Significant and persistent impact of timber harvesting on soil microbial communities in Northern coniferous forests

Forest ecosystems have integral roles in climate stability, biodiversity and economic development. Soil stewardship is essential for sustainable forest management. Organic matter (OM) removal and soil compaction are key disturbances associated with forest harvesting, but their impacts on forest ecosystems are not well understood. Because microbiological processes regulate soil ecology and biogeochemistry, microbial community structure might serve as indicator of forest ecosystem status, revealing changes in nutrient and energy flow patterns before they have irreversible effects on long-term soil productivity. We applied massively parallel pyrosequencing of over 4.6 million ribosomal marker sequences to assess the impact of OM removal and soil compaction on bacterial and fungal communities in a field experiment replicated at six forest sites in British Columbia, Canada. More than a decade after harvesting, diversity and structure of soil bacterial and fungal communities remained significantly altered by harvesting disturbances, with individual taxonomic groups responding differentially to varied levels of the disturbances. Plant symbionts, like ectomycorrhizal fungi, and saprobic taxa, such as ascomycetes and actinomycetes, were among the most sensitive to harvesting disturbances. Given their significant ecological roles in forest development, the fate of these taxa might be critical for sustainability of forest ecosystems. Although abundant bacterial populations were ubiquitous, abundant fungal populations often revealed a patchy distribution, consistent with their higher sensitivity to the examined soil disturbances. These results establish a comprehensive inventory of bacterial and fungal community composition in northern coniferous forests and demonstrate the long-term response of their structure to key disturbances associated with forest harvesting.     

The response of mammals to forest fire and timber harvest in the North American boreal forest

1. This paper reviews and compares the effects of forest fire and timber harvest on mammalian abundance and diversity, throughout successional time in the boreal forest of North America. 2. Temporal trends in mammal abundance and diversity are generally similar for both harvested and burned stands, with some differences occurring in the initiation stage (0–10 years post disturbance). 3. Small mammals and ungulates are most abundant immediately post disturbance, and decrease as stands age. Lynxes and hares utilize mid-successional stands, but are rare in young and old stands. Bats, arboreal sciurids and mustelids increase in abundance with stand age, and are most abundant in old growth. 4. Substantial gaps in the data exist for carnivores; the response of these species to fire and harvest requires research, as predator–prey interactions can affect mammal community structure in both early and late successional stages. 5. The lack of explicit treatment of in-stand forest structure post disturbance, in the reviewed literature made comparisons difficult. Where forest structure was considered, the presence of downed woody material, live residual trees and standing dead wood were shown to facilitate convergence of mammal communities to a pre-disturbance state for both disturbance types. 6. Mammalian assemblages differed considerably between successional stages, emphasizing the importance of maintaining stands of each successional stage on the landscape when implementing forest management strategies.     

Long-term effects of fire on ant communities (Hymenoptera: Formicidae) in Pinus brutia forests of south-western Turkey

We studied how forest fire affects the structure of ant communities in the long term and how microhabitat variables that influence communities of ants in different succession stages change. For this purpose, we selected five sites burnt 3 to 26 years prior to the study and a control site unburnt for at least 50 years. Sampling of ants was conducted in four pit-fall traps in four transects in three replication plots at every successional site and in two plots at the control site. Microhabitat variables regarding the vegetation structure and litter layers were recorded and related to the abundances of ants. The results show that subshrubs, leaves, and needles were the most important microhabitat variables that affected the ant communities. In certain ant genera, significant changes depending upon successional gradient were determined. While the genera Aphaenogaster and Cataglyphis had non-linear relationships with successional gradient, negative linear relationships were found in Crematogaster and Prenolepis. Messor is the only genus caught in high numbers in the earliest successional stage. It showed a decrease with successional gradient. Significant changes in ant communities along the successional gradient were associated with the characteristics of vegetation and the litter layer.     

