Acorn production prediction models for five common oak species of the eastern United States

Acorn production varies considerably among oak (Quercus) species, individual trees, years, and locations, which directly affects oak regeneration and populations of wildlife species that depend on acorns for food. Hard mast indices provide a relative ranking and basis for comparison of within- and between-year acorn crop size at a broad scale, but do not provide an estimate of actual acorn yield—the number of acorns that can potentially be produced on a given land area unit based on the species, number, and diameter at breast height (dbh) of oak trees present. We used 10 years of acorn production data from 475 oak trees to develop predictive models of potential average annual hard mast production by five common eastern oak species, based on tree diameter and estimated crown area. We found a weak (R² = 0.08–0.28) relationship between tree dbh and acorn production per unit crown area for most species. The relationship between tree dbh and acorn production per tree was stronger (R² = 0.33–0.57). However, this is because larger-dbh trees generally have larger crowns, not because they have a greater capacity to produce more acorns per unit crown area. Acorn production is highly variable among individual trees. We estimated that dbh of at least 60 dominant or codominant oak trees per species should be randomly sampled to obtain an adequate representation of the range of dbhs (≥12.7 cm dbh) in a given forest area, and achieve precise estimates when using these equations to predict potential acorn production. Our predictive models provide a tool for estimating potential acorn production that land managers and forest planners can apply to oak inventory data to tailor estimates of potential average annual acorn production to different forest management scenarios and multiple spatial scales. © 2011 The Wildlife Society.     

Fatty acid and phospholipid composition of five psychrotrophic Pseudomonas spp. grown at different temperatures

The free fatty acid and phospholipid composition of 5 psychrotrophic marine Pseudomonas spp. have been determined in chemostat culture with glucose as the limiting substrate over the range 0–20°C. The predominant fatty acid present in all the isolates was hexadecenoic acid (C16:1) together with lesser quantities of octadecenoic acid (C 18:1) whilst none contained acids with chain lengths exceeding 18 carbon atoms. Decreasing the growth temperature from 20°C to 0°C resulted in little significant change in fatty acid composition. The principal phospholipid components of the five psychrotrophic pseudomonads have been identified as phosphatidylserine, phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. Decreasing the growth temperature did not elicit significant changes either in the total quantities of phospholipid synthesized or in the concentration of individual phospholipid components in any of the isolates. All the psychrotrophs showed maximum glucose uptake between 15°C and 20°C and the rate decreased rapidly as the temperature was decreased towards 0°C.Abbreviations PS Phosphatidylserine - PE phosphatidylethanolamine - PG phosphatidylglycerol - DPG diphosphatidylglycerol     

Investigation ofJuniperus species of the United States for new Sources of Cedarwood Oil

Economic Botany - The 11 taxa of Juniperus with widespread distribution in the United States and with significant biomass production were investigated to determine their yields of cedarwood oil and...     

Estimates of root system topology of five plant species grown at steady-state nutrition

Results from a controlled growth-analysis experiment were used to illustrate some methods for measuring and describing root system topology. The experiment was performed in a nutrient solution system with an exponential nutrient supply and steady-state growth, to achieve well-defined levels of whole-plant nutrient status. Five naturally coexisting grassland species were included: The slow-growing forbs Polygala vulgaris L. and Crepis praemorsa (L.) F. L. Walth., and the grass Danthonia decumbens (L.) DC. were compared with the more common, fast-growing grasses Agrostis capillaris L. and Dactylis glomerata L. The most marked difference in morphological indices was a much higher specific root length in the grasses than in the forbs, which implies thinner roots. In contrast to the conclusions of previous studies, an index of the topology for the grasses was very similar to that for the forbs. The specific root lenght and link length apparently vary more between species and nutrient levels than topology does, and may therefore be more ecologically important. The only clear plastic response to growth-limiting nitrogen supply was a markedly increased link length in P. vulgaris. There were also indications that nitrogen limitation led to more herringbone-like root systems in P. vulgaris and C. praemorsa. In general, there was a clear tendency for the estimates of topology to change with plant size, which may make many topological indices, especially those based on regression slopes, very difficult to interpret. Until interactions with plant size, other morphological parameters and among-plant competition can be properly understood, the relevance of root topology for plant performance remains unclear. This revised version was published online in June 2006 with corrections to the Cover Date.     

Some hematologic values of bison from five areas of the United States.

Seventeen hematologic values of the American Bison (Bison bison) from five areas of the United States were determined using standard techniques. The means of the principal blood measurements for all bison were 10.08 +/- 1.43 million erythrocytes/mm3, 8.03 +/- 1.41 thousand leukocytes/mm3, 16.92 +/- 1.43 gm % hemoglobin and 47.11 +/- 4.06% hematocrit. There was a significant variation (P less than 0.05) among age groups of males for erythrocytes, neutrophils, lymphocytes and monocytes. However, no significant variation between female age groups or sexes was found for any of the blood cell values determined.     

