Plant Enclosure Research Articles

Gully Erosion Control Practices in Northeast China: A Review

Gully erosion is the destructive and dramatic form of land degradation in Northeast China. The region is the grain production and ecological security base of China where the fertile and productive Mollisols are distributed. Though the region was agriculturally developed relatively recently, it went through high intensity cultivation and fast succession processes within short-time scales. Coupled with irrational farming practice choice and land use, hillslope erosion and gully erosion are seriously threatening agricultural production and environmental stability in the region. The awareness of gully erosion by the local governments started in the 1970s, and conservation measures were thus implemented. In this paper, based on our survey, communications with local farmers and stakeholders as well as investigation for gully erosion for the past three years, we summarize the practical and efficient practices to manage gully erosion developed by researchers and farmers in Northeast China during the past 50 years. These practices include various drop structures, soil check dams, masonry check dams, gabion check dams, wicker check dams, continuous live wicker, a shrub plant enclosure, and an arbor plant enclosure. We specifically expound how a gully erosion practice is set up and identify the site conditions for which they are well-suited. The application of these practices depends on topography, gully size, and local economy. Bioengineering techniques in Northeast China, such as continuous live wicker, a shrub plant enclosure, and an arbor plant enclosure, are highly effective in controlling gully erosion. Problems and challenges are also presented.

Multiple intraguild predators reduce mortality risk of a mutual agricultural pest prey in simple, but not in complex, experimental settings

AbstractMultiple predator species that coexist with each other and their mutual prey can have combined effects on prey mortality that are similar to the sum of each predator's individual impact (linear effects), greater than the sum of each predator's individual impact (risk enhancement), or less than the sum of each predator's individual impact (risk reduction). Understanding multiple predator effects is important to determine the impact of predators on pest prey in agroecosystems. If two predators share the same broad spatial domain and hunting mode and engage in intraguild predation, then their combination is expected to result in risk reduction for a mutual prey. We tested this hypothesis using both additive and replacement experimental designs on two species of generalist wolf spider predators (Tasmanicosa leuckartii and Hogna crispipes) that hunt in the same domain, and a mutual insect prey (cotton bollworm Helicoverpa armigera). We used two types of enclosures: a small simple laboratory enclosure, and a larger more complex cotton plant enclosure. We found that in the small simple laboratory enclosures, the presence of two spiders led to risk reduction of Helicoverpa larva mortality as expected, but in larger more complex cotton plant enclosures the presence of both species resulted in linear effects rather than risk reduction on Helicoverpa mortality. Furthermore, intraguild predation did not change multiple predator effects in laboratory or plant enclosures. This study has implications for managing arthropod predators in agroecosystems; contrary to predictions of ecological frameworks, coexistence of predators that share the same hunting mode and hunting domain may not lead to risk reduction on a mutual prey in more complex environments, where encounters among predators can be lower. Conservation of multiple predators of a single guild can play an essential role on biological control of insect pests.

Diurnal Pattern of Leaf, Flower and Fruit Specific Ambient Volatiles above an Oil Palm Plantation in Pará State, Brazil

Oil palm plantations are rapidly expanding in the tropics because of insatiable global demand for fruit oil to be used in food, biofuels and cosmetics. Here we show that three tissue-specific volatiles can be quantified in ambient air above an African-American hybrid oil palm plantation in Brazil and linked photosynthesis (isoprene), floral scent (estragole), and for the first time, fruit oil processing (6-methyl-5-hepten-2-one, MHO). Plant enclosure techniques verified their tissue specific emission sources with ambient concentrations displaying distinct diurnal patterns above the canopy. Isoprene concentrations were near zero at night, but dramatically increased during the day while estragole showed elevated concentrations at night suggesting a light-independent, temperature-driven emission pattern from flowers. MHO also showed elevated concentrations at night and both estragole and MHO increased during the day. Our observations demonstrate that the African-American oil palm hybrid is strong isoprene emitter and suggest that MHO is a specific oxidation product of lycopene released during the industrial processing of palm oil. This study highlights the potential value of quantifying volatile oil palm signals in the atmosphere as a novel, non-invasive method to better understand biological functioning and its interactions with the environment including carbon assimilation, floral-insect interactions, and fruit oil production/processing.

