Decaying Woody Debris Research Articles

Descriptions of the mature larva and adult female of Pseudopyrochroa girardi Young from Southwest China (Coleoptera: Pyrochroidae: Pyrochroinae), with natural history observations.

Larvae of Pseudopyrochroa girardi were collected beneath bark and in coarse, decaying woody debris of dead logs in Yaan City, Sichuan Province, China. The species association was confirmed by rearing both males and females to the adult stage. The last instar larva is described and illustrated, along with the first description of the adult female. Observations relating to the larval/pupal macro- and microhabitats and natural history are also provided and illustrated. A brief discussion of the significance of such discoveries is presented in relation to the Mountains of Southwest China global biodiversity hotspot and conservation implications relating to forests and saproxylic species like Pyrochroidaae.

Stand stage affects wild bee communities in working pine forests

Wild bees provide critical pollination services to both crops and native forest plants. Evidence suggests that wild bees are declining due to factors such as habitat loss, disease, pesticide use, and climate change. Privately owned, working loblolly pine (Pinus taeda L.) forest landscapes cover a large area in the southeastern U.S. and may be important for wild bee conservation. However, there is little research on wild bees in private, working forests. Hence, our research objectives were to compare wild bee populations and communities among different stages within working, loblolly pine forest landscapes and assess stand structure and composition effects on wild bees. We sampled bees and forest attributes in four stages [0–3 years (recently established), 4–7 years (pre-thinned, closing canopy), 8–13 years (pre-thinned, closed canopy), and 14–20 years (post-thinned)] of privately owned, working pine forests in the Southeastern Plains Ecoregion of Georgia. We collected 5,933 bees from 88 species in two years. Wild bees were 2–5 times more abundant in recently established stages, and more diverse in recently established and post-thinned stages. Functional dispersion, a measure of beta diversity, was also greater in recently established and post-thinned stages. Canopy openness, percent of plants flowering, and percent cover of minimally decayed woody debris were important variables driving the bee community composition in recently established stages. Number of snags and litter layer depth were important variables driving the bee community composition in older stages with a closing or closed canopy. Working pine forests support a diverse community of wild bees and have high conservation value for these pollinators. Overall, wild bees appear to benefit from various stand stages, especially open canopy stands with a diverse structure. Promoting and maintaining open canopy conditions in managed pine landscapes may assist with conserving wild bee communities in this region. This can be achieved by planting trees at wider spacing, thinning as early as possible, and supporting fewer trees per hectare or a lower basal area.

Descriptions of the mature larva and pupa of Pseudopyrochroa facialis (Fairmaire) from Southwest China (Coleoptera: Pyrochroidae: Pyrochroinae), with redescriptions of adult stages and notes on natural history.

Larvae and pupae of Pseudopyrochroa facialis were collected beneath bark and in coarse, decaying woody debris of a standing, dead Cyclobalanopsis glauca tree in Guiyang City, Guizhou Province, China. The species association was confirmed by rearing both males and females to the adult stage. This represents the first record of a mainland Chinese species of Pseudopyrochroa to be reared in order to establish species association and identity. The mature larva and pupa are described and illustrated along with descriptions and illustrations of reared and additional adult males and females. Observations relating to the larval/pupal macro- and microhabitats and natural history are provided.

Prescribed burning reduces species richness of wood-decay fungi in the forests of northwest Arkansas.

The present study, which was carried out at three localities in the Ozark Mountains of northwest Arkansas, investigated the effects of prescribed burning on wood-decomposing fungi using samples of decaying woody debris (DWD) placed in plastic incubation chambers. One of the localities had not been subjected to recent prescribed burning, whereas the other localities contained both an unburned area as well as an area recently subjected to burning. In all three localities, small pieces of decaying woody debris (DWD) were collected, placed in the incubation chambers and the latter kept moist for any extended period of time. Pieces of DWD collected in the areas subjected to burning typically displayed evidence of considerable charring. Fruiting bodies appearing in the incubation chambers were removed and identified by sequencing of ribosomal DNA region. A total of 101 specimens representing 80 different taxa were recorded in the entire investigation, but the numbers of both specimens and taxa were appreciably higher for the unburned collecting sites. As such, the data obtained indicate that prescribed burning lowers the species richness of the wood-decomposing fungi associated with DWD at a particular locality. The unique aspect of the present study was the use of incubation chambers to characterize the taxa of fungi associated with CWD.

