Woody Structures Research Articles

Seasonally dry tropical forests in the late Pleistocene of Mesopotamia, Argentina and their relationship to environmental changes during the Last Interglacial

ABSTRACTThe concept of seasonal forests groups structural types of vegetation that are related to climatic seasonality in the tropics of South America. Consequently, this determines the physiognomy of the vegetation, from semi‐deciduous to strongly deciduous. The strongest link between seasonally dry tropical forests (SDTFs) is their floristic composition, where Leguminosae and Anacardiaceae dominate the woody flora. The fossil records of the Neogene of northwestern Argentina reveal a list of species found in various locations and formations of the Miocene–Lower Pleistocene obtained from studies of pollen, woods (logs), cuticles, impressions of leaves and fruits. The analysis of sediments and woody structures from the Tapebicuá, Toropí/Yupoí and El Palmar Formations (Upper Pleistocene) of the Mesopotamia region allowed us to identify several pollen taxa and silicified wood fragments (mineralized). The woody and shrubby association whose current relatives characterize the SDTF is composed of the 16 fossil species described here belonging to seven families. In our samples, Anadenanthera colubrina and Myracrodruon balansae are the most significant members of the families Leguminosae and Anacardiaceae, which are dominant in the SDTF. The paleobotanical species described in this study confirm the extension of the SDTF to the province of Corrientes, coinciding with various climatic events (dry subtropical, semi‐desert and warm‐humid climate) that would have favored the development of these forests during the Pleistocene in this region. The absolute dates obtained for the Toropí/Yupoí and Tapebicuá Formations confirm their synchronicity and correlation to Marine Isotope Stage 5. The palynological analysis, the presence of Menendoxylon and the sedimentological data allow us to infer the existence of a seasonally dry humid paleoclimate in northeastern Argentina during the Late Pleistocene favorable to the development of the SDTF.

Occurrence of common frog (Rana temporaria) and common toad (Bufo bufo) adults and metamorphs in agricultural fields in Germany: Potential for exposure to plant protection products.

To characterize the potential for exposure of amphibian terrestrial life stages to plant protection products (PPP), we studied the occurrence and habitat use of adult and metamorph common frogs (Rana temporaria) and common toads (Bufo bufo) in an agricultural landscape in Germany. The four selected study sites were breeding ponds with approximately 80% agricultural land within a 1-km radius. Adults were monitored by radio tracking for two years, and metamorph numbers were assessed for one summer using pitfall traps alongside drift fences. The results demonstrate that adults were rarely present in arable fields at any of the sites (overall 0.5% and 4% of total observations for frogs and toads, respectively). Metamorph captures in arable fields were more variable, ranging from 1.2% to 38.8% (frogs) and from 0.0% to 26.1% (toads) across study sites. Unsurprisingly, most captures in arable fields for both toad and frog metamorphs occurred at the site where the pond was completely surrounded by arable fields. Overall, the presence of adult amphibians in arable fields was limited and, for the metamorphs, occurred primarily when crops were denser and PPP spray interception higher. Diurnal hiding behavior was observed with the highest activity recorded at night, further reducing the risk of dermal exposure from direct PPP overspraying. In addition, it appeared that alternative habitats, such as woody structures or water bodies in the broader surrounding area, were preferred by the animals over the arable areas. The use of buffer zones around water bodies in agricultural areas would be an effective risk mitigation measure to protect terrestrial adults and metamorphs residing there and would reduce spray drift entry into water bodies during PPP application. It is hoped that these results will contribute to the discussion of risk assessment and mitigation options for amphibians. Integr Environ Assess Manag 2024;20:2218-2230. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Cultivar ideotype for intensive olive orchards: plant vigor, biomass partitioning, tree architecture and fruiting characteristics

