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1.
Akio Takenaka 《Ecological Research》1986,1(2):129-140
Ecophysiological comparisons were made of the growth and photosynthetic characteristics between seedlings of deciduousQuercus serrata and evergreenQuercus myrsinaefolia. Q. myrsinaefolia seedlings naturally occurring in secondary coppice forests showed exponential-like growth in height with age, while sympatricQ. serrata seedlings were considerably smaller in height, their growth being limited by shortage of light. The photosynthetic characteristics
measured under laboratory conditions showed no bases for the differences in growth between the two species on the forest floor:
Light compensation points of the seedlings raised under 5% daylight were almost identical for the two species, being about
6.0 μE·m−2·s−1. Growth analysis of seedlings planted in a coppice forest showed that bothQ. serrata andQ. myrsinaefolia could hardly grow during the summer under the shrub layer, when relative photon flux density (RPFD) was 0.9±0.5%. In the
winter, when RPFD under the leafless canopy increased to 29.3±2.7%, the dry matter production of the evergreen seedlings ofQ. myrsinaefolia was much improved. Current-year seedlings of the species showed NAR of 0.102±0.021 g·dm−2·mo−1 during the winter. Temperature dependency of photosynthesis and increment of leaf temperature by direct solar beam also indicated
active photosynthesis ofQ. myrsinaefolia on the forest floor during the winter. 相似文献
2.
T. Hura F. Dubert T. Dąbkowska E. Stupnicka-Rodzynkiewicz A. Stokłosa A. Lepiarczyk 《Acta Physiologiae Plantarum》2006,28(6):537-545
The purpose of this study was to determine the content of selected phenolic compounds in white mustard, buckwheat, spring
barley, oat and rye grown under field conditions. Moreover, the allelopathic efficiency of these compounds was evaluated by
sensitivity of Echinochloa crus-galli. The aromatic acids: trans-cinnamic, salicylic, ferulic, chlorogenic, p-hydroxybenzoic, protocatechuic, p-coumaric and vanillic were separated from
crop plants by TLC and determined spectrophotometrically.
Differences in concentrations of analysed compounds were observed for most of the examined plant species. The highest concentration
was noticed for cinnamic acid and ranged from 360 μg·g−1 DW in rye to 2770 μg·g−1 DW in spring barley. The relatively high concentration was noticed for ferulic acid (from 73.8 μg·g−1 DW in buckwheat to 1046 μg·g−1 DW in spring barley) and p-coumaric acid (from 50 μg·g−1 DW in oat to 1499 μg·g−1 DW in buckwheat). The observed differences in the phenolics content between two successive vegetation seasons can reflect
the effect of abiotic and biotic environmental factors on the phenolics level in studied plants.
In the greenhouse experiment the effect of particular compounds on the growth of Echinochloa crus-galli was also studied. It has been found that the examined phenolics, and especially trans-cinnamic acid and mixture of phenolic compounds, significantly inhibit the growth of Echinochloa crus-galli. The obtained results may contribute to the explanation of the biological activity of some phenolic compounds. 相似文献
3.
Phenotypic plasticity allows organisms to cope with environmental variation and may aid in the evolution of novel traits. However, whether phenotypic plasticity is beneficial, or if acclimation responses might be constrained to particular ecotypes is generally poorly explored. Here we test the beneficial acclimation hypothesis (BAH) and its alternatives for desiccation resistance to atmospheric moisture in mesic‐ and xeric‐adapted Glossina species. Highly significant interactions among acclimation and test humidity were detected for water loss rates indicative of significant phenotypic plasticity. Ordered‐factor anova was unable to reject predictions of the ‘drier is better’ acclimation hypothesis in xeric Glossina morsitans and mesic G. austeni. Evidence for the ‘deleterious acclimation hypothesis’ was found for mesic G. palpalis as expected from the moist habitats it typically occupies. By contrast, support for the ‘optimal acclimation hypothesis’ was found in xeric G. pallidipes. Little support for BAH was obtained in the present study, although other hypotheses, which might enhance fitness within the environments these species are typically exposed to, were supported. However, acclimation responses were not necessarily constrained to xeric/mesic ecotypes which might be expected if adaptation to a particular environment arose as a trade‐off between plastic responses and living in a particular habitat. These results highlight the complexity of acclimation responses and suggest an important role for phenotypic plasticity in moderating environmental effects on evolutionary fitness in Glossina. 相似文献
4.
