Mature Conifer Research Articles

Projection of the probability of local extinction of canopy tree species in forest landscapes

Tree species are endangered mainly by the exploitation of old-growth forests, and in Japan by a change from traditional coppicing (Satoyama) to monoculture plantations. The protection of old-growth forest or the revival of traditional Satoyama management might avoid local extinctions. To evaluate these possibilities, we developed a model to project the dominance and probabilities of local extinction of tree species in deciduous forests by combining land-use change and canopy tree replacement matrices. The land-use change matrix represents the probability of land-use transition during a unit interval (25 years). We calculated the probabilities of transition among old-growth forest, immature secondary forest, mature secondary forest, conifer plantation, and pasture from historical records. The probabilities of canopy replacement in old-growth and secondary forests were estimated from canopy–understory associations. Changes in canopy composition after logging of old-growth and secondary forests and forest recovery following abandonment of clear-cut plantations and pasture were estimated from field data. Using the combined matrix model, we projected the abundance and probabilities of local extinction of 19 tree species under four scenarios: business as usual, forest protection, Satoyama (traditional coppice management), and Satoyama forest protection. Satoyama management increased the abundance of disturbance-dependent species but contributed little to the reduction of local extinction. Forest protection decreased extinction probabilities and the dominance of tree species did not change greatly. In particular, forest protection greatly decreased the local extinction probabilities of species with continuous recruitment in old-growth forest, such as Fagus crenata, F. japonica, and Acer mono, but Satoyama did not.

Inventory of aspen trees in spruce dominated stands in conservation area

The occurrence of aspen trees increases the conservation value of mature conifer dominated forests. Aspens typically occur as scattered individuals among major tree species, and therefore the inventory of aspens is challenging. We characterized aspen populations in a boreal nature reserve using diameter distribution, spatial pattern, and forest attributes: volume, number of aspens, number of large aspen stems and basal area median diameter. The data were collected from three separate forest stands in Koli National Park, eastern Finland. At each site, we measured breast height diameter and coordinates of each aspen. The comparison of inventory methods of aspens within the three stands was based on simulations with mapped field data. We mimicked stand level inventory by locating varying numbers of fixed area circular plots both systematically and randomly within the stands. Additionally, we also tested if the use of airborne laser scanning (ALS) data as auxiliary information would improve the accuracy of the stand level inventory by applying the probability proportional to size sampling to assist the selection of field plot locations. The results showed that aspens were always clustered, and the diameter distributions indicated different stand structures in the three investigated forest stands. The reliability of the volume and number of large aspen trees varied from relative root mean square error figures above 50% with fewer sample plots (5–10) to values of 25%–50% with 10 or more sample plots. Stand level inventory estimates were also able to detect spatial pattern and the shape of the diameter distribution. In addition, ALS-based auxiliary information could be useful in guiding the inventories, but caution should be used when applying the ALS-supported inventory technique. This study characterized European aspen populations for the purposes of monitoring and management of boreal conservation areas. Our results suggest that if the number of sample plots is adequate, i.e. 10 or more stand level inventory will provide accurate enough forest attributes estimates in conservation areas (minimum accuracy requirement of RMSE% is 20%–50%). Even for the more ecologically valuable attributes, such as diameter distribution, spatial pattern and large aspens, the estimates are acceptable for conservation purposes.

How dynamic are understory communities and the processes structuring them in mature conifer forests?

Even though understory plant communities play important roles in northern forest ecosystems, our understanding of their long‐term successional dynamics and the associated driving processes is still limited. This study used spatially explicit data from five, long‐term, permanent plots in mature lodgepole pine (Pinus contorta) stands in the Canadian Rocky Mountains to: (1) assess whether understory communities showed homogenization over time either within or between plots and if compositional changes observed were supportive of either the initial or relay floristics model; and (2) evaluate the relative importance of the environment vs. dispersal limitations in structuring these understory communities and how this changes over time. We found between‐plot convergence and within‐plot homogenization over time, largely due to increasing cover of mosses and later successional species. These changes were mainly in relative abundance, thus supporting the initial floristic model. However, the appearance of late successional species and the disappearance of early successional species over the study period suggested that the relay floristic model was also important. Most of the variation in understory species composition and richness was explained by spatial variables that were independent of environmental factors, suggesting that dispersal limitation was important in these communities. However, environmental variables explained an important fraction of the variation in species richness and composition, especially in more xeric environments; from this we infer that deterministic processes still played an important role in structuring these communities. In most plots, our results also showed increasing importance of dispersal limitations following canopy closure and we attribute this to both the homogenisation of the understory environment and increased abundance of later successional species which were more dispersal limited.

