Conifer-dominated Forests Research Articles

Vegetation dynamics, angiosperm radiation and climatic changes in the Lusitanian Basin (Portugal) during Albian times

The mid-Cretaceous is characterised by significant evolutionary changes in terrestrial ecosystems. During this period, the typical vegetation consisting of ferns, conifers and other gymnosperms was replaced by an angiosperm-dominated flora. Long ranging and continuous records from the continental realm are mostly lacking due to the prevalence of sedimentary gaps. Here a comprehensive palynological and clay mineralogical dataset covering early Albian to early Cenomanian strata from the shallow marine São Julião section (Lusitanian Basin, Portugal) is analysed to reconstruct the vegetation composition as well as climate and weathering conditions in the continental realm. The palynological assemblage is dominated by non-saccate Classopollis and Inaperturopollenites gymnosperm pollen with low abundances of spores and angiosperm pollen. The clay mineralogical data is mainly composed of kaolinite and mica and shows two conspicuous intervals of high kaolinite abundances in the late Albian. Based on the ecological preferences of the associated parent plants of the spore-pollen assemblage, a gradual relative temperature increase is inferred in the hinterland of the Lusitanian Basin during the early Albian to early Cenomanian interval. The clay mineralogy and palynological record show that the climate in the continental hinterland of the Lusitanian Basin was semi-arid to sub-humid and punctuated by two distinct humid phases during the late Albian. Multivariate statistical analyses and a comparison with the nearby Guincho section demonstrate the significance and reproducibility of the spore-pollen record. Furthermore, the palynological assemblage implies that angiosperms and ferns occupied similar palaeo-ecological habitats, namely as understorey in Cheirolepidaceae, Araucariaceae and Cupressaceae conifer-dominated forests.

Conifer Presence May Negatively Affect Sugar Maple’s Ability to Migrate into the Boreal Forest Through Reduced Foliar Nutritional Status

The discipline of ecology suffers from a lack of knowledge of non-climatic factors (for example, plant–soil, plant–plant and plant–insect interactions) to predict tree species range shifts under climate change. The next generation of simulation models of forest response to climate change must build upon local observations of species interactions and growth along climatic gradients. We examined whether sugar maple (Acer saccharum) seedlings were disadvantaged with respect to soil nutrient uptake under coniferous canopies, as this species would need to migrate northward into conifer-dominated forests in response to climate change. An experimental design was applied to 3 sites, forming the largest possible latitudinal/climatic gradient for sugar maple in Quebec (Canada) and isolating the effect of conifer presence on its seedling’s nutritional status. We tested whether: (1) both soil and climate and (2) presence of conifers affected foliar nutrient levels of sugar maple seedlings. Climate and soil (through pH) strongly affected nutrient availability for sugar maple seedlings and predicted 63.7% of their foliar nutrient variability. When controlling for site effects, we found a significant negative effect of conifers on foliar Ca and Mg levels of maple seedlings, which can adversely affect their overall health and vigour. When considering projected modifications of the forest environment due to climate change, we suggest that northward migration of sugar maple will be negatively affected by the presence of conifers through reduced foliar nutrition.

Canopy closure determines arthropod assemblages in microhabitats created by windstorms and salvage logging

Conifer-dominated forests of the Northern Hemisphere are prone to natural disturbances, such as windstorms, which create canopy openings by downing single trees to complete stands. The size of a windthrow determines how strongly microclimatic conditions are changed. After windstorms, damaged trees are commonly logged to ‘salvage’ economic returns, but effects on biodiversity are often negative. One cause of these negative effects on biodiversity might be the alteration of storm-created microhabitats, for example, as branches are cut off and root plates are flipped back into their pits when trunks are removed. The effect of these alterations of microhabitats on biodiversity under open and closed canopies, which represent extremes of microclimatic conditions, remains unclear. To investigate the relative importance of canopy closure and microhabitats for arthropod assemblages, we created six artificial windthrows located under an open canopy and six under a closed canopy by uprooting three spruce trees per plot. We used permutational analysis of variance to test whether cutting branches off uprooted trees and allowing them to rot on the forest floor affects branch-dwelling saproxylic beetles and whether repositioning upright root plates in their pits affects assemblages of carabids, epigeal spiders and harvestmen. Our final data set comprised 7657 arthropod individuals belonging to 28 species of saproxylic beetles, 28 species of carabids, 85 species of epigeal spiders, and 8 species of harvestmen. Carabid abundance was higher under a closed canopy and the number of epigeal spider species was higher under an open canopy. Canopy closure also significantly affected the assemblage composition of saproxylic beetles, carabids and epigeal spiders, with a higher mean moisture affinity of these assemblages on plots under a closed canopy. Arthropod assemblages of root plates and root plate pits did not differ, but the composition of branch-dwelling saproxylic beetle assemblages on cut and uncut branches significantly differed. Overall, assemblages of saproxylic beetles, carabids, epigeal spiders and harvestmen were pre-dominantly determined by canopy closure and not by alteration of storm-created microhabitats. Nevertheless, entire crowns of downed spruce trees should be retained in salvage-logged forests to provide this microhabitat for saproxylic beetle assemblages typical for naturally disturbed forests.