In order to achieve higher and earlier yield, modern olive orchards are increasingly intensified, with tree densities up to > 1500 trees hectare-1. With increasing tree densities, individual-tree canopy volume must be proportionally reduced. Not all cultivars are adaptable to high and very high orchard densities, because of excessive vigor and/or insufficient bearing when the canopy is pruned to a small volume. However, what makes an olive cultivar suitable for intensive and super intensive orchards is not clear. Recently, few studies have addressed this topic, suggesting that tree architecture and early bearing are essential traits. Yet, what architectural and productive features are important, how they work and whether they are interrelated remains elusive. This review summarizes and interprets the literature on olive, as well as the more abundant literature available for other fruit species, aiming to provide a comprehensive knowledge framework for understanding how tree architectural characteristics, plant vigor, and fruiting vary across olive genotypes, and how they are interconnected. It is concluded that, among the architectural characteristics, greater branching and smaller diameters of woody structures are particularly important features for cultivar suitability to intensive and super intensive olive orchards. Greater branching allows to produce more fruiting sites in the small volume of canopy allowed in these systems. It also reduces investments in woody structures, liberating resources for fruiting. Additional resources are liberated with smaller structure diameters. Greater branching also increases resources by increasing biomass partitioning into leaves (i.e. the photosynthetic organs), relative to wood. Since yield is affected by the competition for resources with vegetative growth, reducing resource investments in woody structures and/or increasing resource directly, increases yield. Yield, in turn, depresses vegetative growth, reducing vigor and the need for pruning. High yields also produce short shoots which have relatively greater investments in leaf mass and area, and lower in the woody stem, making them more suitable than long shoots to support concurrent fruit growth. This single framework of interpretation of how the different architectural and fruiting characteristics work and interact with one-another, will provide guidance for cultivar selection and breeding for intensive and super intensive olive orchards.

The “chi-chi” of Ginkgo biloba L. grows downward with horizontally curving tracheids having compression-wood-like features

The old Ginkgo biloba L. trees often develop cylindrical woody structures that grow downward from the underside of the large branches near the trunks. This structure is traditionally called “chi-chi” (a breast) in Japan. The structure of chi-chi has not been investigated in detail because of the rarity of such old trees of G. biloba. This study examined the chi-chi from wood anatomy and chemistry viewpoints. After debarking, there were many woody bulges and latent buds. There were hollows corresponding to these latent buds on the inner side of the bark. In the transverse section obtained from the tip part of the chi-chi sample, we found tracheids curving in a horizontal plane, and the parenchymatous latent bud tissue is the center of the swirl. Microscopic observations and X-ray micro-computed tomography suggest the growing course of the chi-chi due to several swirls contiguous to each other. From these observations, the downward growth of the chi-chi starting from the cambium cell division might be driven by the woody bulges with latent buds. The cell walls of the curved tracheids were not thickened, not rounded, and had no intercellular spaces, but their S3 layers disappeared. Furthermore, the results of thioacidolysis and acetyl bromide analyses exhibited p-hydroxyphenyl subunits deposition to lignin and high lignin content on the tip part of the chi-chi. These results suggest that the curved tracheids in the chi-chi have compression-wood-like properties to some extent.

Underground trees inhabit varied environmental extremes across the Afrotropics.

Geoxyles, a distinctive feature of Afrotropical savannas and grasslands, survive recurrent disturbances by resprouting subshrub branches from large below-ground woody structures. Underground trees are a type of geoxyle that independently evolved within woody genera of at least 40 plant families in Africa. The environmental limits and determinants of underground tree biogeography are poorly understood, with the relative influence of frost and fire debated in particular. We aim to quantify variability in the niche of underground tree species relative to their taller, woody tree/shrub congeners. Using occurrence records of four Afrotropical genera, Parinari (Chrysobalanaceae), Ozoroa (Anacardiaceae), Syzygium (Myrtaceae) and Lannea (Anacardiaceae), and environmental data of nine climate and disturbance variables, the biogeography and niche of underground trees are compared with their open and closed ecosystem congeners. Along multiple environmental gradients and in a multidimensional environmental space, underground trees inhabit significantly distinct and extreme environments relative to open and closed ecosystem congeners. Niche overlap is low among underground trees and their congeners, and also among underground trees of the four genera. Of the study taxa, Parinari underground trees inhabit hotter, drier and more seasonal environments where herbivory pressure is greatest. Ozoroa underground trees occupy relatively more fire-prone environments, while Syzygium underground trees sustain the highest frost frequency and occur in relatively wetter conditions with seasonal waterlogging. Lannea underground trees are associated with the lowest temperatures, highest precipitation, and varying exposure to disturbance. While underground trees exhibit repeated convergent evolution, varied environments shape the ecology and biogeography of this iconic plant functional group. The multiplicity of extreme environments related to fire, frost, herbivory and waterlogging that different underground tree taxa occupy, and the distinctiveness of these environments, should be recognized in the management of African grassy ecosystems.