Cationic composition of 22 species of bacteria grown in seawater medium.

Twenty-two species of bacteria of marine, estuarine, and terrestrial origin were analyzed for cationic content by atomic absorption spectrophotometry after growth in a basal seawater medium. Alcaligenes marinus was analyzed from eight separate but replicate determinations yielding the following cationic concentrations: Na, 5,600 +/- 2,260; Mg 1,580 +/- 740; K, 700 +/- 360; Ca, 790 +/- 390; Mn, 1.7 +/- 0.5; Fe, 256 +/- 57; Ni, 1.7 +/- 0.7; Cu, 14 +/- 4; Zn, 122 +/- 27; Cd, 2.8 +/- 0.7; and Pb, 10 +/- 3 ppm/(dry weight). Washing A. marinus cells before analyses was necessary due to interstitial medium within the cell pellets after centrifugation and loose cationic retention by the cells. The principal source of error in the procedure was ascribed to variability due to washing cells with 0.5 M ammonium formate. The mean cationic concentrations for trace elements in the 22 bacterial cultures grown in the basal seawater medium to constant optical density and washed three times with 0.5 M ammonium formate were: Mn, 2.4 +/- 3.8; Fe, 262 +/- 112; Ni, 2.3 +/- 1.8; Cu, 24 +/- 17; Zn, 146 +/- 72; Cd, 3.8 +/- 2.5; and Pb, 17 +/- 21 ppm (dry weight). Major ions were concentrated only occasionally by the cells after washing, whereas Mn, Fe, Ni, Cu, Zn, Cd, and Pb were concentrated from the medium by the following factors on the average: 180, 1,600, 140, 1,200, 750, 1,900, and 900, respectively.     

Cationic composition of 22 species of bacteria grown in seawater medium.

Twenty-two species of bacteria of marine, estuarine, and terrestrial origin were analyzed for cationic content by atomic absorption spectrophotometry after growth in a basal seawater medium. Alcaligenes marinus was analyzed from eight separate but replicate determinations yielding the following cationic concentrations: Na, 5,600 +/- 2,260; Mg 1,580 +/- 740; K, 700 +/- 360; Ca, 790 +/- 390; Mn, 1.7 +/- 0.5; Fe, 256 +/- 57; Ni, 1.7 +/- 0.7; Cu, 14 +/- 4; Zn, 122 +/- 27; Cd, 2.8 +/- 0.7; and Pb, 10 +/- 3 ppm/(dry weight). Washing A. marinus cells before analyses was necessary due to interstitial medium within the cell pellets after centrifugation and loose cationic retention by the cells. The principal source of error in the procedure was ascribed to variability due to washing cells with 0.5 M ammonium formate. The mean cationic concentrations for trace elements in the 22 bacterial cultures grown in the basal seawater medium to constant optical density and washed three times with 0.5 M ammonium formate were: Mn, 2.4 +/- 3.8; Fe, 262 +/- 112; Ni, 2.3 +/- 1.8; Cu, 24 +/- 17; Zn, 146 +/- 72; Cd, 3.8 +/- 2.5; and Pb, 17 +/- 21 ppm (dry weight). Major ions were concentrated only occasionally by the cells after washing, whereas Mn, Fe, Ni, Cu, Zn, Cd, and Pb were concentrated from the medium by the following factors on the average: 180, 1,600, 140, 1,200, 750, 1,900, and 900, respectively.     

美国对入侵种的管理对策

外来种入侵是产生当前世界生物多样性危机的重要原因之一。目前外来种入侵问题已经引起人们的普遍关注。1999年2月美国联邦政府发布总统令,号召联邦政府机构执行人员防止外来入侵种所造成的严重环境威胁,指示有关职能部门行使职权阻止引入入侵种并且恢复本地种。总统令指示建立一个入侵物种理事会,并就理事会、联邦机构的职责做了相应界定。美国农业部等部门支持的入侵植物管理国家策略项目,提出了针对入侵种的三项国家目标一入侵种的预防、控制和本地种的恢复。国家管理策略的制定不同层次的人们提供了合作、教育和研究的机遇。美国政府部门以及有关社会团体已经就外来种入侵危害防范积极展开行动,包括制定标准防止入侵种进入,控制、根除入侵种,向民众进行有关外来种入侵的教育,增加财政年度预算等等。     

Contrasting patterns of phytoplankton community pigment composition in two salt marsh estuaries in southeastern United States

