Forest Canopy Cover Research Articles

Response of beetles (Coleoptera) to repeated applications of prescribed fire and other fuel reduction techniques in the southern Appalachian Mountains

Coleoptera are important components of forest ecosystems and can be affected by forest management schemes aimed at limiting fuel build-up. Our research objective was to determine if repeated applications of fuel reduction treatments resulted in changes in abundance or diversity of beetle (Coleoptera) families, genera, and species within upland mixed hardwood forests in the southern Appalachians Mountains, North Carolina, USA. We established three replicate blocks (∼56 ha) and split each block into four fuel reduction treatments. Treatments included prescribed burning, mechanical felling, a combination of prescribed burning and mechanical felling, and a control (i.e., no fuel reduction techniques applied). We implemented treatments multiple times (2 mechanical thinnings and 4 prescribed burns) over the course of a 15-year period. Using pitfall and colored pan traps, we captured 7037 coleopterans comprised of 62 families over a three-year period. Total coleopteran abundance and diversity were similar across all treatments; however, some beetle families, genera, and species responded to treatments. Nitidulidae were significantly more abundant within controls compared to all other treatments in 2015, whereas Mordellidae generally had higher abundances in mechanical and burns compared to mechanical in 2015 and mechanical and controls in 2016. Chrysomelidae was significantly more abundant in mechanical and burns compared to all other treatments over the entire duration of the study. However, Staphylinidae abundance was significantly lower in mechanical and burns compared to the other treatments. Numerous genera and species also showed variable treatment-level responses. Burn treatments killed some mature trees and reduced forest canopy cover, resulting in higher light availability and thereby greater herbaceous cover and diversity on the forest floor. This vegetation in the understory of burned treatment units may be partially responsible for many of the treatment-level responses of beetle taxa we documented. This study took place after several rounds of fuel reduction techniques were applied over a 15 year period. Some beetle abundance responses were immediate; whereas other groups seemed to be influenced by the application of treatments over time, highlighting the need to examine long-term responses to forest management practices.

Habitat of Nepenthes spp. in the area of Sampit Botanic Gardens, Central Kalimantan, Indonesia

Hidayat S, Dodo, Purnomo DW, Helmanto H, Supriyatna I. 2018. Habitat of Nepenthes spp. in the area of Sampit Botanic Gardens, Central Kalimantan, Indonesia. Biodiversitas 19: 1258-1265. Nepenthes spp are protected plant and most of them are at least concern criteria. The research purpose is to explore the habitat information that supports the existence of Nepenthes in the area around Sampit Botanic Gardens, Central Kalimantan. Three different sites have been selected in this research. In each sites, seven sampling plots have been made by purposively sampling, each plot measuring 5x5 m2. In the Gelam Forest (Melaleuca quinquenervia), two Nepenthes species have been found, namely Nepenthes gracilis and Nepenthes mirabilis. In two other sites, in Peat Swamp Forest and Alang-alang Forest (Imperata cylindrica), dominated by N. mirabilis. Combretocarpus rotundatus is a tree in the Peat Swamp Forest that is mostly climbed by Nepenthes. Scleria sumatrensis and Stenochlaena palustris are two species of plants that are always found in the three research sites, but the dominant family is Melastomataceae primarily represented by Melastoma malabathricum. Nepenthes mirabilis can be found in the three research sites with an equal number, but N. gracilis was only abundant in the Gelam forest. By using imageJ software, obtained canopy cover in Gelam forest only 10%. Meanwhile, based on laboratory test, the soil in the Gelam forest is dominated by the dust fraction and is relatively more fertile than the Alang forest. In this case, Nepenthes favored open canopy, but was quite watery and relatively fertile.

