Chamaecyparis Nootkatensis Research Articles

Valencene synthase from the heartwood of Nootka cypress (Callitropsis nootkatensis) for biotechnological production of valencene

Nootkatone is one of the major terpenes in the heartwood of the Nootka cypress Callitropsis nootkatensis. It is an oxidized sesquiterpene, which has been postulated to be derived from valencene. Both valencene and nootkatone are used for flavouring citrus beverages and are considered among the most valuable terpenes used at commercial scale. Functional evaluation of putative terpene synthase genes sourced by large-scale EST sequencing from Nootka cypress wood revealed a valencene synthase gene (CnVS). CnVS expression in different tissues from the tree correlates well with nootkatone content, suggesting that CnVS represents the first dedicated gene in the nootkatone biosynthetic pathway in C. nootkatensis The gene belongs to the gymnosperm-specific TPS-d subfamily of terpenes synthases and its protein sequence has low similarity to known citrus valencene synthases. In vitro, CnVS displays high robustness under different pH and temperature regimes, potentially beneficial properties for application in different host and physiological conditions. Biotechnological production of sesquiterpenes has been shown to be feasible, but productivity of microbial strains expressing valencene synthase from Citrus is low, indicating that optimization of valencene synthase activity is needed. Indeed, expression of CnVS in Saccharomyces cerevisiae indicated potential for higher yields. In an optimized Rhodobacter sphaeroides strain, expression of CnVS increased valencene yields 14-fold to 352 mg/L, bringing production to levels with industrial potential.

Microsatellite primers for the Pacific Northwest conifer Callitropsis nootkatensis (Cupressaceae).

• Premise of the study: Microsatellite primers were developed for Nootka cypress (Callitropsis nootkatensis) to provide quantitative measures for gene conservation that can assist in guiding management decisions for a species experiencing climate-induced decline.• Methods and Results: Using multiplexed massively parallel sequencing, we identified 136,785 microsatellite-containing sequences from 489,625 Illumina paired-end 80-bp reads. After stringent filtering, we selected 144 primer pairs and screened variation at these loci in five populations of C. nootkatensis. Loci show between three and 36 dinucleotide repeats per locus, with an average of 13. Screening of these markers in the Pacific Northwest relative Chamaecyparis lawsoniana demonstrated no marker transferability. This finding highlights the narrow taxonomic utility of microsatellite markers in Callitropsis.• Conclusions: These microsatellites show high polymorphism and can be used for routine screening of natural variation in Callitropsis nootkatensis, and will be particularly helpful in identifying clones and inbred relatives at the stand-level.

Management and productivity of cedar-hemlock-salal scrub forests on the north coast of British Columbia

The outer north coast of British Columbia has extensive areas (approx. 235,000ha) of old-growth forests characterized by western redcedar (Thuja plicata), yellow-cedar (Chamaecyparis nootkatensis) and salal (Gaultheria shallon) on gentle to moderate slopes with imperfectly-drained soils and deep forest floor accumulations. Uncertainty surrounding the long-term sustained yield of these low productivity forests led to the establishment of an operational trial in 2001 on Porcher Island, British Columbia, to address management issues, including the risk of paludification with tree removal, the uncertainty in site potential estimates, and the possible extent of nutrient deficiency amelioration with soil raking, mounding or phosphorus fertilization. Each site treatment was randomly replicated four times in an 18ha cutblock. In the second year following logging, the aerobic depth of the soil (as determined by the extent of rust on steel pins) averaged 16.9cm and did not differ between unharvested and harvested plots, suggesting losses in canopy interception and evapotranspiration did not alter the site hydrological balance. Western redcedar survival was 95% with planting and browse protection, and site index estimates of the plantation by age 12 averaged 19.5m at 50years (range 7.6–25.9), in stark contrast to measurements of 3.9m obtained from old-growth stands. Cedar foliar N concentrations increased significantly (range 0.9–1.3%) with the mineral content of soil mounds, demonstrating the benefit of mixing subsoils into the rooting zone, but the wide range in forest floor depths resulted in mounds being overall no more effective than light raking of the forest floor in improving productivity. Phosphorus fertilization (75kgha−1) also provided no gains in soil fertility or cedar nutrition, and initial increases in inorganic P were not detected in soils after 10years. Both site treatments stimulated the natural establishment of red alder (Alnus rubra), averaging 3950 stems per ha, which may both facilitate and compete with the cedar plantation over time. Overall we found few obstacles to sustainable yields from cedar-hemlock-salal scrub forests, albeit with the recognition of longer rotation lengths and smaller volume increments than current operational sites on the north coast of British Columbia.