Seasonal dynamics of fine root biomass, root length density, specific root length, and soil resource availability in a Larix gmelinii plantation 总被引:1,自引:0,他引:1
Cheng Yunhuan Han Youzhi Wang Qingcheng Wang Zhengquan 《Frontiers of Biology in China》2006,1(3):310-317
Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive
to many global change factors. Despite the importance of fine root turnover in plant C allocation and nutrient cycling dynamics
and the tremendous research efforts in the past, our understanding of it remains limited. This is because the dynamics processes
associated with soil resources availability are still poorly understood. Soil moisture, temperature, and available nitrogen
are the most important soil characteristics that impact fine root growth and mortality at both the individual root branch
and at the ecosystem level. In temperate forest ecosystems, seasonal changes of soil resource availability will alter the
pattern of carbon allocation to belowground. Therefore, fine root biomass, root length density (RLD) and specific root length
(SRL) vary during the growing season. Studying seasonal changes of fine root biomass, RLD, and SRL associated with soil resource
availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover. The objective
of this study was to understand whether seasonal variations of fine root biomass, RLD and SRL were associated with soil resource
availability, such as moisture, temperature, and nitrogen, and to understand how these soil components impact fine root dynamics
in Larix gmelinii plantation. We used a soil coring method to obtain fine root samples (⩽2 mm in diameter) every month from May to October
in 2002 from a 17-year-old L. gmelinii plantation in Maoershan Experiment Station, Northeast Forestry University, China. Seventy-two soil cores (inside diameter
60 mm; depth intervals: 0–10 cm, 10–20 cm, 20–30 cm) were sampled randomly from three replicates 25 m × 30 m plots to estimate
fine root biomass (live and dead), and calculate RLD and SRL. Soil moisture, temperature, and nitrogen (ammonia and nitrates)
at three depth intervals were also analyzed in these plots. Results showed that the average standing fine root biomass (live
and dead) was 189.1 g·m−2·a−1, 50% (95.4 g·m−2·a−1) in the surface soil layer (0–10 cm), 33% (61.5 g·m−2·a−1), 17% (32.2 g·m−2·a−1) in the middle (10–20 cm) and deep layer (20–30cm), respectively. Live and dead fine root biomass was the highest from May
to July and in September, but lower in August and October. The live fine root biomass decreased and dead biomass increased
during the growing season. Mean RLD (7,411.56 m·m−3·a−1) and SRL (10.83 m·g−1·a−1) in the surface layer were higher than RLD (1 474.68 m·m−3·a−1) and SRL (8.56 m·g−1·a−1) in the deep soil layer. RLD and SRL in May were the highest (10 621.45 m·m−3 and 14.83m·g−1) compared with those in the other months, and RLD was the lowest in September (2 198.20 m·m−3) and SRL in October (3.77 m·g−1). Seasonal dynamics of fine root biomass, RLD, and SRL showed a close relationship with changes in soil moisture, temperature,
and nitrogen availability. To a lesser extent, the temperature could be determined by regression analysis. Fine roots in the
upper soil layer have a function of absorbing moisture and nutrients, while the main function of deeper soil may be moisture
uptake rather than nutrient acquisition. Therefore, carbon allocation to roots in the upper soil layer and deeper soil layer
was different. Multiple regression analysis showed that variation in soil resource availability could explain 71–73% of the
seasonal variation of RLD and SRL and 58% of the variation in fine root biomass. These results suggested a greater metabolic
activity of fine roots living in soil with higher resource availability, which resulted in an increased allocation of carbohydrate
to these roots, but a lower allocation of carbohydrate to those in soil with lower resource availability.