Estimating aboveground carbon density and its uncertainty in Borneo's structurally complex tropical forests using airborne laser scanning

Abstract. Borneo contains some of the world's most biodiverse and carbon-dense tropical forest, but this 750 000 km2 island has lost 62 % of its old-growth forests within the last 40 years. Efforts to protect and restore the remaining forests of Borneo hinge on recognizing the ecosystem services they provide, including their ability to store and sequester carbon. Airborne laser scanning (ALS) is a remote sensing technology that allows forest structural properties to be captured in great detail across vast geographic areas. In recent years ALS has been integrated into statewide assessments of forest carbon in Neotropical and African regions, but not yet in Asia. For this to happen new regional models need to be developed for estimating carbon stocks from ALS in tropical Asia, as the forests of this region are structurally and compositionally distinct from those found elsewhere in the tropics. By combining ALS imagery with data from 173 permanent forest plots spanning the lowland rainforests of Sabah on the island of Borneo, we develop a simple yet general model for estimating forest carbon stocks using ALS-derived canopy height and canopy cover as input metrics. An advanced feature of this new model is the propagation of uncertainty in both ALS- and ground-based data, allowing uncertainty in hectare-scale estimates of carbon stocks to be quantified robustly. We show that the model effectively captures variation in aboveground carbon stocks across extreme disturbance gradients spanning tall dipterocarp forests and heavily logged regions and clearly outperforms existing ALS-based models calibrated for the tropics, as well as currently available satellite-derived products. Our model provides a simple, generalized and effective approach for mapping forest carbon stocks in Borneo and underpins ongoing efforts to safeguard and facilitate the restoration of its unique tropical forests.

A landscape genetic analysis of swamp rabbits (Sylvilagus aquaticus) suggests forest canopy cover enhances gene flow in an agricultural matrix

Habitat loss and fragmentation pose a continued and immediate threat to wildlife and create a persistent need for ecological information at the landscape scale to guide conservation efforts. Landscape features influence population connectivity for many species and genetic analyses can be employed to determine which of these features are most important. Because population connectivity through dispersal is important to the persistence of swamp rabbits (Sylvilagus aquaticus (Bachman, 1837)) at the northern edge of their range, we used a landscape genetic approach to relate gene flow to landscape features that may impact dispersal success. We tested resistance values for attributes of land cover, watercourse corridors, canopy cover, and roads and used causal modeling and redundancy analysis to relate these representations of landscapes to genetic distance for swamp rabbits in southern Illinois, USA. Models that included canopy cover had the strongest correlations with genetic distance and were supported by our methods whereas other models were not. We concluded that high tree canopy cover enhances gene flow and landscape connectivity for swamp rabbits in southern Illinois. Our study provides important empirical evidence that landscape variables may impact the habitat connectivity of swamp rabbits. Preserving dispersal routes for swamp rabbits should focus on improving canopy cover, in both bottomland and upland, to connect suitable habitat.

Estimation of Forest Aboveground Biomass and Leaf Area Index Based on Digital Aerial Photograph Data in Northeast China

Forest aboveground biomass (AGB) and leaf area index (LAI) are two important parameters for evaluating forest growth and health. It is of great significance to estimate AGB and LAI accurately using remote sensing technology. Considering the temporal resolution and data acquisition costs, digital aerial photographs (DAPs) from a digital camera mounted on an unmanned aerial vehicle or light, small aircraft have been widely used in forest inventory. In this study, the aerial photograph data was acquired on 5 and 9 June, 2017 by a Hasselblad60 digital camera of the CAF-LiCHy system in a Y-5 aircraft in the Mengjiagang forest farm of Northeast China, and the digital orthophoto mosaic (DOM) and photogrammetric point cloud (PPC) were generated from an aerial overlap photograph. Forest red-green-blue (RGB) vegetation indices and textural factors were extracted from the DOM. Forest vertical structure features and canopy cover were extracted from normalized PPC. Regression analysis was carried out considering only DOM data, only PPC data, and a combination of both. A recursive feature elimination (RFE) method using a random forest was used for variable selection. Four different machine-learning (ML) algorithms (random forest, k-nearest neighbor, Cubist and supporting vector machine) were used to build regression models. Experimental results showed that PPC data alone could estimate AGB, and DOM data alone could estimate LAI with relatively high accuracy. The combination of features from DOM and PPC data was the most effective, in all the experiments considered, for the estimation of AGB and LAI. The results showed that the height and coverage variables of PPC, texture mean value, and the visible differential vegetation index (VDVI) of the DOM are significantly related to the estimated AGB (R2 = 0.73, RMSE = 20 t/ha). The results also showed that the canopy cover of PPC and green red ratio index (GRRI) of DOM are the most strongly related to the estimated LAI, and the height and coverage variables of PPC, the texture mean value and visible atmospherically resistant index (VARI), and the VDVI of DOM followed (R2 = 0.79, RMSE = 0.48).