A Warming-Induced Biome Shift Detected in Tree Growth of Mountain Hemlock [Tsuga mertensiana(Bong.) Carrière] Along the Gulf of Alaska

Abstract Recent observations of divergence between tree growth at high-latitude sites and temperature, as well as the decline of yellow cedar [Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little] in southeast Alaska due to warming, emphasize a need to investigate nonstationary climate response of Alaskan coastal forests to warming in other tree species. Comparison of annual tree growth in mountain hemlock [Tsuga mertensiana (Bong.) Carriere] to mean monthly temperature and precipitation data from Sitka, Alaska, from A.D. 1830s to 1990s along an elevational transect reveals nonstationarity in tree growth response to climate that suggests an ongoing biome shift. We observe a marked weakening in the positive relationship between annual growth and warmer growth season temperatures at low-elevation hemlock sites, and a concurrent increase in growth and sensitivity at higher elevations coupled with increased correlation between growth and April precipitation at all sites along our transects. As previously ...

A Warming-Induced Biome Shift Detected in Tree Growth of Mountain Hemlock [Tsuga mertensiana(Bong.) Carrière] Along the Gulf of Alaska

Recent observations of divergence between tree growth at high-latitude sites and temperature, as well as the decline of yellow cedar [Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little] in southeast Alaska due to warming, emphasize a need to investigate nonstationary climate response of Alaskan coastal forests to warming in other tree species. Comparison of annual tree growth in mountain hemlock [Tsuga mertensiana (Bong.) Carrière] to mean monthly temperature and precipitation data from Sitka, Alaska, from A.D. 1830s to 1990s along an elevational transect reveals nonstationarity in tree growth response to climate that suggests an ongoing biome shift. We observe a marked weakening in the positive relationship between annual growth and warmer growth season temperatures at low-elevation hemlock sites, and a concurrent increase in growth and sensitivity at higher elevations coupled with increased correlation between growth and April precipitation at all sites along our transects. As previously observed with yellow cedar, the mechanism of the hemlock biome shift may be due to an increased susceptibility of roots to damage from late frosts resulting from earlier seasonal loss of protective snowpack.

A Warming-Induced Biome Shift Detected in Tree Growth of Mountain Hemlock [Tsuga mertensiana (Bong.) Carrière] Along the Gulf of Alaska

Recent observations of divergence between tree growth at high-latitude sites and temperature, as well as the decline of yellow cedar [Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little] in southeast Alaska due to warming, emphasize a need to investigate nonstationary climate response of Alaskan coastal forests to warming in other tree species. Comparison of annual tree growth in mountain hemlock [Tsuga mertensiana (Bong.) Carrière] to mean monthly temperature and precipitation data from Sitka, Alaska, from A.D. 1830s to 1990s along an elevational transect reveals nonstationarity in tree growth response to climate that suggests an ongoing biome shift. We observe a marked weakening in the positive relationship between annual growth and warmer growth season temperatures at low-elevation hemlock sites, and a concurrent increase in growth and sensitivity at higher elevations coupled with increased correlation between growth and April precipitation at all sites along our transects. As previously observed with yellow cedar, the mechanism of the hemlock biome shift may be due to an increased susceptibility of roots to damage from late frosts resulting from earlier seasonal loss of protective snowpack.

Does canopy wetness matter? Evapotranspiration from a subtropical montane cloud forest in Taiwan