Habitat selection in the post-breeding period by Hazel Grouse Tetrastes bonasia in the Bohemian Forest

The Hazel Grouse (Tetrastes bonasia) is a cryptic forest-obligate bird species with special habitat requirements, including structured mixed forests at the local scale and good connectivity at the landscape level. These conditions are rarely met in Central European forests, with the exception of those in mountainous areas, such as the Bohemian Forest, Czech Republic. To explain habitat use in the Bohemian Forest by the Hazel Grouse during the post-breeding period more precisely, we used a small dataset as part of a long-term study to model the probability of occurrence for Hazel Grouse. We found that site occupancy by Hazel Grouse in the Bohemian Forest was high in dense spruce forests characterized by short sighting distances (20–40 m). It increased sharply with small proportions of deciduous trees (5–10 %) in a conifer-dominated forest and remained high at intermediate ground vegetation height (20–50 cm). Other elements that were positively associated with site occupancy of Hazel Grouse were the presence of anthills and fallen logs, and higher crown closure. Site occupancy decreased with a higher proportion of grass cover but was positively influenced by higher proportions of herbs and bilberry. Outcomes of this study may be used to inform forest and conservation practitioners for improvements of Hazel Grouse habitat in Central European mountain areas but also to assess forest sites for their suitability as Hazel Grouse habitats.

Identification of conifer stomata in pollen samples from western North America

Conifer stomata provide important paleoecological information for determining the composition of past plant communities, particularly at the local scale and when plant macrofossils are absent. To aid efforts to identify conifer stomata in fossil pollen samples from western North America, we describe the stomatal morphology of 19 conifer species that occur in the region, with emphasis on species that are present in the conifer-dominated forests along the northwest Pacific coast. We measured 10 morphological traits in a total of 315 stomata from these species. Morphological variability within species and the degree of morphological overlap among species precludes reliable identification to the species level; however, stomatal morphology is relatively consistent within genera and sufficiently unique to permit identification to genus. We used classification and regression trees to identify the critical morphological features for stomata identification and to build classification models. We then used these classification models as the basis for dichotomous identification keys for complete and incomplete conifer stomata. Identification of conifer stomata in fossil pollen samples from western North America should enhance paleoecological records from the region by providing evidence of local conifer presence and potentially clarifying their arrival times. Conifer stomata also provide a possible avenue for increasing taxonomic resolution in some paleoecological records: Pseudotsuga and Larix as well as members of the Cupressaceae family have indistinguishable pollen morphologies, but our results show that their stomata can be differentiated in most instances.

Great Gray Owls Nesting in Atypical, Low-Elevation Habitat in the Sierra Nevada, California

Abstract Great Gray Owls (Strix nebulosa) in the Sierra Nevada were once believed to nest strictly within mid-elevation conifer forests in close proximity to montane meadows. However, recent observations of Great Gray Owls nesting at lower elevations suggest the lower-montane zone of the Sierra Nevada, where oak-dominated woodlands transition to conifer-dominated forests, may also provide habitat for this California-listed endangered species. We describe the reproductive success, apparent occupancy rate, and habitat associated with eight Great Gray Owl nests monitored between 2006–2014 on commercial timberlands in the lower-montane zone of the central Sierra Nevada, California. Reproductive success was high, with several breeding attempts producing three fledglings, and an average of 1.9 ± 0.9 young fledged during 21 breeding attempts. Apparent occupancy rates were also high (87.5% ± 20.9%) in the years following the discovery of a territory. Nests were in large-diameter (x¯ = 102.5 cm) trees, but sma...