Health, safety, and environmental risk assessment of steel production complex in central Iran using TOPSIS.

This research was carried out with the aim of presenting an environmental management plan for steel production complex (SPC) in central Iran. Following precise identification of the plant activities as well as the study area, possible sources of environmental pollution and adverse impacts on the air quality, water, soil, biological environment, socioeconomic and cultural environment, and health and safety of the employees were determined considering the work processes of the steel complex. Afterwards, noise, wastewater, and air pollution sources were measured. Subsequently, factors polluting the steel complex were identified by TOPSIS and then prioritized using Excel Software. Based on the obtained results, the operation of the furnaces in hot rolling process with the score 1, effluent derived from hot rolling process with the score 0.565, nonprincipal disposal and dumping of waste at the plant enclosure with the score 0.335, walking beam process with the score 1.483 respectively allocated themselves the highest priority in terms of air, water, soil and noise pollution. In terms of habitats, land cover and socioeconomic and cultural environment, closeness to the forest area and the existence of four groups of wildlife with the score 1.106 and proximity of villages and residential areas to the plant with the score 3.771 respectively enjoyed the highest priorities while impressibility and occupational accidents with the score 2.725 and cutting and welding operations with score 2.134 had the highest priority among health and safety criteria. Finally, strategies for the control of pollution sources were identified and Training, Monitoring and environmental management plan of the SPC was prepared.

Volatile organic compound emissions from elephant grass and bamboo cultivars used as potential bioethanol crop

Volatile organic compound (VOC) emissions from elephant grass (Miscanthus gigantus) and black bamboo (Phyllostachys nigra) were measured online in semi-field chamber and plant enclosure experiments during growth and harvest using proton-transfer reaction mass spectrometry (PTR-MS), proton-transfer reaction ion-trap mass spectrometry (PIT-MS) and gas chromatography-mass spectrometry (GC–MS). Both cultivars are being considered for second-generation biofuel production. Before this study, no information was available on their yearly VOC emissions. This exploratory investigation shows that black bamboo is a strong isoprene emitter (daytime 28,516 ng gdwt−1 h−1) and has larger VOC emissions, especially for wound compounds from the hexanal and hexenal families, than elephant grass. Daytime emissions of methanol, acetaldehyde, acetone + propanal and acetic acid of black bamboo were 618, 249, 351, and 1034 ng gdwt−1 h−1, respectively. In addition, it is observed that elephant grass VOC emissions after harvesting strongly depend on the seasonal stage. Not taking VOC emission variations throughout the season for annual and perennial species into account, may lead to an overestimation of the impact on local air quality in dry periods. In addition, our data suggest that the use of perennial grasses for extensive growing for biofuel production have lower emissions than woody species, which might be important for regional atmospheric chemistry.

Quantitative and enantioselective analysis of monoterpenes from plant chambers and in ambient air using SPME

Abstract. A headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS) system has been developed for quantifying enantiomeric and nonenantiomeric monoterpenes in plant chamber studies and ambient air. Performance of this system was checked using a capillary diffusion system to produce monoterpene standards. The adsorption efficiency, competitive adsorption and chromatographic peak resolution of monoterpene enantiomer pairs were compared for three SPME fibre coatings: 75 μm Carboxen-PDMS (CAR-PDMS), 50/30 μm divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) and 65 μm divinylbenzene-polydimethylsiloxane (DVB-PDMS). Key parameters such as the linearity and reproducibility of the SPME system have been investigated in this work. The best compromise between the enantiomeric separation of monoterpenes and competitive adsorption of the isoprenoids on the solid SPME fibre coating was found for DVB-PDMS fibres. The optimum conditions using DVB-PDMS fibres were applied to measure the exchange rates of monoterpenes in the emission of Quercus ilex using a laboratory whole plant enclosure under light and dark conditions, as well as in ambient air. With 592 and 223 ng m−2 s−1 respectively, β-myrcene and limonene were the predominant monoterpenes in the emission of Q. ilex. These values were closely comparable to those obtained using a zNose and cartridge GC-FID systems.