Effect of variation in forest harvest intensity on winter occupancy of Barred Owls and Eastern Screech‐Owls in deciduous forests of the east‐central United States

Responses of resident owls to changes in forest structure associated with forest management in the Central Hardwood Forest Region of the United States have not been widely studied. We estimated the winter occupancy of Barred Owls (Strix varia) and Eastern Screech‐Owls (Megascops asio) in forests with varying levels of timber harvest in southern Indiana. Surveys were conducted from 2009 to 2013 in two state forests undergoing active harvesting, a national forest unit with little recent harvesting, and a forested state park with no harvesting since about 1940. We hypothesized that 1) Barred Owl occupancy would vary inversely with harvesting intensity because they prefer mature forest, 2) Eastern Screech‐Owl occupancy would be greatest in the actively managed forests given their affinity for edge habitat, and 3) Eastern Screech‐Owls would avoid Barred Owl sampling areas and, thus, Barred Owl predation. Barred Owl occupancy was lowest in the non‐harvested state park relative to other areas, and Eastern Screech‐Owls were less likely to co‐occur in Barred Owl sampling areas. We found no evidence that forest management was inversely related to Barred Owl occupancy or that active edge creation associated with forest management increased the magnitude of Eastern Screech‐Owl occupancy. Reduced rates of Barred Owl occupancy in the state park may have resulted from high levels of recreational activity, whereas increased rates of Eastern Screech‐Owl occupancy in the park may have resulted from ample hunting opportunities in an environment with fewer Barred Owl predators. Recreational activity, prey availability, and interspecific antagonism likely have greater influences than timber harvesting on winter site occupancy of these owls in our study areas.     

Corticolous bryophytes in microphyll fern forests of south-east Queensland: distribution on Antarctic beech (Nothofagus moorei)

Fine-scale variation in corticolous bryophyte communities was examined on the lower trunk of Antarctic beech (Nothofagus moorei) trees within microphyll fern forests of south-east Queensland. Analysis of the variation revealed that the composition and structure of the community altered with both the height above ground level and the direction of exposure. Patterns of distribution were thought to primarily reflect changes in the moisture availability on and around the basal trunk of Nothofagus moorei trees and the degree of desiccation tolerance exhibited by the various taxa.     

Initial responses of rove and ground beetles (Coleoptera,Staphylinidae, Carabidae) to removal of logging residues following clearcut harvesting in the boreal forest of Quebec,Canada

Increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. Here we evaluate the initial changes in the abundance, species richness and community composition of rove (Staphylinidae) and ground beetles (Carabidae), immediately following 1) stem-only harvesting (SOH), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (WTH), in which stems, tops and branches are removed in mature balsam fir stands in Quebec, Canada. Beetles were collected throughout the summer of 2011, one year following harvesting, using pitfall traps. Overall catch rates were greater in uncut forest (Control) than either stem-only or whole-tree harvested sites. Catch rates in WTH were greater than SOH sites. Uncut stands were characterized primarily by five species: Atheta capsularis, Atheta klagesi, Atheta strigosula, Tachinus fumipennis/frigidus complex (Staphylinidae) and to a lesser extent to Pterostichus punctatissimus(Carabidae). Increased catch rates in WTH sites, where post-harvest biomass was less, were attributable to increased catches of rove beetles Pseudopsis subulata, Quedius labradorensis and to a lesser extent Gabrius brevipennis. We were able to characterize differences in beetle assemblages between harvested and non-harvested plots as well as differences between whole tree (WTH) and stem only (SOH) harvested sites where logging residues had been removed or left following harvest. However, the overall assemblage response was largely a recapitulation of the responses of several abundant species.     

Sensitivity of managed boreal forests in Finland to climate change, with implications for adaptive management

This study investigated the sensitivity of managed boreal forests to climate change, with consequent needs to adapt the management to climate change. Model simulations representing the Finnish territory between 60 and 70 degrees N showed that climate change may substantially change the dynamics of managed boreal forests in northern Europe. This is especially probable at the northern and southern edges of this forest zone. In the north, forest growth may increase, but the special features of northern forests may be diminished. In the south, climate change may create a suboptimal environment for Norway spruce. Dominance of Scots pine may increase on less fertile sites currently occupied by Norway spruce. Birches may compete with Scots pine even in these sites and the dominance of birches may increase. These changes may reduce the total forest growth locally but, over the whole of Finland, total forest growth may increase by 44%, with an increase of 82% in the potential cutting drain. The choice of appropriate species and reduced rotation length may sustain the productivity of forest land under climate change.     

