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How to c onvert Scots pine monocultures into mixed stands. Dorota Dobrowolska Forest Research Institute Department of Forest Ecology Poland. Forest cover in Poland. Forests cover 29. 4 % of Poland ( 9 197.9 thousand ha)
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How to convert Scots pine monocultures into mixed stands Dorota Dobrowolska Forest Research Institute Department of Forest Ecology Poland
Forest cover in Poland • Forests cover 29.4% of Poland (9 197.9thousand ha) • Most of them (77.2%) are national forests under the administration of the State Forests National Forest Holding • National parks encompass an area of 2.0%, and private forests 17.1%. Map of StateForests
Forests in Poland • Coniferous tree species dominate on 69.1% of the forest area, • Scots pine is the main tree species (58.5%), except the mountainous regions - Norway spruce (west) and spruce with European beech (Fagus sylvatica L.) (east), or a few smaller areas with variable species composition. • Polish forests are relatively young; the average age is 56 (58 for state forests). • The yearly volume increment is 8.6 m3 per ha. A greater increment of volume is observed in the last years (9.9 m3 per ha). • Volume - 269 m3/ha (state forests- 275 m3/ha) • Natural regeneration - 15.5%
Introduction • For centuries, humans have influenced European forests resulting in reduction of forest covered land area, changes in forest species distribution and soil conditions (Spiecker 2000). • Agricultural expansion and intensification have decreased the overall area of forests and woodlands, simplified the structure of the remaining forests and broken up forest areas into smaller and more isolated fragments (Lamb and Gilmour 2003). • Fast growing tree species such as Norway spruce (Piceaabies (Karst.) L.) and Scots pine (Pinussylvestris L.) were promoted in large areas typically covered with broadleaf or mixed species stands to increase commercial timber growth (Spiecker 2000; Bernadzki 2006). • The consequences of these changes include the following: reductions in landscape productivity; widespread reductions in biodiversity and the supply of various ecological goods and services (Lamb and Gilmour 2003).
Conversion of stands – Why? • Preferences for coniferous tree species in the past, changes in the present environment (site eutrophication, climate change) and an increase in the non-commercial forest functions (protection and society) promote stand conversion. • The secondary coniferous stands are susceptible to environmental stress factors such as air pollution, pathogen infection, wind and snow damage (Zientarski et al. 1994). • Conversion or reintroduction of the secondary coniferous stands into mixed broadleaf forests could increase their resilience (Spiecker 2000).
General rule Generally, the worse stand status and better site conditions are,the sooner the process of stand conversion is needed (Leibundgut 1988).
Needs of forest conversion • The necessity for forest restoration was first noticed in the last century (Włoczewski 1949). • The problem of stand conversion is still important. • The needs forforest conversion in State Forests are assessed for 300-500 thousands ha (Przybylska et al. 2007). • The forest area where the conversion is needed will not decrease; i.e. conversion of stands growing on post agriculture lands has not finished yet, conversion of forests damaged by industry and coal mines has been continued (Bernadzki 2006).
Definition • Stand restoration means re-establishing the structure, productivity and species diversity of the forest originally present. • In time, ecological processes and functions will match those of the original forest and re-establish the productivity of some, but not necessarily all, of the plant species originally present. • For ecological or economic reasons the new forest may include species not originally present. In time, the original forest’s protective function and ecological services may be re-established (Lamb and Gilmour 2003).
Scots pine conversion • Young pine forests (30-50- year old) which occur on rich sites ought to be converted as well, especially weakened (not vital), not stable or dying. • Partial conversion can be used to change the structure and species composition of Scots pine stands planted on post agriculture stands (Bernadzki 2006). These forests are very susceptible to pathogen diseases (Sierota 1987). • Special treatments like introducing the second layer, planting different tree species in gaps in younger stages or shrubs in older stages, special cuttings have changed stand structure and prepared them for regeneration phase. • Spontaneous regeneration of beech, hornbeam (Carpinusbetulus L.), silver fir and sycamore (Acer pseudoplatanus L.) is observed in planted pine stands in the Carpathian (Maciejewski 2011).
Scots pine regeneration • Non-tended natural regeneration of pine grows better than the tended natural and artificial ones. The results encourage to initiate and use the Scots pine natural regeneration, which increases the ability of pine stands to adapt and tolerate different stressors (Wolski and Robakowski 2008). • The competition of forest floor vegetation is animportant factor for pine regeneration. The bilberry (Vacciniummyrtillus) is the major species limiting the occurrence and density of pine seedlings in pine stands (Gmyz and Skrzyszewski 2010). • Lichens and mosses areindicatorsof microsites suitable for pine regeneration (Gmyz and Skrzyszewski 2010). • Successful Scots pine regeneration occurs in mature stands with the density index of 0.4 (Paluch 2004) or 0.5 (Gil at al. 2004) or on fenced area with left seed trees (Paluch 2004).
Recruitment of tree species under the canopy of Scots pine • Firstly silver fir is recruited into very young pine stands (less than 20-year-old). • Beech establishes in 30-40-year-old pine stands (Magnuski et al. 2004). • The latest tree recruiting into pine stands are pedunculate (Quercusrobur L.) and sessile oak (Q. sessilisLiebl.) (Gniot 2002; Paluch 2005).
Oak regeneration in gaps Garwolin ForestDistrict
Gap size determines the establishment and growth of oak regeneration in pine stands
The relationship between the number of oak trees surrounding the gaps and the density of oak regeneration in 91 gaps
Oak recruitment under pine canopy Nowe Ramuki ForestDistrict Europeanjay (Garrlusglandarius)
Regeneration after blowdown Szast Protected Forest
Conclusions • Spontaneous oak regeneration can play an important role in conversion processes of mixed Scots pine stands to native broadleaved forests. • The integration of oak natural regeneration into forest management can be used for the improvement of silvicultural practices in mixed pine stands. • The development of proper methods of management and protection allows increasing stand biodiversity and sustainability. • Natural regeneration increases the sustainability and biodiversity of the stand. • Winddisturbance does not pose a risk to forest continuity.The recruitment densities should be sufficient to ensureforest regeneration. • Disturbance in the Szast Protected Forest has increased speciesdiversity and created a new forest generation that varies in age,height, and species structure.