Biomass Production and Carbon Storage Potential of Selected Old-Growth Temperate Forests in Garhwal Himalaya, India

Fifteen old-growth temperate forest types were assessed for biomass productivity and carbon (C) storage potential by laying out sample plots randomly in each forest type along with an altitudinal transect in Garhwal Himalaya. The average total carbon density values ranged between 96.53 ± 4.92 Mg C ha−1 (moist mixed-deciduous forest) to 307.11 ± 11.28 Mg C ha−1 (Cedrus deodara forest). It was observed that conifer-dominated forest types had higher average biomass and C stocks as 479.01 Mg ha−1 and 220.34 Mg C ha−1 respectively. In broadleaf dominated forest types, these values were 394.08 Mg ha−1 and 177 Mg C ha−1 respectively. The study suggests that owing to their long rotation periods the growth of conifers should be encouraged particularly in the inaccessible areas of higher Himalaya and old-growth forests should be protected as they continue to sequester C.

Native American depopulation, reforestation, and fire regimes in the Southwest United States, 1492–1900 CE

Native American populations declined between 1492 and 1900 CE, instigated by the European colonization of the Americas. However, the magnitude, tempo, and ecological effects of this depopulation remain the source of enduring debates. Recently, scholars have linked indigenous demographic decline, Neotropical reforestation, and shifting fire regimes to global changes in climate, atmosphere, and the Early Anthropocene hypothesis. In light of these studies, we assess these processes in conifer-dominated forests of the Southwest United States. We compare light detection and ranging data, archaeology, dendrochronology, and historical records from the Jemez Province of New Mexico to quantify population losses, establish dates of depopulation events, and determine the extent and timing of forest regrowth and fire regimes between 1492 and 1900. We present a new formula for the estimation of Pueblo population based on architectural remains and apply this formula to 18 archaeological sites in the Jemez Province. A dendrochronological study of remnant wood establishes dates of terminal occupation at these sites. By combining our results with historical records, we report a model of pre- and post-Columbian population dynamics in the Jemez Province. Our results indicate that the indigenous population of the Jemez Province declined by 87% following European colonization but that this reduction occurred nearly a century after initial contact. Depopulation also triggered an increase in the frequency of extensive surface fires between 1640 and 1900. Ultimately, this study illustrates the quality of integrated archaeological and paleoecological data needed to assess the links between Native American population decline and ecological change after European contact.

Bark-scratching of storm-felled trees preserves biodiversity at lower economic costs compared to debarking

The simultaneous control of insect pests and compliance of conservation targets in conifer-dominated forests has intensified public debate about adequate post-disturbance management, particularly in protected areas. Hence, mechanical bark treatments, such as debarking, of disturbance-affected trees have been widely promoted as an on-site method of pest control that accounts for conservation targets because woody biomass is retained. However, the effects of debarking to non-target biodiversity remain unclear. We analyzed data from a two-and-a-half-year field survey of wood-inhabiting fungi, saproxylic beetles and parasitoid wasps in twelve artificial windthrows, created by pulling down mature Norway spruce trees (Picea abies) with winches. Each experimental windthrow comprising one control tree, one completely debarked tree and one bark-scratched tree. Insects were sampled using stem emergence traps. Fruiting bodies of wood-inhabiting fungi, number of wood wasp emergence holes, and number of holes made by foraging woodpeckers were assessed by visual counts. We recorded the amount of time needed to complete debarking by machine, bark-scratching by machine and bark-scratching by chainsaw each on 15 separate trees to estimate the economic costs of mechanical bark treatments.Our results revealed that both debarking and bark-scratching significantly decreased numbers of the emerging target pest Ips typographus to in median 4% (debarked) and 11% (scratched bark) of the number of individuals emerging from untreated control trees. Compared to control trees, debarking significantly reduced the species density of wood-inhabiting fungi, saproxylic beetles, and parasitoid wasps. By contrast, bark-scratching did not reduce the overall species density of wood-inhabiting fungi, saproxylic beetles or parasitoid wasps. The time needed for bark-scratching by machine was significantly lower than debarking, whereas bark-scratching by chainsaw needed a similar amount of time as conventional debarking. However, bark-scratching did have some negative effects in common with debarking, such as the significant reduction of wood wasps emergence holes and the reduction of holes made by foraging woodpeckers. Hence, bark-scratching of downed trees, like debarking, might affect higher trophic levels of biodiversity and should be applied only if pest management is urgently needed. We urge policy makers and natural resource managers to rapidly shift current pest management toward new techniques of bark-scratching, particularly in protected areas. Such a shift in post-disturbance pest-control will foster ecosystem integrity at lower economic cost compared to debarking.