A multistage model of preservation in fossil plants from the Llewellyn Formation (Pennsylvanian), St. Clair, Pennsylvania, U.S.A

Exceptionally preserved plant fossils from St. Clair, Pennsylvania, have long been part of museum and private collections. Fossil leaf fragments and stems from the underclay of the Buck Mountain Coal (Reading Anthracite Company quarry), lowest Llewellyn Formation (late Pennsylvanian, Virgilian), combine outer layers of coalified organic material (phytoleim) with strikingly white kaolinite, quartz, and the low-grade metamorphic mineral pyrophyllite in the interior. The surficial dark, coalified material appears to preserve the dense outer layers (cuticle, epidermis, and palisade layer) and some cells of the spongy mesophyll in the fossilized leaves. XRD spectra of separated phytoleim contain graphite peaks. Raman spectra with peaks near 1600 and 1320 cm−1 indicate that the phytoleim is composed of disordered graphitic material. ID/IG ratios from ca. 0.3 to 0.45 are consistent with greenschist facies metamorphic conditions forming the anthracite coal. The interior pyrophyllite is highly crystalline, with large crystals often oriented perpendicular to leaf surfaces. Hydrothermal formation of pyrophyllite requires relatively limited groundwater flow conditions and temperatures between ca. 275 and 350 °C. Although many fossil leaves are compressed, some are near their original thickness. We infer that the remains were replaced prior to significant burial and compression of the sediment by an early-forming mineral phase, possibly pyrite, which was in turn replaced by kaolinite and then pyrophyllite at higher temperature and pressure. Woody structures such as cuticle and veins, which had resisted replacement by the initial low temperature phase, were coalified at higher temperatures.

A multi-scale analysis on the importance of patch-surroundings for farmland birds

Agricultural intensification has profoundly changed agricultural landscapes with important biodiversity impacts. There is increasing knowledge on the general effects of landscape structure and management practices on plant and animal species but understanding the role of surrounding landscape structure for patch-scale biodiversity is more complex. While it can be reasonably assumed, that adjacent habitats are more important than more distant ones, the importance of landscape structure has often been tested at the landscape scale but rarely at smaller scales such as patch-surroundings. We assessed the influence and interdependences of landscape composition and configuration (LCC) and land use/land cover (LULC) on bird species richness and abundance through a multi-scale analysis with specific focus on the surrounding patches. In two agricultural regions in Switzerland, we collected point data of birds on 36 transects (500 m) and combined them with detailed spatial data on LULC. Bird richness and abundance were correlated to sets of landscape metrics as proxies for LCC computed at the transect-scale as well as for the patch surroundings. We analysed patch LULC as well as the most important patch-surrounding metrics using generalized linear mixed models. The results illustrate that patch LULC is the most important predictor of bird richness and abundance. Woody structures increase bird richness, followed by extensive management on patch scale. On the transect-scale semi-natural structure and heterogeneous LCCs are beneficial for bird richness and abundance. The effect of patch-surrounding structure LCCs is only small and interacts with patch LULC. Birds in grassland benefit from fallows in the surroundings, while in cropland they tend to respond positively to surrounding extensive grassland. Our results highlight that considering surroundings can help improve patch-based biodiversity assessments, which will then better predict the consequences of farmland management and make the outcome more applicable for practice.

Structural complexity characterizes fine‐scale forest conditions used by Pacific martens

AbstractWhen wildlife species exhibit unexpected associations with vegetation, replication of studies in different locales can illuminate whether patterns of use are consistent or divergent. Our objective was to describe fine‐scale forest conditions used by Pacific martens (Martes caurina) at 2 study sites in northern California that differed in forest composition and past timber harvest. We identified denning and resting locations of radio‐marked martens and sampled structure‐ and plot‐level vegetation using standardized forest inventory methods between 2009–2021. Woody structures used by martens were significantly larger than randomly available structures across types (e.g., live tree, snag, log) and at both study sites. Den and rest structures occurred in areas characterized by higher numbers of logs and snags, lower numbers of live trees and stumps, larger diameter live trees and logs, and greater variation in live tree and log diameter. Features of denning and resting locations were largely consistent across study sites and were generally representative of fine‐scale forest heterogeneity and increased structural complexity, conditions that martens have been widely associated with at broader spatial scales (i.e., home range or landscape). The spatial occurrence of denning and resting locations may indicate that fine‐scale structural complexity facilitates marten foraging while reducing predation risk. Our work offers timely and directed information that can guide forest management in the context of increased landscape change.