Fog, fog drip, and streamflow in the Santa Cruz Mountains of the California Coast Range

AbstractThe onshore movement of marine fog is a common occurrence during summer months along much of the contiguous US Pacific Coast. Because the fog season tends to occur during the precipitation‐free dry season, any additional input of moisture or reduction in loss of moisture through evapotranspiration provided by the marine layer can be an important factor in local hydrologic systems. To quantify some of the effects of fog on regional dry‐season hydrology, a study site within the Santa Cruz Mountains of central California was established. The fog‐laden coastside and predominately fog‐free San Francisco Bay side of the study area provide an excellent opportunity to assess the impacts of the presence and absence of fog on ecohydrological processes. Streamflow, fog drip, and soil moisture were measured from May to September. Fog drip was essentially nonexistent on the bayside and highly variable on the coastside. Maximum rates and seasonal totals of drip occurred within stands of mature conifers (Sequoia sempervirens and Pseudotsuga menziesii) along exposed, often windy ridgelines. Fog‐drip totals up to 961 mm were recorded over 2·5 months. Consequently, frequent infiltration events to depths of 23 cm were documented. Over the course of the study, soil moisture levels at high‐fog‐drip locations either increased or were equivalent to spring conditions at the onset of data collection. Increases of flow in coastside streams, under otherwise receding conditions, were found to coincide with fog and fog‐drip events. These results confirm that the presence of fog can significantly affect dry‐season hydrologic conditions of some coastal locations. Copyright © 2014 John Wiley & Sons, Ltd.

Bias in the use of broadscale vegetation data in the analysis of habitat selection

Effective conservation efforts often depend on accurate identification of habitat requirements. Studies that identify habitat requirements for animals typically investigate use of structural habitat (vegetation) instead of functional habitat (conditions for biological fitness). The spatial scale of data could bias the match between functional and structural habitat because broadscale structural habitat maps exclude small habitat patches (inclusions) and broadscale location error can bias estimates of habitat use. To investigate how spatial scale affects the match between functional and structural habitat, we backtracked American marten (Martes americana) and fisher (Pekania [formerly Martes] pennanti) movement paths during winter and compared results from selection and tortuosity analyses conducted with broadscale (4 ha) and fine-scale (0.02 ha) structural habitat data. Functional habitat (rest sites and prey kill sites) occurred disproportionately in hemlock–cedar. Finescale structural habitat data detected greater selection and tortuosity within hemlock–cedar by traveling martens, but broadscale structural habitat data did not, which demonstrates that combining fine-scale location data with fine-scale structural habitat data improves the match between functional and structural habitat and understanding of habitat requirements. Selection and tortuosity indexes were poorly correlated, indicating that factors other than structural habitat influenced movement patterns. Within-stand structural habitat heterogeneity is important to martens and fishers, especially when heterogeneity includes mature conifer inclusions within primarily deciduous forests. Broadscale data may identify structural habitat associated with required types, rather than required habitat itself, when functional habitat corresponds with landscape features such as inclusions.

Corticosterone in territorial male Swainson’s Thrushes varies in relation to forest age but not vegetation cover

Glucocorticoids are thought to be related to habitat quality and may provide information about the relative health of individuals. We used a model selection approach to test whether plasma glucocorticoid levels of the Swainson's thrush (Catharus ustulatus) were associated with two attributes that may reflect breeding habitat quality in coniferous plantation forests: stand age and vegetation cover. For baseline corticosterone, the top model included stand age with limited support for models that included vegetation cover. Mean baseline corticosterone for terri- torial male thrushes sampled in mature stands was 78.2 % higher than territorial males sampled in early seral stands. For handling-induced corticosterone, there was limited separation among candidate models, and only one model, containing stand age and Julian day, was better supported than the null model. Despite previous research that has shown hardwood cover is an important component of breeding habitat quality for thrushes, our investigation found limited evidence that vegetation cover was associ- ated with either baseline or handling-induced corticoste- rone levels. Given that early seral and mature conifer forests are characterized by markedly different habitat features, we hypothesize that the observed differences in baseline corticosterone represent either reduced fitness of male thrushes in mature stands or an adaptive adjustment of glucocorticoid levels to match local environmental conditions that equalize fitness across stands of different ages.

