Function Of Tree Species Research Articles

Diversity and function of tree species in human-modified Atlantic Forest landscapes

Diversity and function of tree species in human-modified Atlantic Forest landscapes

Downed wood dynamics in the riparian and littoral zone of small lakes in tolerant hardwood forests

Large wood (LW) is an important structural feature in forested lake ecosystems, but little is known about the production of LW in riparian forests and its movement across the forest–lake ecotone, both of which we describe here for eight small (<30 ha) lakes in Ontario, Canada. The creation of snags through live-tree death varied by species, ranging from 0.24% year−1 for eastern white cedar to 5.60% year−1 for balsam fir. Snag breakage was best described as a function of snag height and snag fall described as a function of tree species, decay stage, and diameter. Long LW pieces and pieces generated close to the lake were more likely to be deposited at the shoreline. The density of LW at the shoreline was 125–550 pieces·km−1, and density and volume of LW were positively related to riparian slope. LW was a stable resource at the shoreline, with a recruitment rate about equal to the loss rate and average movement along the shoreline of 2.89 cm·year−1. LW volumes at the shoreline and in the littoral zone of the lake were positively related to lakebed slope. LW could reside in the littoral zone for centuries, providing physical structure for multiple generations of aquatic organisms in these small lakes. Our results indicate that critical habitat for fish that need aquatic LW extends at least 5 m into riparian forest and that removal of trees within 5 m of the forest edge would reduce LW input to the littoral zone.

Tree-related microhabitats are similar in mountain forests of Europe and North America and their occurrence may be explained by tree functional groups

Key messageDrivers of the abundance and richness of tree-related microhabitats are similar in mountain forests of Europe and North America and their occurrence may be explained by tree functional groups.A common approach to support forest-dwelling species in managed forests is to preserve valuable habitat trees. To assess the quality of habitat trees, a hierarchical typology of tree-related microhabitats (TreMs) is applied in the European context for inventory standardization. The first aim of this study was to evaluate whether it is possible to use this hierarchical typology as a standard protocol regardless of location, which is important for potentially standardizing future studies of TreMs, by testing whether the typology could be applied to the western North American mountain forests of Idaho. The second aim of the study was to analyse drivers that influence TreMs in forests of the region. Thirdly, we assessed whether the occurrence of TreMs could be explained by functional groups of trees across the western mountain forests of Idaho and Central European mountain forests, using TreM inventory data previously collected in the Black Forest, Germany. Abundance and richness of TreMs per tree were analyzed as a function of tree species, live status (dead vs. live trees), diameter at breast height (DBH), and site factors (latitude and altitude). Our results show that the TreM typology could be applied with slight modifications in the forests of Idaho. The abundance and richness of TreMs per tree increased with DBH. Snags offered more TreMs per tree than live trees. We were able to group tree species from the two continents in functional groups that were related to the occurrence of certain TreMs. Tree functional groups offer an opportunity to predict the role of certain tree species for habitat provision through TreMs. Combinations of trees from different functional groups could be used to optimize provisioning of TreMs within forest stands.

Tree species effects on understory forage productivity and microclimate in a silvopasture of the Southeastern USA

Ecosystem services provided by silvopastoral systems are mediated by specific management practices, environmental conditions, and overall design of the system. We hypothesized that selection of tree species affects understory forage nutritive value and productivity, light/shade environment, and microclimate. The silvopastoral system was located at the Center for Environmental Farming Systems in Goldsboro, North Carolina, USA. Three overstory tree-species were Pinus palustris (PP; longleaf pine), Pinus taeda (PT; lobloblly pine), and Quercus pagoda (QP; cherrybark oak). The understory forage component consisted of a four-way mixture of native warm-season grasses [big bluestem (Andropogon gerardii, ‘Eastern’, KY origin), eastern gamagrass (Tripsacum dactyloides, MO origin), indiangrass (Sorghastrum nutans, ‘NC ecotype’), and switchgrass (Panicum virgatum, ‘Alamo’)]. The experimental design was an RCBD with 3 replicates. There was no effect of seedbed preparation (till versus no-till) on forage establishment. Understory dry matter yield, crude protein and total digestible nutrient concentrations of the harvested forage were not affected by tree species, with the exception at the 3.5 south sampling point. Overstory effects on microclimate variables were not different among tree-species, but were more noticeable during the daytime of the summer months, and were at the most 1-degree point for temperature and temperature-humidity index and 3 points for relative humidity. The silvopasture design in our study provided year-round shade by the tree-component, with varying levels of shade (ranging from 90 to 6% of incident photosynthetic active radiation) due to geographic location, tree species, and season. Our results describe and highlight the potential of trees in a silvopasture design in the southeastern USA to mitigate changes in temperature, humidity, the temperature-humidity index, and forage productivity and as a function of tree species and at different distance from the trees.

