Mixed Deciduous Stands Research Articles

Оценка секвестрационного потенциала осиново-березовых древостоев островных лесостепей Средней Сибири

The forest-steppes of Central Siberia occupying submontane troughs and intermountain basins separated by taiga vegetation are considered insular. Forest woody vegetation is mainly represented by birch, aspen, larch and pine stands. A decisive role in the ecological sustainability of forest areas is played by larch plantations. This study has aimed to identify the characteristics of the dynamics of individual forest elements in the mixed deciduous stands within the forest area. The tasks have been to identify the characteristics of the forest area, characterize the dynamics of the taxation parameters of major and minor elements of the mixed stands and assess the contribution of the stands to the carbon balance. The work is based on the data of 548 strata. We have established the characteristics of the forest area age structure and how the stands of various completeness and productivity are represented in it. We have also estimated the variability of the average stands taxation parameters in different age periods. The average values obtained have become the basis for mathematical modeling of the table of the dynamics of the taxation parameters of the mixed stands. It turns out that the process to a reasonable degree of adequacy is reflected by the Weibull distribution. The accuracy of the equations has been estimated by the value of the coefficient of determination (R2) and the standard error of the equation (S). On the basis of the obtained mathematical models, we have constructed the table of the dynamics of the average taxation parameters of the stands of the forest elements and of the mixed stand as a whole. The biological system of forest woody vegetation under consideration has a significant carbon sequestration potential. However, there is currently no generally accepted procedure for assessing the effectiveness of this process. Russian and foreign researchers have collected a large amount of data from different regions, but they have been using different methods. To estimate carbon stocks in the stands that are the object of the study, we have used the conversion-volume method for estimating carbon stocks in forest plantations. The result is the obtained data illustrating the dynamics of carbon stocks in the aspen-birch stands in the insular forest-steppes of Central Siberia.

Modelling the influence of different harvesting methods on forest dynamics in the boreal mixedwoods of western Quebec, Canada

Forest management aims to better understand effects of natural disturbance regimes on forest dynamics and use this knowledge to formulate guidelines in forest planning, thereby narrowing gaps between managed and unmanaged forest landscapes. Using forest simulators to reconstruct forest dynamics in relation to ecosystem processes, including disturbances, could help forest managers to better understand harvesting effects on forest dynamics. Using SORTIE-ND, a spatially explicit forest simulator, we generated stand dynamics for 100 years following simulated clear-cut and partial harvests (dispersed vs aggregated, with 30% and 60% basal area removal). Based on the hardwood: conifer basal area ratio, we grouped post-fire stands into three stand types corresponding to natural post-fire succession (deciduous, mixed deciduous, and mixed coniferous) and assessed long-term effects of clear-cutting and partial harvesting on each. Our results suggest that spatial configurations of harvested and residual trees had a greater effect on stand dynamics than did tree removal intensity. Following dispersed partial harvesting, both deciduous and mixed deciduous stands had species composition and structure similar to unharvested stands of the next successional stage. In these same stand types, aggregated harvests and clear-cutting favoured increased regeneration and basal area increments of aspen, which set succession back to aspen dominance, as has been observed after wildfire. Dispersed partial harvests (both 30% and 60%) and 30% aggregated cuts, in mixed coniferous stands, maintained recruitment and dominance of conifers to levels comparable with unmanaged stands. Clear-cutting in all stand types greatly modified stand compositional and structural attributes, and, when conducted in stands where aspen was abundant, performed as a stand-replacing disturbance, setting succession back to early developmental stages, i.e., to aspen dominance. We conclude that partial harvesting, which emulates gap dynamics similar to undisturbed stands, can maintain natural stand dynamics.

