Amount Of Coarse Woody Debris Research Articles

Long-term changes in coarse woody debris abundance in three Appalachian headwater streams with differing best management practices

IntroductionTimber harvests influence coarse woody debris (CWD) dynamics both initially and long-term—contributing a significant amount of CWD as slash immediately after harvest, but also removing some or all of the mature trees necessary to produce CWD over time. Whereas shelterwood and other similar timber harvest systems retain varying amounts of the overstory, preserving CWD production after harvest, commercial clearcutting essentially eliminates sources of fresh CWD until regenerating trees are large enough to contribute CWD through fallen limbs or trunks, often decades after harvest. Forestry best management practices (BMPs) are critical for reducing the water quality impacts of timber harvest, but their effects on riparian and stream CWD are not well understood.MethodsThe current project explores CWD dynamics (surveyed in 2001, 2004, 2009, and 2020) in three eastern Kentucky watersheds receiving differing timber harvest treatments in 1983: unharvested control, BMPs (clearcut with a protected streamside management zone), and no BMPs (clearcut).ResultsAnalysis of hydrology data over the period of record demonstrated significant flooding in 2004 that likely “reset” CWD in the study watersheds. Coarse woody debris volume was higher in control (3.33 m3/ha) than no BMP (1.03 m3/ha) in 2020, with CWD accumulation rates ranging from 0.039 m3/ha in the no BMP watershed to 0.19 m3/ha in the control.DiscussionWhile not significantly different, CWD volume was nominally higher in the BMP watershed than the No BMP watershed, suggesting that, in addition to their many other benefits, streamside management zones help facilitate CWD provisioning during stand initiation after a commercial clearcut harvest. Furthermore, this study suggests that provisioning of CWD may not recover after clearcut harvesting for 100 years or more.

Forest Regeneration Patterns Differ Considerably between Sites with and without Windthrow Wood Logging in the High Tatra Mountains

Our research focused on the impact of post-disturbance management on the subsequent forest stands in the territory of the High Tatra Mts. situated in the northern part of Slovakia. The field work was carried out within the post-disturbance area in 2019, i.e., 15 years after the windstorm. In total, we used data from 80 monitoring plots (MP): 40 plots situated inside the managed part and 40 in the unmanaged areas. Post-disturbance management specifically consisted of logging of wind-thrown wood; therefore, the main difference between the two areas (salvaged versus unsalvaged) was the amount of coarse woody debris (CWD) left on site. We focused on the characteristics of newly regenerated forest stands: the number of trees and tree species per MP, tree height and browsing (mostly by red deer, Cervus elaphus) were recorded as was their growth substrate, i.e., soil or CWD. Higher tree densities, larger trees as well as higher tree species richness were found at salvaged plots. In addition, more evident dominance of Norway spruce (Picea abies (L) Karst.) was recorded at unsalvaged plots. Common rowans (Sorbus aucuparia L.) were frequent at both plot types. Birch trees (Betula sp.) were very frequent at salvaged plots, while only a few birch individuals were recorded at unsalvaged ones. The proportion of trees growing on CWD was 15% at unsalvaged and 3% at salvaged plots. Trees growing on the soil contained nearly double the aboveground biomass than those on CWD. Red deer browsing was approximately two times more frequent at salvaged than unsalvaged plots. While rowan was extremely prone to browsing, spruce was damaged negligibly. These main findings could have two contradictory conclusions, the positive one being that differentiated post-disturbance management within a certain area can combine both forestry and nature conservation interests. Moreover, it can generate parallel forests with different properties that might positively influence the future stability of forest ecosystems as a whole. The negative side might be that contrasting post-disturbance management can cause an uneven distribution of red deer population and intensive browsing in areas favourable for game.