Postglacial population genetic differentiation potentially facilitated by a flexible migratory strategy in Golden-crowned Kinglets (Regulussatrapa)

Relatively recently, temperate regions in North America were covered by extensive ice sheets, making them inhospitable to contemporary flora and fauna. Since the retreat of the ice sheets, these regions have been recolonized by a diversity of taxa, some of which have undergone rapid postglacial divergence. Evidence supports the hypothesis that some taxa persisted in unglaciated refugia during the Last Glacial Maximum, such as on Haida Gwaii (formerly the Queen Charlotte Islands). Many taxa on Haida Gwaii are genetically distinct from mainland populations at neutral molecular markers possibly as the result of isolation in refugia or postglacial colonization. The Golden-crowned Kinglet (Regulus satrapa Lichtenstein, 1823) is a continentally distributed, short-distance migratory passerine inhabiting mature conifer forests including those on Haida Gwaii. We used five microsatellite markers and a 568 base-pair fragment of the mitochondrial control region to determine the likelihood that Haida Gwaii region acted as a refugium for this species during the last ice age. We report significant gene flow between Haida Gwaii and the western North American mainland from mitochondrial markers, but significant population genetic differentiation at nuclear markers. We also report genetic divergence between eastern and western Golden-crowned Kinglets, as well as higher genetic diversity and population substructuring within the western population than within the eastern population. The east–west differentiation probably arose due to isolation in separate Pleistocene refugia south of the ice sheets. However, population differences within the west are likely caused by more recent processes; contemporary differentiation of Haida Gwaii Golden-crowned Kinglets most likely occurred postglacially.

Estimating the Total Economic Impact of Black Bear Peeling in Western Oregon Using GIS and REMI

In parts of the Pacific Northwest, black bears emerge from winter dens with depleted fat reserves and feed on mature conifers by stripping bark and consuming sugar-rich sapwood. Peeling by bears affects commercial conifers through direct loss of the tree or degraded log quality at stand harvest. Bears generally peel trees from 15-30 years old in intensively managed forests until preferred foods such as fruits and berries are available, and a single bear can peel several trees per day. Dying trees have a signature red canopy and are detected in annual aerial forest health surveys; however, trees that scar over peeling are not detected by aerial surveys. Previous studies reported results of damage summaries for northwest Oregon from flights, adjusted for bias; however, they offered no estimates of economic impact. Using landowner survey data, another study estimated an annual timber loss to bears at approximately $11.5 million across part of western Oregon. While informative, these estimates used broad assumptions to derive primary impacts and did not address secondary impacts. We used aerial health surveys, the national land cover database, and the Regional Economic Models Inc. (REMI) PI+ model to estimate the primary and secondary (indirect and induced) impacts of bear peeling in western Oregon. Because the accuracy and precision of aerial estimates (i.e., percentage of dead trees/polygon) was unknown, we calculated 4 scenarios of loss: 1%, 10%, 30%, and 100% loss. Under these scenarios, black bear damage to commercial forests negatively impacted Oregon’s gross domestic product between $0.9-$89 million annually, and resulted in an annual loss of between 11 and 1,012 jobs in the state. We will explain our methodology in this study as well as current efforts to improve the accuracy and precision of damage estimates, and ultimately our understanding of the economic impacts of black bear peeling.

Foliar Analyses of Conifers On Serpentine and Gabbro Soils In the Klamath Mountains

Soils, timber site data, and the foliage of mature conifer trees were sampled at 16 Klamath Mountains sites with serpentine soils and four sites with gabbro soils. The basal areas of trees at the gabbro sites were greater than the basal areas at the serpentine sites. Tree height growth, based on old growth site curves, was significantly greater on the gabbro soils than on the serpentine soils. The main soil difference was about five times greater exchangeable Mg from the serpentine soils than from the gabbro soils. The higher Mg in serpentine soils was not reflected in higher concentrations of Mg in the foliage of yellow pine (Pinus spp.), Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco), or incense cedar (Calocedrus decurrens [Torr.] Florins) trees on serpentine soils, but Ca was significantly higher in the Douglas-fir tree foliage on gabbro soils. The high Mg in the serpentine soils may interfere with the utilization of Ca by Douglas-fir trees causing their foliage to have lower Ca concentrations than in the foliage of Douglas-fir trees on gabbro soils. For each of the three tree species (yellow pine, Douglas-fir, and incense cedar), foliar N, P, and K concentrations were not appreciably different on serpentine versus gabbro soils. Although soil N and P were not determined, organic matter concentrations did not differ between serpentine and gabbro soils.

