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Artificial pollination of black walnut (Juglans nigra L.) is not practical and timber breeders have historically utilized only open-pollinated half-sib families. An alternate approach called \"breeding without breeding,\" consists of genotyping open-pollinated progeny using DNA markers to identify paternal parents and then constructing full-sib families. In 2014, we used 12 SSR markers to genotype 884 open-pollinated half-sib progeny harvested from two clonal orchards containing 206 trees, comprised of 52 elite timber selections. Seed was harvested in 2011 from each of two ramets of 23 clones, one upwind and one downwind, based on prevailing wind direction from the west-southwest. One orchard was isolated from wild black walnut and composed of forward selections while the other orchard was adjacent to a natural forest containing mature black walnut composed of backward selections. Isolation significantly increased within-orchard pollination (85%) of the progeny from the isolated orchard compared to 42% from the non-isolated orchard. Neither prevailing wind direction nor seed tree position in the orchard affected paternity patterns or wild pollen contamination. Genetic diversity indices revealed that progeny from both orchards were in Hardy-Weinberg equilibrium with very little inbreeding and no selfing. A significant level of inbreeding was present among the forward selected parents, but not the first generation (backward selected) parents. Some orchard clones failed to sire any progeny while other clones pollinated upwards of 20% of progeny.

As climate changes, many regions of the world are projected to experiencemore intense droughts, which can drive changes in plant community composition through a variety ofmechanisms.During drought, communitycomposition can respond directly to resource limitation, but biotic interactions modify the availability of these resources. Here, we develop the Community Response to Extreme Drought framework (CRED),which organizes the temporal progression ofmechanisms and plant– plant interactions that may lead to community changes during and after a drought. The CRED framework applies someprinciples of the stress gradient hypothesis (SGH), which proposes that the balance between competition and facilitation changeswith increasing stress. TheCRED framework suggests that net biotic interactions (NBI), the relative frequency and intensity of facilitative (+) and competitive (−) interactionsbetweenplants,will changetemporally,becomingmorepositiveunder increasing drought stress andmore negative as drought stress decreases. Furthermore,we suggest that rewettingrates affect the rate of resource amelioration, specifically water andnitrogen, altering productivity responses and the intensity and importance ofNBI, all of whichwill influence droughtinduced compositional changes. System-specific variables and the intensity of drought influence the strength of these interactions, and ultimately the system’s resistance and resilience to drought.

Invasive shrubs in forest understories threaten biodiversity and forest regeneration in the eastern United States. Controlling these extensive monotypic shrub thickets is a protracted process that slows the restoration of degraded forest land. Invasive shrub removal can be accelerated by using forestry mulching heads, but evidence from the western United States indicates that mulching heads can promote exotic species establishment and mulch deposition can reduce native plant species abundance. We compared the effectiveness of the mulching head and the “cut-stump” method for controlling the invasive shrub Amur honeysuckle (Lonicera maackii), as well as their impacts on native plant community recovery, in mixed-hardwood forests of Indiana. After two growing seasons, mulching head treatment resulted in greater L. maackii regrowth and regeneration. The recovery of native plant abundance and diversity following shrub removal did not differ between the two methods. However, mulch deposition was associated with increased abundance of garlic mustard (Alliaria petiolata), an invasive forb. Increasing mulching head treatment depth reduced L. maackii regrowth, but additional study is needed to determine how it affects plant community responses. The mulching head is a promising technique for invasive shrub control and investigating tradeoffs between reducing landscape-scale propagule pressure and increased local establishment will further inform its utility.

Artificial pollination of black walnut (Juglans nigra L.) is not practical and timber breeders have historically utilized only open-pollinated half-sib families. An alternate approach called \"breeding without breeding,\" consists of genotyping open-pollinated progeny using DNA markers to identify paternal parents and then constructing full-sib families. In 2014, we used 12 SSR markers to genotype 884 open-pollinated half-sib progeny harvested from two clonal orchards containing 206 trees, comprised of 52 elite timber selections. Seed was harvested in 2011 from each of two ramets of 23 clones, one upwind and one downwind, based on prevailing wind direction from the west-southwest. One orchard was isolated from wild black walnut and composed of forward selections while the other orchard was adjacent to a natural forest containing mature black walnut composed of backward selections. Isolation significantly increased within-orchard pollination (85%) of the progeny from the isolated orchard compared to 42% from the non-isolated orchard. Neither prevailing wind direction nor seed tree position in the orchard affected paternity patterns or wild pollen contamination. Genetic diversity indices revealed that progeny from both orchards were in Hardy-Weinberg equilibrium with very little inbreeding and no selfing. A significant level of inbreeding was present among the forward selected parents, but not the first generation (backward selected) parents. Some orchard clones failed to sire any progeny while other clones pollinated upwards of 20% of progeny.