Positive interactions between great longhorn beetles and forest structure

Great longhorn beetles (GLBs) may affect forest structure, because their larvae colonize trees and create networks of cavities further exploited by other species, resulting in dead or broken branches and tree mortality. At the same time, tree size, condition and location are known to affect the likelihood of tree colonization by GLBs. Here, we study the relationship between GLBs and the structure of old-growth holm oak Mediterranean forests in Sardinia, Italy. Generalized linear models were used to relate presence of GLBs with structural parameters that can be affected by or can affect these ecosystem engineers. We found a strong positive relationship between GLBs and the number of trees with cavities, while the relationships between GLBs and the number of dead wood decaying classes, amount of coarse woody debris, stand basal area, forest canopy layer complexity were positive but weak. Overall, our results suggest that larval activity of GLBs could be responsible for increased tree cavity and dead wood formation, enhancing forest structure. On the other hand, forests with larger and older trees could be more likely to be colonized by GLBs. While it is not possible with observational studies to disentangle to what extent GLBs affect forest structure or vice versa, it seems likely that reciprocal interactions may enhance the structure of holm oak forests. Therefore, parasitism from native GLBs should be seen and understood more as a key ecological process that enhances the structure of Mediterranean holm oak forest habitats.

The effects of harvest frequency on coarse woody debris and its use by fauna

Abstract Context Forest harvest practices have the potential to alter habitat available to forest fauna. One aspect of harvesting practice that has received little research attention is the effect of multiple rotations on available habitat, and its use by fauna. Aims We examined one component of habitat that is critical to many taxa, coarse woody debris (CWD). In forests of north-eastern New South Wales, Australia, we aimed to assess whether harvest (moderate intensity for saw-logs) frequency influences CWD levels, and whether fauna activity on CWD varies with harvest frequency and with CWD attributes. Methods Using habitat surveys and camera trapping, we compared CWD quantity and quality in unharvested sites with those that had been harvested once, twice and three times, and assessed fauna use of CWD. Key results We found significantly greater volume of non-hollow CWD, and of medium-sized pieces (15–30 cm diameter), in sites harvested three times versus unharvested sites. Camera trapping showed that the activity and composition of fauna were similar across these harvest treatments. Our results also found that a broad range of fauna used a variety of logs, including large and small logs in various states of decay. Conclusions Consistent with other Australian studies, our results suggested that there are no detectable impacts of harvesting on hollow or large CWD. Further studies using radio-tracking or similar methods are needed to more comprehensively assess how CWD is used by fauna. Implications CWD was used broadly by a range of species and should be targeted for retention under ecologically sustainable forest management practices to ensure that it continues to be present in harvested landscapes. This is particularly important in places where an intensification of practices is being considered.

Coarse woody debris features of a warm temperate deciduous broad-leaved forest, northern China

Stocking and structural composition of a deciduous broad-leaved forest were determined to predict coarse woody debris quantity by quantifying the empirical relationships between these two attributes. The most ecologically significant families by stem density were Salicaceae, Betulaceae, Fagaceae, and Aceraceae. Populus davidiana was the most dominant species followed by Betula dahurica, Quercus mongolica, and Acer mono. The four species accounted for 69.5% of total stems. Numerous small-diameter species characterized the coarse woody debris showing a reversed J-shaped distribution. The coarse debris of P. davidiana, B. dahurica, and Q. mongolica mainly comprised the 10–20 cm size class, whereas A. mono debris was mainly in the 5–10 cm size class. The spatial patterns of different size classes of coarse woody debris were analyzed using the g-function to determine the size of the tree at its death. The results indicate that the spatial patterns at the 0–50 m scale shifted gradually from an aggregated to a random pattern. For some species, the larger coarse debris might change from an aggregated to a random distribution more easily. Given the importance of coarse woody debris in forest ecosystems, its composition and patterns can improve understanding of community structure and dynamics. The aggregation pattern might be due to density dependence and self-thinning effects, as well as by succession and mortality. The four dominant species across the different size classes showed distinct aggregated distribution features at different spatial scales. This suggests a correlation between the dominant species population, size class, and aggregated distribution of coarse woody debris.