Evapotranspiration (ET) and canopy wetness were measured over a 2-year intensive field campaign at the Chi-Lan Mountain cloud forest site in Taiwan. Eddy covariance and sap flow methods were applied to measure ET and tree sap flow of the endemic yellow cypress (Chamaecyparis obtusa var. formosana). ET was 553 mm yr−1 over the study period with an annual rainfall and fog deposition of 4893 and 288 mm yr–1, respectively. The duration of canopy wetness exceeded actual fog or rain events (mostly in the afternoon), and the intercepted water was evaporated later in the following dry morning. The cumulative wet duration accounted for 52% of time over the study period, which was longer than the duration of rainfall and fog altogether (41%). As it adapted to the extremely moist environment, the yellow cypress behaved in a wet-enhanced/dry-reduced water use strategy and was sensitive to short periods of dry atmosphere with high evaporation potential. During dry days, the sap flow rate rose quickly after dawn and led to conservative water use through midday and the afternoon. During periodically wet days, the canopy was mostly wetted in the morning, and the interception evaporation contributed largely to the morning ET. The initiation of morning sap flow was postponed 1–3 h, and the sap flow rate tended to peak later at midday. The midday canopy conductance was higher in the periodically wet days (10.6 mm s–1) as compared with 7.6 mm s−1 in the dry days. Consequently, the dry-reduced water use strategy led to much lower annual ET with respect to the available energy (~46%) and high precipitation input (~11%). The moist-adapted ecohydrology we report reveals the vulnerability of montane cloud forests to prolonged fog-free periods. More research is urgently needed to better understand the resilience of these ecosystems and formulate adaptive management plans. Copyright © 2012 John Wiley & Sons, Ltd.

The phenolic monoterpenoid carvacrol inhibits the binding of nicotine to the housefly nicotinic acetylcholine receptor

The phenolic monoterpenoid carvacrol, which is found in many plant essential oils (thyme, oregano and Alaska yellow cedar), is highly active against pest arthropods, but its mechanisms of action are not fully understood. Here, carvacrol is shown to bind in a membrane preparation containing insect nicotinic acetylcholine receptors (nAChRs). [(14) C]-Nicotine binding assays with Musca domestica (housefly) nAChRs were used in this study to demonstrate carvacrol's binding to nAChRs, thereby acting as a modulator of the receptors. Carvacrol showed a concentration-dependent inhibition of [(14) C]-nicotine binding in a membrane preparation of housefly heads containing nAChRs, with IC50 = 1.4 μM, in a non-competitive pattern. Binding studies with neonicotinoid insecticides revealed that imidacloprid and thiamethoxam did not inhibit the binding of [(14) C]-nicotine, while dinotefuran, from the guanidine subclass of neonicotinoids, inhibited nicotine binding like carvacrol. Carvacrol binds to housefly nAChRs at a binding site distinct from nicotine and acetylcholine, and the nAChRs are a possible target of carvacrol for its insecticidal activity.

Geographic variation and adaptation to current and future climates of Callitropsis nootkatensis populations

Forty-one range-wide Callitropsis nootkatensis (D. Don) Orsted (syn. Chamaecyparis nootkatensis (D. Don) Spach) populations were tested at 12 geographically and ecologically diverse sites throughout British Columbia, Canada. There were significant region and population within region effects for 15-year height at most sites but not for adaptability, a binary trait combining survival and cold hardiness. Across-site analysis revealed significant site by population within region interaction for both traits. These interactions were less pronounced when just the core sites were analysed and without two southern disjunct populations. Based on a productivity index that combined height, survival, and cold hardiness, populations were adapted to broad temperature gradients compared with most temperate tree species and were relatively insensitive to moisture. Only the northern California population from the extreme southernmost part of the species’ range had consistent and significant adaptive differentiation, showing maladaptation characterized by severe cold damage and mortality at all test sites. Northern populations grew slowly but survived well. Productivity of this montane species is likely to increase in situ with projected warming across the range of tested sites. Transfer to sites warmer than the population origin increases productivity. Currently and in the long term, populations from the core of the species’ range can be widely transferred for reforestation with minimal risk of maladaptation, provided highly inbred sources from isolated, small populations and sites at risk for yellow cypress decline are avoided.

ABILITY OF NATURAL EXTRACTS TO LIMIT MOLD GROWTH ON DOUGLAS-FIR SAPWOOD

The ability of selected plant extracts from wood and foliage to inhibit mold regrowth on fungal colonized wood was evaluated on Douglas-fir sapwood. Most foliage extracts produced some inhibition of Graphium or Trichoderma species, but isolations of other fungi increased following treatment. Five out of eight wood extracts produced 50% reductions in isolations, and those from Alaska cedar, western juniper, and incense cedar produced at least 80% reductions. The results indicate that wood extracts may be useful for reducing the incidence of mold on wood products, but none of the materials evaluated completely inhibited the test fungi. These extracts may provide a useful value-added application for by-products of lumber production from these species.