Diversity of Cellulolytic Microorganisms Associated with the Subterranean Termite Reticulitermes grassei

Reticulitermes grassei is a subterranean termite species that forages on woody structures of the Iberian Peninsula, and is often a building and crops pest. A total of 23 microorganisms associated with the activity of R. grassei were isolated from colonized ecosystems in southern Spain. They were morphologically and molecularly characterized, with fungi being the most prevalent ones. The fungi showed high values of optimum growth temperature, suggesting that they could be able to survive and develop in warm regions. Their cellulolytic activity was tested in carboxymethylcellulose (CMC) agar, concluding that all fungal isolates produce cellulases, and the enzymatic index (EI) was revealed in CMC agar with Gram's iodine solution, with Penicillium citrinum showing the highest EI and Trichoderma longibrachiatum the highest mycelial growth rate on CMC. A preliminary microorganism dispersion assay was carried out with the termites, concluding that these insects may have a positive influence on fungal dispersion and the subsequent colonization of new substrates. Our study suggests that fungi associated with R. grassei may potentially be of interest in biotechnological fields such as biofuel production and the food industry.

Orthopteran Diversity in Steep Slope Vineyards: The Role of Vineyard Type and Vegetation Management.

The abandonment of traditional agricultural practices and subsequent succession are major threats to many open-adapted species and species-rich ecosystems. Viticulture on steep slopes has recently suffered from strong declines due to insufficient profitability, thus increasing the area of fallow land considerably. Changing cultivation systems from vertically oriented to modern vineyard terraces offers an opportunity to maintain management economically viable and thus reduces further abandonment. Hillside parallel terraces favor mechanization, and their embankments offer large undisturbed areas that could provide valuable habitats. We investigated the effects of vineyard abandonment, different vineyard management types (vertically oriented vs. terraced), and local parameters on Orthoptera diversity in 45 study sites along the Upper Middle Rhine Valley in Germany. Our results show that woody structures and vineyard abandonment reduced Orthoptera diversity at the local and landscape scale due to decreased habitat quality, especially for open-adapted species. In contrast, open inter-rows of actively managed vineyard types supported heat-adapted Caelifera species. On terrace embankments, extensive management and taller vegetation benefited Ensifera species, while short and mulched vegetation in vertically oriented vineyards favored the dominance of one single Caelifera species. Our results highlight the significance of maintaining viticultural management on steep slopes for the preservation of both open-adapted Orthoptera species and the cultural landscape.

Short-term hydromorphological and ecological responses of using woody structures for river restoration in a tailing-impacted tropical river.

Gualaxo do Norte River (GNR), in southeastern Brazil, was impacted by iron ore tailings from the Fundão Dam rupture (November 2015). The deposition of tailings on the riverbed has changed the hydrogeomorphological characteristics of the GNR, resulting in a decrease in the diversity of physical habitats and ecological biodiversity. As part of the process of restoration and management of this damaged ecosystem, the river restoration project ReNaturalize was implemented to restructure the geomorphological characteristics and the physical habitat and to enhance the reestablishment of biota, mainly for macroinvertebrates and fishes. For this goal, 203 wooden structures, such as tree trunks, branches, and grass were installed in two sections of GNR (T6R and T7R), totaling 1.8 km long. The effectiveness of the project was evaluated by an assessment that followed a before and after and control and impacted (BACI) design. Upstream of each Restored reach there is a Control and a Reference reach. Four campaigns were carried out, two before and two after the restoration process. After 14 months of the woody installation, an increase in hydraulic retention in the restored reaches was observed (T6R-20.2%; T7R-63.5%), when compared with the Control reaches, which favored the accumulation of sediments (T6R-388 metric tons; T7R-396 metric tons). This enhanced the formation of natural tailings barriers and promoted the enrichment of substrate types (T6R-39.2%; T7R-43%). The benthic macroinvertebrate community showed an increase in the total abundance (T6-110%), including the most sensitive groups (T6R-124%; T7R-124%). For fish, the increase was up to 81.38% with hand nets capture, indicating the recruitment of juveniles, and the abundance and the biomass of some species were also higher (up to 100%) than the Control reaches. The results indicated that the Restored reach is already qualitatively and quantitatively better than the Control reach and similar to the Reference reach, indicating the success of the study. Integr Environ Assess Manag 2023;19:648-662. © 2022 SETAC.

