Eastern Redcedar Juniperus Virginiana Research Articles

Effects of post oak (Quercus stellata) and smooth brome (Bromus inermis) competition on water uptake and root partitioning of eastern redcedar (Juniperus virginiana).

Eastern redcedar Juniperus virginiana is encroaching into new habitats, which will affect native ecosystems as this species competes with other plants for available resources, including water. We designed a greenhouse experiment to investigate changes in soil moisture content and rooting depths of two-year-old J. virginiana saplings growing with or without competition. We had four competition treatments: 1) none, 2) with a native tree (Quercus stellata), 3) with an invasive grass (Bromus inermis), and 4) with both Q. stellata and B. inermis. We measured soil moisture content over two years as well as root length, total biomass, relative water content, midday water potential, and mortality at the end of the experiment. When J. virginiana and B. inermis grew together, water depletion occurred at both 30-40 cm and 10-20 cm. Combined with root length results, we can infer that J. virginiana most likely took up water from the deeper layers whereas B. inermis used water from the top layers. We found a similar pattern of water depletion and uptake when J. virginiana grew with Q. stellata, indicating that J. virginiana took up water from the deeper layers and Q. stellata used water mostly from the top soil layers. When the three species grew together, we found root overlap between J. virginiana and Q. stellata. Despite the root overlap, our relative water content and water potential indicate that J. virginiana was not water stressed in any of the plant combinations. Regardless, J. virginiana saplings had less total biomass in treatments with B. inermis and we recorded a significantly higher mortality when J. virginiana grew with both competitors. Root overlap and partitioning can affect how J. virginiana perform and adapt to new competitors and can allow their co-existence with grasses and other woody species, which can facilitate J. virginiana encroachment into grasslands and woodlands. Our data also show that competition with both Q. stellata and B. inermis could limit establishment, regardless of water availability.

Plant-soil feedback from eastern redcedar (Juniperus virginiana) inhibits the growth of grasses in encroaching range.

The encroachment of woody plants into grasslands is an ongoing global problem that is largely attributed to anthropogenic factors such as climate change and land management practices. Determining the mechanisms that drive successful encroachment is a critical step towards planning restoration and long‐term management strategies. Feedbacks between soil and aboveground communities can have a large influence on the fitness of plants and must be considered as potentially important drivers for woody encroachment. We conducted a plant–soil feedback experiment in a greenhouse between eastern redcedar Juniperus virginiana and four common North American prairie grass species. We assessed how soils that had been occupied by redcedar, a pervasive woody encroacher in the Great Plains of North America, affected the growth of Andropogon gerardi, Schizachyrium scoparium, Bromus inermis, and Pascopyrum smithii over time. We evaluated the effect of redcedar on grass performance by comparing the height and biomass of individuals that were grown in live or sterilized conspecific or redcedar soil. We found redcedar created a negative plant–soil feedback that limited the growth of the cool season grasses B. inermis and P. smithii, reducing their overall biomass by >60%. These effects were found in both live and sterilized redcedar soils. In live soils, some growth suppression can be attributed to the negative effects of soil microbes. The limitation of grass growth in sterile soils indicates redcedar may exude an allelochemical into the soil that limits grass growth. Our results demonstrate that plant–soil feedback created by redcedar inhibits the growth of certain grass species. By creating a plant–plant interaction that negatively affects competitors, redcedars increase the probability of seedling survival until they can grow to overtop their neighbors. These results indicate plant–soil feedback is a mechanism of native woody plant encroachment which could be important in many systems yet is understudied.