Effects of species and environmental factors on browsing frequency of young trees in mountain forests affected by natural disturbances

We analyzed the effects of natural disturbances on relationships between forest regeneration and ungulate browsing. Specifically, we asked if natural disturbances affect preferences of ungulate herbivores towards tree species and size classes; and how local and landscape-scale environmental factors affect spatial patterns of ungulate browsing in disturbed forest ecosystems. Our research was conducted in the Tatra National Park, a mountain range affected by large-scale intense disturbances over the last few decades. We used field data collected in a network of regularly distributed 600 circular sample plots where young trees were recorded and examined for browsing signs. Using forage ratio, the Ivlev’s electivity index and chi square tests, we found that the preferences of wild ungulates were similar to those known from undisturbed forests. Our analyses showed preference for deciduous species, especially rowan, sycamore maple and goat willow. The most common species, Norway spruce was strongly avoided by browsing ungulates. Short saplings from 0.5 m to 1.3 m tall were the most browsed size class. Effects of environmental variables on browsing were analyzed with zero-inflated negative binomial models. The occurrence of browsing was positively related to the total number of young trees and mature tree mortality. This suggests the influence of disturbances on spatial patterns of browsing pressure. The browsing frequency (number of browsed individuals per plot) was affected by mature tree mortality and densities of young palatable trees, including silver fir, sycamore maple and rowan. Elevation, geology, soil type, and potential solar radiation did not show any significant influence on the browsing frequency. Browsing frequency was also positively related to the distance to roads and hiking trails, indicating the role of human pressure upon the behaviour of ungulate herbivores. In addition, we analyzed the effects of accumulation of coarse woody debris (CWD) on browsing frequency and found this relationship to be nonlinear. Analysis for all tree species revealed that at low levels of CWD, the browsing frequency increased with CWD accumulation as a consequence of forest regeneration. However, a large amount of CWD (>25 m3) resulted in a decrease in browsing frequency, and this relationship was species-specific.

Influence of Forest Management Activities on Forest Fire Fuels in Coarse Woody Debris for Pinus densiflora Stands in South Korea

본 연구는 산불에 취약한 대표 침엽수종인 소나무 임분을 대상으로 산림시업이 고사율과 고사목 연료량에 미치는 영향을 분석하고자 하였다. 이를 위해 제 6차 국가산림자원조사 고사목 자료 중 시업지 소나무림 40plots, 비시업지 소나무림 14plots를 분석자료로 사용하였다. 시업지 임분의 고사율은 약 1.6%, 비시업지 임분의 고사율은 5.3%으로 나타났으며, 산불확산에 영향을 미치는 고사목의 산불연료량은 비시업지 임분이 2.2TOE ha-1으로 시업지 임분 1.6TOE ha-1에 비해 높게 나타났다. 부후등급별로 비교한 결과, 산불에 가장 취약한 고사Ⅰ등급이 차지하는 비율은 시업지 22%, 비시업지 29%으로 비시업지 임분에서 더 높은 고사목 분포를 보이고 있었으며, 부후도가 높아질수록 비시업지 임분이 시업지 임분에 비해 차지하는 연료량이 상대적으로 더 높게 나타났다. 따라서, 비시업지임분에서 지표화에서 수관화로 확산시키는 역할을 하는 고사목이 차지하는 연료량이 더 높게 추정됨에 따라 산불확산위험성이 더 높을 것으로 판단된다.The objective of this study is to estimate the effects of forest management activities on mortality rates and fuel characteristics of coarse woody debris for Pinus densiflora stands in South Korea. This study used 40 managed plots and 14 unmanaged plots from the 6th National Forest Inventory plots. The results indicated that mortality rates of the managed stands were about 1.6% while those of the unmanaged stands were about 5.3%. The amount of coarse woody debris affecting forest fire spread was 2.2TOE ha⁻¹ for the unmanaged stands, while 1.6TOE ha⁻¹ for the managed stands. According to the results of decay class analysis, the ratio of decay class I, the most vulnerable to forest fires, was 22% for the managed stands while 29% for the unmanaged stands. Therefore, the unmanaged pine stands had higher fuel loads for forest fire in terms of coarse woody debris and higher decay rates than the managed Pinus densiflora stands. This information could be very useful to understand forest fire fuels in coarse woody debris for Pinus densiflora stands in South Korea.

