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French forest Growing-stock volume and distribution

Growing-stock volume and distribution

Current state

The mean growing-stock volume of the French forests is estimated at 2.8 billion cubic meters. [1] This volume calculated by the French National Forest Inventory (NFI) represents the stem volume of live trees with a diameter at breast height greater than 7.5 cm, from the stump to a minimum top diameter of 7 cm over bark.

The growing-stock volume per hectare is 172 m³.
Privately-owned forests account for 2/3 (72%) of the growing-stock volume.
The volume per hectare is highest in public forests, at 198 m³/ha.

Volume of living trees per hectare by administrative region in 2023 (m3/ha).
Definition of the growing stock.

For more information, see the article "More than 190 tree species inventoried in France"



Broadleaves (hardwoods) account for almost 2/3 of the growing stock, which represents 1.8 billion m3.

Oaks (including pedunculate, sessile, pubescent and evergreen oaks) make up more than a quarter (29%) of the total growing-stock and 44% of the hardwoods’ growing stock. Beech accounts for 10% of the total growing stock.

Conifers (softwoods) account for almost 1 billion cubic meter.

Norway spruce accounts for 6% of the growing stock and silver fir for 8%. Together, Norway spruce and silver fir represent 40% of the softwoods in terms of growing stock.

Growing-stock volume of the main tree species.



For broadleaves, trees with a diameter below 37.5 cm account for more than 50% of the growing stock volume. For conifers, 80% of the volume is composed of trees with diameters between 17.5 and 57.5 cm.

Growing-stock volume, depending on diameter classes and leaf type [2].


Evolution of the growing stock

Over the past 4 decades, a significant increase in growing stock has been observed, rising from 1.8 billion m3 in 1985 [3] to 2.8 billion m3 today, which represents a 50% increase.

This increase amounts to almost 1 billion m3, which corresponds to the current growing stock in the Grand Est, Bourgogne-Franche-Comté and Centre-Val de Loire regions combined.

During this period, the growing stock per hectare increased from 137 m3/ha to 172 m3/ha. Meanwhile, the number of trees per hectare slightly decreased. Stands are producing more because of larger and/or taller trees.

The increase in growing stock is higher for hardwoods (+65%, +720 Mm3) compared to softwoods (+38%, +270 Mm3).

Evolution of the growing stock of living trees between 1985 and 2023.


Deadwood

In addition to measurements from live trees, data are also collected from standing and fallen deadwood. In 2023, the volume of standing deadwood represents 148 million m3, or 5% of the volume of all (live and dead) standing trees. Fallen deadwood accounts for 289 million m3. On average, one hectare of forest area contains 9 m3 of standing deadwood and 18 m3 of fallen deadwood.

Footnotes

[1The results are extracted from the inventory campains (led between 2019 and 2023), with 2021 as the mean year.

[2Diameter classes are centered. For example, the 10-15 class includes trees with diameters [7.5-17.5 cm], the 20-25 class includes trees with diameters [17.5-27.5 cm], etc. Trees smaller than 7.5 cm in diameter are not included.

[3Results from forest inventories at department scale, led between 1978 and 1994, with 1985 as the mean year.


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