Forest Site Types Research Articles

Humus cover and its fabric depending on pedo-ecological conditions and land use: an Estonian approach to classification of humus forms

The fabric of humus cover (HC) may be very variegated, depending on local pedo-ecological conditions (origin and composition of deposits, topography, moisture regime, soil climate, plant cover composition). This multiplicity can be expressed by the HC types (or humus forms). On natural areas, where the HC is formed as a result of long-term equilibrated mutual influences of soil cover and plant cover, the fabric and properties of the HC may be used as an ecological indicator in the evaluation of the functioning character and intensity of the soil-plant system (or also the whole ecosystem). In Estonia, besides natural areas, the classifications of HCs are also elaborated for arable areas. Regardless of the profound changes in the fabric of the HC occurring with land-use change (from natural land to arable and vice versa), certain inherited properties are sustained in newly formed HCs. In this paper the fabric and properties (thickness, carbon and nitrogen stocks) of the main HC types (19 in total) are analysed and ecological aspects of HC formation are explained. Data on tree layer taxation, agro-chemical parameters of the soil cover, and ground vegetation productivity are presented with the HC types used as the ecological background. The relationships of soil cover with soil and forest site type are analysed against the background of soil matrix tables and ordination net of forest sites, respectively. Comparative analysis of the Estonian HC classification with the European Reference Base for humus forms (ERB) showed a relatively good correspondence of the Estonian classification of HC types with ERB's humus forms.

Koncept geobiotopu ako možnej vyššej stanovištnej jednotky pre diferencovanie manažmentu lesov

The paper proposes and justifies an alternative concept of aggregation of forest site types in higher units for purposes of differentiation of forest management. Analysis of variance was performed for both: the natural occurrence of tree species in reserves, as well as the production potential of tree species measured on the representative plots according to Zlatnik´s altitudinal vegetation zones and edaphictrophic series. Based on the results of this analysis, an aggregation of forest site types was suggested along the elevation gradient of climatop, and along the edaphic-trophic and the edaphic-hydric gradients of edaphotop. By intersection of such created 32 categories of geotope with the basic formation groups of forest habitats by Braun-Blanquet geo-botanical school, 53 reconstructive geo-biotopes were formed. The proposed unit was compared using the F-test, Akaike information criterion (AIC), and the index of classification efficiency (EQ) with current typological units in terms of its ability to describe the variability of the analyzed parameters. Finally, the qualitative association of the compared classification models with the European classification systems was assessed. Based on the results obtained, it can be concluded that the site unit geo-biotop is at least comparable with currently used unit MGFT, with the number of categories

The consequences of the forest fire in Sphagnosa forest site type ecosystem

The consequences of the forest fire in Sphagnosa forest site type ecosystem

Response reaction of scots pine Pinus sylvestris L. after forest fire in forest site type Vacciniosa turf. mel. in Klīve forest district

Response reaction of scots pine Pinus sylvestris L. after forest fire in forest site type Vacciniosa turf. mel. in Klīve forest district

Tree age effect on fine-root and leaf morphology in a silver birch forest chronosequence

The influence of forest ageing on fine-root morphology and relations between fine-root and leaf characteristics is poorly studied. The aim of this study was to analyse age-driven changes in ectomycorrhizal roots (EcM roots) and leaf morphology in a chronosequence of silver birch (Betula pendula Roth.), which would provide a better understanding of adaptation responses and acclimation capacity of tree roots and leaves. The chronosequence included six age classes (3, 6, 14, 32, 45, and 60 years.). All stands had regenerated naturally and grew in a highly productive Oxalis forest site type in Estonia. Most changes in the morphology of EcM roots and leaves of silver birch occur faster at a young age. The functional parameters—mean specific area of EcM root (SRA) and leaf specific area (SLA) as well as leaf N—decreased with age. EcM root SRA and specific root length (SRL) decreased with stand age as a result of increased mean diameter and tissue density. In age classes of 6, 14, and 32 years, the total number of dominating EcM taxa was 34, and the distribution of four different dominating EcM exploration types (contact-, short-, medium-, long-distance) was similar. We conclude that high values of SRA, SLA, and leaf N measured in young silver birch stands indicate high activity of physiological processes necessary for fast-growing young trees. A decrease of SLA and SRA and N in the chronosequence of fertile stands of silver birch is most probably caused by down-regulation of growth, affecting simultaneously leaves and fine roots.