Acoustical performance of power plant enclosure walls—a critical assessment of needs

The acoustical design of power generating facilities invariably requires knowledge of the transmission loss characteristics of acoustical enclosures, from component specific housings to generation buildings. Many of the composite wall configurations used by vendors are either proprietary or of such recent design that laboratory test data (TL per ASTM E90) are not available. Several factors contribute to uncertainty in the application of test data. At frequencies of 125 Hz and below, all such laboratory based test data should be considered suspect, especially since for plants in which sound emissions are heavily attenuated, the low frequencies tend to become progressively more dominant at far field positions. Thus the far field A-weighted sound levels from power plants, especially those of low noise design, are governed by sound energy in precisely the frequency range for which the TL’s for walls and enclosures are least reliable. Further, the size and mounting of power plant walls differs significantly from the same walls mounted in an ASTM E90 test facility. This paper gives a critical assessment of the sources of the uncertainties, suggestions for methodologies to obtain more reliable TL data and discusses the effects to be expected, illustrated by way of selected examples.

Artifact evidence in carbonyl compound sampling using the enclosure technique with cuvette system.

Biogenic hydrocarbon emission rates from individual plant species have been estimated experimentally placing small plants or branches in enclosures and measuring the emission rates of the compounds. All-Teflon chambers (cuvettes) where air samples are drawn through tubes packed with adsorbents, have been commonly used for plant enclosure. Sampling of carbonyl compounds emitted from plants has been done using 2,4-dinitrophenylhydrazine coated particles and the derivative carbonyl compounds have been analyzed by HPLC-UV. In this work, the enclosure technique using a cuvette for measurements of carbonyl compound emissions from plants was evaluated. Blank measurements in an empty cuvette have revealed quite different results for experiments performed under laboratory and field conditions. Rigorous univariate statistical analysis of the data obtained indicate that the analytical procedure to determine carbonyl compounds at trace levels in emission samples using the cuvette may lead to positive artifacts during field sampling. This analysis applied to laboratory measurements showed no difference in the results for the cuvette and external lines. Multivariate statistical calculations point out that solar light intensity accounts for the high carbonyl compound levels, especially for acetaldehyde, in the empty cuvette.

Comparability of biogenic VOC emission rate measurements under laboratory and ambient conditions at the example of monoterpene emissions from Scots pine (Pinus sylvestris)

Laboratory experiments under controlled environmental conditions are a useful tool to investigate the influence of different environmental parameters on VOC emissions from plants individually. Before using the obtained results to interpret measurements under ambient conditions, it has to be ensured that the laboratory system is suitable for performing emission rate measurements under ambient-like conditions to derive algorithms describing the emissions of volatile organic compounds as a function of physical variables like temperature and light intensity. Here we compare results from monoterpene emission rate measurements with Scots pines (Pinus sylvestris L.) under both ambient environmental conditions using a mobile plant enclosure chamber, and under controlled laboratory conditions in a continuously stirred tank reactor. The different analytical instruments to quantify monoterpene emissions were compared in an intercalibration experiment. Measurements of the mixing ratios of α -pinene, β -pinene, 3-carene, camphene, and limonene on the order of some hundred parts per trillion differed by less than 20%. The laboratory system has proven capable of providing ambient-like conditions and results of monoterpene emission rate measurements under laboratory conditions could be extrapolated to the natural environment. Monoterpene emission rate measurements with identical specimens of Scots pines conducted within small temporal differences under similar laboratory and outdoor conditions agreed well. Both laboratory and outdoor experiments clearly showed that distinct and constant values neither exist for the standard emission rates nor for the emission pattern of monoterpenes from Scots pine. Temporal variations in the standard emission rates from identical specimens and plant-to-plant variations were on the order of one magnitude.