Forestry carbon budget models to improve biogenic carbon accounting in life cycle assessment

Currently, wood and wood construction materials have limitations in how carbon fluxes are accounted for in life cycle assessments. The biogenic carbon balance of wood is often considered to be neutral, meaning that the carbon sequestered by biomass through photosynthesis is considered equal to the carbon feedstock in wood that is eventually released throughout its life cycle. Several publications have recently shown that this assumption could lead to accounting errors. This research work aims to improve the biogenic carbon accounting of the forestry phase of the life cycle of softwood products. This involved specifically modelling carbon fluxes as a function of tree species, growing conditions and forest management practices, from Canadian managed forests. A baseline natural forest scenario was run for 1000 years until the carbon stocks were assumed to reach an approximate steady-state, followed immediately by a harvest scenario that was simulated for another 100 years. The ecosystem carbon costs of the harvest activity were calculated for 117 species and region forest landscapes across Canada and expressed per cubic meter of harvested wood. Most landscapes showed net sequestration after 100 years of harvest history. Exceptions to this included outlier landscapes characterized by low average annual temperatures and precipitation where slightly positive values (net emissions) were found. The mean time to ecosystem cost neutrality for each species ranged from 16 to 60 years. Knowing the time since forest management has started on a particular forest landscape now enables managers to obtain an estimate of ecosystem carbon cost per cubic meter of wood harvested for most of Canada's forests and commercial tree species. These ecosystem carbon costs can be used to generate regionalized cradle-to-gate life cycle inventories for harvested wood products across Canada.

High-pruning of European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.): work efficiency for target pruning as a function of tree species, pruning height, branch characteristics, pole saw type and operator

ABSTRACTThe objective of this study was to establish an operational model of productive work time per tree (work efficiency) for high-pruning of young European beech and pedunculate oak depending on tree species, pruning height, branch characteristics, pole saw type and operator. The final model included all of these independent variables with branch characteristics specified in terms of number of live branches and cross-sectional area of the thickest branch at the cut. Work time increased with increasing values of each of the three numeric variables. For a given pruning height the size of the largest branch was for all practical purposes more influential than the number of live branches. Beech took 28% longer to prune than oak. The German Ergo-Schnitt saw was 21% slower than the Japanese Silky Hayauchi saw. The variation in worker performance within our study was larger than that attributed to tree species and pruning equipment.

Low Herbivory among Targeted Reforestation Sites in the Andean Highlands of Southern Ecuador.

Insect herbivory constitutes an important constraint in the viability and management of targeted reforestation sites. Focusing on young experimental stands at about 2000 m elevation in southern Ecuador, we examined foliar damage over one season as a function of tree species and habitat. Native tree species (Successional hardwood: Cedrela montana and Tabebuia chrysantha; fast-growing pioneer: Heliocarpus americanus) have been planted among prevailing local landcover types (abandoned pasture, secondary shrub vegetation, and a Pinus patula plantation) in 2003/4. Plantation trees were compared to conspecifics in the spontaneous undergrowth of adjacent undisturbed rainforest matched for height and foliar volume. Specifically, we tested the hypotheses that H. americanus as a pioneer species suffers more herbivory compared to the two successional tree species, and that damage is inversely related to habitat complexity. Overall leaf damage caused by folivorous insects (excluding leafcutter ants) was low. Average leaf loss was highest among T. chrysantha (7.50% ± 0.19 SE of leaf area), followed by H. americanus (4.67% ± 0.18 SE) and C. montana (3.18% ± 0.15 SE). Contrary to expectations, leaf area loss was highest among trees in closed-canopy natural rainforest, followed by pine plantation, pasture, and secondary shrub sites. Harvesting activity of leafcutter ants (Acromyrmex sp.) was strongly biased towards T. chrysantha growing in open habitat (mean pasture: 2.5%; shrub: 10.5%) where it could result in considerable damage (> 90.0%). Insect folivory is unlikely to pose a barrier for reforestation in the tropical Andean mountain forest zone at present, but leafcutter ants may become problematic if local temperatures increase in the wake of global warming.