Terpenoids of the Heartwood of Chamaecyparis Nootkatensis

Two monoterpenes and two sesquiterpene diols were isolated and identified for the first time from the methanol extract of the heartwood of Alaska yellow cedar (AYC) tree. The two monoterpenes were identified as (1S)-2-oxo-3-p-menthenol (1) and (4R)-4-hydroxy-4-isopropylcyclohex-1-enecarboxylic acid (2). The two sesquiterpenes were identified as (5S, 7R, 10R, 11R)-eudesm-4(14)-ene-11, 12-diol (kudtdiol, 3) and (4R, 5S, 7R)-1(10)-eremophilene- 11,12-diol (tedonodiol, 4). Structures for these compounds were confirmed on the basis of spectroscopic data and in comparison with related known compounds. In addition, 10 other previously known AYC constituents were also isolated from the methanol extract of the heartwood of AYC including nootkatin, chamic acid, chaminic acid, carvacrol, methyl carvacrol, chanootin, nootkatene, nootkatone, valencene and valencene-13-ol.

Investigating the spatial heterogeneity of a subtropical montane cloud forest plantation with a QuickBird image

Forest plantations, consisting of a single, even-age species, have long been recognized as homogeneous landscapes. However, the heterogeneity of the system may be amplified by bioclimate, which in turn can be modified by physical environments. This study attempted to assess the ramifications of two major factors, topography and the edge effect, on a subtropical montane cloud forest (MCF) yellow cypress (Chamaecyparis obtusa var. formosana, CHFO) plantation in Taiwan by integrating field observations, a high spatial resolution QuickBird satellite image and spatial layers of topography. Our regional analysis indicated that there was a negative relationship between slope and the size of CHFO. Surprisingly, we also observed a significant amount of natural broadleaf plant patches within the site, and large-size patches were frequently encountered at low elevation. For the edge-effect analysis, the area (0−30 m) along the road and natural edges yielded low canopy area and carbon (kgC stem−1) for each individual CHFO plant, as well as low CHFO population (stems ha−1) and carbon (MgC ha−1) densities. Contrarily, large broadleaf plant patches were found along the road edges. Our findings suggest that topography and the edge effect may alter the spatial patterns of nutrients and bioclimate that vary the structure of the vegetation; the heterogeneity of forest plantation may be underestimated. This study also demonstrates the feasibility of integrating field, remote-sensing and geographical information system (GIS) techniques to quantify forest structure at the landscape scale. The derived structure parameters can be further utilized to model ecosystem carbon dynamics over a vast region.

×Hesperotropsis, a new nothogenus for intergeneric crosses between Hesperocyparis and Callitropsis (Cupressaceae), and a review of the complicated nomenclatural history of the Leyland cypress

AbstractThe widely cultivated Leyland cypress, a hybrid between Nootka cypress and Monterey cypress that was originally named Cupressus xleylandii, exemplifies the instability of names of nothogenera when there are changes in generic placement of the parental taxa. Because of recent phylogenetic research, the parent species of Leyland cypress have each been put in four different genera, leading to 13 possible nothospecific names for this hybrid. Here we present the correct nomenclature for the Leyland cypress under these different taxonomic concepts. We also propose a new nothogenus, ×Resperotropsis, for crosses between Hesperocyparis and Callitropsis, and publish three new combinations in xHesperotropsis, including xHesperotropsis leylandii for the Leyland cypress.

Uranium oxide and other airborne particles deposited on cypress leaves close to a nuclear facility