Isoprene emission capacity for US tree species

Isoprene emission capacity measurements are presented from 18 North American oak ( Quercus) species and species from six other genera previously found to emit significant quantities of isoprene. Sampling was conducted at physiographically diverse locations in North Carolina, Central California, and Northern Oregon. Emissions from several sun leaves of each species were measured at or near standard conditions (leaf temperature of 30°C and photosynthetically active radiation of 1000 μmol m −2 s −1) using environmentally controlled cuvette systems and gas chromatography with reduction gas detectors. Species mean emission capacity ranged from 39 to 158 μg C g −1 h −1 (mean of 86), or 22 to 79 nmol m −2 s −1 (mean of 44). These rates are 2–28 times higher than those previously reported from the same species, which were summarized in a recent study where isoprene emission rates were assigned based on published data and taxonomy. These discrepancies were attributed to differences in leaf environment during development, measurement technique (branch or plant enclosure versus leaf enclosure), and lack of environmental measurements associated with some of the earlier branch enclosure measurements. Mass-based emission capacities for 15 of 18 oak species, sweetgum ( Liquidambar styraciflua), and poplars ( Populus trichocarpa and P. deltoides) were within ranges used in current biogenic volatile organic compound (BVOC) emission models, while measured rates for the remaining three oak species, Nyssa sylvatica, Platanus occidentalis, Robinia pseudoacacia, Salix nigra, and Populus hybrids ( Populus trichocarpa × P. deltoides) were considerably higher. In addition, mean specific leaf mass of the oak species was 30% higher than assumed in current emission models. Emission rates reported here and in other recent studies support recent conclusions that isoprene emission capacities for sun leaves of high emitting species may be better represented by a value of 100±50 μg C g −1 h −1 during hot summer conditions. We also find that intermediate isoprene emission rates previously suggested for some tree species may not represent their true emission capacities, and that broadleaf plant species may have either low (<1.0 μg C g −1 h −1) or very high (∼100 μg C g −1 h −1) genetic capacity to emit isoprene when mature foliage is exposed to a high ambient temperature and light environment.

Transplanting Native Plants to Revegetate Abandoned Farmland in the Western Mojave Desert

AbstractNursery‐grown, native plant species have potential application for revegetating disturbed arid and semiarid lands. We evaluated nursery‐grown fourwing saltbush [Atriplex canescens (Pursh) Nutt.], allscale saltbush [A. polycarpa (Torrey) S. Watson], bladderpod (Isomeris arborea Nutt.), honey mesquite [Prosopis glandulosa Torrey var. torreyana (L. Benson) M. Johnston], and rubber rabbitbrush [Chrysothamnus nauseosus (Pallas) Britton] transplanted to abandoned agricultural land throughout the western Mojave Desert. Two types of temporary plant enclosure for herbivory and environmental protection (plastic cones and wire cages) and three mulch treatments (straw, bark, and none) were tested at all six sites. Rubber rabbitbrush was difficult to propagate in the nursery and is not recommended for transplanting. Significant differences in plant performance occurred between sites with similar aerial environments but contrasting degrees of edaphic disturbance. Plastic cones were significantly superior to wire cages for plant vigor and survival but no differences were detected between mulch treatments. Fourwing saltbush was generally successful over all treatments and sites and is recommended for transplanting in this area. In a larger plot study, narrow augered holes led to superior survival of honey mesquite relative to wide, hand‐dug holes, and plastic cones were superior to wire cages. Mortality of all species was high due to dry, but not atypical, weather during the 2 yr of the study. We conclude that transplanting without intensive irrigation does not guarantee survival of even the most successful species. Its greater cost relative to direct seeding may not be warranted for large‐scale restoration of arid and semiarid environments.