Exploring invasibility with species distribution modeling: How does fire promote cheatgrass (Bromus tectorum) invasion within lower montane forests?

AbstractAimCheatgrass (Bromus tectorum) is notorious for creating positive feedbacks that facilitate vegetation type conversion within sagebrush steppe ecosystems in the western United States. Similar dynamics may exist in adjacent lower montane forest. However, fire‐forest‐cheatgrass dynamics have not been examined. We used species distribution modeling to answer three questions about fire and invasibility in lower montane forests: (Q1) Does fire create more suitable habitat for cheatgrass? (Q2) If so, which site attributes are altered to increase site suitability? (Q3) Does fire increase connectivity among suitable habitat and enhance spread?LocationShoshone National Forest, Wyoming, USA.MethodsWe measured cheatgrass presence–absence in 93 plots within Interior Douglas‐fir (Pseudotsuga menziesii var. glauca) forests. Random Forests predicted cheatgrass distribution with and without fire using nine site attributes: elevation, slope, aspect, solar radiation, annual precipitation, maximum temperature in July, minimum temperature in January, forest canopy cover and distance to nearest trail or road. Additionally, invasion pathways and spread were mapped using Circuitscape.ResultsCheatgrass distribution was controlled by topographic and climate variables in the absence of fire. In particular, cheatgrass was most likely to occur at low elevation along dry, south‐ and east‐facing slopes. High‐severity fire increased potential cheatgrass distribution when forest canopy cover was reduced to below 30%. This process created new invasion pathways, which enhanced cheatgrass spread when modelled in Circuitscape.Main conclusionsOur study showed that in the absence of fire, drier south‐ and east‐facing slopes at low elevation are most susceptible to cheatgrass invasion. However, high‐severity fire increased the total area susceptible to invasion—allowing cheatgrass to expand into previously unsuitable sites within lower montane forests in the western United States. These results are important for present day management and reflect that integrating responses to disturbance in species distribution models can be critical for making predictions about dynamically changing systems.

Evaluating scenarios of landscape change for Sunda clouded leopard connectivity in a human dominated landscape

The forests of Borneo support some of the highest biodiversity in the world, yet have experienced among the world's highest rates of deforestation. Such rapid forest loss and associated fragmentation reduces the availability of suitable habitat for wildlife and creates dispersion barriers. Understanding the prevalence and impacts of this anthropogenic disturbance, and developing ways in which to mitigate such changes, is thus critical to the conservation of Borneo's wildlife. Here, we applied a path selection function with conditional logistic regression and used it to develop a resistance surface for a population of Sunda clouded leopards (Neofelis diardi) residing within a fragmented and human dominated landscape in Malaysian Borneo. We used cumulative resistant kernel and factorial least-cost path analysis to predict how connectivity may change in response to four future scenarios involving conversion of remaining unproductive forest to palm oil plantations, conversion of unproductive palm oil back to forest, and restoration of a riparian buffer zone along the river, and combination of the two forest restoration scenarios. We showed that Sunda clouded leopard movement is facilitated by forest canopy cover and resisted by non-forest vegetation, particularly recently cleared/planted and underproductive (flooded) plantation areas with low canopy closure. By combining resistant kernel and factorial least-cost path modelling we mapped core areas and the main linkages among them, and identified several key pinch points that may limit regional connectivity of the population. We predict that Sunda clouded leopard connectivity in the region can be greatly enhanced through the protection of privately owned forest patches and the reforestation of underproductive oil palm plantation areas, and creation of a forested buffer zone along the river. Conversely, we show that if the region's unprotected forests were to be converted to plantations then connectivity across the Kinabatangan floodplain would be significantly reduced.