Ecological Aspects of the Pirate Perch (Aphredoderus Sayanus) in East Texas Streams

Aphredoderus sayanus (Pirate Perch) is a cryptic fish species inhabiting rivers throughout the eastern United States. We sampled Pirate Perch across 16 streams in 4 river basins (Trinity, Neches, Sabine, and Cypress) within east Texas to examine their relative abundance, habitat associations, and to describe their diet and reproductive biology. Ninety-five individuals were collected across all river basins, with streams within the Neches River containing the highest number of occurrences. Instream habitat conditions varied among basins, with major differences reflected by flow regimes, water depth, and substrate diversity. Pirate Perch were primarily associated with streams having lentic flows, shallow waters that contained woody structures, and substrates dominated by leaf litter and detritus. Insectivory was confirmed for the species. Microplastics were also documented for the first time in their stomach contents. Maximum fecundity was 2161 eggs, and ova development indicated multiple clutches of eggs during their reproductive period.

Microwave-Assisted Lignin Extraction-Utilizing Deep Eutectic Solvents to Their Full Potential.

The current research intended to investigate the suitability of different choline-chloride-based deep eutectic solvents for their role in microwave lignin extraction. Lignin, a widely spread biopolymer in plants and woody structures, is a valuable replacement for fossil-fuel-based materials. While some promising applications have been trialled already, the extraction of this material from its matrix still causes problems. Here, we highlight an efficient and fast method to extract lignin from untreated larch bark with deep eutectic solvents in a standard domestic microwave. We developed a straightforward, green methodology, which can be used on various reaction scales, with materials available to many researchers. Lignin was extracted within only 30 min of microwave irradiation in yields of up to 96%. Compared to traditional deep eutectic extraction by conventional heating, the reaction time was cut by 87% and the energy costs were reduced by 93.5%. The hydrogen bond donors were exchanged and different types, namely acid-based, hydroxyl-based and amide-based donor systems, were evaluated for their suitability concerning microwave lignin extraction. This study presents a novel approach towards energy-efficient and green lignin valorisation, without the inherent need for costly equipment.

Exploring the Branch Wood Supply Potential of an Agroforestry System with Strategically Designed Harvesting Interventions Based on Terrestrial LiDAR Data

Agroforestry systems hold potential for wood and tree biomass production without the need of felling trees. Branch wood harvesting provides access to considerable amounts of lignocellulosic biomass while leaving the tree standing. Aiming at alternatives for wood provision, we assessed the actual woody structure of a silvopastoral system in the African Savannah ecoregion, utilising terrestrial LiDAR technology and quantitative structure models to simulate branch removals and estimate harvesting yields. In addition, the stand structure and harvested wood were examined for the provision of four types of assortments meeting local needs, and operational metrics for each treatment were derived. The stand had large variability in woody structures. Branch harvesting interventions removed up to 18.2% of total stand volume, yielded 5.9 m3 ha−1 of branch wood, and delivered 2.54 m3 ha−1 of pole wood quality, retaining on average more than 75% of the original tree structures. Among the most intense simulations, a mean of 54.7 litres (L) of branch wood was provided per tree, or approximately 34.2 kg of fresh biomass. The choice of an ideal harvesting treatment is subject to practitioners’ interests, while the discussion on aspects of the operation, and stand and tree conditions after treatment, together with outputs, assist decision making. The partitioning of tree structures and branch removal simulations are tools to support the design of tending operations aiming for wood and tree biomass harvesting in agroforestry systems while retaining different functional roles of trees in situ.