Macrolichen substrate selection: Patterns among aspen, non-aspen hardwood, and conifer-dominated forests in the Wasatch Mountains, Utah

Abstract Lichens in montane, forested ecosystems of the Intermountain West and central Rocky Mountains tend to be understudied. Focusing on forested ecosystems in Utah, specifically Santaquin and Payson Canyons, we describe lichen community diversity and composition and their relation to percent aspen cover, and contrast lichens in aspen, non-aspen hardwood and coniferous environments. We collected 351 macrolichens, a total of 34 species and 15 genera, from 22 circular plots with a 34.7 m radius. We found three major gradients in lichen community composition in our study area. First, many species of Xanthomendoza had strong positive correlations with increasing aspen cover, while several Melanohalea species declined with greater aspen cover. Xanthomendoza galericulata was a significant indicator for aspen forests, but this lichen was not limited to aspen as it colonizes various barks flexibly. Second, corticolous and saxicolous taxa positively associated with a trend in lichen species richness, while terr...

Palaeoenvironment, palaeoclimate and age of the Brassington Formation (Miocene) of Derbyshire, UK

The Brassington Formation is the most extensive Miocene sedimentary succession onshore in the UK. Because of its unique position at the margin of NW Europe, the pollen from this lithostratigraphical unit provides evidence on the development of vegetation affected by North Atlantic currents and hypothesized atmospheric circulation changes during the Middle to Late Miocene climate cooling. Palynostratigraphy suggests that the uppermost Kenslow Member of the Brassington Formation is not coeval. Previously, all occurrences of the Kenslow Member were assumed to be contemporary. The oldest pollen assemblage is from the more southern Bees Nest Pit, which represents a subtropical conifer-dominated forest of late Serravallian age ( c . 12 Ma). A younger assemblage was observed from the more northern Kenslow Top Pit; this indicates that a subtropical mixed forest was present during the early Tortonian (11.6–9 Ma). The shift from a conifer-dominated to a mixed forest was related to precipitation. Although the total precipitation did not change between the two assemblages, the younger assemblage had more uniform rainfall throughout the year. The diachronous nature of the Kenslow Member means that the depositional model of the Brassington Formation needs revising, and this will have implications for Neogene to recent uplift of the southern Pennines. Supplementary material: All valid formally defined palynomorph taxa below the generic level that are mentioned in this paper, with full author citations, are available at http://www.geolsoc.org.uk/SUP18889 .

Short-term development of a multilayered forest stand after target diameter harvest in southern Sweden

Harvest strategies that emulate natural disturbances are being promoted to restore multilayered forest heterogeneity, notably the harvest of largest trees. However, their use also increases management complexity, and more information on their practical feasibility and effects on forests is needed. Therefore, in this study, target diameter cutting treatments were applied to a heterogeneously structured stand in southern Sweden (exemplifying a conifer-dominated forest of the hemiboreal forest region in northern Europe) to assess their effects on gap dynamics, natural regeneration, and stand growth. The target diameter cutting resulted in an exponentially decreasing gap size distribution, with the largest canopy gaps measuring 0.1–0.2 ha. The gap closure rate was higher than reported rates for gaps in natural forests. After 5 years, sufficient numbers of seedlings had regenerated, but proportions of intermediate- and late-successional tree species were low. The observed stand growth exceeded rates simulated using the growth model Standwise in the Heureka forest planning software package. The findings from this case study are useful for refining the general concept of close-to-nature forestry, but they need to be complemented with the information available from other regeneration studies after partial harvest.