__________
Translated from Acta Phytoecologica Sinica, 2005, 29(3): 403–410 [译自: 植物生态学报, 2005, 29(3): 403–410] 相似文献
5.
Photosynthetic response to dynamic changes of light and air humidity in two moss species from the Tibetan Plateau 总被引:1,自引:0,他引:1
Bryophytes are widely distributed in alpine meadow and wetlands on the Tibetan Plateau, where light intensity and air moisture
are highly variable in time. To address how bryophytes respond to their light and moisture environments, we examined dynamic
photosynthesis in two moss species, Distichium inclinatum common in meadow, and Encalypta alpine frequently found in wetland. Photosynthetic induction response was faster in the two moss species than in most vascular species.
In both species the 90% induction time after a sudden light increase from 50 to 600 μmol m−2 s−1 was within 3 min. The induction was faster in mosses experiencing a period of weak light than in those in total darkness.
E. alpina, the wetland species, showed more rapid induction response and shorter post-illumination CO2 fixation to sunflecks than D. inclinatum, the meadow species. Photosynthetic rate (A
max) under saturated light in the two species increased linearly with increasing air relative humidity (RH). The meadow species
D. inclinatum showed higher A
max under low RHs, but exhibited lower A
max under high RHs in comparison with the wetland moss E. alpina. Moreover, the quantum efficiency increased linearly with increasing RH, indicating that air humidity plays a critical role
in photochemical activities in the alpine mosses. The study suggests that there are acclimations in dynamic photosynthesis
in response to light and humidity, and the acclimations would benefit a high leaf carbon gain in the two alpine moss species
in their common habitats. 相似文献
6.
Our current ability to detect and predict changes in forest ecosystem productivity is constrained by several limitations.
These include a poor understanding of belowground productivity, the short duration of most analyses, and a need for greater
examination of species- or community-specific variability in productivity studies. We quantified aboveground net primary productivity
(ANPP) over 3 years (1999–2001), and both belowground NPP (BNPP) and total NPP over 2 years (2000–2001) in both mesic and
xeric site community types of the mixed mesophytic forest of southeastern Kentucky to examine landscape variability in productivity
and its relation with soil resource [water and nitrogen (N)] availability. Across sites, ANPP was significantly correlated
with N availability (R2 = 0.58, P = 0.028) while BNPP was best predicted by soil moisture content (R2 = 0.72, P = 0.008). Because of these offsetting patterns, total NPP was unrelated to either soil resource. Interannual variability
in growing season precipitation during the study resulted in a 50% decline in mesic site litter production, possibly due to
a lag effect following a moderate drought year in 1999. As a result, ANPP in mesic sites declined 27% in 2000 compared to
1999, while xeric sites had no aboveground production differences related to precipitation variability. If global climate
change produces more frequent occurrences of drought, then the response of mesic sites to prolonged moisture deficiency and
the consequences of shifting carbon (C) allocation on C storage will become important questions. 相似文献
7.
Stomatal and nonstomatal limitations of photosynthesis in 19 temperate tree species on contrasting sites during wet and dry years 总被引:3,自引:1,他引:2
A unique approach was used to evaluate stomatal and nonstomatal constraints to photosynthesis in 19 naturally occurring, deciduous tree species on xeric, mesic and wetmesic sites in central Pennsylvania, USA, during relatively wet (1990) and dry (1991) growing seasons. All species exhibited significantly decreased stomatal conductance to CO2 (gc) in 1991 compared to 1990. The mesic species had drought related decreases in photosynthesis (A) attributed primarily to increased absolute stomatal limitation to A (Lg), whereas in the wet-mesic species, the absolute mesophyll limitation (Lm) was at least as important as Lg in limiting A during drought. The xeric species maintained relatively high A during drought despite decreased gc. In the xeric and mesic species, Lm decreased and Lg increased during drought due to stomatal closure. From xeric to mesic to wet-mesic, the relative stomatal limitation (Ig) generally decreased faster, and relative mesophyll limitations to A increased faster, with increasing gc suggesting greater photosynthetic capacity (i.e. greater potential maximum A) with increasing drought tolerance rank of species. Few species exhibited a significant drought-related decrease in photosynthetic capacity. The results of this landscape-based study indicate that the interaction of stomatal and nonstomatal limitations of A vary in a manner consistent with species' drought tolerance and site conditions, and that nonstomatal constraints to A in field plants during a moderate, season-long drought were generally not as severe as reported in controlled studies. 相似文献
8.
