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opencc-zeroOct 2020View details →

Variations in tree growth provide limited evidence of species mixture effects in Interior West U.S.A. mixed-conifer forests

1. In mixed stands, species complementarity (e.g., facilitation and competition reduction) may enhance forest tree productivity. Although positive mixture effects have been identified in forests worldwide, the majority of studies have focused on two-species interactions in managed systems with high functional diversity. We extended this line of research to examine mixture effects on tree productivity across landscape-scale compositional and environmental gradients in the low functional diversity, fire-suppressed, mixed-conifer forests of the U.S. Interior West. 2. We investigated mixture effects on the productivity of Pinus ponderosa, Pseudotsuga menziesii, and Abies concolor. Using region-wide forest inventory data, we created individual-tree generalized linear mixed models and examined the growth of these species across community gradients. We compared the relative influences of stand structure, age, competition, and environmental stress on mixture effects using multi-model inference. We analyzed growth of neighboring tree species to infer whether a mixture effect in a single species translated to the stand-level. 3. We found support for a positive mixture effect in P. menziesii, although our results were equivocal in light of a weaker but still plausible alternative model. Growth of P. menziesii neighboring species in mixed stands declined or held constant depending on aridity, suggesting that a positive mixture effect in P. menziesii does not necessarily extend to the stand level. We found no evidence for mixture effects in P. ponderosa, A. concolor or their neighboring species. 4. Complementarity appears to have a limited influence on tree growth in the mixed-conifer systems of the U.S. Interior West, reflecting limited functional diversity. Historical changes in stand structure following fire exclusion, particularly high stand densities, may limit the potential for positive species mixture effects. The limited species pool of Interior West forests increases the risk that, without careful management, what functional diversity exists could be lost to compositional changes resulting from stand dynamics or disturbance.

opencc-zeroNov 2023View details →

Data from: Thinning and prescribed burning increase shade-tolerant conifer regeneration in a fire excluded mixed-conifer forest

Fire exclusion and past management have altered the composition, structure, and function of frequent-fire forests throughout western North America. In mixed-conifer forests of the California Sierra Nevada, fire exclusion has exacerbated the effects of drought and endemic bark beetles, resulting in extensive mortality of fire-adapted pine species. Thinning and prescribed fire are widely used in these forests to reduce fuels, moderate fire behavior, and restore ecosystems. Tree regeneration influences future forest composition and structure, and therefore future resilience to disturbances, but long-term effects of thinning and prescribed burning on tree regeneration after prolonged fire exclusion are poorly understood. We measured tree regeneration one year prior to, and periodically for 16 years following thinning and prescribed burning in a mixed-conifer forest in the Sierra Nevada, California, USA. We asked three questions. How did the composition and density of tree regeneration change after thinning and prescribed burning? Did pretreatment vegetation types influence conifer regeneration density after treatments? Did planting after overstory thinning increase regeneration density of native pine species? Sixteen years after treatments, combined natural regeneration of shade-tolerant white fir (Abies concolor) and incense-cedar (Calocedrus decurrens) averaged 2,032 trees per hectare (tph) after understory thinning, and 7,745 tph after understory thinning combined with prescribed burning, increases of 37% and 146% from pretreatment densities. In contrast, combined natural regeneration of white fir and incense-cedar averaged 497 tph after overstory thinning, 780 tph after overstory thinning with prescribed burning, 113 tph after prescribed burning alone, and 807 tph in untreated controls, all of which were declines from pretreatment densities. Natural regeneration of white fir and incense-cedar was consistently an order of magnitude greater than Jeffrey pine (Pinus jeffreyi) and sugar pine (Pinus lambertiana), whose combined densities 16 years after treatments averaged 37 tph across treatments and did not significantly respond to thinning and/or prescribed burning. Natural conifer regeneration after treatments varied by pre-treatment vegetation type (closed canopy, Ceanothus cordulatus shrub-dominated, and open sparse), with large increases of natural regeneration after understory thinning in closed canopy and Ceanothus shrub vegetation types. Planting increased sugar pine regeneration density after overstory thinning, marginally increased Jeffrey pine regeneration after overstory thinning combined with prescribed burning, and increased white fir regeneration after overstory thinning with and without burning. No treatments reduced white fir and incense-cedar natural regeneration while simultaneously increasing natural pine regeneration, suggesting new thinning, burning, and planting approaches may be required to meet regeneration restoration objectives.