Phytoplankton community pigment composition and water quality were measured seasonally along salinity gradients in two minimally urbanized salt marsh estuaries in South Carolina in order to examine their spatial and temporal distributions. The North Inlet estuary has a relatively small watershed with minimal fresh water input, while the Ashepoo, Combahee, and Edisto (ACE) Basin is characterized by a relatively greater influence of riverine drainage. Sampling stations were located in regions of the estuaries experiencing frequent diurnal tidal mixing and had similar salinity and temperature regimens. Phytoplankton community pigment composition was assessed by using high-performance liquid chromatography (HPLC) and multivariate statistical analyses. Shannon diversity index, principal-component, and cluster analyses revealed that phytoplankton community pigments in both estuaries were seasonally variable, with similar diversities but different compositions. The temporal pigment patterns indicated that there was a relatively weak correlation between the pigments in ACE Basin and the relative persistence of photopigment groups in North Inlet. The differences were presumably a consequence of the unpredictability and relatively greater influence of river discharge in the ACE Basin, in contrast to the greater environmental predictability of the more tidally influenced North Inlet. Furthermore, the timing, magnitude, and pigment composition of the annual phytoplankton bloom were different in the two estuaries. The bloom properties in North Inlet reflected the predominance of autochthonous ecological control (e.g., regenerated nutrients, grazing), and those in ACE Basin suggested that there was greater influence of allochthonous environmental factors (e.g., nutrient loading, changes in turbidity). These interestuarine differences in phytoplankton community structure and control provide insight into the organization of phytoplankton in estuaries.     

The relationship between the seed bank and species composition of plant communities in two British salt marshes

The composition of the seed bank was compared with that of the above-ground vegetation in two British salt marshes. Vegetation and seed banks were sampled in autumn and spring. There was a relatively low correlation between seed bank and vegetation in most perennial-dominated zones. Percentage annual plant cover was significantly positively correlated to percentage similarity value between vegetation and seed bank. Cluster analysis indicated that the zones dominated by annuals and by Suaeda vera on the ungrazed Nod Marsh in Norfolk formed groups between seed bank and vegetation, whereas on the Llanrhidian Marsh in Wales the seed bank of four of the six zones formed a group.     

Ballistic seed projection in two herbaceous species

We found that the majority of ballistic seeds tested [N = 74 of 78 in Vicia sativa ssp. nigra (Fabaceae); N = 25 of 27 in Croton capitatus var. capitatus (Euphorbiaceae)] were projected at angles that would yield a greater distance than the average of seeds with the same initial speed projected at random angles. In addition, the median of fractional distance error (maximum distance - seed distance)/(maximum distance), of the seeds were 0.11 and 0.04 for V. sativa and C. capitatus, respectively. Seed projection distance was modeled by using initial projection angle, initial speed, and measured drag, along with other seed data. We improved upon previous such studies by using dual-angle high-speed stroboscopic photography to determine initial projection angle and speed. We also measured seed drag in a low-turbulence wind tunnel. Seed projection positions on the plant, which also affect seed projection distance, were found to be primarily from the top of the plant, with 98 of 137 and 407 of 407 fruits in the upper half of the plant for V. sativa and C. capitatus, respectively. Our findings are significant because they suggest that in addition to the ballistic projection mechanism itself, the species studied have additional adaptations that result in enhanced seed projection distance from the parent plant.     

Predispersal seed predation on five Piper species in tropical rainforest

Absolute number of seeds lost to predispersal seed predators and proportion of total seeds lost per infructescence were compared among five Costa Rican Piper species of different annual fecundities. Mean seed number and mean seed size in the five species were negatively correlated. The impact of predation on these species was inversely related to the number of seeds they produced. The two early successional species had very high fecundities, a combination of many seeds per infructescence, many infructescences per plant, and, in one species, year-round reproduction. Although seed predators destroyed as many or more seeds of these early successional species than they did of the less fecund, late successional species, this loss accounted for a relatively minor proportion (9 and 12%) of the seeds of the early successional species. In contrast, late successional species produced fewer, larger seeds in a smaller number of infructescences and were not continually in fruit. One of these species, which produced intermediate numbers of intermediately sized seeds, lost 30% of the seeds in each infructescence on average. Seed predators destroyed a larger proportion (65 and 76%) of the seeds per infructescence in the two species with fewest seeds per infructescence. High levels of insect damage in these late successional species caused many of their infructescences to abort prematurely. Taken together these factors resulted in annual fecundities several orders of magnitude smaller in shade-tolerant Piper species than the annual fecundities of shade-intolerant, early successional species. Seedlings of the two early successional species were common in large gaps and other sunny clearings and seedlings of the species with 30% seed loss were occasional, whereas no seedlings were seen of the two species with the highest proportional seed loss, suggesting that seed predation on the latter species may limit seedling recruitment.     