Yoshio Ino 《Ecological Research》1990,5(2):195-205
Net photosynthesis and dark respiration (CO2 flux) of Antarctic mosses were measured at Langhovde, East Antarctica, from 9 to 17 January 1988. Moss blocks were taken
from communities in the Yukidori Valley (69°14′30″S, 39°46′00″E) at Langhovde. Each block was composed ofCeratodon purpureus andBryum pseudotriquetrum, orB. pseudotriquetrum. The upper part of the block was used to measure net photosynthesis and dark respiration. The net photosynthesis of each
sample was measured in the field for one or three days with two infrared CO2 gas analyzers and an assimilation chamber. The relationships of net photosynthetic rate and dark respiration rate, to the
water content of the sample, the intensity of solar radiation and the moss temperature were estimated from the field data.
The maximum rate of net photosynthesis was about 4 μmol CO2 m−2s−1 at saturating radiation intensity and at optimum temperature, about 10°C. Environmental features of moss habitats in the
Yukidori Valley are discussed in relation to these results. 相似文献
9.
Early season cuticular conductance and gas exchange in two oaks near the western edge of their range
Seasonal changes in minimum leaf conductance to water vapor (gmin), an estimate of cuticular conductance, and photosynthetic gas exchange in two co-occurring oak species in north-east Kansas (USA) were examined to determine if leaf gas exchange characteristics correlated with differences in tree distribution. Bur oak (Quercus macrocarpa Michx.) is more abundant in mesic gallery forest sites, whereas chinquapin oak (Quercus muehlenbergii Englm.) is more abundant in xeric sites. Early, during leaf expansion, gmin was significantly lower in chinquapin oak than in bur oak, though midday water potentials were similar. After leaves had fully expanded, gmin decreased to seasonal minimum values of 4.57 (±0.274) mmol m-2 s-1 in bur oak, and 2.66 (±0.156) mmol m-2 s-1 in chinquapin oak. Water potentials at these times were significantly higher in chinquapin oak. As leaves were expanding, photosynthesis (Anet) was significantly higher in chinquapin oak than in bur oak. Later in the growing season, Anet and gleaf increased dramatically in both species, and were significantly higher in bur oak relative to chinquapin oak. We concluded that bur and chinquapin oak have a number of leaf gas exchange characteristics that minimize seasonal water loss. These characteristics are distinct from trees from more mesic sites, and are consistent with the distribution patterns of these trees in tall-grass prairie gallery forests. 相似文献
10.