Methane Efflux from Emergent Vegetation in Peatlands

1 Methane emissions from emergent plants in two peatlands were measured in plant enclosure experiments. During the summer growing season, methane emissions on a plant dry mass basis from Scheuchzeriapalustris (130 + 14 4umol g-' day-') were higher than from other peatland plants, such as Chamaedaphne calyculata (20 + 3 umol g-' day-') and Carex oligosperma (91 + 38 4umol g-' day-'), but were lower than from Calla palustris (280 + 37 umol g-' day-'). 2 The contribution to net methane efflux from S. palustris, the dominant emergent plant in one peatland, was 15.6 + 2.2 mmol m-2 day-', based on the plant enclosure experiments and areal biomass measurements. These results were not significantly different from the difference between measurements of methane efflux using chambers enclosing clipped and unclipped plots (12.0-27.9 mmol m-2 day-'). 3 We determined that methane transport through S. palustris contributed between 64 and 90% of the net methane efflux from the peatland, while the other peatland without plants capable of rapid methane transport had significantly lower methane efflux. The higher annual efflux from peat with aerenchymatous plants appears to be due to several factors, including increased substrate production which enhances methane production, reduction in methane oxidation, as well as easier methane transport from the site of production. 4 Plants capable of transporting methane regulated the methane pool in the saturated zone by depleting both dissolved methane in the pore-waters and the concentration of methane in gas bubbles trapped in the saturated peat. 5 Our experiments indicate that methane transport through S. palustris is due to molecular diffusion, and is not influenced by pressurization or stomatal aperture.

Determination of the biogenic emission rates of species contributing to VOC in the San Joaquin Valley OF California

Abstract As part of an extensive effort to characterize biogenic hydrocarbon emission rates in the San Joaquin Valley and surrounding areas during the SJVAQS/AUSPEX field experimental period, July–August 1990, measurements were made for the first time of isoprene, terpene, and other VOC emission rates from blue oak (Quercus douglasii), foothill pine (Pinus sabiniana), and a ground cover plant called tarweed (Holocarpha sp.) at a rural site near Mariposa, CA. A flow-through plant enclosure method was used to measure the emission flux rates from these species; the plant limb or whole plant was flushed with clean air just prior to hydrocarbon sampling. Samples of the plant emissions were collected on Tenax GC or Tenax GC-Carbosieve S-I1 cartridges and analysed by gas chromatography- Fourier transform infrared-mass spectrometry (GC-FTIR-MS). Quantifiable biogenic emissions from two blue oak specimens consisted only of isoprene, with an average emission rate of 8.4 μg g−1 dry biomass h−1. Emission rates (above the detection of about 0.05 μg−1 h−1) from two foothill pine specimens consisted mostly of α-pinene; an average emission rate of 0.64 μg−1 h−1 of α-pinene was observed. The tarweed species emitted both α- and β-pinenes, along with other terpene and oxygenated species, some of which have been tentatively identified. The emission rates of biogenic hydrocarbons from foothill pine and blue oak species as determined in this study make these species potentially significant contributors to summertime VOC levels in the San Joaquin Valley of California, based on vegetation classification data and the predominant summer meteorology.