Straddling the divide: den use by brushtail possums (Trichosurus vulpecula) in urban parklands

In Australia, brushtail possums (Trichosurus vulpecula) are declining in natural habitats but have adapted to urban environments so readily that some human residents consider them to be a nuisance. Although this situation represents a conundrum for management, the use of urban habitats by the species remains poorly studied. We conducted our study in six urban parklands, a setting that represents an intermediary between a fully-urban and fully-natural environment. To determine factors that influence the presence of hollows in trees and their use by brushtail possums, physical characteristics of 240 mature trees in six parks in the Adelaide Parklands, South Australia were assessed. To investigate hollow use more comprehensively, 18 possums were radio-tracked. Presence of hollows in trees was a function of tree species and tree size, with hollows formed in both exotic and native species. Tree form and number of hollows were significant predictors of the use of hollow-bearing trees by possums. Use of exotic trees was high, with only 34 % of recorded den trees being native (non-indigenous) species. Radio-tracked individuals were relatively sedentary, with an average daytime denning area of 0.08 ha. While the majority of animals used multiple den sites, all individuals favoured a single den. Use of a variety of anthropogenic structures was high, even when trees were available. On average, sites supported ~1.5 brushtail possums per hollow-bearing tree. A correlation between number of hollows per hectare and possum density (r =0.892, P =0.017) suggests that altering a given area’s density of hollows or anthropogenic structures could influence the density of possums within it.

Growing stock volume estimation from L-band ALOS PALSAR polarimetric coherence in Siberian forest

This paper investigated the potential of L-band ALOS PALSAR full polarimetric radar data for forestry applications. In order to characterize the polarization response as a function of growing stock volume (GSV), weather conditions and different tree species in Siberian forests, the polarization phase difference between HH and VV polarizations and the magnitude of the polarimetric HHVV-coherence have been analyzed. Moreover, the retrieval accuracy of forest growing stock volume (GSV) has been evaluated. The investigations were conducted on forest stand level and maximum GSV was 350m3/ha. Using multi-temporal L-band ALOS PALSAR polarimetric coherence data and extensive sets of the forest inventory data at a stand level, we observed a clear decrease of polarimetric coherence with an increase in GSV, with Pearson's correlation coefficient between −0.74 and −0.79. The correlation improved to −0.87 for the forest stands with high relative stocking >70% (i.e. more homogeneous forest stand structure) and the sensitivity of the polarimetric coherence to GSV increased to ~250m3/ha GSV. The polarization phase difference (PPD) also allowed forest to be discriminated from non-forest areas. Comparison of PPD during thawing and unfrozen weather conditions at the time of image acquisition revealed a higher contribution of a volume scattering at the latter conditions. In addition, differences in polarimetric coherence and phase difference were observed as a function of tree species. In particular, stands of larch typically exhibited a +0.1 polarimetric coherence under unfrozen conditions compared to aspen, birch and pine. There was also less variability in the PPD compared to other tree species, both under thawing and unfrozen conditions. An exponential model was used to characterize the polarimetric coherence behavior as a function of GSV. The retrieval of GSV was better under unfrozen conditions, with an RMSE of 33m3/ha and R2 of 0.73. The retrieval error was slightly higher (RMSE=51m3/ha and R2=0.61) under thawing conditions. In the case of the forest stands with the area larger than 30ha and the relative stocking of at least 70%, the GSV retrieval error decreased to RMSE of 16m3/ha and to RMSE=19m3/ha respectively.

Isotopic composition of carbon (δ13C) and nitrogen (δ15N) in foliage and soil as a function of tree species.

Isotopic composition of carbon (δ13C) and nitrogen (δ15N) in foliage and soil as a function of tree species.

Contrasting diagenetic pathways of higher plant triterpenoids in buried wood as a function of tree species

Terpenoid biomarkers with high chemotaxonomic value, which can be used for the identification of an angiosperm input to sedimentary organic matter are desirable for studies devoted to the reconstitution of past environmental change. There is also a need, in the framework of archaeometric investigations, for reliable biomarkers to allow wood species determination from archaeological remains. In this context, we report the analysis of the triterpene content of buried wood and bark from oak, alder and birch, and comparison with that of the corresponding fresh material. Identification of new biomarkers led us to elucidate the diagenetic transformations undergone by triterpenoids in buried wood. A large set of triterpenoid biomarkers characterized by the presence of an oxygenated functionality in ring A at C-2 only could be exclusively evidenced in buried oak wood. An overall diagenetic pathway leading from the predominant polyfunctionalized triterpenoids in fresh oak wood (oxygenated functionalities at C-2/C-3/C-19/C-23/C-24/C-28) via numerous C-2 and C-2,C-3 functionalized intermediates to C-2 oxygenated aromatic triterpenoids is proposed. The evolution of the triterpenoid assemblage with respect to the level of diagenetic alteration could be followed. In contrast, the predominant triterpenoids in fresh alder and birch are common C-3 functionalized compounds. Their degradation follows the classical degradation/aromatization pathways reported for C-3 oxygenated triterpenes, ring A degradation appearing to represent only a minor process. In addition, the formation of phenolic triterpenoids, which have only been reported from brown coal, was observed.