Establishing adequate advanced oak reproduction prior to final overstory removal is crucial for regenerating oak forests in the eastern U.S. Many management approaches exist to this end, but benefits associated with any individual technique can depend on the suite of techniques employed and the geographic location. At four mixed-hardwood upland forest sites in central and southern Indiana, we tested factorial combinations of deer fencing, controlled-release fertilization, and various silvicultural techniques (midstory removal, crown thinning, and a shelterwood establishment cut) for promoting the growth and survival of underplanted red oak seedlings. Crown thinning resulted in slow growth and low survival. Midstory removal and the shelterwood establishment cut were nearly equally effective for promoting seedling growth. Seedling survival was strongly influenced by fencing, and differences in survival between silvicultural treatments were minimal when fencing was employed. Fertilization had minimal effects overall, only increasing the probability that unfenced seedlings were in competitive positions relative to surrounding vegetation. We suggest that underplanting oak seedlings can augment natural reproduction, but the practice should be accompanied by a combination of midstory removal and fencing, at a minimum, for adequate growth and survival.

Invasive shrubs in forest understories represent a threat to biodiversity and forest regeneration in the Eastern United States. Lonicera maackii [Rupr.] Herder (Amur honeysuckle, Caprifoliaceae) is a prevalent invasive shrub species in the Midwest, and has been documented in more than 30 states. Once a handful of established L. maackii shrubs reach maturity, prolific fruit production and extensive dispersal by wildlife can lead to explosive population growth and the formation of dense, monotypic thickets across wide areas of forested land. Light limitation, changes to soil nutrient cycling, increased throughfall interception, cascading effects on wildlife (e.g., increased rates of seed predation), and possible allelopathy all contribute to the effects of L. maackii on understory plant communities. While evidence from other invasive shrub taxa indicates that short-term plant community recovery following shrub control may not fully reflect the composition of pre-invasion communities, understory herbaceous cover and native seedling densities can rebound rapidly even after decades of L. maackii invasion. However, the ability of these shrubs to resprout readily from pre-formed buds in the stump and the susceptibility of shrub control sites to reseeding from surrounding invasions provide a challenge for lasting control. Forestry mulching heads are being used with increasing frequency for invasive shrub control in the Eastern U.S. While this technique offers the potential to accelerate the removal of dense shrub thickets over large areas, its ecological effects are understudied in this context. For L. maackii control, the effectiveness of mulching heads for mitigating resprouting and the impacts of this technique on recovery of the understory plant community relative to the widespread cut-stump method are unknown. Despite several lines of evidence that soil processes in forests invaded by L. maackii are modified in ways that are largely associated with accelerated decomposition rates, the effects of honeysuckle removal on soil properties remain poorly understood. Some effects of L. maackii on soil properties can be slow to develop, and invasive shrubs can have lasting legacies on soils, suggesting that the effects of shrub removal may not be evident in the short-term. However, the tendency of these shrubs to resprout when cut may have relatively rapid implications for belowground processes, due to the potential for flushes of root exudates to accelerate decomposition of soil organic matter (SOM), known as a rhizosphere priming effect. I compared the forestry mulching (“Fecon”) head to cut-stump removal in terms of its effectiveness at controlling L. maackii and its impacts on native plant community recovery, while also isolating the effects of mulch deposition from the effects of removal treatments themselves. I also examined soil chemistry and soil microbial community function in bulk soils following shrub removal and in rhizosphere soils directly associated with roots of resprouting (in treatment areas) or undamaged (in reference areas) honeysuckle. Two growing seasons after the initial shrub removal treatments, L. maackii regrowth was higher in Fecon-treated plots than cut-stump plots, but depth of the Fecon head application was an important determinant of stump sprouting in other shrub removal sites. While further data are necessary to determine the effect of Fecon treatment depth on native community recovery, the two removal treatments were no different in the recovery of native seedlings, herbaceous flora, and herbaceous-layer diversity indices following shrub removal. Herbaceous spring perennials were slower to respond to shrub removal than other components of the understory plant community. Soil microbial community function was analyzed using the MicroResp technique for multiple substrate induced respiration (MSIR) responses. MSIR responses in bulk soils were lower in removal areas than reference areas for nearly all substrates the first year, coinciding with relatively elevated responses in the rhizosphere soils of resprouting shrubs. Rhizosphere soils of resprouting shrubs also had higher SOM and organic C than untreated shrubs, particularly in the first year, suggesting a flush of rhizodeposits from cutting and regrowth. The strongest drivers of MSIR profiles were soil organic matter (SOM) and pH. Bulk soil chemistry responses to shrub removal initially reflected a reduction in the effects of honeysuckle on throughfall precipitation—higher ammonium and lower Mg—and did not show any evidence of a rhizosphere priming effect, despite elevated microbial activity and organic C in the rhizosphere of resprouting shrubs. However, changes in bulk soil chemistry between years reflected honeysuckle rhizosphere soil, and this effect was stronger in treatment areas. Honeysuckle mulch was associated with greater soil potassium concentration. Although both shrub removal techniques will require follow-up control methods to kill resprouting shrubs and new seedlings, forestry mulching heads are a promising technique to accelerate the control of invasive shrubs. This study is the first to document the potential for invasive shrub control to affect soil properties through rhizodeposition by the target species, but leaves open questions as to the role of shrub mortality on rhizodeposition, as I did not examine soils associated with the roots of successfully killed L. maackii shrubs. Future work on soil legacy effects of invasive woody species should consider the influence of root inputs from the target species elicited by control efforts.