Recovery and allocation of carbon stocks in boreal forests 64 years after catastrophic windthrow and salvage logging in northern Japan

To mitigate the negative effects of climate change, it is necessary to conserve carbon stocks in forests. Typhoons fell many standing trees and generate a substantial amount of coarse woody debris (CWD). In boreal forests, CWD contributes to maintaining carbon stocks for a long time after a disturbance because the decomposition rate of CWD is relatively low. We know that salvage logging after a disturbance tremendously decreases the forest carbon stock over the short term after logging but know little about its long-term effects. We targeted a catastrophic windthrow caused by a super typhoon in 1954 in boreal forests in northern Japan and estimated the long-term effects of salvage logging after the windthrow on the above- and belowground carbon stocks by comparing old-growth forests with low damage from the super typhoon in 1954 or any subsequent typhoons (OG), forests damaged by the typhoon with remaining CWD (i.e., windthrow, WT), and forests damaged by the typhoon followed by salvage logging (WT + SL). The CWD carbon stock of decay class 5 (i.e., the most decayed CWD) in WT was significantly larger than that in OG and WT + SL, suggesting that the CWD in decay class 5 in WT had been generated by the typhoon 64 years ago, and the negative effect of salvage logging on the carbon stock still remains apparent in the CWD carbon stock of decay class 5. The carbon stock of the organic (O) layer in WT was larger than that in WT + SL, probably because of three factors: (1) the slower decomposition rate of fallen leaves and twigs of conifers than broadleaves, as conifer litter is abundant in WT; (2) greater carbon transition from the CWD to the O layer in WT; and (3) the occurrence of a lower decomposition rate in the O layer in WT. However, the total carbon stock in WT + SL has almost recovered to the level of that in WT within the last 64 years. The carbon stocks of broadleaves that grew rapidly after the disturbance and the newly accumulated dead trees generated throughout the stand developmental process might contribute to the recovery of carbon stock in WT + SL. These results indicate that salvage logging affects the allocation of carbon in the forest even after 64 years after a catastrophic windthrow, although there was no large difference in total carbon stock.

Natural and human-related determinants of dead wood quantity and quality in a managed European lowland temperate forest

Much is known about the minimum thresholds for dead wood that would ensure the persistence of saproxylic organisms and maintain the overall biodiversity of forest ecosystems, but reaching those thresholds is still a challenge in forests where nature conservation is not the sole goal (e.g., Natura 2000 forests managed for timber). Understanding what determines the quantity and quality of dead wood in managed forests is a prerequisite for developing methods to increase its retention without decreasing a forest’s production. We surveyed the volume, number, stage of decay, and species identity of standing and lying coarse woody debris (CWD) in 183 stands in a complex of lowland Natura 2000 forests in southern Poland, and then determined the relationships between these parameters and tree stand structure, intensity of previous silviculture interventions, accessibility of terrain, and local community impact. CWD volume varied from 0.1 to 66.3 m3 ha−1 (average 6.9 m3 ha−1), which is up to several times less than the recommended thresholds. Large-sized CWD and CWD of species known to support rich communities of saproxylic organisms (e.g., Carpinus betulus) were clearly underrepresented. Wood of economically less valuable species was often left in the forest, which boosted the diversity of CWD microhabitats. CWD quantity and quality was significantly shaped by both natural and human-related factors. Among the latter, harvesting intensity and proximity to human settlements affected CWD negatively, while terrain-related difficulties (distance to roads, watercourse density) affected it positively. Surprisingly, the site accessibility effect was important even though the studied area is level and covered by a dense road network. The results suggest that cost-effective CWD management plans for Natura 2000 forests, or, more broadly, multifunctional forests, should discourage some practices accompanying timber harvesting (e.g., fragmenting of pieces of aged CWD), promote practices that positively affect CWD (e.g., not harvesting low-value timber), and set aside small areas to accelerate CWD retention. These things should be done wherever their effects are unlikely to be reversed, i.e., at sites difficult for forestry vehicles to access and away from human settlements.