Spatial and temporal variability of biological indicators of soil quality in two forest catchments in Belgium

Biological indicators, measurements based on the presence and activity of soil organisms, are increasingly being considered in assessments of forest soil quality. In addition to chemical indicators, such as soil organic carbon and pH, biological indicators can provide an early diagnosis of changes in soil quality and processes in response to environmental change and forest management actions. We investigated the spatial and temporal variability of selected bio-indicators in the forest floor of two catchments over three years. We further evaluated the sensitivity of these indicators to changes in the dominant tree species following reforestation and natural regeneration. Indicators of microbial abundance and activity (microbial biomass, potential respiration) and carbon maintenance costs (metabolic quotient) were higher under young spruce and mixed deciduous stands than pure stands of oak and beech. Our results indicate a greater microbial activity in autumn but a wider range of carbon substrate utilisation in spring. Assessment of seasonal differences in bio-indicator values is vital for the evaluation and planning of long-term studies and the development of reference values for forest soils in Belgium. Our results highlight the usefulness of these bio-indicators in identifying changes in soil quality, particularly in response to management activities, at small spatial scales.

Assessing the impacts of the decline of Tsuga canadensis stands on two amphibian species in a New England forest

AbstractDisturbances such as outbreaks of herbivorous insects and pathogens can devastate unique habitats and directly reduce biodiversity. The foundation tree species Tsuga canadensis (eastern hemlock) is declining due to infestation by the nonnative insect Adelges tsugae (hemlock woolly adelgid). The decline and expected elimination of hemlock from northeastern U.S. forests is changing forest structure, function, and assemblages of associated species. We assessed 10 years of changes in occupancy, detection probability, and relative abundance of two species of terrestrial salamanders, Plethodon cinereus (eastern red‐back salamander) and Notopthalmus viridescens viridescens (eastern red‐spotted newt), to the experimental removal in 2005 of T. canadensis at Harvard Forest. Salamanders were sampled under cover boards and using visual encounter surveys before (2004) and after (2005, 2013, 2014) canopy manipulations in replicate 0.81‐ha plots. In 2004, occupancy of P. cinereus was 35% lower in stands dominated by T. canadensis than that in associated mixed‐hardwood control stands, whereas detection probability and estimated abundance of P. cinereus were, respectively, 60% and 100% greater in T. canadensis stands. Estimated abundance of N. v. viridescens in 2004 was 50% higher in T. canadensis stands. Removal of the T. canadensis canopy increased occupancy of P. cinereus but significantly reduced its estimated detection probability and abundance. Estimated abundance of N. v. viridescens also declined dramatically after canopy manipulations. Our results suggest that ten years after T. canadensis loss due to either the adelgid or pre‐emptive salvage logging, and 50–70 years later when these forests have become mid‐successional mixed deciduous stands, the abundance of these salamanders likely will be <50% of their abundance in current, intact T. canadensis stands. This study adds to our understanding of how forest disturbance, directly and indirectly caused by invasive species, can contribute to declines in the relative abundance of amphibians.

The Relative Abundance of the Juvenile Phase of the Eastern Red-Spotted Newt at Harvard Forest Prior to the Arrival of the Hemlock Woolly Adelgid

The invasive insect pest Adelges tsugae (Hemlock Woolly Adelgid) threatens the ecologically unique Tsuga canadensis (Eastern Hemlock)-dominated forest type throughout its range. Relatively little is known about how the loss of this forest type will affect the relative abundance of amphibians. This study assessed the relative abundance of the juvenile phase of Notophthalmus viridescens viridescens (Eastern Red-spotted Newt, Red Eft) in Eastern Hemlock-dominated stands (n = 5) and mixed deciduous stands (n = 5) at Harvard Forest in Petersham, MA, using both transect surveys of the forest floor surface (n = 368 Red Eft observations over four seasons), and intensive searches of quadrats (n = 27 Red Eft observations over two seasons). Using data from transect surveys, the average relative abundance of Red Efts was more than two times greater in Eastern Hemlock-dominated stands than in mixed deciduous stands, however the differences were not statistically significant (P = 0.146). Quadrat surveys yielded relative abundance estimates for Red Efts that were more than 5 times greater in Eastern Hemlock-dominated stands than in mixed deciduous stands, but again the differences were not statistically significant (P = 0.213).