opencc-zeroDec 2021View details →

Simulated treatment effects on bird communities inform landscape‐scale dry conifer forest management

Human land use and climate change have increased forest density and wildfire risk in dry conifer forests of western North America, threatening various ecosystem services, including habitat for wildlife. Government policy supports active management to restore historical structure and ecological function. Information on potential contributions of restoration to wildlife habitat can allow assessment of tradeoffs with other ecological benefits when prioritizing treatments. We predicted avian responses to simulated treatments representing alternative scenarios to inform landscape‐scale forest management planning along the Colorado Front Range. We used data from the Integrated Monitoring in Bird Conservation Regions program to inform a hierarchical multispecies occupancy model relating species occupancy and richness with canopy cover at two spatial scales. We then simulated changes in canopy cover (remotely sensed in 2018) under three alternative scenarios, (1) a "fuels reduction" scenario representing landscape‐wide 30% reduction in canopy cover, (2) a "restoration" scenario representing more nuanced, spatially variable treatments targeting historical conditions, and (3) a reference, no‐change scenario. Model predictions showed areas of potential gains and losses for species richness, richness of ponderosa pine forest habitat specialists, and the ratio of specialists to generalists at two (1 km2 and 250 m2) spatial scales. Under both fuels reduction and restoration scenarios, we projected greater gains than losses for species richness. Surprisingly, despite restoration more explicitly targeting ecologically relevant historical conditions, fuels reduction benefited bird species richness over a greater spatial extent than restoration, particularly in the lower montane life zone. These benefits reflected generally positive species associations with moderate canopy cover promoted more consistently under the fuels reduction scenario. In practice, contemporary forest management is likely to lie somewhere between the fuels reduction and restoration scenarios represented here. Therefore, our results inform where and how active forest management can best support avian diversity. Although our study raises questions regarding the value of including landscape‐scale heterogeneity as a management objective, we do not question the value of targeting finer-scale heterogeneity (i.e., stand and treatment level). Rather, our results combined with those from previous work clarify the scale at which targeting structural heterogeneity and historical reference conditions can promote particular ecosystem services.

Fig. 8 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 8 a-i, (graphic scale). Glyptostroboxylon tenerum (Kraus) Conwentz, 1884; (Specimen Li.483). a-c: Cross section - quite abrupt transition, distinct growth rings; large thin-walled tracheids; parenchyma few, diffuse; d-f: Tangential section - irregular uniseriate small pits on tracheids; parenchima with nodular end walls (arrow); rays exclusively uniseriate; g-i: Radial section - tracheidal pitting 1-2-seriate, opposite; rays homocellular, cells all procumbent; cross field with 1-2(-3) cupressoid pits or taxodioid (arrows), more numerous in marginal cross fields, and slightly irregular.

Fig. 6 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 6 a-i, (graphic scale). Taxodioxylon taxodii Gothan, 1906. (Specimen Tf.122). a-c: Cross section - quite gradual transition, distinct growth rings; large tracheids; parenchyma few, diffuse; d-f: Tangential section - pitting on tracheids absent; axial parenchyma end-walls nodular (arrow); rays uniseriate; g-i: Radial section - tracheidal pitting 1-2-seriate, pairs opposite; rays homocellular, cells all procumbent; poorly preserved cross field pitting with 1-2(4) taxodioid oculipores.

Fig. 7 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 7 a-i (graphic scale). Glyptostroboxylon rudolphii Dolezych et van der Burgh, 2004; (Specimen Li.481) a-c: Cross section - abrupt transition, quite distinct growth rings; thick-walled tracheids; d-f: Tangential section - few pits on tracheids, parenchyma with nodular transverse wall; rays exclusively uniseriate; g-i:. Radial section - radial pitting 1-3- seriate, opposite; rays homogeneous, parenchymal cells sll procumbent, marginals taller; poorly preserved cross-fields with 1-4 glyptostroboid to taxodioid pits (arrows).

Fig. 4 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 4 a-i. (graphic scale). Tetraclinoxylon velitzelosii Süss, 1997. (Specimen Tf.132). a-c: Cross section - quite abrupt transition, distinct growth rings; tracheids with typicaly round lumina (arrow); parenchyma few; d-f: Tangential section - pitting on tracheids absent; parenchyma with dark remains; low rays (arrow); g-i: Radial section - stiations on tracheids (arrow) and pitting 1(2)-seriate, opposite or irregular; poorly preserved cross fields (arrow).

