[GZ06] Deadwood
Key message
Deadwood is an important animal and plant habitat that contributes to the biodiversity of forest ecosystems. According to Slovenia Forest Service data, the volume of standing and fallen trees without stumps and branches in 2010 was 10.11m3/ha, which represented approximately 4% of the entire wood stock of forest stands. In virgin forests, however, the deadwood volume can be even several dozen times larger.
Definition
This indicator shows the amount of fallen and standing deadwood. The data is presented for five-year periods from 1990 onwards and for each year after 2005. Annual values are estimates.
Deadwood in forests includes standing dead trees as well as fallen trees, trunks, branches, stumps and roots. The actual volume of stumps and roots is hard to determine, which is why it is mostly not included in the monitoring of forest ecosystems. However, estimates and measurements for these parameters do exist.
The data on deadwood provided by the Slovenia Forest Service includes entire standing and fallen tree trunks not including stumps and branches. For better international comparison, the data from the Global Forest Resources Assessment, which includes all aboveground tree parts, is also presented within the indicator.
Charts
Zavod za gozdove Slovenije, 2010, Global Forest Resources Assessment, FAO, 2010.
| 1990 | 1995 | 2000 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | ||
|---|---|---|---|---|---|---|---|---|---|---|
| standing trunk (ZGS)* | m3/ha | 3.29 | 3.58 | 3.86 | 4.4 | 4.51 | 4.62 | 4.73 | 4.84 | 4.95 |
| lying trunk (ZGS)* | m3/ha | 3.43 | 3.73 | 4.03 | 4.6 | 4.71 | 4.82 | 4.94 | 5.05 | 5.16 |
| total (ZGS)* | m3/ha | 6.72 | 7.31 | 7.89 | 9 | 9.22 | 9.45 | 9.67 | 9.89 | 10.11 |
| - | ||||||||||
| all standing biomass (GFRA) | m3/ha | 3.6 | 3.9 | 4.2 | 4.8 | 4.92 | 5.04 | 5.16 | 5.28 | 5.4 |
| all lying biomass (GFRA) | m3/ha | 9.1 | 9.9 | 10.7 | 12.2 | 12.5 | 12.8 | 13.1 | 13.4 | 13.7 |
| total (GFRA) | m3/ha | 12.7 | 13.8 | 14.9 | 17 | 17.42 | 17.84 | 18.26 | 18.68 | 19.1 |
Global Forest Resources Assessment, FAO, 2010.
| Austria | Czech republic | Italy | Hungary | Germany | Netherlands | Norvay | Poland | Slovakia | Slovenia | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
| total | t/ha | 2.65 | 13.44 | 4.02 | 4.88 | 4.97 | 8.22 | 3.68 | 1.18 | 16.04 | 9.26 |
| United Kingdom |
|||||||||||
| total | t/ha | 1.04 |
Goals
To preserve forest biodiversity at the level of ecosystems and species.
Comment
Deadwood has a very important role in forests. It has a crucial role in the circulation of organic matter and is an important habitat for flora and fauna (Virgin forest Slovenia '93, 1993). It is the stand parameter where the greatest differences occur between managed and virgin forests (Bončina, 1997).
According to the Slovenia Forest Service, the volume of deadwood in Slovenian forests in the period 1990–2010 grew by 66%, amounting to 10.11 m3/ha in 2010. Stumps and branches are not included in this volume. According to the Global Forest Resources Assessment, which includes all aboveground tree parts, the deadwood volume was 19.1 m3/ha. In assessing trends, special caution is required, as the indicator was previously assessed on the basis of conversion factors for growing stock (which has been increasing in Slovenia over the decades). The indicator has only been based on measurements in recent years. Nevertheless, it can be said with great certainty that there is more deadwood in Slovenian forests today than there was a hundred years ago due to differing forest management.
The volume of deadwood can differ greatly from place to place. It depends on site conditions and the state of forests and, most of all, on the (non)management of forests. Therefore, the volume of deadwood in virgin forests (e.g. 153.8 m3 of deadwood [above the third diameter class] per hectare in the Krokar virgin forest or 247 m3/ha in the Rajhenavski Rog virgin forest) can greatly exceed the volume in comparable neighbouring multi-purpose forests (Pisek, 2010).
Recently, several deadwood volume studies have been conducted in Slovenia. When forest habitat types pursuant to the Habitats Directive (Council Directive 92/43/EEC) were compared (Kutnar et al., 2009) with other forests, it was established that forests of the studied habitat types have 19% more deadwood (11.4% compared to 9.6% in other forests), which means that in Slovenian forests in general, there is 3.8% of deadwood relative to growing stock. This share is somewhat higher than indicative optimal values, which range between 0.5% and 3% of growing stock (Papež et al., 1997).
According to a study (Poljanšek, 2008) in which all Slovenian forests with available data from sampling plots of the Slovenia Forest Service were included, there are, on average, 26 dead trees per hectare (with the total volume of 10 m3/ha) in Slovenian forests, which represents 3.6% of the total growing stock of forest stands. The share of broadleaf trees in deadwood is 56% and the share of conifers is 44%).
According to the FAO Global Forest Resources Assessment (FAO, 2010), the volume of deadwood in Slovenia is among the highest in Europe. However, these comparisons were not made on the basis of comparable site conditions (figure GZ06-2). Also, in this case, the indicator is often assessed on the basis of conversion factors for growing stock in other countries. Most countries also lack amounts of time long enough for growing stock development, which directly affects the assessment of trends.
Considering the trend of the development of growing stock in Slovenia, which has been growing constantly for several decades, we can also assume that the volume of deadwood will increase provided that the management model remains unchanged. However, higher intensity of felling and increased exploitation of less valuable wood products that are currently left unexploited, as they are commercially unattractive, could reverse the growing trend in the future.