Response of tree-ring width to climate warming and selective logging in larch forests of the Mongolian Altai

Aims The Mongolian Altai is an old settlement area, which is populated by pastoral nomads since 2000–3000 years. Forests in this region (at ca. 2300 m a.s.l.) are highly fragmented and border on steppe and alpine grasslands, which are used for mobile livestock husbandry. The climate in Central Asia is warming to levels clearly above the global average, which affects the vegetation. Furthermore, the transition from planned to market economy and the decollectivization of livestock 20 years ago has strongly changed land use practices in Mongolia, especially resulting in an increase in recent logging activities. We were interested in the question how climate warming and selective logging influence the annual stem growth and the stand structure.Methods The impact of climate and land use by the pastoral nomads on the annual stem increment of more than 1800 trees of Siberian larch (Larix sibirica) was analyzed. Different groups of trees with divergent growth trends depending on the social position and stand history were identified by non-metric multidimensional scaling and analysis of similarities. Long-term trends in the annual stem increment were analyzed by establishing separate regional growth curves for trees of different age classes.Important findings Instrumental climate data substantiate an increase of temperature by 2.1°C since 1940 at constant precipitation. Trees benefit from the increased temperatures. Climate–response analysis revealed that radial stem increment was promoted by the temperature in early summer, but also high precipitation in spring and in the year before tree-ring formation. Forest dynamics is also strongly influenced by anthropogenic activities. In addition to the natural forest dynamics, logging resulted in divergent growth trends within given age classes and habitats (forest interior and forest edge); overall, 22 groups of trees with different characteristics in the annual radial stem increment were identified. A tree-ring series-based reconstruction of logging intensity since 1935 suggests that moderate selective logging occurred throughout the study period. However, selective logging was strongly intensified after 1990 as the result of the breakdown of the Communist regime in Mongolia and the transition from centrally planned to market economy. Because tree stump densities showed that the ratio of felled to live trees was 2:1 in the interior or even 0.9:1 at the edges of the forests and most logging occurred during the past 20 years, it must be concluded that the forests of the Mongolian Altai are presently exploited far beyond the level of sustainability. A close correlation of the ratio of felled to live trees with the density of summer camps of pastoral nomads in the vicinity suggests that trees are primarily felled by the local population.     

Restoration ecology in the Anthropocene: learning from responses of tropical forests to extreme disturbance events

Extreme disturbance events denote another aspect of global environmental changes archetypal of the Anthropocene. These events of climatic or anthropic origin are challenging our perceived understanding about how forests respond to disturbance. I present a general framework of tropical forest responses to extreme disturbance events with specific examples from tropical dry forests. The linkage between level of disturbance severity and dominant mechanism of vegetation recovery is reflected on a variety of initial trajectories of forest succession. Accordingly, more realistic and cost‐effective restoration goals in many tropical forests likely consist in maintaining a mosaic of different successional trajectories while promoting landscape connectivity, rather than encouraging full‐ecosystem recovery to pre‐disturbance conditions. Incorporating extreme disturbance events into the global restoration ecology agenda will be essential to design well‐informed ecosystem management strategies in the coming decades.     

带状采伐对毛竹林林下植被物种多样性的影响

成本上升、利润下降严重影响毛竹林经济效益及竹农生产积极性,研究毛竹林新型经营管理技术、方法势在必行。本研究通过控制采伐宽度及采伐面积,观测一年恢复期后江苏宜兴国有林场内五种宽度(3 m、5 m、8 m、12 m、15 m)毛竹林带状样地郁闭状态及林下植被物种多样性特征,分析物种多样性对毛竹林采伐宽度及恢复状态的响应机制,研究表明:(1)研究区毛竹林下物种53科95属110种(灌木计37科64属76种,草本计18科30属34种),以蔷薇科、菊科、大戟科、茜草科、百合科、唇形科、禾本科、马鞭草科等为主。(2)物种丰富度随着毛竹郁闭度增加而降低,且人为采伐对物种丰富度(特别是木本植物)有显著促进作用,以8 m和15 m宽度带状样地物种增加最多。(3)带状采伐促进林下植被物种多样性,但降低了林下植被物种均匀度;8 m和15 m宽度带状样地Shannon-Wiener指数、Simpson指数及Gleason物种丰富度表现优于参考样地毛竹林;五种宽度带状样地林下植被物种均匀度小于参考样地,在相同宽度样地类型中,保留样地比采伐样地物种均匀度高。(4)带状采伐对8 m和15 m宽度采伐样地林下植被生物...     

Novelties in Begonia (Begoniaceae) from the coastal forests of Brazil

Two new narrow endemic species ofBegonia from the Atlantic coastal forests of Brazil,B. espiritosantensis andB. ibitiocensis, are described and illustrated.Begonia schenkii var.calvescens, an endemic taxon from the states of Santa Catarina and Rio Grande do Sul, is transferred to species rank, and described and illustrated. A distribution map is provided for all three taxa.     