Importance of Coarse Woody Habitat Complexity to Yellow Perch Egg Skein Deposition and Survival

AbstractHabitat introductions are often implemented in aquatic systems to meet fishery management goals. Conifer trees have been used to augment spawning habitat for Yellow Perch Perca flavescens to support and suspend their unique egg skeins above the lake bottom in hopes of increasing reproduction and recruitment; however, little is known about the influence of tree characteristics on the reproductive success of Yellow Perch. Our objective was to evaluate the effects of tree complexity on the skein deposition and survival rates of Yellow Perch. In February 2020, 30 eastern red cedar Juniperus virginiana trees were manipulated to one of five complexities (from 1 = least complex [all branches removed] to 5 = most complex [all branches retained]; n = 6 per complexity) and placed on the ice. After ice‐off and tree submersion, we conducted snorkeling surveys every 2 d from March 31 to May 5, 2020, and recorded the number and viability of the skeins. We observed 35 Yellow Perch egg skeins. Yellow Perch preferred to deposit their egg skeins on tree complexities 4 and 5, whereas deposition on tree complexities 1, 2, and 3 was random. The nest survival models estimated that skeins that were deposited on tree complexities 1, 2, and 5 had a 27‐d survival estimate of 0.07 (95% CI = 0.06 to 0.08) that was lower (β = −1.29; 95% CI = −2.32 to −0.27) than that for skeins that were deposited on complexities 3 and 4, with a survival estimate of 0.48 (95% CI = 0.43 to 0.52). Our results indicate that Yellow Perch prefer to deposit their egg skeins on intermediate cedar tree complexities that resulted in increased skein deposition and survival. Given our results, once introduced trees have deteriorated below an intermediate complexity, managers should consider supplemental introductions of more complex trees that benefit the reproduction of Yellow Perch.

Retention and Dimensional Changes of Evergreen Brush Piles Within a Flood Control Reservoir

Abstract Brush piles (i.e., trees and large woody debris) are often installed in reservoirs to supplement fish habitat. The retention and dimensional change of brush piles after installation is important information that can be used to maximize the effectiveness of this management action. We evaluated the retention and dimensional change of 70 eastern red cedar Juniperus virginiana and bald cypress Taxodium distichum brush piles in an embayment of a drawdown reservoir up to four annual cycles of submergence and exposure. We used satellite imagery to supplement our onsite measurements of retention. We also examined spatial patterns of brush pile retention and dimensional change. Brush piles were lost at 10% per year, and their volume was lost at 14% per year. We compared our rates of brush pile retention and dimensional change with those from a holdout data set of 50 brush piles. Estimates between data sets did not differ statistically. Spatial patterns of retention and dimensional change coincided with morphological features in our study area, suggesting that retention and dimensional change is influenced by variable physical forces (e.g., wave action and flow) at installation locations. Our estimates of brush pile retention and dimensional change can be used to generally sustain desirable brush densities. For example, to maintain a fixed total volume of brush in our study embayment, roughly 23% of the total brush volume installed would need to be replaced annually. Similar research in reservoirs managed for other purposes is needed, as length and cycle of inundation could lead to variable rates of retention and dimensional change. Additionally, advancements into computer-assisted detection and volume estimation could reduce the time and effort needed to monitor brush piles.

Shade affects fine-root morphology in range-encroaching eastern redcedars (Juniperus virginiana) more than competition, soil fertility and pH

Fine-root morphological variables are often directly correlated with soil nutrient availability and water absorption. Indirectly, these morphological variables could be related to nutrient depletion by other plants. The relationships of fine-root variables with shade, direct or indirect, are unknown. I tested the relationships between a number of soil quality variables (levels of nitrogen and lime), competition with a co-dominant tree, and shade for the range-encroaching eastern redcedar Juniperus virginiana. I measured seven fine-root parameters as indices of potential nutrient-uptake or competitive ability. I also assessed the relationships of these fine-root parameters with foraging return (i.e., tissue nitrogen, non-structural carbohydrates, relative growth rate and biomass). There were no significant (main) effects of soil amendments (added nitrogen and lime) or tree competition on any of the seven root parameters. There was a significant (indirect) effect of shade (affecting five out of seven fine-root morphological variables), and a significant interaction effect between fertilizer and lime amendments, although the last-mentioned interaction affected one fine-root variable only. There were two additional pieces of evidence that support the effect of shade: a significant difference between shaded and unshaded plants in the slope of the negative relationship between root diameter and specific root length, and a significant overall difference among all fine-root morphological variables in a principal components analysis between shaded and unshaded plants. I found that fractal dimension was the only variable for which there were positive correlations with foraging return, probably because a higher fractal dimension leads to more effective use of nutrients. I expected a negative correlation between foraging returns and fine-root characteristics that incurred substantial costs. I only found a significant cost for specific root length, which may be mediated by the unmeasured parameter of root lifespan.