Diversity patterns of Coleoptera and saproxylic communities in unmanaged forests of Mediterranean mountains

Abstract Beetle communities are excellent indicators to monitor biodiversity in forest environments. The most common indicators monitored for assessing the effectiveness of the sustainable forest management measures are deadwood amount, forest structure, and microhabitat traits. In Mediterranean mountain forests, however, the relationships between stand-level attributes and species diversity indicators have been still poorly studied. We have investigated the patterns of species diversity of beetle communities in relation to stand structural traits in two unmanaged forests located in central Apennines (Italy). The two forest stands are characterized by different tree species composition and management history. The experimental area extends over approximately 300 ha, within which 50 circular plots of 530 m2 were sampled for each studied forest. Coleoptera were collected using window flight traps and emergence traps on decaying deadwood. We evaluated i) the differences in species diversity (richness, Shannon diversity and Simpson diversity) between the two forests and ii) the beetle Shannon diversity and composition in relation to selected forest variables, with a particular focus on saproxylic species. Principal Component Analysis followed by rarefaction analysis were applied to examine differences in species diversity. Within each forest stand, a Boosted Regression Tree model and a Non-Metric Multidimensional Scaling were performed to relate the species Shannon diversity and community assemblages to the forest structural attributes. Results revealed how these forest structural attributes have a fundamental role in influencing the diversity of Coleoptera and their assemblages. Forest vertical heterogeneity, snag volume and tree dominance were the most important variables for saproxylic assemblages in these Mediterranean mountain forests, while the amount of coarse woody debris positively affected the overall beetle diversity and that of saproxylic species. At stand level, differences in species diversity were mainly driven by tree composition, probably indicating that food resources, determined by tree species, are of primary importance in determining species assemblages and beetle diversity in these forests; while at plot level, we found that the variables, which drove species composition and beetle diversity, varied between the two forests. This study provides the basis for the integration of independent biodiversity indicators in sustainable solutions for the conservation of unmanaged forests in Mediterranean mountain systems.

Habitat suitability models of Korean crevice salamander (Karsenia koreana) at forested area in Daejeon metropolitan city, Republic of Korea

ABSTRACT We studied the relationship between the Korean crevice salamander (Karsenia koreana) and several environmental factors, thereby contributing to the basic ecological knowledge required for the future conservation of salamander populations. The aims of this study were to derive a habitat suitability model for K. koreana using presence-absence data for the species and habitat factor information, and to identify the environmental factors that greatly influence the occurrence of K. koreana. In 2015 and 2017, 179 survey plots within five forested areas of Daejeon Metropolitan City were surveyed for the presence of K. koreana using both line transect surveys and time-constrained surveys. Three categories of environmental factors were measured for each habitat. Habitat suitability model of K. koreana was derived from this information, and factors that significantly affected the presence of K. koreana were determined. The presence of K. koreana was detected at 77 survey plots within the five forested areas. In terms of forest structural factors, the amount of coarse woody debris and the percentage cover of various substrate types were found to be major factors determining the occurrence of K. koreana. Leaf litter depth and pH were found to be important soil condition factors, and water temperature, dissolved oxygen, and channel width were the major water condition factors. These factors need to be referenced and utilized for the future conservation of the species, and extensive studies are needed to identify further correlations among these factors.

Legacy effects of logging on boreal forest understorey vegetation communities in decadal time scales in northern Finland

We followed how forest thinning, repeated twice during a period of 93 years, altered understorey plant community composition, affected the succession of forest understorey vegetation and the accumulation of logs in the long-term. The study was carried out in northern Finland by resampling 20 permanent experimental plots, established after a wildfire in 1920. Understorey vegetation was inventoried in 1961, 1986 and 2013 with forest thinning treatments done in 1953 and 1987, using four and three different harvesting intensities, respectively. We found succession to override the effects of forest logging until the latest study period (2013). We observed negligible long-term effects of logging on understorey communities during the two mid-successional stages (1961, 1986), when the forest was 41 and 66 years old respectively. The impacts of logging on understorey vegetation were strongest in the latest successional stage (2013), the forest being at the age of 93 years. In the latest successional stage (2013) logged plots had less coarse woody debris than unlogged plots. Forest management thus influenced the key feature for forest biodiversity and potential habitats for endangered species. These findings are of major interest since the studies of long-term impacts of less intensive forest management practices are scarce. Our results suggest that in addition to possible immediate impacts, harvesting treatments have legacy effects (subtle or delayed inherited effects of forestry in the past) that influence the forest understorey vegetation community composition and the amount of coarse woody debris. This finding deserves special attention when planning of species conservation, multiple use of forests and sustainable forestry.

