Effect of Thinning on Evaporation of Scots Pine Forest

Abstract

This paper presents the results of a study carried out on a Scots pine stand, aged over 70 years, growing on ICP Forests land. The stand underwent late thinning, this being the last operation performed prior to complete felling, which will take place when the trees reach an age of approximately 100 years. The thinning, which reduced the basal area by 20%, caused a decrease in LAI by approximately 30% on average and an increase in the gap fraction by almost 50%. The thinning of the tree canopy increased by more than 40% the quantity of light reaching the lower levels of the tree stand and the soil. Comparison of the results for actual evapotranspiration and tree transpiration with potential evapotranspiration (T ETP -1 , EVT ETP -1) revealed an 8% increase in tree transpiration, while the actual evapotranspiration of the ecosystem increased by 14% after thinning. This increase was partly the result of the higher tree transpiration, but another factor may have been the increased evapotranspiration of forest floor vegetation and the soil, resulting from the greater quantity of light reaching the forest floor. The ratio of the pines' transpiration to the actual evapotranspiration of the ecosystem (T EVT -1 ) was practically unchanged, from 0.60 before thinning to 0.61 after. Modelling was also carried out (based on a Plant Water model) for average meteorological conditions to determine the effect of thinning on the rate at which the trees depleted supplies of soil water. This effect was greatest in September, when plant available water was present for 9 days longer than prior to thinning. In the months with the highest levels of transpiration (from May to August) the period in which plant available water was present lengthened by 2-3 days.

Terrestrial Laser Scanning in Assessing the Effect of Different Thinning Treatments on the Competition of Scots Pine (Pinus sylvestris L.) Forests

“…[21,23]. There are some studies that have used traditional forest mensuration methods to examine the effects of thinning treatments on growth and yield [1,24,25], stand stability [21,26], adaptiveness to droughts [27][28][29], evaporation [30,31], provision of ecosystem services [32][33][34][35], carbon and nutrients [36,37], and even biodiversity [38,39] at both the tree and stand levels. However, mapping trees is a labor-intensive task, and it is a key aspect of the computation of distance-dependent CIs.…”

Selection Cuttings as a Tool to Control Water Table Level in Boreal Drained Peatland Forests

“…Stand interception evaporation has been suggested to scale almost linearly with stand density (Mazza et al, 2011), whereas transpiration responds in a nonlinear manner as light availability decreases in more dense canopies (Bréda et al, 1995;Lagergren and Lindroth, 2004;Launiainen et al, 2016). Forest floor evaporation depends on the amount of throughfall and radiation reaching the forest floor; thus, it is generally higher the more open the canopy (Boczoń et al, 2016;Launiainen et al, 2019). Last, the role of runoff depends on ditching parameters, peat properties, WTL, and rainfall amount and frequency, meaning that it is more pronounced during wet years and sites with low ET (Sarkkola et al, 2013).…”

Silvicultural Efficiency of the Thinning Efficiency of Pinus sylvestris L. Plantation in the Dry Subzone of Northern Kazakhstan Steppes

“…The plantations are established with a high planting density, which ensures rapid closure of the crowns of the trees. However, the high planting density causes the need for temporary felling of maintenance to clean up potential waste, reduce fire risk and moisture transpiration by trees (Lagergrena et al, 2008;Kazuhiko et al, 2013;Ruano et al, 2013;Gavinet et al, 2015;Boczon et al, 2016). Timofeev & Georgievski (1957) denote that for various purposes, improvement thinning can be used as a main silvicultural method of cultivation of healthy and highly productive forests.…”