Spatial Heterogeneity of SOM Concentrations Associated with White-rot Versus Brown-rot Wood Decay

White- and brown-rot fungal decay via distinct pathways imparts characteristic molecular imprints on decomposing wood. However, the effect that a specific wood-rotting type of fungus has on proximal soil organic matter (SOM) accumulation remains unexplored. We investigated the potential influence of white- and brown-rot fungi-decayed Abies nephrolepis logs on forest SOM stocks (i.e., soil total carbon (C) and nitrogen (N)) and the concentrations of amino sugars (microbial necromass) at different depths and horizontal distances from decaying woody debris. The brown-rot fungal wood decay resulted in higher concentrations of soil C and N and a greater increase in microbial necromass (i.e., 1.3- to 1.7-fold greater) than the white-rot fungal wood decay. The white-rot sets were accompanied by significant differences in the proportions of the bacterial residue index (muramic acid%) with soil depth; however, the brown-rot-associated soils showed complementary shifts, primarily in fungal necromass, across horizontal distances. Soil C and N concentrations were significantly correlated with fungal rather than bacterial necromass in the brown-rot systems. Our findings confirmed that the brown-rot fungi-dominated degradation of lignocellulosic residues resulted in a greater SOM buildup than the white-rot fungi-dominated degradation.

Descriptions of the mature larvae for two species of Pseudopyrochroa from Taiwan (Coleoptera: Pyrochroidae: Pyrochroinae), with notes on their natural history.

Field collections and rearing have established the first species-level associations for larvae of Pyrochroidae from Taiwan. Larvae of Pseudopyrochroa carinifrons and Pseudopyrochroa fainanensis were collected from beneath bark and in coarse, decaying woody debris of dead logs and successfully reared to the respective adult stages. The mature larvae are described and salient features are illustrated. Notes on larval habitats and natural history are also provided.

Quantifying lignin and holocellulose content in coniferous decayed wood using near-infrared reflectance spectroscopy

To determine the independent decomposition rates of lignin and cellulose of decayed woody debris, a technique for the rapid analysis of lignin and cellulose is required. We applied a near-infrared spectroscopy (NIRS) technique to measure the lignin and holocellulose content in decayed wood. We succeeded in creating partial least-squares (PLS) models to estimate the lignin and holocellulose content in the decayed wood of five species using NIR spectra. Although the accuracy was acceptable for the estimation of a five-species mixed model (R2 = 0.970 for lignin and R2 = 0.962 for holocellulose), it was further improved when the model was applied to each species independently. This combination of NIRS and a PLS model is a valuable tool for the determination of the lignin and holocellulose content in decayed wood. The technique is time efficient (3 min per sample) and non-hazardous (no acid treatment is required).

Stand structure and small mammals in intensively managed forests: Scale, time, and testing extremes

Stand thinning and fertilization have the potential to create a diversity of forest habitat conditions to meet the goals of biodiversity conservation while sustaining wood and biomass production. Three factors are crucial to a better scientific understanding of how wildlife habitats develop in managed forests: real-world scale of treatments using adaptive management, several decades of time to monitor responses, and the testing of extreme treatments. Communities of arboreal and forest-floor small mammals occupy young coniferous stands and may serve as indicators of change in forest structure and function, and hence biodiversity. We tested the hypotheses (H) that, when compared with unmanaged (unthinned and old-growth) stands, large-scale pre-commercial thinning (PCT) and PCT with repeated fertilization, up to 16–21years after the onset of treatments, would enhance (H1) stand structure, (H2) abundance of southern red-backed voles (Myodes gapperi) and species diversity of forest-floor small mammals, and (H3) abundance of northern flying squirrels (Glaucomys sabrinus), in young lodgepole pine (Pinus contorta) stands in the south-central interior of British Columbia, Canada.Mean diameters and heights of crop trees in thinned stands were less than those in old-growth stands, but the low-density stands did have greater mean diameters than those in unthinned stands. Mean crown volume of pine crop trees was significantly greater in the low- and medium-density stands than in the high-density, unthinned, or old-growth stands. Mean density of overstory (range of 1010–1590 stems/ha) and understory conifers were similar in the thinned and old-growth stands. Mean species and structural diversity of total conifers were significantly higher in the heavily thinned (⩽1000stems/ha) than other stands. For vascular plants, mean abundance of understory herbs and total structural diversity were higher in heavily thinned and fertilized stands. Thus, some aspects of stand structure supported H1 while others did not.Mean abundance of M. gapperi was higher in old-growth forest than the younger managed and unthinned stands, except in years of low numbers, and hence did not support H2 that these treatments over a longer time-frame would enhance abundance of this species. Fluctuations in numbers, drier forest ecosystems, and slow development of forest-floor habitat with decaying woody debris and fungi may contribute to flexible habitat occupancy for M. gapperi. The second part of H2, that mean species diversity of forest-floor small mammals would be enhanced in heavily thinned and fertilized stands tended to be supported, particularly in the period prior to canopy closure. H3, that abundance of G. sabrinus would be maintained at levels recorded in old-growth forests by PCT of young stands, was supported for medium- and high-density stands.A sustained flow of wood products and structural features with their habitats for wildlife and biodiversity should be achievable with a wide range of stand densities from PCT and variable regimes of nutrient additions in intensively managed forests. Essential key elements include large-scale (operational-size) treatment units and long-term monitoring of installations over decades, preferably at 5- to 10-year intervals.