Assessment of Western taiga habitat in Lahemaa National Park, Estonia

Abstract Diverse structural elements play an important role in sustaining biodiversity in old-growth forests. Therefore, it is important to have thorough knowledge about these habitats and their condition in protected areas. Metsakorralduse Büroo OÜ conducted a large-scale Natura 2000 forest habitat inventory that covered 60% of Lahemaa National Park (LNP) area. Western taiga habitat data (7,191 ha) from this inventory was used for analysis of forest stages. The data was grouped according to stand classes by total area and these classes were compared by deadwood occurrence and relative density. For more precise evaluation of coarse woody debris (CWD) we used 27 sample plots from the Estonian Network of Forest Research Plots (ENFRP) located in LNP. The biggest areas of Western taiga habitat were covered by mature and old stages. CWD occurrence (over 5 m3ha−1 of snags and logs) by habitat representativeness is higher in old and natural forest classes. This logical result is overshadowed by the outcome that the CWD was not substantially present on 32% of the area in the old-growth forest class. This indicates that these areas lack the potential of biological legacies to provide critical niche habitats for different species. The study shows that the CWD quantity in Estonian conditions is similar to that reported in previous studies in this region, but because many of the older forest stage classes do not have any CWD present, these areas should include ecological restoration practices in their conservation planning. By creating snags, logs and gaps in these areas, we are able to create better structural variability and include wood into different decay processes.

Comparing the Quantity and Structure of Deadwood in Selection Managed and Old-Growth Forests in South-East Europe

The knowledge about the impact of selection silviculture on deadwood components is fairly scarce. This study compared two Dinaric old-growth forests (OGFs) with adjacent managed forests (MFs) in which the single-tree selection system has been applied for a century. The comparisons were made in terms of the current amounts of coarse woody debris (CWD), distribution of its decay stages, and diameter structure of different CWD types (snags, logs, stumps). The relationship between the volume of live and dead trees was also examined. In both OGFs and MFs, the most snags were found in the third decay stage, while the volume of logs and stumps increased from the first to fifth decay class. The study showed the clear advantage of OGFs over adjacent selection MFs in terms of CWD volume, whereas the basal area of live trees and growing stock were not always reliable indicators for distinguishing between MFs and OGFs. The diameter distribution of individual CWD types (snags, logs, stumps) also differed significantly between selection MFs and OGFs in all tested pairs. This fact, along with the significant differences in CWD volume, indicates that selection silviculture should be amended to incorporate practices that ensure more natural management of deadwood components.

Invertebrate community response to coarse woody debris removal for bioenergy production from intensively managed forests.

Increased market viability of harvest residues as forest bioenergy feedstock may escalate removal of coarse woody debris in managed forests. Meanwhile, many forest invertebrates use coarse woody debris for cover, food, and reproduction. Few studies have explicitly addressed effects of operational-scale woody biomass harvesting on invertebrates following clearcutting. Therefore, we measured invertebrate community response to large-scale harvest residue removal and micro-site manipulations of harvest residue availability in recently clearcut, intensively managed loblolly pine (Pinus taeda) forests in North Carolina (NC; n=4) and Georgia (GA; n=4), USA. We captured 39,794 surface-active invertebrates representing 171 taxonomic groups using pitfall traps situated among micro-site locations (i.e., purposefully retained piles of hardwood stems and piles of conifer stems and areas without coarse woody debris in NC; windrows and no windrows in GA). Micro-site locations were located within six, large-scale treatments (7.16-14.3ha) in clearcuts. Large-scale treatments represented intensive harvest residue removal, 15% and 30% harvest residue retention, and no harvest residue removal. In NC, ground beetles (Coleoptera: Carabidae) and crickets (Orthoptera: Gryllidae) were three times more abundant in treatments with no harvest residue removal than those with the most intensive harvest residue removal and were reduced in treatments that retained 15% or 30% of harvest residues, although not significantly. Invertebrate taxa richness was greater at micro-site locations with retained hardwood and pine (Pinus spp.) harvest residues than those with minimal amounts of coarse woody debris. In both states, relative abundances of several invertebrate taxa, including cave crickets (Orthoptera: Rhaphidophoridae), fungus gnats (Diptera: Mycetophilidae and Sciaridae), millipedes (Diplopoda), and wood roaches (Blattodea: Ectobiidae), were greater at micro-site locations with retained harvest residues than those with minimal coarse woody debris. Intensified woody biomass harvesting without retention of ≥15% of harvest residue volume may reduce invertebrate taxa richness and abundances of some key invertebrate taxa in regenerating stands. Further, harvest residue management during and after woody biomass harvesting may be an important consideration for maintaining invertebrate diversity and conserving invertebrates that are influential in the maintenance of ecosystem function and integrity in young forests.