Remote sensing proxies of productivity and moisture predict forest stand type and recovery rate following experimental harvest

Site productivity, as affected by soil nutrients and available moisture is often characterized using an edatopic grid. A challenge for forest ecologists and managers working across large areas and in complex landscapes is the need to identify spatially different ecological environments that follow an edatopic classification. Recent advances in remote sensing offer some potential approaches for mapping ecological environments and landscape conditions. It is now feasible to compile long temporal image sequences using Landsat imagery for reconstruction of forest stands and derivation of long term indices of landscape productivity; and the increasing proliferation of airborne laser scanning (ALS) technology also allows for the acquisition of detailed information on topographic elevation and vegetation structure with sub-meter accuracy. In a large area of boreal mixedwood forest in northwestern Alberta, Canada, we examined the utility of using Landsat-derived vegetation greenness (indicating productivity), and ALS-derived cartographic depth-to-water (indicating moisture), to determine forest cover type and vegetation responses following variable retention harvesting. Our results demonstrate that both long-term image sequences from Landsat and ALS-derived topography and vegetation structure act as proxies for edatopic grid components, and are well-suited to differentiating forest cover types. Deciduous-dominated, deciduous-dominated with conifer understory, mixed, and conifer-dominated forests were generally distributed (in order) across a gradient of increasing moisture and decreasing greenness. Landscape greenness was the strongest predictor of vegetation regrowth after disturbance, followed by depth to water and other terrain factors, such as elevation and slope. New advances in, and complementary use of, different remotely sensed information provides a better understanding of both the landscape-scale distribution of forest cover types and patterns of vegetation regrowth following disturbance.

Structural retention requirements for a key ecosystem engineer in conifer-dominated stands of a boreal managed landscape in eastern Canada

The concept of retention forestry brings a new point of view for forest management as more emphasis is put on what is retained as opposed to what is removed during harvesting. Details of retention harvesting prescriptions vary among forest ecosystems reflecting differences in their disturbance dynamics, stand composition and condition, and landscape context. Although recent studies underlie the important role of trembling aspen (Populus tremuloides) in cavity networks of Canadian western temperate forests, limited information exists for conifer-dominated forests such as the black spruce (Picea mariana) forests of central Québec where the proportion of deciduous trees is generally <10%. We used the habitat requirements of an ecosystem engineer of eastern boreal forests, the Black-backed Woodpecker (Picoides arcticus), to determine harvesting prescriptions likely to preserve most of the biodiversity of this ecosystem. We describe the mean physical characteristics of trees selected for nesting, quantify nesting habitat selection at two scales (nest tree and nesting stand), and identify quantitative targets for forest managers to select types and amounts of retention structures that will offer optimal resources to cavity nesting birds and dead wood associated species in managed boreal landscapes. During the three years of this project, we found 18 Black-backed Woodpecker nests: 9 were in old coniferous, 6 in young cuts, and 1 nest in each of the other habitats (barren land, young coniferous and old cut). Selection of nest trees by Black-backed Woodpeckers was influenced primarily by tree species (jack pine; Pinus banksiana) and also by the dbh of trees, while their selection of nesting stand habitat was influenced positively by the mean density of recent-solid snags and negatively by the mean basal area of live trees. Our results show that forest stands with ⩾200 recently decayed snags/ha (⩾9cmdbh) exhibit higher predicted probability of selection for nesting by Black-backed Woodpeckers, and most of the cutblocks with a nest tree originate from harvesting with advance regeneration protection with at least that many snags. Moreover, cutblocks should contain suitable candidate nest trees, with retention of ⩽10 live and dead trees/ha with a dbh⩾27cm, and retention of jack pine snags in proportion of their availability before harvesting in black spruce-dominated forest stands. We recommend that, where forest stands present suitable structures, every stand harvested with retention harvesting should retain ⩾200 recent-solid snags/ha (⩾9cmdbh), which represents about 1 recent-solid snag each 7m (50m2). The medium and long-term persistence of dead wood associated species may not rely only on retention forestry, thus we recommend the protection of patches (100ha) of old forest stands (⩾120y) inside these agglomeration of cutblocks to ensure the dynamic of dead wood creation within the managed landscape.