Estonian Vegetation Database

The main aim of the Estonian Vegetation Database (GIVD ID EU-EE-001) is to provide, as complete as possible, a synopsis of Estonian plant community types, to enable analysis of their species diversity on synusiae/microcoenoses, community and regional scale, to assess the management impact on vegetation and to study successional processes in plant communities. For example, in official Estonian forest site type classification interprets several types rather widely and habitats of some dispersed types (floodplain, hillock and klint/escarpment forests) having great value for biodiversity preservation have been overlooked. In 2011 the inventory of Estonian mire habitats (15,326 in total) was completed, partly including vegetation data, but the latter have not been analysed yet. The most serious shortcoming of the Estonian vegetation database is until now the disunion of grassland data.

PredictingEllenberg's soil moisture indicator value in theBavarianAlps using additive georegression

AbstractQuestionsCan forest site characteristics be used to predictEllenberg indicator values for soil moisture? Which is the best averaged mean value for modelling? Does the distribution of soil moisture depend on spatial information?LocationBavarianAlps,Germany.MethodsWe used topographic, climatic and edaphic variables to model the mean soil moisture value as found on 1505 forest plots from the databaseWINALPecobase. All predictor variables were taken from area‐wide geodata layers so that the model can be applied to some 250 000 ha of forest in the target region. We adopted methods developed in species distribution modelling to regionalizeEllenberg indicator values. Therefore, we use the additive georegression framework for spatial prediction ofEllenberg values with theR‐library mboost, which is a feasible way to consider environmental effects, spatial autocorrelation, predictor interactions and non‐stationarity simultaneously in our data. The framework is much more flexible than established statistical and machine‐learning models in species distribution modelling. We estimated five different mboost models reflecting different model structures on 50 bootstrap samples in each case.ResultsMedianR2values calculated on independent test samples ranged from 0.28 to 0.45. Our results show a significant influence of interactions and non‐stationarity in addition to environmental covariates. Unweighted mean indicator values can be modelled better than abundance‐weighted values, and the consideration of bryophytes did not improve model performance. Partial response curves indicate meaningful dependencies between moisture indicator values and environmental covariates. However, mean indicator values <4.5 and >6.0 could not be modelled correctly, since they were poorly represented in our calibration sample. The final map represents high‐resolution information of site hydrological conditions.ConclusionsIndicator values offer an effect‐oriented alternative to physically‐based hydrological models to predict water‐related site conditions, even at landscape scale. The presented approach is applicable to all kinds ofEllenberg indicator values. Therefore, it is a significant step towards a new generation of models of forest site types and potential natural vegetation.

Influence of environmental factors on the spatial distribution and diversity of forest soil in Latvia

This study was carried out to determine the spatial relationships between environmental factors (Quaternary deposits, topographical situation, land cover, forest site types, tree species, soil texture) and soil groups, and their prefix qualifiers (according to the international Food and Agricultural Organization soil classification system World Reference Base for Soil Resources (FAO WRB)). The results show that it is possible to establish relationships between the distribution of environmental factors and soil groups by applying the generalized linear models in data statistical analysis, using the R 2.11.1 software for processing data from 113 sampling plots throughout the forest territory of Latvia. A very high diversity of soil groups in a relatively similar geological structure was revealed. For various reasons there is not always close relationship between the soil group, their prefix qualifiers and Quaternary deposits, as well as between forest site types, the dominant tree species and specific soil group and its prefix qualifiers. Close correlation was established between Quaternary deposits, forest site types, dominant tree species and soil groups within nutrient-poor sediments and very rich deposits containing free carbonates. No significant relationship was detected between the CORINE Land Cover 2005 classes, topographical situation and soil group.