Pia Parolin Astrid C. Oliveira Maria Teresa F. Piedade Florian Wittmann Wolfgang J. Junk 《Folia Geobotanica》2002,37(2):225-238
Three pioneer tree species —Salix humboldtiana, Cecropia latiloba, Senna reticulata — form monospecific stands in the Central Amazonian white-water flood plain. In contrast toterra firma forests where species composition is unpredictable even for pioneer species, in Central Amazonianvárzea the occurrence of the main colonizing species seems to be predictable. This predictability is linked to characteristic habitat conditions and the low number of pioneer species. This preference for different habitats is reflected by different germination and early growth, by the structural and physiological characteristics, as well as by the reproductive and morphological adaptations of the three main species. The germination rate was above 90% in all species, and the duration until germination ranged between one day inSalix and 14 days inCecropia. Stem elongation was more than 10 cm per month inSalix andCecropia, and about 50 cm per month inSenna. Wood specific gravity ranged from 0.33 g cm−3 inCecropia to 0.45 g cm−3 inSenna. The annual wood increment increased by 1.20 (Cecropia), 1.23 (Salix) to 2.14 cm per year (Senna). All species produced adventitious roots, lenticels and/or stem hypertrophy. Leaf photosynthesis was between 17 and 20 μmol m−2s−1, and reached a maximum of 30 μmol m−2s−1 inSenna. Flowering and fruiting inSalix occurred throughout the year, whereas inCecropia andSenna they were concentrated in the flooded period.Salix humboldtiana occurs mainly at low sites subjected to long periods of inundation and high sedimentation rates. OnceSalix has formed dense forest stands, sedimentation and water currents are reduced at these sites andCecropia latiloba may take over. This species grows on low to middle elevations in the flooding gradient at sites with lower current and sedimentation rates.Senna reticulata does not tolerate submergence and colonizes habitats that may have strong currents and high sedimentation on higher levels in the flooding gradient. 相似文献
11.
Dawson TJ McTavish KJ Munn AJ Holloway J 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2006,176(1):45-53
The Eastern Grey Kangaroo (Macropus giganteus) occurs mostly in the wetter regions of eastern Australia. However, in the past 30–40 years it has moved into more arid regions
(rainfall<250 mm), thus increasing its overlap zone with the xeric adapted Red Kangaroo (Macropus rufus). An increased access to water (supplied for domestic stock) may explain this range extension, but changes in the availability
of preferred feed could also be involved. The water use, drinking patterns and thermoregulatory behaviour of these two species
of kangaroo have been examined in a semi-free range study, during summer at an arid rangeland site. Foraging was largely nocturnal
in both species and during the day they behaved to reduce heat loads. This was especially so for M. giganteus, which showed greater shade seeking. However, it still used more water (72±2.6 mL kg−1 day−1, mean ± SE) than M. rufus (56±7.6 mL kg−1 day−1) and drank twice as frequently. Although M. giganteus produced a less concentrated urine (1422±36 mosmol kg−1) than M. rufus (1843±28 mosmol kg−1), kidney physiology did not explain all of the differences in water metabolism between the species. Water from the feed and
faecal water retention also appear to be involved. Broadly, a better access to reliable water and the utilisation of mesic
microhabitats has enabled M. giganteus to make inroads into the changing rangelands of eastern Australia. However, changes in the vegetation, due to stock grazing,
have also favoured M. giganteus, which is a grass eating specialist. 相似文献
12.
An endophytic Xylaria sp., having broad antimicrobial activity, was isolated and characterized from Ginkgo biloba L. From the culture extracts of this fungus, a bioactive compound P3 was isolated by bioactivity-guided fractionation and
identified as 7-amino-4-methylcoumarin by nuclear magnetic resonance, infrared, and mass spectrometry spectral data. The compound
showed strong antibacterial and antifungal activities in vitro against Staphylococcus aureus [minimal inhibitory concentrations (MIC) 16 μg·ml−1], Escherichia coli (MIC, 10 μg·ml−1), Salmonella typhia (MIC, 20 μg·ml−1), Salmonella typhimurium (MIC, 15 μg·ml−1), Salmonella enteritidis (MIC, 8.5 μg·ml−1), Aeromonas hydrophila (MIC, 4 μg·ml−1), Yersinia sp. (MIC, 12.5 μg·ml−1), Vibrio anguillarum (MIC, 25 μg·ml−1), Shigella sp. (MIC, 6.3 μg·ml−1), Vibrio parahaemolyticus (MIC, 12.5 μg·ml−1), Candida albicans (MIC, 15 μg·ml−1), Penicillium expansum (MIC, 40 μg·ml−1), and Aspergillus niger (MIC, 25 μg·ml−1). This is the first report of 7-amino-4-methylcoumarin in fungus and of the antimicrobial activity of this metabolite. The
obtained results provide promising baseline information for the potential use of this unusual endophytic fungus and its components
in the control of food spoilage and food-borne diseases. 相似文献
13.