Feature: Improving our knowledge of drought‐induced forest mortality through experiments, observations, and modeling

Feature: Improving our knowledge of drought‐induced forest mortality through experiments, observations, and modeling

Impacts of Human Disturbance on Large Prey Species: Do Behavioral Reactions Translate to Fitness Consequences?

Anthropogenic disturbances have been demonstrated to affect animal behavior, distribution, and abundance, but assessment of their impacts on fitness-related traits has received little attention. We hypothesized that human activities and infrastructure cause a decrease in the individual performance of preys because of anthropogenically enhanced predation risk. We evaluated the impacts of commercial logging and road networks on the fitness of a large herbivore known to be sensitive to human disturbance: the forest-dwelling woodland caribou (Rangifer tarandus caribou). For 8 consecutive years (2004–2011) we monitored 59 individuals using GPS telemetry in the Charlevoix region of Québec, Canada. We also used Very High Frequency telemetry locations collected on 28 individuals from 1999–2000. We related habitat selection of adult caribou at various spatio-temporal scales to their probability of dying from predation, and to indices of their reproductive success and energy expenditure. The probability that adult caribou died from predation increased with the proportion of recent disturbances (including cutblocks ≤5 years old) in their annual home range. The respective effects of increasing paved and forestry road densities depended upon the overall road density within the home range of caribou. At a finer scale of 10 to 15 days before their death, caribou that were killed by a predator selected for recent disturbances more than individuals that survived, and avoided old mature conifer stands. The home range area of caribou increased with road density. Finally, the composition of the home range of females had no effect on their reproductive success. We show that human activities and infrastructure may influence the individual performance of large prey species in highly managed regions. We outline the need to consider the full set of impacts that human development may have on threatened animal populations, with particular emphasis on predator-prey relationships and population dynamics.

Intra-annual dynamics of non-structural carbohydrates in the cambium of mature conifer trees reflects radial growth demands

The presence of soluble carbohydrates in the cambial zone, either from sugars recently produced during photosynthesis or from starch remobilized from storage organs, is necessary for radial tree growth. However, considerable uncertainties on carbohydrate dynamics and the consequences on tree productivity exist. This study aims to better understand the variation in different carbon pools at intra-annual resolution by quantifying how cambial zone sugar and starch concentrations fluctuate over the season and in relation to cambial phenology. A comparison between two physiologically different species growing at the same site, i.e., the evergreen Picea abies Karst. and the deciduous Larix decidua Mill., and between L. decidua from two contrasting elevations, is presented to identify mechanisms of growth limitation. Results indicate that the annual cycle of sugar concentration within the cambial zone is coupled to the process of wood formation. The highest sugar concentration is observed when the number of cells in secondary wall formation and lignification stages is at a maximum, subsequent to most radial growth. Starch disappears in winter, while other freeze-resistant non-structural carbohydrates (NSCs) increase. Slight differences in NSC concentration between species are consistent with the differing climate sensitivity of the evergreen and deciduous species investigated. The general absence of differences between elevations suggests that the cambial activity of trees growing at the treeline was not limited by the availability of carbohydrates at the cambial zone but instead by environmental controls on the growing season duration.