Preface: Special Issue on Wildland Fires

Wildland fires are a critical Earth-system process that impacts human populations in each settled continent[...]

A silvicultural strategy for managing uneven-aged beech-dominated forests in Thuringia, Germany: a new approach to an old problem

ABSTRACTMaintaining a permanent forest canopy cover and eventually harvesting wood in a final harvest according to predefined dimensions is often considered as prototype for future management of deciduous forests. An uneven-aged structure is considered by the public to resemble “natural” conditions, and by forest engineers it is considered as being more resilient to disturbances. In the Hainich-Dün region of Thuringia, Germany, beech-dominated selection forests covering about 10,000 ha have been managed for almost 1000 years, initially by irregular use, but as regular selection system since about 200 years. Managing these stands remains difficult, due to the lack of yield tables and a quantification of harvest of uneven-aged stands considering differences in site conditions and handling of over-sized trees. It is the objective of the present study to develop tables of target stand volumes, increments, and harvest for different diameter ranges of uneven-aged stands according to site conditions. The present study is based on repeated grid-based inventories of about 2150 plots, which were partly re-inventoried 3 times over the past 20 years. The recommended target wood volumes vary between 296 and 388 m3 ha−1. Stand growth rates of different yield classes were estimated to range between 6.7 and 7.7 m3 ha−1 yr−1 which is 30% lower than for age class forest. Nevertheless, the economic returns are higher. Thus, selective cutting with single tree selection remains a viable silvicultural system, but it may change over time into small-scale shelter-woods for improving growth of regeneration.

A spatial ensemble approach for broad-area mapping of land surface properties

Understanding rapid global change requires land cover maps with broad spatial extent, but also fine spatial and temporal resolution. Developing such maps presents a unique challenge, as variability in relationships between spectral characteristics (i.e., predictors) and a response variable is likely to increase with the size of the region across which a model is built and applied. Although most mapping approaches apply the same predictor-response relationships globally across the entire modeling region, learned relationships from one local area may be invalid for another when predicting across broad extents. Here, we adapted a spatial ensemble approach borrowed from species distribution modeling to land cover mapping, and evaluated whether the approach could faithfully represent spatial variation in relationships between land cover and spectral data. The spatiotemporal exploratory model (STEM) uses an ensemble of regression trees defined within spatially overlapping support sets, producing a broad-extent map that reflects variability at the spatial scale of each constituent support set. As test cases for reference maps, we used 30-m-resolution forest canopy and impervious surface cover layers from the 2001 U.S. National Land Cover Database (NLCD) for the states of Washington, Oregon, and California. When testing strategies for support set size and sampling intensity, we found that predictor-response relationships were strongest when individual components of the spatial ensemble were small and when sampling intensity was high. Compared to aspatial bagged decision tree and random forest models, we found that the STEM approach successfully captured variation in our source maps, both globally and at scales smaller than the modeling region. Leveraging the spatial structure of a STEM, we also mapped per-pixel spatial variation in prediction confidence and the importance of different predictor variables. After testing appropriate spatial ensemble and sampling strategies, we extended the predictor-response relationships gleaned from the 2001 source maps into a yearly time series based on temporally-smoothed spectral data from the LandTrendr algorithm. The end products were yearly forest canopy and impervious surface cover time series representing 1990–2012. Formal evaluation showed that our temporally extended maps also closely resembled NLCD maps from 2011. The aim of this research was to cultivate the implicit relationships between spectral data and a given map, not improve them, but as the need for time series maps produced at both broad extents and fine resolutions increases, our results demonstrate that an ensemble of locally defined estimators is potentially more appropriate than conventional ensemble models for land cover mapping across broad extents.