Functional response of lignicolous fungal guilds to bark beetle deforestation

Conifer-dominated forests in the northern hemisphere are prone to large-scale natural disturbances, yet our understanding of their effects beyond changes in species diversity is limited. Bark beetle disturbances provide dead wood for lignicolous fungal guilds and increase insolation but also desiccation. We investigated whether species richness of these guilds increases and functional diversity decreases after bark beetle disturbance, which would promote through habitat filtering the coexistence of species adapted to harsh conditions, i.e. light stress for lichens and substrate desiccation for wood-inhabiting fungi.We sampled epixylic and epiphytic lichens (primary producers) and wood-inhabiting fungi (mainly wood decomposers, some form ectomycorrhizas) in the Bohemian Forest (Long Term Ecological Research – LTER – Site Bavarian Forest National Park), an area in Central Europe most heavily affected by the bark beetle Ips typographus, on undisturbed plots and disturbed plots with spruce (Picea abies) dieback 8 years ago. We analysed species diversity, functional diversity (optimized by phylogeny), and functional compositions.Species richness of lichens but not that of wood-inhabiting fungi was higher on disturbed plots than on undisturbed plots. Community compositions of both guilds differed considerably on disturbed and undisturbed plots. On both types of plots, lichen communities were clustered according to functional diversity, which indicated habitat filtering, and fungal communities were overdispersed, which indicated competition. Disturbance increased the strength of these two patterns only slightly and was significant only for fungi. Single-trait analysis revealed changes in the functional composition; on disturbed plots, lichenous species with larger and more complex growth forms and fungi with large, perennial fruit bodies were favoured. Although the forest canopy changed tremendously because of the bark beetle disturbance, the most important driver of lichen and fungal diversity and mean trait assemblages seemed to be the enrichment of dead wood. The changes in insolation and moisture did not act as habitat filters for either guild. This indicated that the assembly patterns of lichen and fungal communities in coniferous forests are not affected by stand-replacing disturbances in contrast to the predictions for other disturbance regimes.

Impact of climate change on cold hardiness of Douglas-fir (Pseudotsugamenziesii): environmental and genetic considerations.

The success of conifers over much of the world's terrestrial surface is largely attributable to their tolerance to cold stress (i.e., cold hardiness). Due to an increase in climate variability, climate change may reduce conifer cold hardiness, which in turn could impact ecosystem functioning and productivity in conifer-dominated forests. The expression of cold hardiness is a product of environmental cues (E), genetic differentiation (G), and their interaction (G×E), although few studies have considered all components together. To better understand and manage for the impacts of climate change on conifer cold hardiness, we conducted a common garden experiment replicated in three test environments (cool, moderate, and warm) using 35 populations of coast Douglas-fir (Pseudotsuga menziesii var.menziesii) to test the hypotheses: (i) cool-temperature cues in fall are necessary to trigger cold hardening, (ii) there is large genetic variation among populations in cold hardiness that can be predicted from seed-source climate variables, (iii) observed differences among populations in cold hardiness insitu are dependent on effective environmental cues, and (iv) movement of seed sources from warmer to cooler climates will increase risk to cold injury. During fall 2012, we visually assessed cold damage of bud, needle, and stem tissues following artificial freeze tests. Cool-temperature cues (e.g., degree hours below 2°C) at the test sites were associated with cold hardening, which were minimal at the moderate test site owing to mild fall temperatures. Populations differed 3-fold in cold hardiness, with winter minimum temperatures and fall frost dates as strong seed-source climate predictors of cold hardiness, and with summer temperatures and aridity as secondary predictors. Seed-source movement resulted in only modest increases in cold damage. Our findings indicate that increased fall temperatures delay cold hardening, warmer/drier summers confer a degree of cold hardiness, and seed-source movement from warmer to cooler climates may be a viable option for adapting coniferous forest to future climate.

Do larger snags stand longer?—snag longevity in mixed conifer–hardwood forests in Hokkaido, Japan

More than half of the dead trees fell down within decade. Besides, DBH effect on snag longevity varied by tree species and was not detected for some species. Management of long-lived snags in temperate mixed forests should be reconsidered. Snags (standing dead trees) provide essential habitats for many species. Those with large diameter at breast height (DBH) are prioritized for retention; one of the reasons is that snag longevity (recruitment to falling down) increases with increasing DBH in conifer-dominated forests. Despite its importance, the DBH effect on hardwood snags is inadequately understood. The aim of this study is to investigate whether and how the DBH effect varies by tree species in mixed conifer–hardwood forests. We checked the current status (standing or falling) of dead trees that had been recorded in 37 permanent plots and applied a generalized linear mixed model. We used tree species, time since death, DBH, and interaction terms as variables. Half of the dead trees with a DBH of 25 cm were estimated to have fallen down within 1–6 years for most of the species. While snag longevity increased with increasing DBH in Abies sachalinensis and Phellodendron amurense, we detected no such effect in Picea and three hardwood species. For highly decayed or long-lived snags, retaining large snags is not always effective. Managers of species-rich mixed forests should consider the variability of the DBH effects and management of dead wood before and after tree mortality.