Margaret Skinner B. L. Parker W. E. Wallner T. M. Odell Diantha Howard J. Aleong 《BioControl》1993,38(1):15-29
A 2-year study was conducted on the distribution of parasitoids of gypsy moth,Lymantria dispar (L.) (Lep.: Lymantriidae), in mesic and adjacent higher elevation transition and xeric forest habitats in Vermont (U.S.A.). In both years, overall parasitism ranged from 12–18% in each habitat. When analyzed according to the life stage at which the host was collected, parasitism rates of greater than 40% were obtained among the late instars.Parasetigena silvestris (Robineau-Desvoidy) andPhobocampe disparis (Viereck) were recovered most commonly from the mesic habitat, andCotesia melanoscelus (Ratzeburg) andBlepharipa pratensis (= Sturmia scutellata) (Meigen) were most common in collections from the xeric area. Parasitism byCompsilura concinnata (Meigen) occurred at similar levels in all three habitats, and this species was responsible for the highest parasitism rates on the site, reaching 40% among the late instars in 1985. Percent parasitism byC. concinnata increased three-four-fold from 1984 to 1985, while parasitism by other species declined. 相似文献
14.
Nutrient and water addition effects on day- and night-time conductance and transpiration in a C3 desert annual 总被引:1,自引:0,他引:1
Recent research has shown that many C3 plant species have significant stomatal opening and transpire water at night even in desert habitats. Day-time stomatal regulation is expected to maximize carbon gain and prevent runaway cavitation, but little is known about the effect of soil resource availability on night-time stomatal conductance (g) and transpiration (E). Water (low and high) and nutrients (low and high) were applied factorially during the growing season to naturally occurring seedlings of the annual Helianthus anomalus. Plant height and biomass were greatest in the treatment where both water and nutrients were added, confirming resource limitations in this habitat. Plants from all treatments showed significant night-time g (~0.07 mol m−2 s−1) and E (~1.5 mol m−2 s−1). In July, water and nutrient additions had few effects on day- or night-time gas exchange. In August, however, plants in the nutrient addition treatments had lower day-time photosynthesis, g and E, paralleled by lower night-time g and E. Lower predawn water potentials and higher integrated photosynthetic water-use efficiency suggests that the nutrient addition indirectly induced a mild water stress. Thus, soil resources can affect night-time g and E in a manner parallel to day-time, although additional factors may also be involved. 相似文献
15.
Vishwanath M. Patil 《In vitro cellular & developmental biology. Plant》1998,34(3):240-243
Summary The purpose of this study was to developin vitro techniques for conserving wild and endemic species ofCeropegia by mass multiplication for subsequent reintroduction in their natural habitat. Micropropagation involving a combination of
axillary bud culture, shoot multiplication, somatic embryogenesis andin vitro tuber formation forCeropegia jainii, a rare plant of the Indian sub continent,C. bulbosa var.bulbosa andC. bulbosa var.lushii, common species, was developed. Nodal explants from all species were cultured on 0.5 MS medium with 8.8 μM (2 mg·l−1) N6-benzyl aminopurine (BA) to regenerate the axillary buds. These produced multiple shoots when transferred to multiplication
medium consisting of 0.5 MS medium with 2.2 μM (0.5 mg·l−1) BA, or microtubers when transferred to 0.5 MS medium with 22.2 μM (5 mg·l−1) BA and 23.2 μM (5 mg·l−1) kinetin.In vitro flowering occurred inC. jainii and not in the other two varieties when the plants were cultured on multiplication media with spermine at 0.25 μM (50 μg·l−1) as an additive. Shoot pieces produced callus on MS medium with 9.05 μM (2 mg·l−1) 2,4-dichlorophenoxy acetic acid. Regeneration of the calli by somatic embryogenesis was achieved when they were transferred
to 0.5 MS medium with 2.2 μM (0.5 mg·l−1) BA. Rooting of the shoots was possible both byin vitro andex vitro means. 相似文献
16.
