-stem Veliparib system of the second rotation (2012–2013) of Selleckchem Carfilzomib the plantation. Due to the high labor intensity with belowground analyses, this study was restricted to two genotypes with a contrasting aboveground habitus, i.e. Koster (P.
deltoides Bartr. (ex Marsh.) × P. nigra L.) and Skado (P. trichocarpa Torr & Gray (ex Hook) × P. maximowiczii Henry). Both genotypes were selected as being the most representative for the plantation based on their parentage, origin and area coverage in the plantation ( Broeckx et al., 2012). The crown structure of Koster was described by the breeder ( Buiteveld, 2007) as ‘closed, broad pyramidal crown with thin branches’. Although this description was based on low-density, single-stem trees, it was confirmed in our high-density SRWC plantation. No such breeder information was available for Skado, but from our observation we could describe this website Skado as having a deeper, more narrow crown (difference in height growth), with fewer, heavier branches. The main characteristics (less and taller shoots in Skado after coppice) still held after coppice in the multi-shoot system. The crown architecture of both genotypes was described in detail and discussed
in Broeckx et al. (2012) and Verlinden et al. (submitted September 2014). Samples were collected on both previous land-use types, i.e. cropland and pasture. Belowground woody biomass was determined by excavation of the root system and the stump immediately after each of the two harvests. In February 2012, five single-stem trees of different stem diameters (from 20 mm to 60 mm at 22 cm height above the soil) were selected from each genotype (Koster and Skado) and for each of both former land-use types (20 trees in total). In February 2014, four multi-shoot trees with a different number of shoots were selected and excavated, for genotype Koster on both former land-use types, but for genotype Skado only on the former cropland land use (16 multi-shoot trees in total). All shoots from each tree were counted and their diameter was measured at 22 cm height above the insertion point. Basal areas were calculated from tree stem and shoot diameter measurements (see further below).