Old rural parks support higher biodiversity than forest remnants

One of the main challenges in biodiversity conservation is to curb a further degradation and loss of high-quality habitats. In agricultural matrix landscapes, the detection of alternative habitats for habitat specialists may be a solution. Historic old parks or landscape gardens around manor houses and castles are cultural heritage of nobles, but their value in harbouring biodiversity is poorly acknowledged. Therefore we evaluated the potential of old rural parks to serve as a habitat for nemoral forest species. We recorded stand structure and the presence of forest biodiversity indicators in 74 closed-canopy stands of historic parks and compared them with 93 neighbouring mature forest remnants on ancient forest land. We estimated the importance of stand structure in relation to habitat type on biodiversity indicators. Finally we suggest single-value indicator-complexes for the cost-efficient assessment of the conservation value of forests and forest-like habitats. Park stands outclassed reference forests in several individual structural characteristics, and in combined indicators of habitat quality and biodiversity. Forests had higher estimates for the combined indicator of dead wood, but large-diameter dead wood types were more abundant in parks. Woodpeckers, several old-growth indicator epiphytes and forest herbs had successfully become established in planted forest-like park fragments. Old rural parks resemble high-conservation-value forests more than the best preserved contemporary forest remnants. After the century needed to overcome immigration delay, old parks do provide a refugium for temperate deciduous forest species. Consequently, biodiversity-targeted management should retain and enhance old-growth attributes in forests and on the peripheries of parks: e.g. preserving old trees to provide service for epiphytes, hollow trees and an understorey mosaic for birds and bats; dead wood elements for saproxylic insects and fungi; limited mowing frequency and increased cutting height for forest herbs. Forestry should enhance the recovery of mixed deciduous stands and avoid conifer plantations.

A new approach to comprehensive quantification of linear landscape elements using biotope types on a regional scale

The structure of a landscape is highly relevant for research and planning (such as fulfilling the requirements of the Water Framework Directive – WFD – and for implementation of comprehensive catchment planning). There is a high potential for restoration of linear landscape elements in most European landscapes. By implementing the WFD in Germany, the restoration of linear landscape elements could be a valuable measure, for example to reduce nutrient input into rivers. Despite this importance of landscape structures for water and nutrients fluxes, biodiversity and the appearance of a landscape, specific studies of the linear elements are rare for larger catchment areas. Existing studies are limited because they either use remote sensing data, which does not adequately differentiate all types of linear landscape elements, or they focus only on a specific type of linear element. To address these limitations, we developed a framework allowing comprehensive quantification of linear landscape elements for catchment areas, using publicly available biotope type data. We analysed the dependence of landscape structures on natural regions and regional soil characteristics. Three data sets (differing in biotopes, soil parameters and natural regions) were generated for the catchment area of the middle Mulde River (2700 km 2) in Germany, using overlay processes in geographic information systems (GIS), followed by statistical evaluation. The linear landscape components of the total catchment area are divided into roads (55%), flowing water (21%), tree rows (14%), avenues (5%), and hedges (2%). The occurrence of these landscape components varies regionally among natural units and different soil regions. For example, the mixed deciduous stands (3.5 m/ha) are far more frequent in foothills (6 m/ha) than in hill country (0.9 m/ha). In contrast, fruit trees are more frequent in hill country (5.2 m/ha) than in the cooler foothills (0.5 m/ha). Some 70% of avenues, and 40% of tree rows, are discontinuous; in contrast, only 20% of hedges are discontinuous. Using our innovative framework, comprehensive information about landscape elements can now be obtained for regional applications. This approach can be applied to other regions and is highly relevant for landscape planning, erosion control, protection of waters and preservation of biotopes and species.

Host preferences and differential contributions of deciduous tree species shape mycorrhizal species richness in a mixed Central European forest.