Measurement of Photosynthetic Gas Exchange in Controlled Environments

Early controlled-environment research used growth chambers primarily as “photoperiod rooms” to study effects of environment on long-term plant developmental processes (Downs and Hellmers, 1975). More recently, growth dynamics analysis has been used to measure photosynthetic productivity of crop canopies or individual plants in controlled environments over periods of only a few days (Knight and Mitchell, 1983). However, as the emphasis of controlled-environment research shifts toward definition of optimum growth conditions (Hoff et al., 1982), there will be increasing demand to measure instantaneous photosynthetic response within modified controlled environments. Net photosynthesis and respiration are measured most conveniently as CO2 consumption or evolution, respectively, by a given area or mass of plant tissue over a defined period. At ≈ 3 5 0 μmol·mol –1(μl·liter –1, vpm), CO2 is a trace gas compared to the major components of air (N2, O2, H2Ov). As such, CO2 is detectable to 1 μmol·mol –1 by thermal conductivity gas chromatography (TCD-GC) or infrared gas analysis. The infrared gas analyzer (IRGA) is amenable to continuous-flow monitoring of the CO2 level in air and will detect near-real-time changes in gas-exchange rate by plants as environmental conditions vary. Modem electronic detector systems permit a degree of miniaturization of IRGAs that allows their portability into growth chambers as well as to the field. Gas exchange by chamber-grown plants may be measured for individual attached leaves, entire shoots, or leaf canopies of multiple plants. Various plant enclosure techniques are used for each type of measurement. Because a limited number of off-the-shelf assimilation chambers are available on the commercial market, many researchers have developed their own cuvettes for specific applications. Assimilation chambers often are constructed from transparent acrylic (plexiglass) or polycarbonate (mylar) plastic. Because these plastics adsorb water vapor (H2Ov) and, consequently, CO2

The effect of increased transpiration on photosynthesis of corn part I. A field portable single plant enclosure system

A climate-controlled, field-portable, single-plant enclosure system is described. The system is capable of measuring the photosynthesis (PS) and transpiration (TS) of a single corn plant on a half-hourly basis to better than ±5% of typical PS values and ±16% of typical TS values. All data acquisition and climate control is aided by a microprocessor-based data acquisition system. Humidity is controlled and TS measured by absorbing transpired water on a column of CaSO 4; PS is obtained from required CO 2 injection rates. Both water vapour and CO 2 concentrations are kept constant and air temperature is maintained close to ambient by a water-to-air heat exchange system. At present, the system is capable of controlling to constant, user-selected CO 2 and water vapour concentrations. The system could be easily modified to study the effects of elevated CO 2 concentrations, levels of various pollutants, changes in air temperature, PPFD, and many other environmental variables.

Automated CO 2 injection system with analogue and digital outputs for measuring photosynthesis in crop enclosures

An inexpensive CO 2 injection system is described. The system, used in conjunction with a CO 2 meter, can automatically inject known amounts of CO 2 into a plant enclosure to maintain the CO 2 concentration and measure plant photosynthetic rate. When the CO 2 meter senses that the CO 2 concentration in the enclosure has fallen below the desired value, a bellows pump withdraws CO 2 from a supply line through a demand valve and injects the CO 2 into the enclosure. Once a pump stroke has been initiated, the pump always completes the full stroke. Each pump stroke is counted, recorded on an impulse counter and converted to a standing analogue voltage for data logging. Pump operation is inhibited while the logger is interrogating the circuit and the analogue signal is reset to zero after each interrogation.

An Electro‐Optical Temperature Controller for Maintaining a Constant or Relative Temperature1

AbstractA simple, inexpensive temperature controller may be constructed utilizing thermistors in a Wheatstone bridge configuration. The unit may be used to maintain a constant temperature or to regulate the temperature of a plant enclosure to that of the naturally varying ambient temperature.

Growth of Plants in Different Oxygen Concentrations

Growth of Plants in Different Oxygen Concentrations

Structural design criteria for secondary containment structures

The basic structural design philosophy and criteria for reactor secondary containment shells is developed. Considering the several loading conditions to which the structure may be subjected, the range of allowable stresses as they relate to desired performance characteristics under various combinations of loadings is discussed. There are three general conditions under which the structure must meet appropriate stress criteria: as a long-term plant enclosure subjected to normal live and dead loads; as a protective structure for the nuclear steam supply system subjected to abnormal external loads and forces such as tornadoes, hurricanes, maximum possible earthquake, and missiles that might be generated by a tornado, turbine failure, or airplanes; and as a containment structure subjected to internal pressure and temperature as a result of a major rupture of the main coolant system.