What is the potential of site units applied into forestry management in Slovakia to describe production of beech stands?

A high number of site units have been recognized so far in Slovakia region. Site units are to reflect diverse ecological condition and production capability of different sites. In Slovakia, there is a huge number of management units (forest site type, management units of forest site types) and ecological site units (forest site type groups), but more detailed and objective analysis and comparison of their ecological and production properties have not been performed yet. The main aim of this paper is thusq quantification of beech growth potential in selected basic and forestry-applied site units used in Slovakia forest management. Data collected within National Forest Inventory in Slovakia (2005–2006) were used for the analysis. Regression models of mean stand diameter and mean stand height were developed. Intercept of models were compared between sites using the t-test. Site units were merged into several groups in terms of beech growth – As for the altitudinal vegetation zones, three groups were identified, in which the beech productivity was rather homogenous. 3rd, 4th, and 5th altitudinal vegetation zones were grouped into the first group. The second group (2nd AVZ) includes poorer sites at lower altitudes (low precipitation as a limiting factor) with lower beech productivity. The third group includes sites at higher altitudes (6th AVZ), where the temperature limits beech growth. In terms of soil properties, two or three groups can be recognized. The first one includes hemioligotrophic and heminitrophilous sites, while the calciphile sites showed lower beech growth potential.

Silver fir (Abies alba Mill.) occurrence in south-eastern part of Iłżeckiej Forest

The study was conducted in Starachowice Forest District in Ilzecka Forest in southern part of Poland. Silver fir was the main tree species in Ilzecka Forests in the past. Nowadays the area is occupied by Scots pine forests, however the percentage of silver fir has recently increased again. The distribution of silver fir is uneven in this region. The article tries to answer the following questions: What does determine the distribution of silver fir stands in Ilzecka Forest? Do the geological conditions influence the occurrence of fir stands? The distribution of fir stands was investigated according to the main environmental parameters such as site types, soil types and underlying geology. The data on stand description were collected from management plans (period 1941-2005), general maps of the Starachowice Forest District and the Geological Map of Poland. The distribution of fir stands depended on forest site types. Soil type did not influence the occurrence of silver fir stands. Forests with silver fir were found both on Mesozoic rock from the Middle Jurassic period and on the strip next to the border separating Middle and the Upper Jurassic periods. More homogeneous fir areas were present on the geological bedrock from the Tertiary and the Middle Jurassic period rather than the Upper Jurassic, which may indicate that geological base substantially influenced fir expansion in the research area.

Butt rot incidence, causal fungi, and related yield loss in Picea abies stands of Latvia

Root and butt rot is the most destructive disease of conifers in the Northern Hemisphere, but little is known about the dynamics of yield loss in stands of different ages, site types, and species composition. This study aimed to estimate butt rot incidence, causal fungi, and related wood yield loss in Picea abies (L.) H. Karst. stands in Latvia. A total of 24 745 stumps were examined on 318 forest sites, and 21.8% of them contained rot. There was a positive correlation between stand age and butt rot frequency. Proportion of other tree species in a stand had no influence on incidence of the rot, but significant differences were observed among different forest site types. The length of decay columns in 114 stems analysed was 6.6 ± 2.6 m on average. Based on the observed butt rot frequencies in Latvian P. abies stands of different age classes, volumes of decay-degraded wood in a fully stocked stand would comprise about 19.7 m3·ha–1 at the age of 40 years, 57.4 m3·ha–1 at 60 years, 54.9 m3·ha–1 at 80 years, 63.1 m3·ha–1 at 100 years, and 91.8 m3·ha–1 at 120 years, corresponding to 6%–16% of a total standing volume.