Emergence of Eucalyptus marginata (jarrah) from seed in Mediterranean-climate forest in response to overstorey,site, seedbed and seed harvesting

Abstract The effects of overstorey, type of site, seedbed, seeding date and seed harvesting by vertebrates and invertebrates on the emergence of Eucalyptus marginata (jarrah) seedlings were studied experimentally in the northern jarrah forest of Western Australia. Seed harvesting by small vertebrates substantially reduced emergence, whereas invertebrates only slightly reduced emergence. Ninety per cent of seed was removed within 1 day when it was on the soil surface and in the open, whereas seed removal was insignificant when the seed was covered by soil. Vertebrates harvested seed more effectively when the understorey and litter were removed and the seed was more visible on the soil surface. Seed harvesting by small vertebrates had less impact on a site where there had been bauxite mining, possibly because the surrounding area was being revegetated with large numbers of seed and the area afforded poor cover for vertebrates. Emergence was less where the overstorey was removed compared to where it was retained, and on the rehabilitated bauxite mined site compared to the forest sites. There was no difference in emergence between the low and high quality forest sites and so the emergence phase could not fully explain the variation in abundance off. marginata seedlings on different quality sites. Post emergence events are likely to be important in explaining this difference between low and high quality sites.     

Traditional management of forests: plant and bird community responses to alternative restoration of oak–hazel woodland in Sweden

Species richness of vascular plants and birds were examined in relation to five types of management (including abandonment) of oak-hazel woodland in south-central Sweden. The biodiversity of this type of woodland is affected by lengthy management in contrast to present emphasis on the fragmentation of more or less pristine forests. The woodlands derive from old deciduous forests but were a source of agricultural commodities from medieval time to end of the 19th century. Vascular plants and birds were censused during spring–summer for four years. Total number of plant species, species of field layer forbs, breeding birds and migrant birds were more numerous at simulated original management with mowing of small interior grasslands than at mechanical clearing or abandonment. Summer grazing led to intermediate numbers. Exotic plants were more common at long-time abandonment. Species richness of trees and shrubs, graminoids, all spring birds, resident birds and non-passerine birds did not exhibit any difference between treatments. Inter-site variation in species richness was usually smaller at abandonment than at true management. Species richness of plants and birds showed positive correlation in the particularly large sites examined. The general findings were in accordance with the intermediate disturbance hypothesis. Original management would secure most potential plant and bird species but extensive cattle grazing would also retain many species.     

Eurhopalothrix depressa sp. n. (Hymenoptera: Formicidae) from Southern Brazil with a Key to the Neotropical Taxa of the Genus

Eurhopalothrix depressa sp. n. is described from Southern Brazil. The species belongs to the bolaui group characterised by well developed propodeal teeth and large specialized clavate hairs on the body. It can be distinguished from all other neotropical Eurhopalothrix species by a distinct ridge dividing the head into a lower anterior and a higher posterior part and by the reduced number of 16 specialised hairs on the head. A key to all New World species of Eurhopalothrix is added.     

Site-dependent growth responses to climate in two major tree species from tropical dry forests of southwest Ecuador

Tropical dry forests (hereafter TDFs) have been extensively logged and converted into croplands or grasslands worldwide. Tumbesian forests in southwest Ecuador are among the most diverse and endangered TDFs. They face seasonal droughts of varied severity and are also subjected to episodic very wet and cloudy conditions during El Niño events. However, we lack a local quantification of their responses to regional climate (temperature, precipitation, cloud cover) and El Niño which could change across sites. Here we use dendrochronology to quantify the radial-growth rates and the responses to climate (mean temperatures, precipitation amount, cloud cover and drought severity) of two major tree species forming annual rings (Geoffroea spinosa, Handroanthus chrysanthus) in three TDFs with different local climate conditions. The lowest (1.0 mm yr⁻¹) and the highest (2.1 mm yr⁻¹) radial-growth rates of both tree species were found in the hottest-driest and moderately hot sites, respectively. G. spinosa growth responded positively to wet, cool and cloudy conditions in the hottest-driest and moderately hot sites, but the most intense response to drought was observed in the driest site at 1–5 months long scales. H. chrysanthus growth reacted positively to high growing-season precipitation in all sites, particularly in the driest site, and to cloudy conditions in moderately hot sites. The growth of H. chrysanthus was negatively associated to the Southern Oscillation Index in the dry-hot and in the moderately hot sites. Tree species coexisting in TDFs show varied growth responses to regional weather variability, drought severity and El Niño events across sites with different local climate conditions.     