Microhabitat Selection of Woody Debris by Dekay's Brownsnake (Storeria dekayi) in a Dune Habitat in Ontario, Canada

Understanding habitat selection is a fundamental goal of ecology and is vitally important for effective species conservation. Dekay's Brownsnake (Storeria dekayi; hereafter “Brownsnake”) is one of the most widespread snake species in eastern North America, and its association with cover objects is generally well known, but details regarding choice of refuges are largely unknown. We investigated Dekay's Brownsnake microhabitat use during annual surveys at Point Pelee National Park, Ontario, Canada from 1990 to 2010. We systematically checked all woody debris in stabilized dune habitat for snakes and noted the size and state of decay of woody debris that was used. Nearly all of our observations were of gravid females under woody debris. Greater use of large, moderately decayed woody debris relative to the range of available debris provided strong evidence of selection. Although most snakes observed were solitary, we found a significant number of aggregations. Female Brownsnakes appear to migrate to stabilized dune from other habitats in the park to select suitable woody debris for gestation and parturition. Although these refuge sites would reduce predation risk, they also provide a moister and cooler microclimate than ambient conditions. Numerous observations of shed skins also suggested that this woody debris provides important microhabitat for ecdysis. Analysis of relative abundance over time showed considerable variation in numbers (1–31/yr) and an increasing trend. Our results provide strong evidence of microhabitat selection by this species and highlight the importance of not making generalizations about microhabitat requirements, even for common snake species.

Fungal decomposition of woody debris of Castanopsis sieboldii in a subtropical old‐growth forest

AbstractFungi, especially basidiomycetes, are the primary agents of woody debris decomposition in terrestrial forest ecosystems. However, quantitative data regarding the abundance and decay activity of wood‐inhabiting fungi are lacking, especially for tropical and subtropical areas. This study demonstrates the dynamics of decay columns of wood‐inhabiting fungi within decaying woody debris of Castanopsis sieboldii and the wood decay activities of those fungi in a subtropical natural forest. Among six basidiomycetes and two ascomycetes observed as sporocarps on fallen boles of C. sieboldii, Microporus affinis was most abundantly observed in terms of frequency of sporocarps and as percentage area of decay columns within cross‐sections of boles, especially those in the early stages of decomposition. In decay columns of M. affinis, both acid‐unhydrolyzable residue (AUR) and holocellulose decayed simultaneously, and wood relative density decreased to 45.8% of that of fresh C. sieboldii wood. A pure culture decay test under laboratory conditions showed that M. affinis was a strong decomposer of AUR and holocellulose. These results suggest that M. affinis has a central role in lignocellulose decomposition of wood of C. sieboldii in the early stages of decomposition.

Trap response and genetic structure of eastern subterranean termites (Isoptera: Rhinotermitidae) in Point Pelee National Park, Ontario, Canada

AbstractReticulitermes flavipes (Kollar) is best known throughout southwestern counties of Ontario, Canada, as an urban pest. Little is known, however, of the presence of this termite in nonurban settings in Ontario. In this study, we confirmed the existence of a population of R. flavipes on the shores of Lake Erie within Point Pelee National Park. A systematic trap survey conducted along the park's semi-vegetated west beach revealed several zones of termite activity. An analysis of trap response at one location indicated an association between termite activity and smaller sized, moderately decayed woody debris. Further, microsatellite DNA analysis suggested the presence of at least three genetically distinct colonies, each likely headed by multiple inbred reproductives. Together these data suggest that termite activity is linked to food quality, and that single colonies are potentially long-lived through multiple generations of inbreeding. Assuming it is derived from a population reported from Point Pelee in 1929, the study population is the oldest known eastern subterranean termite population in Ontario.

