Climate impacts of retention forestry in a Swedish boreal pine forest

Figures & data

Table 1. Characteristics of the forest stands, including volumes and carbon content of the forest before and after harvest, productive machine hours (as a sum of harvester and forwarder) and emissions of CO₂, CH₄ and N₂O from harvest operations. Retention category refers to the % of trees left in the stand after harvest. Volumes refer to stem under bark. Total C include carbon stocks in vegetation (below and above ground) and soil.

Stand name	Retention category	Volume before harvestm^3/ha	Total C before harvesttonC/ha	Volume retainedm^3/ha	Trees retainedN/ha	Wood harvestedtonC/ha	Productive machine hourshr/ha	CO2kg/ha	CH4kg/ha	N2Okg/ha
TM-3	Very low	110	77	3	5	21	9.20	736	11.1	28.2
ETO-3	Very low	133	83	6	20	6	10.7	227	3.41	8.71
DS-3	Very low	40	64	4	12	25	2.84	859	12.9	33.0
TM-10	Low	86	74	11	29	15	6.24	499	7.50	19.1
ETV-10	Low	74	72	9	23	12	5.19	415	6.24	15.9
KS-10	Low	142	87	11	32	25	10.8	867	13.0	33.2
ETV-30	Medium	71	72	17	41	9	4.81	384	5.78	14.7
ETO-30	Medium	81	76	19	67	11	6.37	509	7.65	19.5
DS-30	Medium	135	87	18	65	22	12.1	964	14.5	37.0
ETO-50	High	99	83	33	92	11	5.83	485	7.29	18.6
EFF-50	High	97	82	31	110	11	6.07	466	7.01	17.9
KS-50	High	102	91	43	165	11	6.22	498	7.48	19.1

Figure 1. Radiative forcing following forest harvest across different tree retention levels. Results include contributions to radiative forcing from carbon fluxes and albedo dynamics and aggregate the outcomes of the individual 12 forest stands of the experiment into retention category very low (a), low (b), medium (mid) (c) and high (d). For each forest stand, three buffer zone simulations are considered for modelling post-harvest dynamics, representative of tree growth competition with radius equal to 0 m (Buffer 0), 4 m (Buffer 1), and 6 m (Buffer 2). The average of these simulations in the same retention category are shown with solid lines, and the coloured areas indicate the minimum and maximum values.

Figure 2. Net radiative forcing results after combinations of contributions from CO₂ fluxes and surface albedo changes. (a) comparison of net impacts for the average results in the four retention categories; (b) comparison of net radiative forcing in relative terms, using the results of the very low retention category as a benchmark.

Figure 3. Relationships between radiative forcing per hectare at 10 (a) and 100 years (b) after harvest and key characteristics of the forest stands, such as number of trees retained and fraction of m³ retained. Results (Buffer 1 only) show the net effects and the single contributions from carbon and albedo.

Figure 4. Radiative forcing per ha normalized to the unit of wood harvested (expressed as tons of carbon, tC) 10 years after harvest (Buffer 1 only). (a) normalized contributions from carbon and albedo and net results for the individual forest stands; (b) normalized net radiative forcing as a function of number of trees retained.

Figure 5. Radiative forcing impacts for each of the individual forest stands of GHG emissions from harvest operations (a) and as a function of the corresponding amount of wood harvested (b).