A Brugia species infecting rabbits in the northeastern United States

Brugia sp. microfilariae were observed in more than 60% of wild rabbits collected on Nantucket Island, Massachusetts. The microfilariae measured 294-344 microns in length and had the characteristic subterminal and terminal nuclei observed in other Brugia microfilariae. The microfilaria is similar to those described for Brugia leporis in rabbits in Louisiana. This may be the Brugia species responsible for 21 documented cases of human infection in the northeastern United States.     

Egg size and clutch size in two Daphnia species grown at different food levels

The effect of three different Scenedesmus food concentrations(0.04, 0.2 and 1 mg C l^–1) on maternal investment wasstudied in two cladoceran species of similar size, Daphnia pulicariaand D.hyalina. It was observed that as food concentration decreased(between 1 and 0.2 mg C l^–1), there was an increase insize, protein content, lipid content, carbon and mass of theegg, while, at the same time, the clutch size of the femalesbecame smaller. Such an increase in ‘per offspring investment’was reflected in an increase in body length, body carbon andbody mass of neonates as the food available for females decreased.However, in D.pulicaria this tendency was not maintained downat 0.04 mg C l^–1 in which there was a decrease of theegg characteristics mentioned above. Although, there are notavailable all the egg and neonate parameters of D.hyalina at0.04 mg C l^–1, the body length of the neonates was largerthan at 0.2 and 1 mg C l^–1. These results show that, asfood diminishes, these two cladoceran species are able to respondby decreasing clutch size, but increasing the size of egg, therebyincreasing the probability of neonate survival. This tendencyis probably maintained until the food concentration is too lowand the females have to reduce the energy allocated for reproduction.     

Turning to the dark side: LED light at night alters the activity and species composition of a foraging bat assemblage in the northeastern United States

Artificial light at night (ALAN) is a rapidly intensifying form of environmental degradation that can impact wildlife by altering light‐mediated physiological processes that control a broad range of behaviors. Although nocturnal animals are most vulnerable, ALAN''s effects on North American bats have been surprisingly understudied. Most of what is known is based on decades‐old observations of bats around street lights with traditional lighting technologies that have been increasingly replaced by energy‐efficient broad‐spectrum lighting, rendering our understanding of the contemporary effects of ALAN on North American bats even less complete. We experimentally tested the effects of broad‐spectrum ALAN on presence/absence, foraging activity, and species composition in a Connecticut, USA bat community by illuminating foraging habitat with light‐emitting diode (LED) floodlights and comparing acoustic recordings between light and dark conditions. Lighting dramatically decreased presence and activity of little brown bats (Myotis lucifugus), which we detected on only 14% of light nights compared with 65% of dark (lights off) and 69% of control (lights removed) nights. Big brown bat (Eptesicus fuscus) activity on light nights averaged only half that of dark and control nights. Lighting did not affect presence/absence of silver‐haired bats (Lasionycteris noctivagans), but decreased their activity. There were no effects on eastern red bats (Lasiurus borealis) or hoary bats (L. cinereus), which have been described previously as light‐tolerant. Aversion to lighting by some species but not others caused a significant shift in community composition, thereby potentially altering competitive balances from natural conditions. Our results demonstrate that only a small degree of ALAN can represent a significant form of habitat degradation for some North American bats, including the endangered little brown bat. Research on the extent to which different lighting technologies, colors, and intensities affect these species is urgently needed and should be a priority in conservation planning for North America''s bats.     

Differences in seed longevity at the species level

Abstract Published seed storage data for 92 species derived from 13 localities were subjected to probit analysis to determine the half-viability period (P₅₀) for each sample. Estimates of half-viability period for each species averaged over all 13 localities were calculated using a least square means procedure applied to known values for the half-viability period for each species at each of its storage stations. The results reported here represent an initial step in the objective organization of seed longevity data.     

Assessment of antioxidant activities in roots of Miswak (Salvadora persica) plants grown at two different locations in Saudi Arabia

Traditionally, in Middle Eastern countries, many cultures use chewing sticks of arak for medicinal purposes especially, for oral cleanliness care. It was used by Muslims for treatment of teeth and highly recommended to be used by Muslims during the whole day. Therefore, the present work aimed to determine the total phenolic content and total flavonoids in two Miswak extracts obtained from arak roots collected from two different localities in Saudi Arabia. They were extracted with aqueous ethanol (80%) and used to estimate in vitro their antioxidative abilities. The new findings showed that the two tested extracts contained significantly different amounts of both total phenolic content and total flavonoids. According to the increase of total phenolic contents and total flavonoids obtained from the two extracts, Miswak collected from the southern region was found to contain more contents than those collected from the middle region. The results of antioxidant activities of Miswak root extract obtained by using different in vitro methods were varied depending on the technique used. According to the malondialdehyde (MDA) method, hydrogen peroxide (H₂O₂) scavenging ability and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, the two Miswak extracts exhibited to have high to very high antioxidant activities. Mostly, the values of antioxidant activities of Southern region have been shown to be always the highest.