Management for red spruce conservation in Québec: The importance of some physiological and ecological characteristics – A review

The physiological and ecological characteristics of red spruce (Picea rubens Sarg.) are reviewed and integrated into ecosystem management options. Red spruce is a shade-tolerant, late-successional conifer species found in the temperate forests of northeastern North America. Its wood, being of excellent quality, is prized by the forest industry. Unfortunately, this high-value species has been in decline throughout its entire range for the past 50 years. At high elevations, in northeastern United States, crown dieback caused by the combined effect of atmospheric pollution and climate is largely responsible of this decline. In other areas, such as Québec (Canada), the scarcity of red spruce is mainly caused by forest management practices that are poorly adapted to the species' ecophysiology. Many physiological studies have shown that the species is sensitive to full sunlight (at juvenile and advance growth stages), high temperatures and frost. It also has particular microsite requirements for seed germination and early seedling establishment, such as the presence of large decaying woody debris. Hence, a management strategy adapted for red spruce should favour the use of partial cutting, maintaining some overstory and dead wood. This will emulate the natural dynamics of small canopy gaps and minimize the physiological stresses to regeneration. The ecophysiological aspects of natural and artificial regeneration of red spruce should be examined with respect to the increased use of partial cutting techniques. Key words: advance regeneration, balsam fir (Abies balsamea L.), ecophysiology, ecosystem management, frost susceptibility, light response, microenvironment, red spruce (Picea rubens Sarg.), seedling establishment, shade tolerance, silvicultural systems, thermosensitivity

A review of the long-term effects of post-harvest silviculture on vertebrate wildlife, and predictive models, with an emphasis on boreal forests in Ontario, Canada

Greater fibre yields may be possible in commercial forests through an increased application of post-harvest silvicultural techniques. In Canadian boreal forests, while basic silvicultural regeneration techniques such as planting, seeding, scarifying, and tending, have been employed since the 1940’s, more intensive techniques (intensive forest management (IFM)) such as increased area planted, pre-commercial and commercial thinning, extra tending events, fertilizing, and short rotations may soon be used. There may be effects of basic and more intensive silviculture on biodiversity in the long-term, compared to natural regeneration following logging or especially stand development following natural disturbances. We reviewed approximately 50 papers that reported studies of the long-term effects of post-harvest silviculture on vertebrate wildlife. In particular, large impacts to biodiversity universally occur when native forest types are replaced by rapidly-growing exotic tree species. However, in boreal forests, native tree species are usually planted, and so any effects on associated wildlife communities may be considerably less than in non-native species plantations. Limited long-term information is available, but published studies of effects of basic silviculture and IFM suggested that loss of structures in forest stands was an important common impact that resulted in vertebrate species responses. Fewer structural features in managed forests compared to in natural forests likely results in reduced numbers of animal species dependent on those structures, such as cavity-using species and species for which large decaying woody debris is important. Simplifying stand structures and species composition may result in systems with low connectivity, making them vulnerable to insect and mammalian herbivory. Concentration of IFM in stands on highly productive sites could exacerbate effects (positive or negative), owing to the positive relationship between forest productivity and animal and plant diversity. Species such as black-backed woodpeckers ( Picoides arcticus) may be reduced over large areas by stand conversion to mixedwoods, stand structural changes and especially age-class truncation. On the other hand, IFM may contribute increased habitats to species favoring young to mature coniferous-dominated forests, that normally decline across a landscape following clearcutting in boreal mixed and upland conifer stands. An aspatial model, based on published and local information and expert opinion, suggested that IFM and post-harvest silviculture in Ontario’s boreal forests would produce positive and negative species-specific effects on the vertebrates that we modeled. However, IFM appeared to result in little increased effect over basic post-harvest silviculture. We also expect that stand-level effects of IFM on species would accumulate through time over landscapes, as more stands come under intensive management and the level of effects will be cumulative.