Canada lynx occurrence and forest management in the Acadian Forest

AbstractWe evaluated patterns of occurrence and non‐occurrence for Canada lynx (Lynx canadensis) across a 16,530‐km2 study area in Maine to provide a better understanding of lynx habitat selection and habitat ecology on commercially managed forestlands in the Acadian Forest. Because of the influence of forest structure on lynx habitat selection and abundance of their primary prey, the snowshoe hare (Lepus americanus), and to improve our ability to build robust models, we used habitat information derived from a time series of Landsat satellite imagery spanning the period 1973–2004. We defined and mapped 10 forest types based on forest harvest history, time since harvest, and current forest condition. We compared a suite of models to evaluate relative influences of forest composition, habitat patch configuration, and hare density on habitat selection by lynx at the landscape scale. Occupied areas had greater average hare densities and percentage of mature conifer. Average hare density in occupied areas (0.74 hares/ha) was greater than in unoccupied areas (0.62 hares/ha), but was less than previous research has suggested may be necessary to support lynx populations in the southern portion of the species' range. No occupied areas occurred where average hare density was <0.5 hares/ha. Average hare density at the landscape‐scale was strongly influenced by amount of high‐quality hare habitat (i.e., conifer or mixedwood regenerating forest, 15–35 yr post‐harvest). Edge density between mature conifer and high‐quality hare habitat was substantially greater in occupied areas compared to unoccupied areas. Juxtaposition of those 2 forest types may provide edge habitat where lynx experience easier travel and improved access to prey in landscapes with extensive areas of high‐quality hare habitat where travel and access may be somewhat limited by high understory stem density. Probability of occurrence declined nonlinearly with changes in hare density and percent mature conifer forest in the landscape; thus, suitability of currently occupied landscapes could change markedly with future changes in landscape‐level hare densities and changing habitat associated with forest management. Where lynx conservation is a priority, we recommend that managers focus on creating and maintaining a minimum of 27% high‐quality hare habitat within 100‐km2 areas to promote landscape‐scale hare densities >0.5 hares/ha. © The Wildlife Society, 2013

The impact of catchment conifer plantation forestry on the hydrochemistry of peatland lakes

The hydrochemistry of 26 small blanket bog lakes was examined to assess the impact of conifer plantation forestry on lake water chemistry. Lakes were selected from three distinct catchment land use categories: i) unplanted blanket bog only present in the catchment, ii) mature (closed-canopy) conifer plantation forests only present in the catchment and iii) catchments containing mature conifer plantation forests with recently clearfelled areas. All three catchment land uses were replicated across two geologies: sedimentary (sandstone) and igneous (granite). Lakes with afforested catchments across both geologies had elevated concentrations of phosphorus (P), nitrogen (N), total dissolved organic carbon (TDOC), aluminium (Al) and iron (Fe), with the highest concentrations of each parameter recorded from lakes with catchment clearfelling. Dissolved oxygen was also significantly reduced in the afforested lakes, particularly the clearfell lakes. Analysis of runoff from a nearby recently clearfelled site revealed high biological and chemical oxygen demands, consistent with at least part of the elevated concentrations of TDOC emanating from clearfelled sites having higher biochemical lability. Inorganic fertilisers applied at the start of the forest cycle, the decay of the underlying peat soil and accumulated surface tree litter, and leachate from felled trees are the likely sources of the elevated concentrations of plant nutrients, TDOC, heavy metals and major ions, with excessive peat soil disturbance during clearfelling likely exacerbating the runoff into lakes. Our study has demonstrated a clear, deleterious impact of conifer plantations on the water quality draining from blanket bog catchments, with major implications for the management of afforested peatlands.

Macroinvertebrate assemblages of peatland lakes: Assessment of conservation value with respect to anthropogenic land-cover change

Small blanket bog lakes can contain many rare and threatened aquatic invertebrate species. Their conservation value, however, is threatened throughout Europe by peat extraction and particularly conifer afforestation, which can compromise the physico-chemical habitat quality of peatland lakes through excessive inputs of forestry-derived dissolved and particulate substances. To quantify the effect of conifer plantation forestry on the conservation value of these habitats, we compared the hydrochemistry and assemblages of aquatic Coleoptera, Heteroptera and Odonata of replicate lakes across three distinct catchment land uses: (i) unplanted blanket bog only present in the catchment, (ii) mature conifer plantation forests only present in the catchment and (iii) catchments containing mature conifer plantation forests with recently clearfelled areas. All three catchment land uses were replicated across regions of sedimentary and igneous geology. Lakes with afforested catchments, in both geologies, had elevated concentrations of plant nutrients, total dissolved organic carbon and heavy metals, the highest concentrations being recorded from the clearfell lakes. Coleoptera and Heteroptera assemblages responded strongly to forestry-mediated changes in water chemistry, whereas Odonata assemblages responded more to catchment geology – geology being confounded by altitudinal differences between lakes. The greatest species-quality scores (SQSs) and species richness were recorded from the clearfell lakes. Three of the four International Union for the Conservation of Nature (IUCN) nationally red-listed species recorded during this study were, however, absent from clearfell lakes. Our findings demonstrate that plantation forestry can have a profound impact on the aquatic macroinvertebrate assemblages and conservation value of small blanket bog lakes, primarily via eutrophication. Despite indices such as SQS scores and species richness appearing to reveal a beneficial response of blanket bog lake communities to habitat deterioration, they mask that certain ‘emblematic’ species are being severely negatively impacted by the disturbance caused by plantation forestry. Considering the need for fertiliser to produce economically viable plantation forest crops, coupled with the inefficiencies of peat soils in retaining applied nutrients, the degradation of peatland lakes is likely to become more prevalent as plantation forestry continues to expand worldwide.