Fig. 2 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 2 a-i, (graphic scale). Cupressinoxylon akdikii Özgüven-Ertan, 1977 (Specimen Lfk.156). a–c: Cross section - abrupt transition, distinct growth rings; parenchyma few, diffuse; rays uniseriate; d–f: Tangential section - pitting on tracheids absent or rare, as uniseriate small pits (arrow); rays uniseriate; g–i: Radial section - tracheidal pitting 1(-2)- seriate, opposite; rays homogeneous, badly preserved cross fields with 1-2(-3) cupressoid pits (arrow).

Fig. 3 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 3 a-i. (graphic scale). Juniperoxylon acarcae Akkemik, 2020. (Specimen Lfk.266). a–c: Cross section - transition abrupt, distinct growth rings; parenchyma few, diffuse; rays uniseriate; d–f: Tangential section - pitting on tracheids absent; nodular parenchyma end walls (arrow); rays uniseriate; g–i: Radial section - tracheidal pitting uniseriate; rays homocellular, cells all procumbent, marginals taller; tangential end-walls with juniperoid nodules (inclined arrow); poorly preserved cross fields with 1-2 cupressoid pits, usually arranged as vertical pairs pits (horizontal arrow).

Fig. 1 in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 1 Map of Greece; * marks the areas where the studied fossil wood samples were collected (according with d-maps.com, with modifications).

Fig. 5 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 5 a-i, (graphic scale). Taxodioxylon gypsaceum (Göpp.) Kräusel, 1949. (Specimen Lfk.313). a-c: Cross section - quite gradual transition, distinct growth rings; parenchyma few, diffuse, or in small lines; d-f: Tangential section - unpitted tracheids; parenchyma with end-wall smooth or weakly nodular; g–i: Radial section - tracheidal pitting 1-3-seriate, opposite; rays homocellular, cells all procumbent; poorly preserved cross fields with 1-3 taxodioid pits (arrow), more numerous in taller marginal cross fields, in 2 superposed rows or slightly irregular.

Fig. 9 a-i in Palaeoxylotomical Studies In The Cenozoic Petrified Forests Of Greece. Part Two - Conifers

Fig. 9 a-i. (graphic scale). Pinuxylon pineoides (Kraus) Koeniguer, 1967; (Specimen Lsv.365). a-c: Cross section - gradual transition, distinct growth rings; parenchyma absent; resin canals of pinoid type, with thin walledepithelial cells, partially destroyed; d-f: Tangential section - tracheids, uniseriate rays, axial canal (4), fusiform ray with ray-canal (5-6); g-i: Radial section - tracheidal pitting 1-2-seriate, opposite (8); rays homocellular, cells all procumbent, ray-tracheids weakly dentate; poorly preserved cross-field with 1-3(4) pinoid pits.

opencc-zeroJul 2024View details →

Data from: Vegetation dynamics 1946–2018 in an old-growth conifer forest

We analysed ground vegetation in 250 plots in 2018 in the old-growth Picea abies-dominated forest Säby Västerskog, SE Sweden as a follow-up of studies in 1946 and 1998 with the same layout of plots. The vegetation changes were not clearly directional: the species composition in 2018 was intermediate between that of 1946 and 1998, whereas in 1998 species richness was higher and with the unique presence of a number of species indicating small-scale disturbances. Vaccinium myrtillus increased in cover since 1946 and Avenella flexuosa decreased. This goes against regional trends, attributed to climate warming and changes in nitrogen deposition. Regional changes are overshadowed by fine-scale disturbances and micro-successions.

opencc-by-4.0Sep 2019View details →

A Convolutional Neural Network classifier identifies tree species in mixed-conifer forest from hyperspectral imagery