Comparison of multiple models for remote sensing of carbon exchange using MODIS data in conifer-dominated forests

Boreal forests in the northern hemisphere provide important sinks for storing carbon dioxide (CO2). However, the size and distribution of these sinks remain uncertain. In particular, many remote-sensing models show a strong bias in the simulation of carbon fluxes for evergreen needleleaf forest. The objective of this study is to improve these predictive models for accurately quantifying temporal changes in the net ecosystem exchange (NEE) of conifer-dominated forest solely based on satellite remote sensing, including the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra daytime land-surface temperature (LST), night-time LST′, enhanced vegetation index (EVI), land–surface water index (LSWI), fraction of absorbed photosynthetically active radiation (FPAR), and leaf area index (LAI). Considering that the component fluxes, gross primary production (GPP), and ecosystem respiration (Re), are strongly influenced by vegetation phenology, seasonality information was extracted from time-series MODIS EVI data based on non-linear least-squares fits of asymmetric Gaussian model functions with a software package for analysing the time-series of satellite sensor data (TIMESAT). The results indicated that models directly incorporating phenological information failed to improve their performance for temperate deciduous forest. Instead, three methods to retrieve the component fluxes – GPP and Re – including direct estimates, models incorporating the phenological information, and models developed based on the threshold value (LST 273 K), were explored respectively. All methods improved NEE estimates markedly and models developed based on the threshold value performed best, and provided a future framework for accurate remote sensing of NEE in evergreen forest.

Association of extinction risk of saproxylic beetles with ecological degradation of forests in Europe.

To reduce future loss of biodiversity and to allocate conservation funds effectively, the major drivers behind large-scale extinction processes must be identified. A promising approach is to link the red-list status of species and specific traits that connect species of functionally important taxa or guilds to resources they rely on. Such traits can be used to detect the influence of anthropogenic ecosystem changes and conservation efforts on species, which allows for practical recommendations for conservation. We modeled the German Red List categories as an ordinal index of extinction risk of 1025 saproxylic beetles with a proportional-odds linear mixed-effects model for ordered categorical responses. In this model, we estimated fixed effects for intrinsic traits characterizing species biology, required resources, and distribution with phylogenetically correlated random intercepts. The model also allowed predictions of extinction risk for species with no red-list category. Our model revealed a higher extinction risk for lowland and large species as well as for species that rely on wood of large diameter, broad-leaved trees, or open canopy. These results mirror well the ecological degradation of European forests over the last centuries caused by modern forestry, that is the conversion of natural broad-leaved forests to dense conifer-dominated forests and the loss of old growth and dead wood. Therefore, conservation activities aimed at saproxylic beetles in all types of forests in Central and Western Europe should focus on lowlands, and habitat management of forest stands should aim at increasing the amount of dead wood of large diameter, dead wood of broad-leaved trees, and dead wood in sunny areas.

Guild-specific responses of forest Lepidoptera highlight conservation-oriented forest management – Implications from conifer-dominated forests

The loss of biodiversity in forest ecosystems has led to a discussion on conservation-oriented forest management, particularly in intensively managed coniferous forest of the northern hemisphere. Two conservation-oriented management strategies, namely advancement of multi-layered forests stands and benign neglect of naturally disturbed stands, are currently being promoted over conventional management strategies of single-layered stands and salvage logging after natural disturbances. However, the effect of these conservation-oriented strategies on nocturnal Lepidoptera has not yet been assessed, despite the high contribution of this order to biodiversity. Here we used full assemblage data of forest-dwelling micro-moths and macro-moths to compare species densities and relative abundance of moths of the larval feeding guilds in single-layered and multi-layered stands, and in naturally disturbed salvaged or unsalvaged stands. We demonstrate that forest moth assemblages are sensitive to conservation-oriented forest management strategies. The relative abundance of moths of the saproxylic and detritus-feeding larval guilds was higher in naturally disturbed unsalvaged stands and in multi-layered stands, whereas that of moths of the moss-feeding larval guild was lower in multi-layered stands. These results corroborate the benefit of a benign-neglect strategy in the management of naturally disturbed stands in conserving saproxylic and detritus-feeding moths and in using natural disturbance to guide the enhancement of stand complexity. Our results demonstrate both the power of functional approaches to reveal slight changes in species communities and the importance of including micro-moths (a frequently disregarded group) in studies aimed at developing management implications for forest managers.