Differential responses of Pinus ponderosa and Abies concolor foliar characteristics and diameter growth to thinning and prescribed fire treatments

Thinning and prescribed fire decrease the threat of catastrophic wildfire in western coniferous forests by reducing forest biomass available as fuel. Such treatments have been shown to alter foliar nitrogen (N) and phosphorus (P) concentrations, which may precede changes in stem diameter growth. However, the timing or duration of change in foliar nutrient concentrations of mature conifers is not well understood. I evaluated whether large-scale thinning and prescribed fire treatments impact nutrient characteristics and diameter growth of mature Pinus ponderosa (pine) and Abies concolor (fir) in a suite of experimental treatments (Size-preference Thin, Pine-preference Thin, Thin+Fire, and Fire) and a Control in the Klamath National Forest, CA. I analyzed pine needles to age 6years and fir needles to age 10years for N and P concentration and content. Vector analysis was used to simultaneously evaluate needle size, nutrient concentration and content to illustrate responses that may not be evident via analysis of nutrient concentration alone. There were no differences in foliar N or P concentration or content for pine or fir for any treatment relative to the Control. Nutrient resorption efficiency and proficiency were not affected by treatment for either species. The length of pine needles produced in 2001 was increased by all treatments that involved thinning, and the mass of needles produced in 2004 was increased by the combination of thinning and prescribed fire. There was no effect of treatment on fir needle length or mass for any cohort of needles. Vector diagrams indicated that pine needle N and P were diluted by treatments as needles increased in mass and total nutrient content while nutrient concentration decreased or remained constant. In contrast, fir needle nutrient concentrations increased or remained constant while dry mass and nutrient content decreased. Vector analysis indicated that the response in foliar characteristics of mature conifers differed between the historically dominant pine and the currently dominant, shade-tolerant fir in this northern California mixed-conifer forest, whereas traditional analysis of individual foliar characteristics generally did not detect differences among treatments. All treatments that involved thinning increased mean annual ring width index between pre- and post-treatment time periods for pine, whereas there was no effect for fir. These results suggest that restoration strategies may have negative or no effects on fir whereas the same treatments may favor pine, thereby facilitating re-establishment of a pine-dominated ecosystem that approximates historical conditions in California’s mixed-conifer forests.

The impact of conifer plantation forestry on the Chydoridae (Cladocera) communities of peatland lakes

Conifer plantation forestry is recognised as a potential source of diffuse pollution to surface waters and represents a risk to their ecological status. In this study, the water chemistry and Chydoridae (Cladocera) communities of 26 small blanket bog lakes were investigated to assess the impact of plantation forestry. The study was conducted over a 12-month period in 2009–2010 by comparing lakes with three distinct catchment land uses: (i) unplanted blanket bog only present in the catchment, (ii) mature conifer plantation forests only present in the catchment and (iii) catchments containing mature conifer plantation forests with recently clearfelled areas. All three catchment land uses were replicated across two geologies: sandstone and granite. Lakes with afforested catchments had very high concentrations of plant nutrients (P and N), total dissolved organic carbon (TDOC) and heavy metals (Al and Fe), the highest concentrations being recorded from the clearfelled lakes. Similarly, the chydorid communities differed between lakes of contrasting catchment land use. The dominance of Alonopsis elongata in the unplanted blanket bog lakes shifted to dominance by the smaller bodied Chydorus sphaericus, along with Alonella nana, Alonella excisa and Alonella exigua, in the plantation forestry-effected lakes, consistent with a shift in lake trophy. Our findings have shown that plantation forestry can have a profound impact on the water quality of small peatland lakes, especially at the clearfell stage. The response of the chydorid communities is consistent with plantation forestry exerting a trophic, rather than an acidic or toxic, effect on lake ecosystems.