Species diversity and community structure of rove beetles (Coleoptera: Staphylinidae) attracted to dung of sika deer in coniferous forests of southwest Japan

Insect communities of mammal dung have been known as excellent model ecosystems for scientific study. Ecological surveys of diversity and seasonal patterns of coprophilous rove beetles in relation to wild mammals have rarely been conducted, although the high potential species diversity and abundance of the rove beetles are known. In order to investigate biodiversity of these beetles, we analyzed species composition, abundance, feeding guild and seasonality of rove beetles that were attracted to sika deer Cervus nippon dung by using dung‐baited pitfall traps for a 1.5‐year study in two plantations (cypress, cedar) and one secondary natural forest (pine) in Fukuoka Prefecture, southwest Japan. Consequently, saprophagous Anotylus sp. (Oxytelinae) was dominant in all forests. Analyses of feeding guild structure showed the number of individuals were dominated by saprophagous beetles, but the number of species were dominated by predatory beetles. Seasonal effects suggested that the species richness and abundance of rove beetles are possibly regulated by scarabaeoid dung beetles. These findings feature one example of a coprophilous rove beetle community.     

Impacts of retention felling on coarse woody debris (CWD) in mature boreal spruce forests in Finland

We studied the immediate changes in pre-treatment coarse woody debris (CWD) after retention felling and mechanical site preparation (scarification) in mature Picea abies-dominated boreal forest. Retention felling and scarification were hypothetised to affect the amount of CWD. The disturbance caused to CWD was assumed to depend on species and decay class. Logs were inventoried before fellings, after fellings, and after scarification, estimating the damage percentage for each log. After felling, 7.8% of the total pre-treatment volume of CWD was destroyed in the felled area. After scarification, the decline from pre-treatment volume was 67.6% in the felled area. The amount of CWD decreased also inside the retention tree groups; in the 1st post-treatment season, 4.6% was destroyed of the pre-treatment volume and 20% in the 2nd season. Of the retained trees, 40% were uprooted by the end of the 2nd season. If the majority of the initial downed CWD is destroyed by scarification, as our results show, we can estimate that since scarification became a widely used regeneration method in the 1960s, at least from 4 to 6 million m³ of CWD has already been destroyed in Finland. The role of CWD as a key element for biodiversity in boreal forest is generally accepted, which has led to retention of trees in fellings instead of clear felling. We suggest that at least as important as leaving trees in order to maintain continuum in CWD and species diversity is to preserve existing CWD in fellings over the regeneration phase. This can be done using less destructive harvesting methods, reduced use of scarification and placing retention tree groups in patches with high amounts of CWD.     

Species-specific growth-climate responses of Dahurian larch (Larix gmelinii) and Mongolian pine (Pinus sylvestris var. mongolica) in the Greater Khingan Range,northeast China

Responses of tree growth to climate are usually spatially heterogeneous. Besides regionally varying external environments, species specificity is a crucial factor in determining said spatial heterogeneity. A better understanding of this species specificity would improve our estimations of the warming effects on forests. In this study, we selected two widely-distributed boreal conifers, Dahurian larch (Larix gmelinii) and Mongolian pine (Pinus sylvestris var. mongolica), to compare their growth-climate responses, including long-term growth-climate correlations and short-term growth resilience to drought. We sampled 160 trees and 481 tree-ring cores from the two species in two pure and two mixed forests, located in the Greater Khingan Range, northeast China. We found that Dahurian larch was generally positively correlated with spring temperature and negatively correlated with summer temperature. In contrast, Mongolian pine was more sensitive to summer moisture. Our results suggest that the main climatic limitations were low spring temperatures for Dahurian larch and summer moisture deficits for Mongolian pine. Dahurian larch represented higher growth resistance to drought, while Mongolia pine represented higher recovery. Based on this, we inferred that Dahurian larch was more vulnerable to extreme droughts, while Mongolian pine was more vulnerable to frequent droughts. We also demonstrated the effects of forest type on growth-climate responses. The negative effects of summer temperatures on Mongolian pine seemed to be more significant in mixed forests. As warming continued, Mongolian pine in this area would suffer severer moisture deficits, especially when coexisting with Dahurian larch. Our results suggest that Dahurian larch gained an advantage in the competition with Mongolian pine during high moisture stress. Driven by the warming trends, the species specificity in growth response would ultimately promote the separation of the two species in distribution. This study will help improve our estimations of the warming effects on forests and develop more species-targeted forest management practices.