Environmental Correlates to Population Structure and Health of the Rare Piratebush (Buckleya distichophylla) within Poor Mountain Natural Area Preserve, Virginia

Piratebush (Buckleya distichophylla, Santalaceae) is a dioecious, hemi-parasitic shrub endemic to the Blue Ridge Ecoregion of the Appalachian Mountains. The Poor Mountain Natural Area Preserve (PMNAP) in southwestern Virginia protects the densest known population of this rare plant. Permanent transects were set within this natural area to measure population density, size-class structure and health indicators, and to analyze their relationship to ecological parameters. Within PMNAP, there were 9 ± 2 piratebush per 100 m2 of forest floor with a mean size of 4 ± 1 stems of 1.9 ± 0.6 cm diameter at ground height. Individual shrubs grew across a broad range of aspects, slopes (2–50%), and canopy cover (0–100%), exhibiting minimal crown death and a wide range of foliar color value. Weighted size class structure distribution was positively skewed, with low indication of recent seedling recruitment. Observed adventitious vegetative regeneration may mask the frequency of genetically distinct individuals, and indicate less genetic diversity within this population. Weighted size class was positively correlated to forest canopy cover (P < 0.001) and southerly aspect (P = 0.071). Foliar color value was positively correlated with canopy openness (P < 0.001) but neither weighted size class nor plant vigor. This study indicates that successful sexual reproduction within this piratebush population may be rare, and establishes a detailed baseline assessment of the largest extant piratebush population, enabling future study of factors relevant to the long-term viability of this species.

Extracting the full value of the Landsat archive: Inter-sensor harmonization for the mapping of Minnesota forest canopy cover (1973–2015)

Remote sensing estimates of forest canopy cover have frequently been used to support a variety of applications including wildlife habitat modeling, monitoring of watershed health, change detection, and are also correlated to various aspects of forest structure and ecosystem function. Although data from the long running Landsat earth observation program (1972–present) have been previously utilized to characterize forest canopy cover, the variability in spatial and spectral resolutions between the Landsat sensors has generally limited analyses to readily comparable imagery from the TM and ETM+ sensors, which omits large portions of the full temporal record. In this study, we present an R package, LandsatLinkr, which automates the processes for harmonizing Landsat MSS and OLI imagery to the spatial and spectral qualities of TM and ETM+ imagery, allowing for the generation of annual cloud-free composites of tasseled cap spectral indices across the entire Landsat archive. We demonstrate the utility of LandsatLinkr products, further enhanced through the LandTrendr segmentation algorithm, for characterizing forest attributes through time by developing annual forest masks and maps of estimated canopy cover for the state of Minnesota from 1973 to 2015. The forest mask model had an overall accuracy of 87%, with omission and commission errors for the forest class of 17% and 10%, respectively, and 9% and 16% for non-forest classification. Our resulting maps depicted a significant positive trend in forest cover across all ecological provinces of Minnesota during the study period. A random forest model used to predict continuous canopy cover had a pseudo R2 of 0.75, with a cross validation RMSE of 5%. Our results are comparable to previous Landsat-based canopy cover mapping efforts, but expand the evaluation time period as we were able to utilize the entire Landsat archive for assessment.

Quantitative Palynology Informing Conservation Ecology in the Bohemian/Bavarian Forests of Central Europe.

In 1927, the first pollen diagram was published from the Bohemian/Bavarian Forest region of Central Europe, providing one of the first qualitative views of the long-term vegetation development in the region. Since then significant methodological advances in quantitative approaches such as pollen influx and pollen-based vegetation models (e.g., Landscape Reconstruction Algorithm, LRA) have contributed to enhance our understanding of temporal and spatial ecology. These types of quantitative reconstructions are fundamental for conservation and restoration ecology because they provide long-term perspectives on ecosystem functioning. In the Bohemian/Bavarian Forests, forest managers have a goal to restore the original forest composition at mid-elevation forests, yet they rely on natural potential vegetation maps that do not take into account long-term vegetation dynamics. Here we reconstruct the Holocene history of forest composition and discuss the implications the LRA has for regional forest management and conservation. Two newly analyzed pollen records from Prášilské jezero and Rachelsee were compared to 10 regional peat bogs/mires and two other regional lakes to reconstruct total land-cover abundance at both the regional- and local-scales. The results demonstrate that spruce has been the dominant canopy cover across the region for the past 9,000 years at both high- (>900 m) and mid-elevations (>700–900 m). At the regional-scale inferred from lake records, spruce has comprised an average of ~50% of the total forest canopy; whereas at the more local-scale at mid-elevations, spruce formed ~59%. Beech established ~6,000 cal. years BP while fir established later around 5,500 cal. years BP. Beech and fir growing at mid-elevations reached a maximum land-cover abundance of 24% and 13% roughly 1,000 years ago. Over the past 500 years spruce has comprised ~47% land-cover, while beech and fir comprised ~8% and <5% at mid-elevations. This approach argues for the “natural” development of spruce and fir locally in zones where the paleoecology indicates the persistence of these species for millennia. Contrasting local and regional reconstructions of forest canopy cover points to a patchwork mosaic with local variability in the dominant taxa. Incorporation of paleoecological data in dialogues about biodiversity and ecosystem management is an approach that has wider utility.

