Source-sink relationship 兰兰 rve pools should be associated with Source-sink relationship Source-sink relationship A8 With in situ defoliation, pruning and debudding of treeline trees we intend to test the following hypothesis: (1) A complete removal of previous needle generations (all sources) before spring growth will lead to a massive and seasonally sustained depletion of mobile carbon compounds in all tissue. (2) Pruning of 2/3 of all needled branches (sources and sinks removed) g will have minor negative effects on the reserve pool. (3) Removal of all buds (the major sinks at the beginning of the growing season) will induce an overabundance of carbohydrates when compared to controls. (4) A depletion of reserve pools should be associated with diminished growth. Buds Current-yr. needles 2-year-old needles Stem wood Root wood May Sept July Sept May July Sept May July Sept May July Sept Defoliation experiment Sugar (control) 4.8±0.3 6.8±0.3a 3.6±0.3a 8.8±0.5 6.2±0.8 No data No data No data No data 0.4±0.3 1.3±0.4 0.9±0.1 1.3±0.4a Sugar (treated) 4.4±0.6 4.5±0.3b 1.7±0.3b 6.9±0.7 6.3±0.4 Removed Removed No data No data 0.3±0.3 1.2±0.2 0.8±0.2 0.3±0.3b Starch (control) 4.5±0.2 7.0±0.6 7.5±0.5a 6.6±0.5 14.2±0.9 No data No data No data No data 1.3±0.4 2.6±0.5 3.1±0.5 4.1±0.5a Starch (treated) 4.9±0.4 7.8±0.7 4.9±0.3b 6.6±0.6 15.3±0.7 Removed Removed No data No data 0.9±0.1 2.8±0.5 2.8±0.4 1.2±0.5b Debudding experiment Sugar (control) 1.5±0.6 6.6±0.5a No data No data 4.6±0.6 6.2±0.4 7.3±0.7 0.3±0.2 0.1±0.2 0.1±0.3 1.3±0.4 1.8±0.5 1.3±0.5 S ( d) 1 5 0 7 4 5 0 7b R d R d 5 1 0 5 6 4 0 3 7 3 0 4 0 2 0 2 0 2 0 3 0 3 0 3 1 0 0 3 2 3 0 3 1 3 0 4 Source-sink relationship Sugar (treated) 1.5±0.7 4.5±0.7b Removed Removed 5.1±0.5 6.4±0.3 7.3±0.4 0.2±0.2 0.2±0.3 0.3±0.3 1.0±0.3 2.3±0.3 1.3±0.4 Starch (control) 5.3±0.3 7.1±0.6 No data No data 15.0±0.8 15.6±0.7 4.9±0.7 1.4±0.3 1.5±0.5 1.1±0.3 4.5±1.0 3.5±0.5a 4.2±0.8 Starch (treated) 4.1±0.4 6.5±0.8 Removed Removed 15.4±0.9 17.0±0.9 5.1±0.6 1.3±0.3 1.4±0.4 1.9±0.7 4.4±0.6 6.4±0.6b 6.1±0.6 Pruning experiment Sugar (control) 3.7±0.6 5.8±0.6 5.1±0.2 9.3±0.4 6.3±0.4 6.2±0.4 8.8±0.4 0.2±0.3 0.8±0.6 0.2±0.3 0.5±0.5 1.7±0.8 1.1±0.3 Sugar (treated) 3.6±0.5 5.7±0.6 4.6±0.6 8.5±0.7 5.7±0.6 6.5±0.3 7.8±0.5 0.4±0.4 0.4±0.3 0.1±0.2 0.6±0.4 1.5±0.6 1.3±0.2 Starch (control) 4.7±0.6 5.9±0.5 9.4±0.6 7.4±0.7 15.0±0.7 19.9±0.6 6.9±0.3 2.4±0.7 1.7±0.4a 0.8±0.2 3.3±1.0 7.0±0.4 5.1±0.7a Starch (treated) 4.9±0.4 5.5±0.4 9.6±1.0 5.5±0.4 15.3±1.1 16.9±1.0 6.3±0.7 2.4±0.7 2.5±0.2b 0.7±0.2 2.7±0.8 5.4±0.9 1.5±0.3b Li MH et al. 2002. Trees 16, 331-337 15 0 20.0 25.0 30.0 ration (% d.m.) Control Defoliation Pruning Current year needles Debudding 2-yr. old needles Source-sink relationship 0.0 5.0 10.0 15.0 May July Sept. NSC concentr Control Treated Root wood * * May July Sept. needles * May July Sept. Branch wood * Li MH et al. 2002. Trees 16, 331-337 2-yr. needles 1-yr. needles Current-yr. needles Buds Defoliation Debudding * Pruning Source-sink relationship Li MH et al. 2002. Trees 16, 331-337 0.0 5.0 10.0 15.0 20.0 Root wood Stem wood Branch bark Branch wood ** * *** 0.0 5.0 10.0 15.0 20.0 0.0 5.0 10.0 15.0 20.0 Control Treated * Non-structural carbohydrates concentration (% d.m.)