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3.1.E. Carbon storage in soil and tree biomass

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GIS analysis – Vardan Asatryan (NAS RA)
Presentation of results – Elena Bukvareva (BCC-Armenia);  

The assessment of soil carbon stocks was made using data from the World Soils 250m Organic Carbon Stocks dataset. Carbon stock in tree biomass was estimated using the area of tree cover from ESRI (2023) and the average carbon content of wood. According to the Acopian Center, a pilot study conducted in forests near the town of Vanadzor (northeastern Armenia) revealed a value of 98 tC/ha. However, data from State of the World’s Forests, FAO, 2011 estimate the total carbon stock in living forest biomass in Armenia at 13 million tons, with an average of 48 tC/ha across the country. We used this average in our calculations.

Figure 31E-1. Soil carbon stocks, t/ha; for details see project web-GIS, section Ecosystem Services

Carbon stocks in Armenia, provinces and vegetation zones

The average soil carbon content across provinces ranges from 62 to 32 tС/ha and across vegetation zones (Section 2.3) from 64 to 29 tC/ha. Total carbon stock in 0-30 cm depth soils in Armenia amounts to 158.4 MtC, and in tree biomass 15 MtC (in 2023). The total carbon stock in soils and tree biomass amounts to 173 MtС. Due to the relatively small forest area in Armenia, the main carbon stock (91,4%) is stored in soils.

Carbon content in the 30-cm soil layer in most marzes ranges between 52–61 t/ha. In Armavir and Ararat, it is lower (32 and 44 t/ha, respectively) due to the carbon-poor semi-desert soils (Figure 31E-2 a). The total carbon stock is highest in marzes Syunik, Lori, and Gegharkunik (25-28 MtC), and lowest in marz Armavir (4 MtC) because of low carbon content in soil and small area of ecosystems (Table 31E-1; Figure 31E-2 b). The carbon stock in tree biomass makes a noticeable addition to soil carbon only in marzes Tavush and Lori.

According to the World Soils 250 m Organic Carbon Stocks dataset, soil carbon content is highest in mountain grassland zones (64 t C/ha) and in the forest and steppe zones (57–59 t C/ha). The lowest carbon content is found in desert and semi-desert soils (29–35 t C/ha) (Table 31E-2; Figure 31E). Soil carbon stock is highest in the steppe, forest, and subalpine zones, and lowest in the juniper zone due to its limited extent. Total carbon stock is highest in the forest zone because of the substantial contribution from tree biomass.

Figure 31E-2. Carbon stocks across marzes: a) Carbon content in the 30-cm soil layer, tС/ha; b) Carbon stock in soil and tree biomass, MtC . Area of the marz Gegharkunik is accounted excluding Lake Sevan

Figure 31E-2. Carbon stocks across vegetation zones: a) Carbon content in the 30-cm soil layer, tС/ha; b) Carbon stock in soil and tree biomass, MtC

Changes in carbon stock in tree biomass from 2017 to 2023

Changes in carbon stock were assessed based on changes in the area of tree cover, using ESRI data. Across marzes, the most significant absolute decline was observed in Syunik, and the most significant relative decline was observed in Armavir marz (Table 31E-1; Figure 31E-3). Across vegetation zones, stocks declined in all zones except the desert (which has no woody vegetation) and broadleaf woodlands. The largest decline occurred in the forest zone; however, compared with 2017, it amounted to only 4% (Table 31E-2; Figure 31E-4).Figure 31E-3. Changes in carbon stock in tree biomass from 2017 to 2023 across marzes: a) Changes in carbon stock, MtC; b) Changes in carbon stock relative to 2017,%

Figure 31E-4. Changes in carbon stock in tree biomass from 2017 to 2023 across vegetation zones: a) Changes in carbon stock, MtC; b) Changes in carbon stock relative to 2017,%

Table 31E-1. Carbon stock in marzes and changes in it from 2017 to 2023

Province	Mean carbon content in the 30 cm soil layer (tC/ha)	Area (excluding Lake Sevan), ha	Carbon stock in soil, MtC	Area of trees, ESRI 2017,  ha	Area of trees, ESRI 2023,  ha	Carbon stock in tree biomass, 2017, MtC	Carbon stock in tree biomass, 2023, MtC	Total carbon stock in soil and tree biomass, 2023, MtC	Changes in carbon stock in tree biomass from 2017 to 2023
									MtC	% relative to 2017
Aragatsotn	52	273612	14.10	5254	4825	0.25	0.23	14.34	-0.02	-8.2
Ararat	44	211491	9.37	3047	2620	0.15	0.13	9.50	-0.02	-14.0
Armavir	32	126370	4.10	284	55	0.01	0.00	4.10	-0.01	-80.5
Gegharkunik	61	397392	24.14	13493	12956	0.65	0.62	25.01	-0.03	-4.0
Kotayk	56	211480	11.90	17174	15310	0.82	0.73	12.63	-0.09	-10.9
Lori	62	376300	23.41	86951	88374	4.17	4.24	27.65	0.07	1.6
Shirak	58	271863	15.87	1308	1343	0.06	0.06	15.93	0.00	2.6
Syunik	58	449335	26.27	63426	50774	3.04	2.44	28.71	-0.61	-19.9
Tavush	57	272624	15.60	130410	131633	6.26	6.32	21.92	0.06	0.9
Vayots Dzor	58	229654	13.36	4710	3813	0.23	0.18	13.54	-0.04	-19.0
All pro-vinces	56	2820122	158.11	326059	311701	15.65	14.96	173.32	-0.69	-4.6

Table 31E-2. Carbon stock in vegetation zones and changes in it from 2017 to 2023

	Carbon content in the 30 cm soil layer (tC/ha)	Area, ha	Carbon stock in soil, MtC	Area of trees, ESRI 2017,  ha	Area of trees, ESRI 2023,  ha	Carbon stock in tree biomass, 2017, MtC	Carbon stock in tree biomass, 2023, MtC	Total carbon stock in soil and tree biomass, 2023, MtC	Changes in carbon stock in tree biomass from 2017 to 2023, MtC	Changes in carbon stock in tree biomass from 2017 to 2023, % relative to 2017
Marsh	45.9	39055	1.79	246.8	146.6	0.01	0.01	0.02	-0.005	-40.6
Alpine meadows and carpets	63.6	163794	10.42	588.6	106.4	0.03	0.01	0.03	-0.023	-81.9
Subalpine meadows	64.2	460885	29.60	51282.2	43987.0	2.46	2.11	4.57	-0.350	-14.2
Meadow-steppe	63.6	318335	20.26	13415.2	13327.4	0.64	0.64	1.28	-0.004	-0.7
Forest	58.7	564380	33.14	432710.2	416416.2	20.77	19.99	40.76	-0.782	-3.8
Juniper	57.2	13560	0.78	901.2	720.7	0.04	0.03	0.08	-0.009	-20.0
Broadleaf woodland	49.8	117317	5.84	43015.7	46096.8	2.06	2.21	4.28	0.148	7.2
Steppe	57.1	696619	39.78	18417.5	16405.2	0.88	0.79	1.67	-0.097	-10.9
Semidesert	35.0	437940	15.32	1137.1	602.9	0.05	0.03	0.08	-0.026	-47.0
Desert	29.1	752	0.02	0.0	0.0	0	0	0.00	0.000	0