Factors affecting somatic embryogenesis in conifers

This review seeks to examine the extreme response of isolated somatic plant cells of apical meristematic tissues of mature conifer trees towards specific stress conditions in vitro resulting in somatic embryogenesis. Signal molecules regulating embryo development have been described in angiosperms, but very little is known about somatic rejuvenation in conifers. Recent studies on cloning of mature conifers provide new perspectives on signal molecules on cellular dedifferentiation into the embryogenic pathway. Our recent studies show that signal molecules such as butenolide, calcium ions, salicylic acid, antioxidants, amino acids, triacontanol and 24-epibrassinolide all play an important role in the conversion of somatic cells into an embryogenic pathway in many recalcitrant pines. This constitutes a major breakthrough in forest biotechnology with many practical applications in clonal forestry.

Allometries, biomass stocks and biomass allocation in the thermophilic Spanish juniper woodlands of Southern Spain

The principal objective of this study was to investigate the variations of allometric relationships, biomass stocks and biomass allocation in a Spanish juniper thermophilic community (Juniperus thurifera var. hispanica Mill.) in response to two levels of woodland maturity: mature woodlands, which are situated in shallow stony soils with trees over 140years old and low tree density, and young woodlands, with trees under 100years old growing in deeper soils (generally, abandoned farmland). Branch- and tree-level allometric models were fit from measurements carried out on branches, stems and roots in 42 felled trees. Although age and site are confounded for this juniper community, it is expedient to utilize site-specific equations because the two woodlands showed distinct growth patterns as a result of their very different soil qualities and ages. At the branch level, the relationship was matched for foliage biomass depending on the site. At the tree level, site location significantly affected variables in allometric relationships that were not strictly cumulative (i.e., leaves, branch wood and fine-root biomass). Goodness of fit was improved by including the relative height of the first live whorl (pruning effect) as an additional predictor of crown and coarse root biomass. The young woodland supported more biomass stock across all components due to better soil. Biomass allocation measured in stems, coarse roots and fine roots was significantly higher in the mature woodland, although the young woodland did accumulate more dry mass in the crown. Differences in biomass allocation may be explained by both the age and strategies of J. thurifera to maximize nutrient and water capture for survival in poor soils (site quality effects). Our results also showed that, in mature woodlands, this species accumulates one of the smallest biomass stocks cited for temperate mature conifer stands (7.6Mgha−1) but has a high root to shoot ratio (0.43) as a consequence of growing in poor soil conditions.

Nebria brevicollis (Fabricius, 1792) in North America, benign or malign? (Coleoptera, Carabidae, Nebriini)

Nebria brevicollis (Fabricius) is one of the most frequently encountered and widely distributed carabid beetles in Europe. Until recently, the only North American records were based on two single specimens, both from the 1930’s in southeastern Canada. In 2008, this species was found at thirteen different sites in five counties in northwestern Oregon. As of the end of 2010, it has been found in thirty-four different sites in ten Oregon counties, with a north-south range of ~150 km and an east-west range of ~90 km. It was also detected in 2010 in southwestern Washington (Vancouver), just north of Portland and the Columbia River.The ecological amplitude of Nebria brevicollis in Oregon rivals that of the most eurytopic native carabid species, e.g., Pterostichus algidus LeConte and Scaphinotus marginatus (Fischer von Waldheim). It has been found in highly degraded heavy industrial sites, agricultural fields, city parks, gardens, second growth woodlands, mature conifer forests, montane rock gardens, and otherwise pristine stands of old growth noble fir, with elevations ranging from essentially sea level to 1,249 meters. Climates at these locales vary from that of the Mediterranean Willamette Valley floor, where snow rarely occurs and summers are hot and dry, to the summit of the Oregon Coast Range, where deep snow may be present from November through April and summers are cool. The carabid communities in which Nebria brevicollis has been found range from those predominantly of fellow exotic species, e.g., at heavily perturbed sites, to those where it is the only exotic species, such as at the Coast Range summit.Nebria brevicollis is clearly an invasive species in that it is not restricted to anthropogenic habitats, is rapidly expanding its North American range, and can be abundant in essentially pristine settings. What is not yet clear is whether it is or will become a damaging species. Although it is already the most abundant carabid species in some settings, based upon pitfall catches, it is unknown whether this represents competitive superiority, trap vulnerability, or utilization of previously untapped or non-limiting resources. Deleterious ecological effects could include not only competition with other predators (including other carabid species) in agricultural and natural settings but also predation upon non-adult stages of threatened and endangered species of butterflies.