Seasonal reflectance dynamics of common understory types in a northern European boreal forest

The influence of the seasonal cycle of boreal forest understory has been noticed in global remote sensing of vegetation, especially in remote sensing of biophysical properties (e.g. leaf area index) of the tree-layer in a forest. A general problem in the validation of operationally produced global biophysical vegetation products is the lack of ground reference data on the seasonal variability of different land surface types. Currently, little is known about the spectral properties of the understory layers of boreal forests, and even less is known about the seasonal dynamics of the spectra. In this paper, we report seasonal trajectories of understory reflectance spectra measured in a European boreal forest. Four study sites representing different forest fertility site types were selected from central Finland. The understory composition was recorded and its spectra measured with an ASD FieldSpec Hand-Held UV/VNIR Spectroradiometer ten times during the growing period (from May to September) in 2010. Our results show that the spectral differences between and within understory types are the largest at the peak of the growing season in early July whereas in the beginning and end of the growing season (i.e. early May and late September, respectively) the differences between the understory types are marginal. In general, the fertile sites had the brightest NIR spectra throughout the growing season whereas infertile types appeared darker in NIR. Our results also indicated that a mismatch in the seasonal development of understory and tree layers does not occur in boreal forests: the understory and tree layer vegetation develop at a similar pace in the spring (i.e. there are no or only few spring ephemerals present), and the forests with the strongest seasonal dynamics in tree canopy structure (LAI) have also the strongest dynamics in understory spectra.

The ecology of tree regeneration in mature and old forests: combined knowledge for sustainable forest management

We focused our attention on quantifying the factor complex of forest regeneration in 423 mature and old stands with contrasting environmental conditions. We recorded the microhabitat selection of tree recruits, the frequency of tree seedlings, and evaluated the drivers of sapling abundance and diversity. The majority of forest regeneration was established on undisturbed forest floor. Dead wood was a frequent substrate in spruce-(co)dominated forests. Seedling frequency within a stand was related to the site-type specific productivity gradient of stands—pine seedlings were common in low-productivity and spruce in high-productivity boreal forests. Seedlings of temperate broad-leaved trees dominated in productive boreonemoral forests, except for oak, which showed a uniform distribution of abundance in all forest site-types. Sapling abundance was dictated by forest site-type, and facilitated by stand diversity, variability in stand closure, lying dead wood, abundant moss, and a thick organic layer. Only in boreal forests was sapling abundance suppressed by the abundant spruce and younger trees. Upon considering the relationship between sapling abundance and species richness, sapling diversity was dependent on forest site-type, suppressed by stand density and dead wood (old gap) abundance, and facilitated by stand diversity. In addition, boreonemoral stands, competition from herbs, and facilitation by mosses occurred. The observed pattern of tree recruitment points to the importance of top-down effects of the overstory, competing or facilitating interactions with forest floor vegetation, and availability of regeneration microhabitats, which in complex make their ecology comparable with forest herbs. Natural forest regeneration can be enhanced if silvicultural methods support mixed stands and enhance field layer diversity. Oak can provide the universal tree species to improve stand structure over a wide range of habitats.

Consistency in the classification of oligotrophic forest sites and forest vegetation in Scots pine stands of successive age classes in Bolesławiec Forest

Przemiany ubogich siedlisk borowych a aktualny stan roślinności runa w drzewostanach sosnowych kolejnych klas wieku w Nadleśnictwie Bolesławiec

Addition of coarse woody debris – The early fungal succession on Picea abies logs in managed forests and reserves