SummaryMycorrhizal species richness and host ranges were investigated in mixed deciduous stands composed of Fagus sylvatica, Tilia spp., Carpinus betulus, Acer spp., and Fraxinus excelsior. Acer and Fraxinus were colonized by arbuscular mycorrhizas and contributed 5% to total stand mycorrhizal fungal species richness. Tilia hosted similar and Carpinus half the number of ectomycorrhizal (EM) fungal taxa compared with Fagus (75 putative taxa). The relative abundance of the host tree the EM fungal richness decreased in the order Fagus > Tilia >> Carpinus. After correction for similar sampling intensities, EM fungal species richness of Carpinus was still about 30–40% lower than that of Fagus and Tilia. About 10% of the mycorrhizal species were shared among the EM forming trees; 29% were associated with two host tree species and 61% with only one of the hosts. The latter group consisted mainly of rare EM fungal species colonizing about 20% of the root tips and included known specialists but also putative non-host associations such as conifer or shrub mycorrhizas. Our data indicate that EM fungal species richness was associated with tree identity and suggest that Fagus secures EM fungal diversity in an ecosystem since it shared more common EM fungi with Tilia and Carpinus than the latter two among each other.Electronic supplementary materialThe online version of this article (doi:10.1007/s00572-010-0338-y) contains supplementary material, which is available to authorized users.

Effects of forest stand type on oribatid mite (Acari: Oribatida) assemblages in a southwestern Quebec forest

Despite the ubiquity of oribatid mites in soil and litter systems, and their importance in decomposition and nutrient cycling processes, little is known of the factors underlying the composition of their assemblages. Our objective was to address this by determining how oribatid assemblage composition changes by forest stand type. This work was done in and near a hardwood forest in southwestern Quebec, Canada. We sampled mites by collecting 1 L of litter and 170 cm3 of soil from four sites in each of four distinct habitat types: American beech stands, sugar maple stands, mixed deciduous stands and mixed conifer plantations. Samples were collected in July and September 2005, and June 2006, and over 6500 oribatid mites were collected and identified to species. Abundance and species richness differed between forest types: for abundance conifer>beech>maple>mixed deciduous while for species richness beech and conifer>maple>mixed deciduous. Ordination analyses revealed that conifer plantations and beech stands supported distinct assemblages, while there were some overlap in the assemblages found in maple stands and mixed deciduous stands. These data support the importance of aboveground plant communities in affecting the composition of oribatid assemblages even at local scales and provide insight into additional impacts that may be caused by shifts in plant species ranges due to global changes.

The Relative Abundance of Eastern Red-Backed Salamanders in Eastern Hemlock-dominated and Mixed Deciduous Forests at Harvard Forest

In anticipation of the loss of Tsuga canadensis (Eastern Hemlock) dominated forests due to infestation by Adelges tsugae (Hemlock Woolly Adelgid), this study assessed the relative abundance of the ecologically important terrestrial salamander, Plethodon cinereus Green (Eastern Red-backed Salamander), in five Eastern Hemlock-dominated stands and four mixed deciduous stands at Harvard Forest in Petersham, MA. Pooling data from four seasons (fall 2003-fall 2004; excluding winter), the relative abundance of P. cinereus as measured by the monitoring of artificial cover objects (ACOs) was significantly higher in Eastern Hemlock-dominated stands than in mixed deciduous stands (n = 444 P. cinereus observations). The relative abundance of P. cinereus was not significantly different in the two forest types as measured by natural cover object (NCO) searches over two seasons (fall 2003 and spring 2004), although sample sizes were small (n = 45 P. cinereus observations). This evidence that Eastern Hemlock-dominated forests provide equal or greater quality habitat for P. cinereus as mixed deciduous forests at Harvard Forest contrasts with studies from other areas of Eastern Hemlock's range, which have found the abundance of P. cinereus to be lower in this forest type. The conversion of Eastern Hemlock-dominated forest to mixed deciduous forest will have either have a negative impact or no impact on the relative abundance of P. cinereus at Harvard Forest.