How to quantify forest management intensity in Central European forests

Existing approaches for the assessment of forest management intensity lack a widely accepted, purely quantitative measure for ranking a set of forest stands along a gradient of management intensity. We have developed a silvicultural management intensity indicator (SMI) which combines three main characteristics of a given stand: tree species, stand age and aboveground, living and dead wooden biomass. Data on these three factors are used as input to represent the risk of stand loss, which is a function of tree species and stand age, and stand density, which is a function of the silvicultural regime, stand age and tree species. Consequently, the indicator consists of a risk component (SMIr) and a density component (SMId). We used SMI to rank traditional management of the main Central European tree species: Norway spruce (Picea abies [Karst.] L.), European beech (Fagus sylvatica L.), Scots pine (Pinus sylvestris L.), and oak (Quercus robur L. and Quercus petraea L.). By analysing SMI over their whole rotation period, we found the following ranking of management intensity: oak<beech<pine≪spruce. Additionally, we quantified the SMI of actual research plots of the German Biodiversity exploratories, which represent unmanaged and managed forest stands including conifer forests cultivated outside their natural range. SMI not only successfully separate managed from unmanaged forests, but also reflected the variability of forest management and stand properties across the entire sample and within the different management groups. We suggest using SMI to quantify silvicultual management intensity of stands differing in species composition, age, silvicultural system (even-aged vs. uneven-aged), thinning grade and stages of stand conversion from one stand type into another. Using SMI may facilitate the assessment of the impact of forest management intensity on biodiversity in temperate forests.

A comparison between natural forests and reforested lands in terms of runoff generation potential and hydrologic response (case study: Kasilian Watershed)

Afforested lands are different from natural forests in terms of hydrologic conditions, runoff generation potential, and sediment generation rate. These differences emerge due to changes in soil structure and vegetation density, litter amount, trees heights, and so on. In this study, a comparison has been made between natural forests and afforested lands in Kasilian &amp;ndash; a watershed located in Mazandaran province, Northern Iran. To achieve this purpose, harmonious units have been defined by overlay analysis of these layers in GIS environment: slope, aspect, Digital Elevation Model (DEM) and soil. Then, the location of couple plots was defined by field studies in the harmonious units. The plot locations were selected in a way that runoff generation was a function of tree species and tree conditions, assuming that rainfall intensity is equal in all areas. Initial loss and runoff volume were measured in even plots after rainfall. Then, the initial loss parameter in a rainfall-runoff model was applied to compare runoff volume and peak discharge in the afforested lands and natural forests. The rainfall-runoff model was presented using GIS and HEC-HMS model. The results showed that reforested lands have lower infiltration, lower initial loss, and higher runoff due to lower density, canopy, litter, and soil compaction. Furthermore, the runoff generation potential of reforested lands is several times higher than that of natural forests.

Tree girdling affects the soil microbial community by modifying resource availability in two subtropical plantations

We used tree girdling and phospholipid fatty acid (PLFA) analysis to evaluate the effect of nutrient availability and rhizodeposition on soil microbial community composition in two plantations (Acacia crassicarpa and Eucalyptus urophylla) in subtropical China. The magnitude of the girdling effect was also evaluated as a function of tree species and time after girdling (2 months vs. 9 months). In both plantations, tree girdling reduced the concentration of fungal PLFAs and increased the concentration of bacterial PLFAs with a consequent decrease in the fungi/bacteria ratio, but did not affect the concentration of total PLFAs. Tree girdling affected the concentration of gram-negative PLFAs and the ratio of gram-positive bacteria to gram-negative bacteria at 9 months but not at 2 months after girdling. The ratio of cy17:0 to 16:1ω7c was increased by girdling of A. crassicarpa, indicating a stressful and nutrient-deficient habitat for soil microorganisms, but was inconsistent for girdling of E. urophylla. In the A. crassicarpa plantation, responses to girdling for most microbial groups were associated with changes in dissolved organic carbon (DOC), dissolved organic nitrogen (DON), the ratio of carbon to nitrogen, and soil pH. In the E. urophylla plantation, responses to girdling were associated with changes in DON, DOC, and NO3−-N. These results confirm that (i) recent photosynthates allocated belowground affect soil C and N availability and therefore greatly affect microbial community composition in subtropical plantations; (ii) the magnitude of the tree girdling effect increases with time after girdling and differs between plant species; and (iii) soil microbial communities are closely linked to vegetation types and plant C allocation.