Enhanced activity of actinides and some decay products has been reported for the leaves of cypress trees (Chamaecyparis nootkatensis) at the edge of the Malvési uranium-processing facility, southwestern France. The enhanced activity is due to the release of actinides via the smokestacks and from artificial ponds inside the facility. This study was conducted to characterize airborne particulate matter deposited on the leaf surfaces and to investigate whether or not radioactive particles may be identified. Air-dried leaf samples were examined by scanning electron microscopy, in combination with energy-dispersive X-ray spectrometry. The samples were scanned systematically in both secondary and backscattered electron modes. Particles ranging in size from <200 nm to ~40 μm were found on most portions of the adaxial leaf surface, but they are especially abundant at the boundary between facial and lateral leaves. The majority of the analyzed particles could be attributed to five principal classes: carbonates, silicates, sulfates, oxides/hydroxides, and halides. In addition, other types of particles were found, including Fe alloys; scheelite-group phases; phosphates; sulfides; and fly ash spheres. Similar particles were also observed on the surface of a wheat sample used for comparison. Of special interest are U-rich particles, which were observed on the cypress leaves only and which were identified as U oxides, except for one particle, which was a U-oxide-fluoride. These U-rich particles were released into the atmosphere by the nuclear facility prior to their deposition on the leaf surfaces. As most of the U-rich particles are <2.5 μm across, they are respirable. Once inhaled, particles containing alpha-emitting isotopes represent a potentially long-term source of ionizing radiation inside the lungs and thus, pose a threat to the health of people living nearby.

Microsatellite primers for the Pacific Northwest endemic coniferChamaecyparis lawsoniana(Cupressaceae)

Microsatellite primers were developed for the Pacific Northwest conifer, Chamaecyparis lawsoniana (Cupressaceae), to enhance efficiencies in disease-resistance breeding and germplasm screening for gene conservation of this rare species. Using multiplexed massively parallel Illumina sequencing, we identified over 300000 microsatellite-containing sequences from 2 million paired-end microreads. After stringent filtering and primer evaluation, we selected 11 primer pairs and used these to screen variation in four populations of C. lawsoniana. Loci show between three and 10 repeats per locus, with an average of eight. Screening of these markers in the North American relative Callitropsis nootkatensis demonstrated limited marker transferability, but these markers could have utility in Asian species of Chamaecyparis. These microsatellite primers show high polymorphism and should provide a high level of individual discrimination for paternity analysis in defined pedigrees, and routine screening of wild variation in Chamaecyparis lawsoniana.

Ring characteristics and screw withdrawal resistance of naturally regenerated Chamaecyparis obtusa var. formosana trees

The ring characteristics and screw withdrawal resistance (SWR) of naturally regenerated Taiwan yellow cypress (Chamaecyparis obtusa var. formosana) trees were explored. Significant differences in average ring width (RW), earlywood width, latewood width, ring density (RD), earlywood density (ED), latewood density (LD), highest density (Dmax), lowest density (Dmin), latewood percentage (LWP), and SWR were observed between trees, rings (SWR excluded), and tree height positions. The RW components in the radial direction increased from the pith outward to about the 3rd to 5th ring and then decreased to about the 25th ring; it was almost constantly sustained toward the bark side. The RD in the radial direction slowly decreased from the pith outward to the bark side. Average ring width and ring density were significantly affected by the various tree growth rates, radial ring numbers, and tree height positions. ED, LD, Dmax, Dmin, and LWP were the most important factors determining the overall RD. RW did not correlate with tree RD. SWR is correlated with ED, RD, Dmin, LWP, and intra-ring density variation (IDV). Thus, the SWR can be used to predict wood density and in nondestructive evaluation of a living tree.

A landscape-level analysis of yellow-cedar decline in coastal British Columbia

Yellow-cedar (Chamaecyparis nootkatensis D. Don (Spach)) is currently undergoing a dramatic decline in western North America. Recent research suggests that site factors combined with a shift in climate have predisposed yellow-cedar trees to decline. We conducted the first landscape-level analysis of the decline in coastal British Columbia to assess relations between the decline and topographic variables. We used lasso-penalized logistic regression to model yellow-cedar decline presence and absence with topographic variables derived from a digital elevation model. Model results indicated that low elevation sites close to the coast, which are more exposed and have more variation in elevation, are more likely to show evidence of decline. The logistic model fit the data well (Nagelkerke R2= 0.846) and had high predictive accuracy (AUC = 0.98). The topographic variables identified by the model influence degree of soil saturation, temperatures, and snowpack presence in a forest stand, supporting the proposed associations in the current decline hypothesis. The analysis also highlighted the utility of the lasso logistic model for selecting significant variables and mapping areas at high risk for decline. Knowledge of the determinants of the spatial pattern of decline will improve predictability and provide critical information for conservation and management of yellow-cedar.