Long-term patterns and impacts of grey squirrel debarking in Lady Park Wood young-growth stands (UK)

Debarking of trees by American grey squirrels Sciurus carolinensis can be observed widely in British woodland. In this study, squirrel debarking and associated damage and mortality were assessed from 1977 to 2002 in mixed-deciduous stands in Lady Park Wood. Debarking mainly affected beech Fagus sylvatica stems sized 7.5–35 cm dbh, particularly those that were located in the upper stratum and growing most rapidly. Damage escalated during the study period: by 1983 24% of live beech stems in the vulnerable size-range had been badly damaged; this climbed to 48% by 1993, but reached only 54% in 2002, though a substantial number of beech had also been killed by debarking by 2002. Long-term mortality rates ranged from 2.3% to 5.4% per year and population half-life values from 13 to 30 years. The trigger for the initial debarking outbreak seemed to have been a severe drought in 1976. This opened the canopy and thereby released many, previously suppressed, beech trees. Debarking declined after 1993 as the canopy re-closed and beech growth generally declined. Over the same period, however, debarking to other species increased, suggesting it may have become habitual. Not all beech trees or stands where beech was prominent were seriously affected, and some badly damaged beech showed signs of recovery. Nonetheless, debarking had strongly impeded beech and thereby increased the long-term prospects for ash Fraxinus excelsior, lime Tilia cordata/ platyphyllos and other tree species.

Snow accumulation in forests from ground and remote‐sensing data

AbstractWinter‐forest processes affect global and local climates. The interception‐sublimation fraction (F) of snowfall in forests is a substantial part of the winter water budget (up to 40%). Climate, weather‐forecast and hydrological modellers incorporate increasingly realistic surface schemes into their models, and algorithms describing snow accumulation and snow‐interception sublimation are now finding their way into these schemes. Spatially variable data for calibration and verification of wintertime dynamics therefore are needed for such modelling schemes. The value of F was determined from snow courses in open and forested areas in Hokkaido, Japan. The value of F was related to species and canopy‐structure measures such as closure, sky‐view fraction (SVF) and leaf‐area index (LAI). Forest structure was deduced from fish‐eye photographs. The value of F showed a strong linear correlation to structure: F = 0·44 − 0·6 × SVF for SVF < 0·72 and F = 0 for SVF > 0·72, and F = 0·11 LAI. These relationships seemed valid for evergreen conifers, larch trees, alder, birch and mixed deciduous stands. Forest snow accumulation (SF) could be estimated from snowfall in open fields (So) and to LAI according to SF = So (1 − 0·11 LAI) as well as from SVF according to SF = So (0·56 + 0·6 SVF) for SVF < 0·72. The value of SF was equal to So for SVF values above 0·72. The value of sky‐view fraction was correlated to the normalized difference snow index (NDSI) using a Landsat‐TM image for observation plots exceeding 1 ha. Variables F and SF were related to NDSI for these plots according to: F = −0·37NDSI + 0·29 and SF = So (0·81 + 0·37NDSI). These relationships are somewhat hypothetical because plot‐size limitation only allowed one sparse‐forest observation of NDSI to be used. There is, therefore, a need to confirm these relationships with further studies. Copyright © 2004 John Wiley & Sons, Ltd.

First-Year Development of Plant Communities Originating from Forest Topsoils Placed on Southern Appalachian Minesoils

(1) In microplots, forest topsoils from mixed deciduous stands in the Cumberland Mountains of eastern Tennessee were spread over surface minesoils from the same region and supplemented with nitrogen and phosphorus. (2) First-year plant communities originating from seed banks in these topsoils contained about 1-9 x 106 shoots ha-' representing 134 taxa. At the end of the first growing season, oven-dry shoot and root weight was about 8.4 t ha-'. Nutrient analysis suggested that most of the added nutrients were retained in biomass. Roots were extensively colonized with endomycorrhizae. (3) We conclude that forest topsoils in areas being surface mined for coal in southern Appalachia can provide diverse plant communities capable of quick, effective cover on reclaimed mine areas. Results warrant testing of these topsoils on mined sites.