Published online: <a href="https://www.mdpi.com/2072-4292/11/19/2326">https://www.mdpi.com/2072-4292/11/19/2326</a> DOI: 10.3390/rs11192326 Abstract: In this study, we automate tree species classification and mapping using field-based training data, high spatial resolution airborne hyperspectral imagery, and a convolutional neural network classifier (CNN). We tested our methods by identifying seven dominant trees species as well as dead standing trees in a mixed-conifer forest in the Southern Sierra Nevada Mountains, CA (USA) using training, validation, and testing datasets composed of spatially-explicit transects and plots sampled across a single strip of imaging spectroscopy. We also used a three-band ‘Red-Green-Blue’ pseudo true-color subset of the hyperspectral imagery strip to test the classification accuracy of a CNN model without the additional non-visible spectral data provided in the hyperspectral imagery. Our classifier is pixel-based rather than object based, although we use three-dimensional structural information from airborne Light Detection and Ranging (LiDAR) to identify trees (points > 5 m above the ground) and the classifier was applied to image pixels that were thus identified as tree crowns. By training a CNN classifier using field data and hyperspectral imagery, we were able to accurately identify tree species and predict their distribution, as well as the distribution of tree mortality, across the landscape. Using a window size of 15 pixels and eight hidden convolutional layers, a CNN model classified the correct species of 713 individual trees from hyperspectral imagery with an average F-score of 0.87 and F-scores ranging from 0.67–0.95 depending on species. The CNN classification model performance increased from a combined F-score of 0.64 for the Red-Green-Blue model to a combined F-score of 0.87 for the hyperspectral model. The hyperspectral CNN model captures the species composition changes across ~700 meters (1935 to 2630 m) of elevation from a lower-elevation mixed oak conifer forest to a higher-elevation fir-dominated coniferous forest. High resolution tree species maps can support forest ecosystem monitoring and management, and identifying dead trees aids landscape assessment of forest mortality resulting from drought, insects and pathogens. We publicly provide our code to apply deep learning classifiers to tree species identification from geospatial imagery and field training data Digital Publication of the training data polygons and hyperspectral imagery used in the manuscript "A Convolutional Neural Network classifier identifies tree species in mixed-conifer forest from hyperspectral imagery". Code is available in a Jupyter Notebook and can be found here: <a href="https://github.com/jonathanventura/canopy">https://github.com/jonathanventura/canopy</a> National Ecological Observatory Network. 2018. Provisional data downloaded from <a href="http://data.neonscience.org/">http://data.neonscience.org</a> on 22 June 2018. Battelle, Boulder, CO, USA

opencc-by-4.0Oct 2021View details →

Site characterization, regeneration attributes, and juvenile conifer growth characteristics for 25 forest and woodland sites in the southwestern United States

This dataset contains biotic and abiotic site characterization data, juvenile conifer regeneration and growth data, and detailed juvenile growth characteristic data for destructively sampled juvenile conifers. Data are included for 25 forest and woodland sites in the southwestern United States, and were collected in summer 2019. A detailed sampling and analysis methodology is available from the following publication (in press as of 10-2021): Pirtel NL, Bradford JB, Hubbard RM, Abella SR, Kolb TE, Litvak ME, Porter SL and Petrie MD. 2021. The aboveground and belowground growth characteristics of juvenile conifers in the southwestern United States, Ecosphere: in press. Please contact the corresponding author (MD Petrie) with any questions or requests.

opencc-by-4.0Dec 2022View details →

Data from Widespread exposure to altered fire regimes under 2°C warming is projected to transform conifer forests of the Western United States

This archive includes a minimal dataset needed to reproduce the analysis as well as a table (CSV) and spatial polygons (ESRI shapefile) of the resulting output from the publication: Hoecker, T.J., S. A. Parks, M. Krosby & S. Z. Dobrowski. 2023. Widespread exposure to altered fire regimes under 2°C warming is projected to transform conifer forests of the Western United States. Communications Earth and Environment. Publication abstract: Changes in wildfire frequency and severity are altering conifer forests and pose threats to biodiversity and natural climate solutions. Where and when feedbacks between vegetation and fire could mediate forest transformation are unresolved. Here, for the western U.S., we used climate analogs to measure exposure to fire-regime change; quantified the direction and spatial distribution of changes in burn severity; and intersected exposure with fire-resistance trait data. We measured exposure as multivariate dissimilarities between contemporary distributions of fire frequency, burn severity, and vegetation productivity and distributions supported by a 2 °C-warmer climate. We project exposure to fire-regime change across 65% of western US conifer forests and mean burn severity to ultimately decline across 63% because of feedbacks with forest productivity and fire frequency. We find that forests occupying disparate portions of climate space are vulnerable to projected fire-regime changes. Forests may adapt to future disturbance regimes, but trajectories remain uncertain.

publicJul 2024View details →

Data from: Vegetation dynamics 1946–2018 in an old-growth conifer forest

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