Physical and Biological Responses of Forests to Tropical Cyclones Affecting the United States Atlantic Ocean and Gulf of Mexico Coasts

Problem Statement: Natural resources within the southern United States have repeatedly been subjected to the impact of tropical cyclones. While the frequency of tropical cyclones hitting either coast varies from year to year, it is crucial for natural resource managers and land owners to be prepared for the damage resulting from such storms. The goal of this review paper is to synthesize previous research and assess how hurricanes impact coastal forests. Approach: In order to understand the impact on forests in this region, an extensive literature review was preformed. The literature review focused primarily on the southern United States’ forests but included information from other areas that was pertinent in understanding the impact of strong wind events on forests. Results: Although the literature is not entirely consistent in arriving at factors that can be used to describe or predict potential damage to forests, a number of trends were obvious. Forest damage was found to be a function of tree species, proximity to the eye of the hurricane, stand and site characteristics, species-specific responses to storm surges, and topographic exposure. Each of these factors was found to be critical in developing and understanding potential hurricane damage to forest and wildlife values. Conclusions/Recommendations: Such a review paper was found to be a valuable tool for informing natural resource managers and forest land owners of the potential impacts of hurricanes on the forest of the southern United States. This information will help land managers develop a response plan related to hurricane damage.

Disturbance effects of hurricane Hugo on a pristine coastal landscape: North Inlet, South Carolina, USA

Despite its intensity and landfall at high tide, Hurricane Hugo (22 Sept. 1989) had only a modest impact on the geomorphology of the undeveloped coastal landscape at North Inlet, South Carolina. Pre- and post-Hugo aerial photographs (April 1987 and October 1989) showed no change in the salt-marsh creek network, nor could changes be seen in the size or shape of sand bars within the creeks. Several new, small washover fans formed on the adjacent barrier islands. These lobate fans extend 50 to 100 m from the dune line into the back barrier area and are deposited on older but recently formed fans in areas where the islands are thin and devoid of large shrubs and trees. Hugo's failure to have a more dramatic geomorphic effect was probably related to the rapid approach of the storm along a path perpendicular to the coast. This allowed minimal time for the surge to build and for wave attack to modify the shoreface. In contrast, the nearby coastal forest experienced extensive wind damage as well as tree mortality due to soil salinization by the surge. Wind damage was a function of tree species, diameter and soil type. The most severe damage occurred in mixed bottomland hardwood sites on Rutledge (sandy, silicious, thermic Typic Humaquepts) soils. Salt-induced foliage discoloration and defoliation became fully evident in the surge-inundated area by January 1990. Above-normal salt concentrations were found in shallow groundwater samples from sites up to the 3.0-m contour (MSL). Salt concentrations generally decreased inland from the forest-marsh boundary and with the passage of time. Trees standing along the forest-marsh boundary and in swales suffered the most severe salt-induced mortality. As of June 1991, new understory vegetation and pine seedlings appeared to be flourishing in the salt-affected area. Salinization also mobilized ammonium from soil storage as a result of ion exchange with seawater cations and disruption of nitrogen cycling processes. There was a virtual absence of insects and terrestrial vertebrates in the surge-affected forest immediately following Hugo. Flying insects and birds were the first to return but six months after Hugo, the abundance of reptiles and amphibians remained significantly lower than populations observed prior to the storm. Scouring and high salinity had a catastrophic effect on benthic invertebrates in the blackwater streams of the forest. Population density dropped by 97% and biomass declined from 542 mg dry mass·m −2 to only 2.0 mg dry mass·m −2. The community recovered quickly, however, as density and biomass returned to pre-storm levels in three and six months, respectively.

Use of Tree Growth Regulators at Potomac Edison

A production tree growth regulator program was initiated at Potomac Edison in July 1 986. The decision to implement the program was based on information gathered in a research project. The project results show that injection time is a function of tree species and season of year. Results of injection vary with season of year and tree species.