The present study examines relative growth rate (RGR) and its determinants in seedlings of nine Eucalyptus species. Species were selected from mesic (1,800 mm a−1 rainfall) through to semi-arid habitats (300 mm a−1), and thus, notionally vary in “stress” tolerance. Seedlings were grown in a glasshouse during early summer and received
between 33 mol and 41 mol PAR m−2 day−1 . The mean RGR varied among species—from a minimum of 66 mg g−1 day−1 in E. hypochlamydea to a maximum of 106 mg g−1 day−1 in E. delegatensis. RGR was positively related to rainfall at the sites of seed collection. Neither specific leaf area (SLA) nor net assimilation
rate was related to rainfall or RGR. While the absence of relationships with SLA and net assimilation rate contrasts with
other studies and species, we cannot rule out the effects of sample size (n=9 species) and modest ranges in SLA and RGR. The ratio of leaf mass to total mass (LMR) varied from 0.49±0.07 g g−1 in E. socialis to 0.74±0.04 g g−1 in E. delegatensis and was strongly positively related with rainfall (r
2=0.77). Interspecific differences in RGR were strongly related to LMR (positive relationship, r
2=0.50) and the rate of dry matter production per mol of leaf nitrogen (positive relationship, r
2=0.64). Hence, the slow RGR of low-rainfall species was functionally related to a lower growth rate per mol of leaf nitrogen
than high-rainfall species. Furthermore, slow RGR of low-rainfall species was related to greater allocation to roots at the
expense of leaves. Increasing allocation to roots versus leaves is likely an adaptation to soil and atmospheric water deficits,
but one that comes at the expense of a slow RGR. 相似文献
17.
Christine E. Cooper Philip C. Withers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(6):857-868
Quolls (Dasyurus) are medium-sized carnivorous dasyurid marsupials. Tiger (3,840 g) and eastern quolls (780 g) are mesic zone species, northern
quolls (516 g) are tropical zone, and chuditch (1,385 g) were once widespread through the Australian arid zone. We found that
standard physiological variables of these quolls are consistent with allometric expectations for marsupials. Nevertheless,
inter-specific patterns amongst the quolls are consistent with their different environments. The lower T
b of northern quolls (34°C) may provide scope for adaptive hyperthermia in the tropics, and they use torpor for energy/water
conservation, whereas the larger mesic species (eastern and tiger quolls) do not appear to. Thermolability varied from little
in eastern (0.035°C °C−1) and tiger quolls (0.051°C oC−1) to substantial in northern quolls (0.100°C oC−1) and chuditch (0.146°C oC−1), reflecting body mass and environment. Basal metabolic rate was higher for eastern quolls (0.662 ± 0.033 ml O2 g−1 h−1), presumably reflecting their naturally cool environment. Respiratory ventilation closely matched metabolic demand, except
at high ambient temperatures where quolls hyperventilated to facilitate evaporative heat loss; tiger and eastern quolls also
salivated. A higher evaporative water loss for eastern quolls (1.43 ± 0.212 mg H2O g−1 h−1) presumably reflects their more mesic distribution. The point of relative water economy was low for tiger (−1.3°C), eastern
(−12.5°C) and northern (+3.3) quolls, and highest for the chuditch (+22.6°C). We suggest that these differences in water economy
reflect lower expired air temperatures and hence lower respiratory evaporative water loss for the arid-zone chuditch relative
to tropical and mesic quolls. 相似文献
18.
To investigate the variability of primary production of boreal forest ecosystems under the current climatic changes, we compared
the dynamics of annual increments and productivity of the main components of plant community (trees, shrubs, mosses) at three
sites in the north of Siberia (Russia). Annual radial growth of trees and shrubs was mostly defined by summer temperature
regime (positive correlation), but climatic response of woody plants was species specific and depends on local conditions.