Effect of Canopy Cover on Understory Invasive Alien Species in the Wayanad Wildlife Sanctuary, Kerala, India

Objectives:We assessed the diversity of invasive alien plant species in the Wayanad Wildlife Sanctuary (one of the main protected areas located in the Nilgiri Biosphere Reserve) to see whether the density and diversity were associated with forest canopy cover. This study was carried out in the pre-monsoon season from January to March 2015, when deciduous trees had shed their leaves and the canopy was relatively open.Methods: A total of 45 (20 m by 20 m) quadrats in different areas of the sanctuary were sampled. The total area sampled was 1.8 ha. All the plant species with a height of 10 cm and above were recorded and after proper identification only invasive alien species were considered. The GPS coordinates, the type of canopy cover (evergreen or deciduous) and the percentage of canopy cover were also recorded.Results: A total of 22 invasive alien plant species belonging to nine families was recorded. Out of this, 14 species (64%) belong to the Neotropics, 5 species (23%) to Africa, 2 species (9%) to West Indies and 1 species (4%) to South East Asia. Eupatorium odoratum (42.8±6.3) had the highest density followed by Lantana camara (13.6±3.2). Eupatorium odoratum was significantly and negatively correlated with canopy cover (Pearson’s correlation coefficient = -0.38, p=0.03), whereas L. camara was not associated with canopy cover (Pearson’s correlation coefficient = - 0.09, ns). This suggests that E. odoratum is more sensitive to the light levels than L. camara.Conclusion: This study provides little insights into the status of invasive alien species in an area known for its high levels of endemism.

Accuracy and performance of low‐feature GPS collars deployed on bison Bison bison and caribou Rangifer tarandus

Recently, a new generation of global positioning system (GPS) collars has become available that provides limited daily location fixes, a relatively long battery life, and are low‐cost, compared to full‐featured GPS collars. However, their performance is untested, and assessing these biases is needed to inform study designs and data analysis protocols. We used stationary tests of 15 Lotek LifeCycle GPS collars – an example of low‐feature GPS collars – to measure the accuracy of location fixes. In addition, we deployed Lotek Lifecycle GPS collars on 153 caribou Rangifer tarandus and 24 bison Bison bison in Yukon and Alaska, to assess their field performance. We examined differences among species, sex, location fix schedule, and latitude, on four performance metrics (FSR, 3D‐V FSR, DOP and DSR). Stationary trials indicated that mean precision (4.3 ± 4.0 m [SD]) and accuracy (6.0 ± 4.7 m) of location fixes was excellent, and FSR was good (87.2%), albeit both were slightly affected by forest canopy cover. Field performance varied by species and sex. Notably, the mean DSR for male bison was dismal (27.4 ± 24.2%) likely because of their behaviour, and the mean FSR, 3DV‐FSR and DOP, for male caribou was poor (FSR = 57.3 ± 2.0%), compared to collars deployed on female caribou (72.2 ± 1.7%) or female bison (77.9 ± 1.4%). We also observed that the VHF transmitters often failed when the collar malfunctioned. Biases in the accuracy and performance of these low‐cost GPS collars should be taken into account when designing studies. Researchers contemplating investing in low‐feature GPS collars require information on their ‘real‐world’ performance so that they can decide whether they are appropriate for their intended application. Moreover, researchers need to consider biases in their GPS collar data prior to embarking on field studies and when conducting analyses with the data collected from them.