Black Bears Select Large Woody Structures for Dens in Southeast Alaska

ABSTRACTTimber interests target coastal temperate rainforests, and within them stands composed of large trees potentially selected by American black bears (Ursus americanus) for denning. We identified the location of 75 black bear dens (used ≥14 days) in an intensively logged area on Prince of Wales Island, Alaska, USA. We ground‐visited a subset (n = 43) of these sites to measure the diameter of living trees and woody structures used by black bears for denning. We contrasted dens with random trees available in the study area in a series of models to characterize black bear den selection. All but 1 of 43 ground‐visited dens were located within woody structures, and all but 2 of these structures were >1 m diameter at breast height (dbh). We built resource selection functions (RSFs) to investigate black bear den selection across a range of spatial scales, though estimated selection was generally scale invariant. Black bears strongly selected large‐diameter woody structures (dead or alive) as dens at the home‐range scale, with the estimated relative strength of selection (RSS) for a 2‐m‐diameter tree approximately 166 times that of a 1‐m‐diameter tree. The estimated RSS of logged forest was unexpectedly greater (2.75 times) than that of the remaining commercially valuable old‐growth forest. Selection for den structures within stumps in previously logged stands suggests features of the woody structure may be of greater importance to black bears selecting dens than attributes of the surrounding forest. There was no observed correlation between bear den selection and second‐growth age, indicating that stumps may persist as suitable dens well after logging. Because denning is an important part of their life history and the denning structures used by black bears on Prince of Wales Island will eventually decay, retaining habitat value for bears in areas intensively managed for timber harvest requires strategies to recruit very large, old trees throughout the landscape. © 2021 The Wildlife Society.

Measuring the Contribution of Leaves to the Structural Complexity of Urban Tree Crowns with Terrestrial Laser Scanning

Trees have a fractal-like branching architecture that determines their structural complexity. We used terrestrial laser scanning technology to study the role of foliage in the structural complexity of urban trees. Forty-five trees of three deciduous species, Gleditsia triacanthos, Quercus macrocarpa, Metasequoia glyptostroboides, were sampled on the Michigan State University campus. We studied their structural complexity by calculating the box-dimension (Db) metric from point clouds generated for the trees using terrestrial laser scanning, during the leaf-on and -off conditions. Furthermore, we artificially defoliated the leaf-on point clouds by applying an algorithm that separates the foliage from the woody material of the trees, and then recalculated the Db metric. The Db of the leaf-on tree point clouds was significantly greater than the Db of the leaf-off point clouds across all species. Additionally, the leaf removal algorithm introduced bias to the estimation of the leaf-removed Db of the G. triacanthos and M. glyptostroboides trees. The index capturing the contribution of leaves to the structural complexity of the study trees (the ratio of the Db of the leaf-on point clouds divided by the Db of the leaf-off point clouds minus one), was negatively correlated with branch surface area and different metrics of the length of paths through the branch network of the trees, indicating that the contribution of leaves decreases as branch network complexity increases. Underestimation of the Db of the G. triacanthos trees, after the artificial leaf removal, was related to maximum branch order. These results enhance our understanding of tree structural complexity by disentangling the contribution of leaves from that of the woody structures. The study also highlighted important methodological considerations for studying tree structure, with and without leaves, from laser-derived point clouds.

Pruning cuts affect wood necrosis but not the percentage of budburst or shoot development on spur pruned vines for different grapevine varieties

Two experimental studies were performed in this trial. In the first, the aim was to quantify wood necrosis generated by pruning cuts on aboveground permanent (arms and trunks) and non-permanent (spurs) woody structures of 'Cabernet Sauvignon' vines. In the second, the goal was to evaluate the effect of cutting distance from the basal end of the shoot in spur pruned vines on budburst and further shoot development for 'Grenache', 'Cabernet Franc' and 'Malbec' varieties. Based upon the first experiment, the area and depth of wood necrosis was highly influenced by the distance where the pruning cut was performed over the node. Furthermore, the diameter of the spur that was cut was not significantly related to either the area or the depth of the necrotic wood generated after the cut. Aboveground vine wood necrotic area ranged from 9 to 44 % of the total wood area measured in 'Cabernet Sauvignon' cordon trained spur pruned 25-year-old grapevines. For each vine a larger proportion of the necrotic wood (20 to 46 % of necrotic area) was present in the arms when compared to the trunks (1 to 28 % of necrotic area). As a result of the second experiment, spur budburst and further shoot development was not affected by the distance from the node where the pruning cut was performed for any of the cultivars considered in the study contrary to what is commonly believed.