Biologically Important Eremophilane Sesquiterpenes from Alaska Cedar Heartwood Essential Oil and Their Semi-Synthetic Derivatives

The essential oil of Alaska cedar heartwood is known to contain compounds which contribute to the remarkable durability of this species. While previous research has identified several compounds, a complete description of this oil has not been undertaken. In this research a profile of the oil is given in which the major components are identified by GC, isolation and spectroscopic techniques. The major components of the steam distilled essential oil were identified as nootkatin, nootkatone, valencene, nootaktene, carvacrol, methyl carvacrol, nootkatol (2), and eremophil-1(10),11-dien-13-ol (3). The last two compounds were isolated for the first time from Alaska cedar in this research. The absolute stereochemistry at C-2 of nootkatol was shown to have the (S) configuration using the Mosher ester method. Assignment of stereochemistry for valencene-13-ol (3) was established by synthesis from valencene (6). Finally, two related sesquiterpenoids were synthesized from nootkatone and valencene. These sesquiterpenoids were nootkatone-1,10-11,12-diepoxide (5) and valencene-13-aldehyde (4), respectively.

Climate determines upper, but not lower, altitudinal range limits of Pacific Northwest conifers

Does climate determine species' ranges? Rapid rates of anthropogenic warming make this classic ecological question especially relevant. We ask whether climate controls range limits by quantifying relationships between climatic variables (precipitation, temperature) and tree growth across the altitudinal ranges of six Pacific Northwestern conifers on Mt. Rainier, Washington, USA. Results for three species (Abies amabilis, Callitropsis nootkatensis, Tsuga mertensiana) whose upper limits occur at treeline (> 1600 m) imply climatic controls on upper range limits, with low growth in cold and high snowpack years. Annual growth was synchronized among individuals at upper limits for these high-elevation species, further suggesting that stand-level effects such as climate constrain growth more strongly than local processes. By contrast, at lower limits climatic effects on growth were weak for these high-elevation species. Growth-climate relationships for three low-elevation species (Pseudotsuga menziesii, Thuja plicata, Tsuga heterophylla) were not consistent with expectations of climatic controls on upper limits, which are located within closed-canopy forest (< 1200 m). Annual growth of these species was poorly synchronized among individuals. Our results suggest that climate controls altitudinal range limits at treeline, while local drivers (perhaps biotic interactions) influence growth in closed-canopy forests. Climate-change-induced range shifts in closed-canopy forests will therefore be difficult to predict accurately.

Ethanol synthesis by anoxic root segments from five cedar species relates to their habitat attributes but not their known differences in vulnerability to Phytophthora lateralis root disease

Ethanol synthesis by anoxic root segments from Port Orford cedar (Chamaecyparis lawsoniana (A. Murray bis) Parl.); yellow cedar (Chamaecyparis nootkatensis (D. Don) Spach); Atlantic white cedar (Chamaecyparis thyoides (L.) Britton, Sterns &amp; Poggenb.); western redcedar (Thuja plicata Donn ex D. Don), and incense cedar (Calocedrus decurrens (Torr.) Florin ) was compared to determine whether the amounts that they produced during flooding could contribute the known greater vulnerability of Port Orford cedar to infection by Phytophthora lateralis Tucker &amp; Milbrat. Roots were incubated in water at 5, 15, 25, and 35 °C for 14 days with periodic sampling. After 12 h of anoxic stress, Atlantic white cedar and yellow cedar roots produced equal quantities of ethanol that were about two times more than produced by the other three species, which did not differ from one another. The roots remained anoxic for 14 days, with ethanol concentrations increasing 6 to 11 times depending on the species. After 14 days, Atlantic white cedar remained the highest ethanol producer at two to three times more than the other species, whereas incense cedar yields were the lowest. Yellow cedar, western redcedar, and Port Orford cedar had intermediate levels of ethanol. The similarity in responses of Port Orford cedar to the other species is strong evidence that ethanol is not an important contributor to its known greater vulnerability to P. lateralis infection. In general, root incubation temperature affected ethanol synthesis similarly for all species. Increases in temperature from 5 to 15 °C or 15 to 25 °C doubled the ethanol yields at 12 h. Literature ratings of anaerobic tolerance for these cedars were compared with ratings based on their ethanol yields after 12 h or 14 days of anoxia. The latter rating appears to more closely correspond with the cedars associations to wet, mesic environments and their likelihood of experiencing anoxia via flooding.