Tree composition and abundance patterns differ in two watersheds of Forest Park, a large Pacific Northwest urban forest

We compared differences in patterns of tree species composition and abundance in a set of six permanent research plots designated in paired watersheds in a large forested park in Portland, Oregon: one proximal to the urban area and the other proximal to rural areas. All were established in mixed conifer-deciduous stands with similar tree age classes, orientation, topography and other environmental variables. One old-growth plot reference was included in each watershed. The urban plots have experienced periodic disturbances and are continually subjected to continual low-impact disturbances. The urban plots, in contrast to rural plots and to their reference old-growth plots, showed significant differences in tree species composition and ages, sapling numbers, and amount of coarse woody debris. NMDS and nonparametric ANOVA revealed the urban plots as having the greatest ecological distance from all other plots. Soil disturbance, lack of O- and A-horizons, and coarse woody debris were disturbance indicators. Given current patterns of regeneration, the urban plots will be dominated in the future by hardwood species. This projection, when compared with the proximate old-growth patch and with historical records for the urban end of the park, has no historic antecedent. These conclusions are concurrent with findings for other urban forests, where early successional species dominate over long periods of time. The described ecological trends, especially with the domination of invasive species, reflect the urban condition of the forest and constitute a novel state.

The historical disturbance regime of mountain Norway spruce forests in the Western Carpathians and its influence on current forest structure and composition

In order to gauge ongoing and future changes to disturbance regimes, it is necessary to establish a solid baseline of historic disturbance patterns against which to evaluate these changes. Further, understanding how forest structure and composition respond to variation in past disturbances may provide insight into future resilience to climate-driven alterations of disturbance regimes.We established 184 plots (mostly 1000m2) in 14 primary mountain Norway spruce forests in the Western Carpathians. On each plot we surveyed live and dead trees and regeneration, and cored around 25 canopy trees. Disturbance history was reconstructed by examining individual tree growth trends. The study plots were further aggregated into five groups based on disturbance history (severity and timing) to evaluate and explain its influence on forest structure.These ecosystems are characterized by a mixed severity disturbance regime with high spatiotemporal variability in severity and frequency. However, periods of synchrony in disturbance activity were also found. Specifically, a peak of canopy disturbance was found for the mid-19th century across the region (about 60% of trees established), with the most important periods of disturbance in the 1820s and from the 1840s to the 1870s. Current stand size and age structure were strongly influenced by past disturbance activity. In contrast, past disturbances did not have a significant effect on current tree density, the amount of coarse woody debris, and regeneration. High mean densities of regeneration with height >50cm (about 1400 individuals per ha) were observed.Extensive high severity disturbances have recently affected Central European forests, spurring a discussion about the causes and consequences. We found some evidence that forests in the Western Carpathians were predisposed to recent severe disturbance events as a result of synchronized past disturbance activity, which partly homogenized size and age structure and made recent stands more vulnerable to bark beetle outbreak. Our data suggest that these events are still part of the range of natural variability. The finding that regeneration density and volume of coarse woody debris were not influenced by past disturbance illustrates that vastly different past disturbance histories are not likely to change the future trajectories of these forests. These ecosystems currently have high ecological resilience to disturbance. In conclusion, we suggest that management should recognize disturbances as a natural part of ecosystem dynamics in the mountain forests of Central Europe, account for their stochastic occurrence in management planning, and mimic their patterns to foster biodiversity in forest landscapes.