Shade is the most important factor limiting growth of a woody range expander

The expansion of woody plants into grasslands and old fields is often ascribed to fire suppression and heavy grazing, especially by domestic livestock. However, it is also recognized that nutrient availability and interspecific competition with grasses and other woody plants play a role in certain habitats. I examined potential factors causing range- and niche expansion by the eastern redcedar Juniperus virginiana, the most widespread conifer in the eastern United States, in multifactorial experiments in a greenhouse. Historical records suggest that the eastern redcedar is a pioneer forest species, and may be replaced as the forest increases in tree density due to shading. Another possible factor that affects its distribution may be nutrient availability, which is higher in old fields and other disturbed lands than in undisturbed habitats. In its historic range, eastern redcedars are particularly abundant on limestone outcrops, often termed ‘cedar barrens’. However, the higher abundance on limestone could be due to reduced interspecific competition rather than a preference for high pH substrates. I manipulated shade, fertilization, lime, and interspecific competition with a common dominant tree, the post oak Quercus stellata. In a separate experiment, I manipulated fire and grass competition. I measured growth rates (height and diameter) and above- and belowground biomass at the end of both experiments. I also measured total non-structural carbohydrates and nitrogen in these plants. Shade was the most important factor limiting the growth rates and biomass of eastern redcedars. I also found that there were significant declines in nitrogen and non-structural carbohydrates when shaded. These results are consistent with the notion that the eastern redcedar is a pioneer forest species, and that shade is the reason that these redcedars are replaced by other tree species. In the second experiment, I found that a single fire had a negative effect on young trees. There was no significant effect of competition with grass, perhaps because the competitive effect was shading by grasses and not nutrient depletion. Overall, the effects of shade were far more apparent than the effects of fire.

Detailed sterol compositions of two pathogenic rust fungi

Teliospores of cedar-apple rust Gymnosporangium juniperi-virginianae were collected from the eastern red cedar Juniperus virginiana, and aeciospores of quince rust G. clavipes were collected from the fruit of English hawthorn Crataegus laevigata. The sterol fractions were separated by HPLC, and their identities were determined by 600 MHz 1H NMR. Twenty-six sterols were isolated from G. juniperi-virginianae and 18 sterols were isolated from G. clavipes. The principal sterol of both fungi was (Z)-stigmasta-7,24(28)-dien-3beta-ol. Other major sterols were (24S)-ergost-7-en-3beta-ol, (24S)-stigmast-7-en-3beta-ol, and (24S)-stigmasta-5,7-dien-3beta-ol. The sterols of the hosts were found to be very different from those of the fungi. The 24-alkyl sterols of the fungi had the 24alpha-configuration, whereas those of the hosts had the 24beta-configuration. Similarities to the sterol composition of the AIDS pneumonia fungus Pneumocystis carinii are discussed.

A Comparison of Cedar Trees and Fabricated Polypropylene Modules as Fish Attractors in a Strip Mine Impoundment

Two types of attractors, brush units of eastern red cedar Juniperus virginiana and fabricated polypropylene module attractors. were placed in a strip mine impoundment and evaluated for effectiveness in concentrating fish. Scuba diving was used to evaluate the attractors every 2 weeks from July to October. Fish that were 10 cm total length or larger were counted at all study locations and included bluegill Lepomis macrochirus, redbreast sunfish L. auritus. largemouth bass Micropterus salmoides, green sunfish L. cyanellus, crappies Pomoxis spp., and channel catfish Ictalurus punctatus. Of the 623 fish observed during eight dives, brush attractors held 78% . module attractors 17%, and control areas 5%. Comparison of attractors by date and species revealed a tendency for them to attract more fish in July and August than in September and October.