Modern forestry practices have decreased the abundance of coarse woody debris (CWD), and as a result many species that depend on dead wood are now threatened. This implies a need to develop forestry practices that maintain biodiversity. We examined the conservation value of experimental spruce logs (control logs, logs placed in natural shade, and cut tree tops) for wood-inhabiting fungi in two forest stands, one nature reserve and one mature managed forest, in each of seven forest areas in northern Sweden. Here we report the initial findings of the experiment that was established in winter 2001–2002 and data were collected in 2002, 2003 and 2006. A pre-inventory of the local species composition in 2002 revealed a higher per area species richness, including red-listed species, in reserves than in managed forests. Ordination analyses of the experimental logs showed a significant effect of area, while not of stand type in 2003. ANOVA analysis showed no significant effect of stand type on species richness and abundance. In 2006, the species assemblage started to differentiate between the two stand types and forest age, forest site type (moisture), and distance to forest reserves, all explained part of the variation, whereas the amount of CWD, and species composition at the start of the experiment only showed a marginal effect. The early successional fungal community was dominated by two functional groups, humus-decayers and white-rot species, both characterized by a rapid, early colonization and fruit-body formation on the competition-free new substrate. A similar positive response to the new substrate was also observed for the mycorrhizal species in 2006. The high frequency and early appearance of humus-decayers and mycorrhizal species that do not primarily depend upon CWD for their nutrition suggest that their formation of fruiting bodies is limited by substrate availability. Thus some mycorrhizal fungi are apparently rare due to lack of suitable substrate for fruit-body formation. Evidence of dispersal-limitation was observed in 2006. Fomitopsis pinicola, an early colonizer in boreal forests, playing a key role for other wood-inhabiting organisms, colonized significantly more logs in the reserve stands compared with the managed stands. Our data demonstrate that lack of CWD strongly affects both species that depend upon wood for nutrition and species that depend upon wood for fruit-body formation. Thus some species may show an apparent rarity due to lack of suitable substrate. We conclude that creation of CWD appears to be a useful method to maintain or restore fungal diversity in boreal coniferous forests.

Airborne Laser Scanning for the Site Type Identification of Mature Boreal Forest Stands

In Finland, forest site types are used to assess the need of silvicultural operations and the growth potential of the forests and, therefore, provide important inventory information. This study introduces airborne laser scanner (ALS) data and the k-NN classifier data analysis technique applicable to the site quality assessment of mature forests. Both the echo height and the intensity value percentiles of different echo types of ALS data were used in the analysis. The data are of 274 mature forest stands of different sizes, belonging to five forest site types, varying from very fertile to poor forests, in Koli National Park, eastern Finland. The k-NN classifier was applied with values of k varying from 1 to 5. The best overall classification accuracy achieved for all the forest site types and for a single type, were 58% and 73%, respectively. The conclusion is that when conducting large-scale forest inventories ALS-data based analysis would be a useful technology for the identification of mature boreal site types. However, the technique could still be improved and further studies are needed to ensure its applicability under different local conditions and with data representing earlier stages of stand development.

Airborne laser scanning based identification and interpretation on ecologically important old-growth forest habitats in natural conservation areas

Over the last decades, accurate and cost efficient remote sensing techniques in large-scale forest inventories have developed rapidly. In particular, the airborne laser scanning (ALS) has provided new possibilities to quickly and accurately monitor forest ecosystems over large areas. ALS provides three-dimensional data on forest structure and basic forest characteristics (e.g. wood volume per hectare) with good accuracy. Currently, ALS is already applied in the stand level management inventory in many countries. However, the applicability of ALS to detect more rare items and forest characteristics has not yet been entirely assessed. My study focuses on these uncommon forest characteristics and tests the potential of ALS to facilitate biodiversity inventories. Boreal forest stands with high herbaceous plant species diversity, large European aspen (Populus tremula L.) individuals, and old-growth forest canopy gaps have been found to be important biodiversity characteristics in western taiga forests. The field inventories of these forest structures are often time-consuming and, therefore, the inventory methods in various scales should be developed to improve their conservation and management. In this thesis I developed and evaluated ALS based methods to identify the old-growth forest characteristics. All the data were collected from Koli National Park (Koli NP) in eastern Finland. The data used in this thesis included 274 mature forest stands belonging to five different forest site types and varying in size. The spatial and temporal patterns of the chosen biodiversity characteristics were investigated. The longevity of aspen stands was studied based on multi-source data. About one-third of the old-growth forest areas of the Koli NP contained large aspen trees that persisted throughout the period between 1910 and 2004. The results show that aspen can maintain long-term occurrence in old-growth forests and that the species is not only transient or confined to early successional stages. The ALS was used to identify herb-rich forest stands. ALS was capable of distinguishing herb-rich forests from less fertile site types with an accuracy of 88.9%. This was mainly based on the vertical vegetation profiles that characterize forests on high fertility sites. The best overall classification accuracy achieved for all the forest site types was 58.0%. As a basis on earlier studies canopy gaps can be located using ALS data. I found clear differences between the canopy gaps of natural forests and managed forests. In addition, both the density of vegetation and amount of coarse woody debris are utilizable characteristics in the ALS data-based identification of canopy gaps. In the large-scale forest inventories ALS-data proved to be a useful technology for the identification of several forest characteristics related to biodiversity in old-growth boreal sites. In particular, locating the herb-rich stands was found to be accurate.