Comparative Reproductive Ecology of Two Subspecies of Pacific Marten (Martes caurina) in California

Accurate information on reproductive ecology is necessary to develop conservation actions for at-risk wildlife species. Our objective was to describe female reproductive parameters and den use of two subspecies of wild, untrapped Pacific martens (Humboldt marten, Martes caurina humboldtensis; Sierran marten, M. c. sierrae) of conservation interest in California. We used radio telemetry and remotely triggered cameras to monitor 10 Humboldt martens (2014 to 2016) and six Sierran martens (2016 to 2017) over 23 total denning periods. For Humboldt martens, mean parturition date was 13 April, proportion of adult females reproducing was 80% (n = 12 of 15), and mean litter size was 1.8 ± 0.6 kits (x̄ ± SD). For Sierran martens, mean parturition date was 29 April, proportion of adult females reproducing was 87% (n = 7 of 8), and mean litter size was 1.9 ± 0.7 kits. Humboldt and Sierran marten dens were predominantly located in woody structures, with live trees, snags, and logs comprising 91% and 79% of dens, respectively. Although reproductive ecologies of Humboldt and Sierran martens were largely similar, Sierran marten parturition dates were significantly later. We compare our study populations to other North American marten populations and examine factors that could influence consistency or variability in reproductive parameters between populations.

Enhancing flowering plant functional richness improves wild bee diversity in vineyard inter-rows in different floral kingdoms.

Wild bees are threatened by multiple interacting stressors, such as habitat loss, land use change, parasites, and pathogens. However, vineyards with vegetated inter‐rows can offer high floral resources within viticultural landscapes and provide foraging and nesting habitats for wild bees. Here, we assess how vineyard management regimes (organic vs. conventional; inter‐row vegetation management) and landscape composition determine the inter‐row plant and wild bee assemblages, as well as how these variables relate to functional traits in 24 Austrian and 10 South African vineyards. Vineyards had either permanent vegetation cover in untilled inter‐rows or temporary vegetation cover in infrequently tilled inter‐rows. Proportion of seminatural habitats (e.g., fallows, grassland, field margins) and woody structures (e.g., woodlots, single trees, tree rows) were used as proxies for landscape composition and mapped within 500‐m radius around the study vineyards. Organic vineyard management increased functional richness (FRic) of wild bees and flowering plants, with woody structures marginally increasing species richness and FRic of wild bees. Wild bee and floral traits were differently associated across the countries. In Austria, several bee traits (e.g., lecty, pollen collection type, proboscis length) were associated with flower color and symmetry, while in South African vineyards, only bees’ proboscis length was positively correlated with floral traits characteristic of Asteraceae flowers (e.g., ray–disk morphology, yellow colors). Solitary bee species in Austria benefitted from infrequent tillage, while ground nesting species preferred inter‐rows with undisturbed soils. Higher proportions of woody structures in surrounding landscapes resulted in less solitary and corbiculate bees in Austria, but more aboveground nesting species in South Africa. In both countries, associations between FRic of wild bees and flowering plants were positive both in organic and in conventional vineyards. We recommend the use of diverse cover crop seed mixtures to enhance plant flowering diversity in inter‐rows, to increase wild bee richness in viticultural landscapes.

Wood vs. Canopy Allocation of Aboveground Net Primary Productivity in a Mediterranean Forest during 21 Years of Experimental Rainfall Exclusion

A Mediterranean holm oak forest was subjected to experimental partial rainfall exclusion during 21 consecutive years to study the effects of the expected decrease in water availability for Mediterranean vegetation in the coming decades. Allocation in woody structures and total aboveground allocation were correlated with annual rainfall, whereas canopy allocation and the ratio of wood/canopy allocation were not dependent on rainfall. Fruit productivity was also correlated with annual rainfall, but only in Quercus ilex. In the studied site, there were two types of forest structure: high canopy stand clearly dominated by Quercus ilex, and low canopy stand with more abundance of a tall shrub species, Phillyrea latifolia. In the tall canopy stand, the allocation to woody structures decreased in the experimental rainfall exclusion, but not the allocation to canopy. In the low canopy stand, wood allocation in Quercus ilex was very small in both control and plots with rainfall exclusion, but wood allocation in Phillyrea latifolia was even higher than that obtained in tall canopy plots, especially in the plots receiving the experimental rainfall exclusion. These results highlight likely future changes in the structure and functioning of this ecosystem induced by the decrease in water availability. A serious drop in the capacity to mitigate climate change for this Mediterranean forest can be expected, and the ability of Phillyrea latifolia to take advantage of the limited capacity to cope with drought conditions detected in Quercus ilex makes likely a forthcoming change in species dominance, especially in the low canopy stands.