This is the TIMES-MIRROR'S Public Forum. Those who would stand thereon must first give the editor their real names and be responsible for their opinions and statements. Cultivate brevity, clearness of style and timeliness; write plainly and on live topics, and use one...

THE history of farming in America discloses hardly any temptations resisted, and thus threatens serious consequences for us all. In ''The Vanishing Land,'' [Robert West Howard] speaks with the voice of the agricultural establishment but in a subversive undertone. The author of ''Two Billion Acre Farm,'' ''The Horse in America,'' ''Farms'' and other books, he knows how American agriculture works and where its skeletons are buried. ''During the same third of a century,'' he writes, ''American technology took more than sixty-five million acres of cropland out of production, reduced the number of farms by 500,000, allowed hundreds of billions of tons of topsoil to erode into the oceans, lowered our national water reserves to near-drought level, poisoned our waterways and atmosphere, and quadrupled the retail price of food.'' They are united in their belief that modern agriculture cannot continue on its present course. The waste of soil, water, fossil fuels - of the human spirit itself - is too great. Even a cardinal premise of agribusiness is wrong-headed, according to the authors. ''For nothing at present is more destructive of farms and farmers than bumper crops,'' [Wendell Berry] writes. ''High production keeps production costs high and the market prices low.''

The placenta is the extraembryonic organ that supports the fetus during intrauterine life. Although placental dysfunction results in major disorders of pregnancy with immediate and lifelong consequences for the mother and child, our knowledge of the human placenta is limited owing to a lack of functional experimental models 1 . After implantation, the trophectoderm of the blastocyst rapidly proliferates and generates the trophoblast, the unique cell type of the placenta. In vivo, proliferative villous cytotrophoblast cells differentiate into two main sub-populations: syncytiotrophoblast, the multinucleated epithelium of the villi responsible for nutrient exchange and hormone production, and extravillous trophoblast cells, which anchor the placenta to the maternal decidua and transform the maternal spiral arteries 2 . Here we describe the generation of long-term, genetically stable organoid cultures of trophoblast that can differentiate into both syncytiotrophoblast and extravillous trophoblast. We used human leukocyte antigen (HLA) typing to confirm that the organoids were derived from the fetus, and verified their identities against four trophoblast-specific criteria 3 . The cultures organize into villous-like structures, and we detected the secretion of placental-specific peptides and hormones, including human chorionic gonadotropin (hCG), growth differentiation factor 15 (GDF15) and pregnancy-specific glycoprotein (PSG) by mass spectrometry. The organoids also differentiate into HLA-G + extravillous trophoblast cells, which vigorously invade in three-dimensional cultures. Analysis of the methylome reveals that the organoids closely resemble normal first trimester placentas. This organoid model will be transformative for studying human placental development and for investigating trophoblast interactions with the local and systemic maternal environment. An in vitro system that generates three-dimensional cultures of extraembryonic fetal trophoblast cells that differentiate into the two main types of trophoblast can be used to study human placental development.

General relativity 1 predicts that short-orbital-period binaries emit considerable amounts of gravitational radiation. The upcoming Laser Interferometer Space Antenna 2 (LISA) is expected to detect tens of thousands of such systems 3 but few have been identified 4 , of which only one 5 is eclipsing—the double-white-dwarf binary SDSS J065133.338+284423.37, which has an orbital period of 12.75 minutes. Here we report the discovery of an eclipsing double-white-dwarf binary system, ZTF J153932.16+502738.8, with an orbital period of 6.91 minutes. This system has an orbit so compact that the entire binary could fit within the diameter of the planet Saturn. The system exhibits a deep eclipse, and a double-lined spectroscopic nature. We see rapid orbital decay, consistent with that expected from general relativity. ZTF J153932.16+502738.8 is a strong source of gravitational radiation close to the peak of LISA’s sensitivity, and we expect it to be detected within the first week of LISA observations, once LISA launches in approximately 2034. Observations of an eclipsing double-white-dwarf binary with an orbital period of 6.91 minutes that is decaying as predicted by general relativity are reported; once launched, the Laser Interferometer Space Antenna (LISA) should swiftly detect this binary.