Self-pruning of pedunculate oak (Quercus robur L.) stems and the diameter at breast height of trees in commercially managed stands

Proces oczyszczania się pni dębu szypułkowego (Quercus roburL.) a pierśnica drzew w drzewostanach gospodarczych

Stand characteristics and biodiversity indicators along the productivity gradient in boreal forests: Defining a critical set of indicators for the monitoring of habitat nature quality

We quantified the effects of anthropogenic disturbances on the structure and biodiversity of boreal forests on acidic soils and created a statistically supported rational set of indicators to monitor the stand “naturalness”. For that, we surveyed various traits of tree layer, understory, herb layer, forest floor and several widely accepted biodiversity epiphytic indicators in 252 old‐aged boreal stands in Estonia, mostly dominated by Scots pine or Norway spruce. Multifactorial general linear model analyses showed that many forest characteristics and potential indicators were confounded by the gradient of soil productivity (reflected by the forest site type), local biogeographic gradients and also by stand age. Considering confounding effects, boreal forests in a near‐natural state have more large‐diameter trees (diameter at breast height >40 cm) and larger variety of diameter classes, higher proportion of spruce or deciduous trees, a larger amount of coarse woody debris in various stages, a more closed tree canopy and denser understory than managed mature forests. By increasing light availability above the field layer, forest management indirectly increases the coverage of herbs and lichens on the forest floor but reduces the alpha‐ and beta‐diversity of herbs and the proportion of graminoids. Human disturbances reduce the relative incidence of many commonly accepted biodiversity indicators such as indicator lichens, woodpeckers, wood‐dwelling insects or fungi on trees. The test for the predictive power of characteristics reacting on disturbance revealed that only a fraction of them appeared to be included in a diagnostic easy‐to‐apply set of indicators to assess the nature quality of boreal forest: the amount of dead wood, the proportion of deciduous trees, the presence of specially shaped trees and woodpeckers and, as an indicator of disturbances, the forest herb Melampyrum pratensis. Many of these indicators have already been implemented in practice.

Variation of conducting area in stems of European larch (Larix deciduas) growing in fresh mixed coniferous forest and fresh mixed forest sites

The paper presents an attempt to determine conducting area (CA), relative conducting area (CA.k<sup>–1</sup>) and mean ring conducting area (CAar) on discs cut at breast height from stems of larch trees growing in fresh mixed coniferous forest and fresh mixed forest sites, representing four age classes and the main crop according to Kraft’s classification. The value of CA increases with an improvement of the social class of tree position in the community, while no such dependences were found for the value of (CA.k<sup>–1</sup>). The parameter CAar, except for one case in age class IV in the fresh mixed coniferous forest site, increases with an improvement of the position a tree takes in the community and differentiates more markedly under the conditions of fresh mixed forest sites. Relative conducting area (CA.k<sup>–1</sup>) decreases markedly with an increase in the age of trees, which is confirmed by high values of the coefficient of determination. Moreover, the significance of differences between individual trees in the main crop according to Kraft and forest site types was tested in terms of the values of CAar. Calculated values may be used to describe the relationships between conducting area and the size of the assimilating organ more precisely than the total sapwood zone.