Dynamics of annual increments of mosses were opposite to tree growth. The difference in climatic response of the different
vegetation components of the forest ecosystems indicates that these components seem to be adapted to use climatic conditions
during the short and severe northern summer, and decreasing in annual production of one component is usually combined with
the increase of other component productivity. Average productivity in the northern forest ecosystems varies from 0.05 to 0.14 t ha−1 year−1 for trees, from 0.05 to 0.18 t ha−1 year−1 for shrubs and from 0.54 to 0.66 t ha−1 year−1 for mosses. Higher values of tree productivity combined with lower annual moss productivity were found in sites in northern
taiga in comparison with forest-tundra. Different tendencies in the productivity of the dominant species from each vegetation
level (trees, shrubs, mosses) were indicated for the last 10 years studied (1990–1999): while productivity of mosses is increasing,
productivity of trees is decreasing, but there is no obvious trend in the productivity of shrubs. Our results show that in
the long term, the main contribution to changes in annual biomass productivity in forest-tundra and northern taiga ecosystems
under the predicted climatic changes will be determined by living ground cover. 相似文献
19.
Water status and gas exchange of beech (Fagus sylvatica L.) and sessile oak [Quercus petraea (Mattuschka) Liebl.] were studied in a mixed stand in the Montejo de la Sierra forest (central Iberian Peninsula), one of
the southernmost locations of both species in Europe. Gas exchange and water potential were measured in leaves at different
canopy levels over several days in two growing seasons. The daily variation pattern was established with the measurements
of three selected dates per year, representative of the soil moisture content situations in early, mid- and late summer. A
similar daily time course of leaf water potential was found for the two species. Nevertheless, beech showed a most noticeable
decrease of water potential at midmorning and maintained lower leaf water potential than oak in the early afternoon. In 1994
the sessile oak saplings showed higher values of predawn water potential (Ψpd) than beech at the end of summer, when soil moisture content was lowest (20 cm depth). Beech showed a significantly lower
net assimilation rate (A) than sessile oak for leaves under the same PPFD. Maximum net photosynthesis values (A
max) for beech and sessile oak on sunny leaves were 10.1±0.4 μmol m–2 s–1 and 17.8±1.7 μmol m–2 s–1 respectively, and those for water vapour stomatal conductance (g
wv) were 265±31 mmol m–2 s–1 and 438±74 mmol m–2 s–1. Differences in A and g
wv between the two species were maintained throughout the day on all measurement dates. No clear relationship was found between
water status of saplings and stomata performance; there was only a negative correlation between Ψpd and g
wvmid in beech. Nevertheless, a significant response to the air vapour pressure gradient between leaf and air was translated into
stomata closure on an hourly basis, more intensively in beech.
Received: 4 March 1999 / Accepted: 21 December 1999 相似文献
20.
This study investigates the influence of texture, soil moisture and nutrient status on the growth and survival of seedlings of two typical fynbos (Leucadendron pubescens and Passerina vulgaris) and succulent karoo (Ruschia spp.) species, which grow in the boundary zone between these two vegetation types. Seedlings of each species were grown in shalederived and sandstone‐derived soils and under xeric and mesic regimes. Under the xeric regime, the shale‐derived and sandstone‐derived soils represented fine and coarse‐textured soils, respectively. Under the mesic regime, the same soils represented nutrient‐rich and nutrient‐poor soils, respectively. The seedlings of both fynbos species died rapidly under the xeric regime, irrespective of soil type. In contrast, the succulent karoo seedlings survived for over 77 days without water. Under mesic conditions, the fynbos seedlings grew faster than the succulent karoo seedlings, irrespective of soil type. Fynbos seedlings appear to be directly limited by the environment (moisture and salinity), whereas succulent karoo seedlings may be limited by interactions with other plants. 相似文献