Acumulación De Restos Lignino-Celulósicos (Necromasa) En Un Bosque Templado De Antiguo Crecimiento Dominado Por Nothofagus En El Centro- Sur De Chile

Coarse woody debris (CWD) are the necromass in wooded environments and comply with various ecosystems functions, such as seedling nursery, habitat other organisms, store carbon (C) and nutrients, etc.. Volume, necromass, and decay states of CWD dead in an old-growth temperate (OGTF) forest in Puyehue National Park, South-Central Chile were evaluated. In 10 plots of 900 m2 CWD was quantified (≥ 10 cm diameter), whose necromass classified using a scale of five categories/stages of decay, necromass (1 = lowest and 5 = highest degradation). The average forest density was 299 trees ha-1, 112 m2 ha-1 of basal area, and 2.395 m3 of stem volume. The upper arboreal stratum was dominated by N. betuloides. The greatest amount of CWD belonged to N. betuloides (95,2%), where logs (52,7%) and branches (35%), plant structures were present in greater numbers. The bulk of necromass found in advanced states of decomposition (level 4 and 5) with 56,5% and 34,1%, respectively. It was determined that the CWD volume was 632 m3 ha-1, representing a necromass of 321.5 Mg ha- 1. These results demonstrate that the old-growth temperate forests of southern Chile are significant reserves of coarse woody debris, which contributes to the biogeochemistry of these complex and remote ecosystems.

Effects of stump harvesting on soil C and N stocks and vegetation 8–13 years after clear-cutting

Effects of stump harvesting on coarse woody debris (CWD), soil and vegetation were investigated 8–13years after clear-cutting of eight forest stands located at two sites, Honkola and Haukilahti, in Central Finland. Norway spruce (Picea abies) was the dominant tree species in the harvested stands. Four of the stands were subjected to mounding and four were stump-harvested. Logging residues were removed at harvest from all eight stands.The amount of CWD remaining after stump harvesting was estimated from basal area of remaining stumps, diameter and length of logs and by weighing smaller pieces of dead wood. Moss and field layer vegetation cover was estimated by a point-intercept method and the diameter of young trees was measured to estimate basal area. Soil carbon and nitrogen stocks and pH were determined in the humus layer and down to 25cm depth in the mineral soil. The degree of soil disturbance was visually assessed in the field.Basal area measurements on remaining stumps suggested that about 75% of the stumps had been removed from the stump-harvested stands, which is a typical stump harvesting rate in Finland. The amount of remaining stumps and root biomass was significantly lower in stump-harvested stands than in stands where stumps had been retained, whereas differences between mounding and stump harvesting were not significant for the other types of CWD. Stump harvesting had no significant effect on the cover of field layer species, total moss cover or vegetation composition. Total stem density was almost twice as high in stump-harvested stands as in stands where stumps were not harvested, due to significantly higher stem density of Betula pendula Roth., whereas no effect was observed on the basal area of the other tree species. No significant treatment effect on soil carbon and nitrogen stocks or on degree of soil disturbance was detected, but the higher density of Betula indicates higher exposure of mineral soil during the years following stump removal. In conclusion, stump harvesting seems to promote natural establishment of Betula seedlings, but does not change tree productivity.

Resources of dead wood in the municipal forests in Warsaw

Abstract Dead wood plays an important role for the biodiversity of forest ecosystems and influences their proper development. This study assessed the amount of coarse woody debris in municipal forests in Warsaw (central Poland). Based on the forest site type, dominant tree species and age class, we stratified all complexes of the Warsaw urban forests in order to allocate 55 sample plots. For these plots, we determined the volume of dead wood including standing dead trees, coarse woody debris and broken branches as well as uprooted trees. We calculated the amount of dead wood in the distinguished site-species-age layers and for individual complexes. The volume of dead matter in municipal forests in Warsaw amounted to 38,761 m3, i.e. 13.7 m3/ha. The obtained results correspond to the current regulations concerning the amount of dead organic matter to be left in forests. Only in the Las Bielański complex (northern Warsaw) volume of dead wood is comparable to the level observed in Polish national parks or nature reserves, which is still far lower than the values found for natural forests. In general, municipal forests in Warsaw stand out positively in terms of dead wood quantity and a high degree of variation in the forms and dimensions of dead wood.