Using soundscapes to detect variable degrees of human influence on tropical forests in Papua New Guinea.

There is global concern about tropical forest degradation, in part, because of the associated loss of biodiversity. Communities and indigenous people play a fundamental role in tropical forest management and are often efficient at preventing forest degradation. However, monitoring changes in biodiversity due to degradation, especially at a scale appropriate to local tropical forest management, is plagued by difficulties, including the need for expert training, inconsistencies across observers, and lack of baseline or reference data. We used a new biodiversity remote-sensing technology, the recording of soundscapes, to test whether the acoustic saturation of a tropical forest in Papua New Guinea decreases as land-use intensity by the communities that manage the forest increases. We sampled soundscapes continuously for 24 hours at 34 sites in different land-use zones of 3 communities. Land-use zones where forest cover was fully retained had significantly higher soundscape saturation during peak acoustic activity times (i.e., dawn and dusk chorus) compared with land-use types with fragmented forest cover. We conclude that, in Papua New Guinea, the relatively simple measure of soundscape saturation may provide a cheap, objective, reproducible, and effective tool for monitoring tropical forest deviation from an intact state, particularly if it is used to detect the presence of intact dawn and dusk choruses.

Taxonomic and Functional Diversity of a Quercus pyrenaica Willd. Rhizospheric Microbiome in the Mediterranean Mountains

Altitude significantly affects vegetation growth and distribution, including the developmental stages of a forest. We used shotgun Illumina sequencing to analyze microbial community composition and functional potential in melojo-oak (Quercus pyrenaica Willd.) rhizospheric soil for three different development stages along an altitudinal gradient: (a) a low altitude, non-optimal site for forest maintenance; (b) an intermediate altitude, optimal site for a forest; and (c) a high altitude, expansion site with isolated trees but without a real forest canopy. We observed that, at each altitude, the same microbial taxa appear both in the taxonomic analysis of the whole metagenome and in the functional analysis of the methane, sulfur and nitrogen metabolisms. Although there were no major differences at the functional level, there were significant differences in the abundance of each taxon at the phylogenetic level between the rhizospheres of the forest (low and intermediate altitudes) and the expansion site. Proteobacteria and Actinobacteria were the most differentially abundant phyla in forest soils compared to the expansion site rhizosphere. Moreover, Verrucomicrobia, Bacteroidetes and Nitrospirae phyla were more highly represented in the non-forest rhizosphere. Our study suggests that rhizospheric microbial communities of the same tree species may be affected by development stage and forest canopy cover via changes in soil pH and the C/N ratio.

Spatial pattern of atmospherically deposited radiocesium on the forest floor in the early phase of the Fukushima Daiichi Nuclear Power Plant accident

Spatial patterns of atmospherically deposited radiocesium on the forest floor and the temporal evolution were measured in two Japanese cedar stands and a secondary mixed broad-leaved forest in the early phase of the Fukushima Daiichi Nuclear Power Plant accident. In situ measurements of the 137Cs gamma count were made using a portable germanium gamma ray detector. These measurements revealed that the forest floors were contaminated with radionuclides derived from the accident. In the cedar stands, the inter-canopy area had higher 137Cs count rate relative to the under-canopy area, whereas no clear relationship was found between the radiocesium pattern and canopy cover in the mixed broad-leaved forest. Repeated radiocesium measurements revealed that the spatial pattern of radiocesium activity on the forest floor did not substantially change following additional deposition inputs. Furthermore, the magnitude of canopy cover partially explained spatial variability of the 137Cs on the forest floor in cedar stands. These results suggest that canopy structure affected the genesis of the horizontal variability of atmospherically deposited radiocesium on the forest floor during the early phase of the Fukushima accident.

Heterogeneity and scaling of photosynthesis, respiration, and nitrogen uptake in three Atlantic Rainforest streams

AbstractLeaves, epilithon, macrophytes, and fine benthic organic material are central ecosystem compartments to food webs and mediate nutrient fluxes in streams. Most estimates of gross primary production (GPP) and ecosystem respiration (ER) are made at a reach scale, averaging across compartments. Thus, there is little information on how individual compartments contribute to and scale up to whole‐stream estimates across watersheds. We compared estimates of GPP, ER, and nitrogen (N) uptake of individual ecosystem compartments (dm) and stream reaches (~100 m) in three sizes of streams in a preserved Atlantic Rainforest watershed. The smallest stream had dense forest canopy cover, whereas the largest was more open. We measured substratum‐specific rates of GPP and ER, as well as ammonium and nitrate 15N uptake in recirculating chambers. We compared these decimeter‐scale measurements to whole‐stream estimates, using single‐station dissolved oxygen (GPP and ER) and pulsed N uptake methods. Epilithon and macrophytes (when present) were the dominant GPP and N uptake compartments in open‐canopy sites, and leaves contributed strongly to ER at all sites, even though they covered &lt;3 percent of the stream bottom. Ammonium and nitrate uptake per unit N content varied significantly among substrata and streams. Upscaled inorganic N uptake per unit area was greater when macrophytes were present. Chamber measurements overestimated metabolic rates in the larger streams, but not in the smallest one. The smallest transient storage zone streams were more active than the biggest one, and this influenced the mismatch between whole‐stream and chamber nutrient uptake estimates. We conclude that scaling to the whole watershed requires information on location in the watershed (e.g., where canopy cover is dense), rates of individual compartments, and reach‐specific hydrodynamic information as influenced by large‐scale geomorphic details (i.e., the size and activity of the transient storage zones).

A fine‐scale U.S. population estimate of a montane spruce–fir bird species of conservation concern

AbstractBicknell's Thrush (Catharus bicknelli) is one of the most range‐restricted bird species in North America. In the United States (U.S.), it occurs only in the disturbed montane forests of fir (Abies balsamea) and spruce (Picea spp.) in the northeastern states of New York, Vermont, New Hampshire, and Maine. Climate change is expected to substantially diminish this vegetation community (&gt;50% extinction from current range) by 2300. Despite the increasingly tenuous conservation status of the species, fundamental demographic parameters remain unknown and overall population size is uncertain. We used N‐mixture models in a hierarchical Bayesian framework to predict population size and to elucidate spatial and temporal patterns of Bicknell's Thrush abundance in the northeastern United States. From 2011 to 2016, as part of Mountain Birdwatch, citizen‐scientists conducted 14,552 five‐minute point counts at 747 sampling locations along hiking trails. Observers detected Bicknell's Thrush at 49.4% of points and tallied 1079 observations of the species. Bicknell's Thrush abundance was parsimoniously modeled as a complex function of elevation, forest canopy cover, and latitude. Using our model results, and the estimated U.S. range of the Bicknell's Thrush, we produced the first fine‐scale (&lt;1.0 ha resolution) abundance estimate and map of Bicknell's Thrush density across their U.S. range. We predicted the U.S. Bicknell's Thrush population in 2016 as 71,318 (95% credible interval: 56,080–89,748), and 95% of that population occurred above 805 m. Combining our results with existing estimates of population size in Canada suggests a global population size of &lt;120,000; Bicknell's Thrush likely have one of the smallest population sizes of regularly occurring bird species within the contiguous United States and Canada. By cross‐referencing the U.S. Geological Survey Protected Areas Database, we estimated that 76.6% of Bicknell's Thrush habitat occurred on conserved lands across the United States and that this habitat supported 84.6% of the predicted population. The White Mountain National Forest (New Hampshire and Maine) is the largest conservator of Bicknell's Thrush habitat in the United States and supports ~31% of the predicted U.S. population. Our model provides a testable framework for assessing the success of future conservation and management actions on Bicknell's Thrush populations throughout their U.S. range.