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1.
We analyzed the physiological response of the Mediterranean evergreen species (Arbutus unedo L., Cistus incanus L., Erica arborea L., Erica multiflora L., Phillyrea latifolia L., Pistacia lentiscus L., Quercus ilex L., and Rosmarinus officinalis L.) to winter low air temperatures. In occasion of two cold events, in February 2005 (T
min = 1.8 °C), and January 2006 (T
min = 3.1 °C and minimum T
air = −0.40 °C during the nights preceding the measurements), R. officinalis, C. incanus, and E. multiflora had the highest net photosynthetic rate (P
N) decrease (73 %, mean value) with respect to the winter P
N maximum, followed by A. unedo (62 %), P. latifolia and P. lentiscus (54 %, mean value), E. arborea (49 %), and Q. ilex (44 %). Among the considered species, Q. ilex was able to maintain P
N near the maximum for 150 min during the day, A. unedo, P. lentiscus, E. arborea, P. latifolia, E. multiflora, and R. officinalis for 60 min, and C. incanus for 30 min. The calculated mean winter daily P
N ranged from 7.9±0.6 (Q. ilex) to 2.8±0.5 (R. officinalis) μmol(CO2) m−2 s−1. During the study period, chlorophyll (Chl) content decreased by 36 % on an average in the two cold events, and the carotenoid
(Car) to Chl ratio increased by 133 % in Q. ilex, having the highest value in January 2006. Principal component analysis underlined the highest cold resistance of Q. ilex by high P
N and high Car/Chl ratio. On the contrary, R. officinalis and C. incanus had the lowest cold resistance by the highest P
N decrease and the lowest Car/Chl (C. incanus). Thus, winter stress could be an additional limitation to Mediterranean evergreen species production, and the capacity of
the species to maintain P
N near 90–100 % during winter is determinant for biomass accumulation. 相似文献
2.
Adaptive photosynthetic strategies of the Mediterranean maquis species according to their origin 总被引:2,自引:0,他引:2
In consideration of their origin the adaptive strategies of the evergreen species of the Mediterranean maquis were analysed. Rosmarinus officinalis L., Erica arborea L., and Erica multiflora L. had the lowest net photosynthetic rate (PN) in the favourable period [7.8±0.6 mol(CO2) m–2s–1, mean value], the highest PN decrease (on an average 86 % of the maximum) but the highest recovery capacity (>70 % of the maximum) at the first rainfall in September. Cistus incanus L. and Arbutus unedo L. had the highest PN during the favourable period [15.5±5.2 mol(CO2) m–2s–1, mean value], 79 % decrease during drought, and a lower recovery capacity (on an average 54 %). Quercus ilex L., Phillyrea latifolia L., and Pistacia lentiscus L. had an intermediate PN in the favourable period [9.2±1.3 mol(CO2) m–2s–1, mean value], a lower reduction during drought (on an average 63 %), and a range from 62 % (Q. ilex and P. latifolia) to 39 % (P. lentiscus) of recovery capacity. The Mediterranean species had higher decrease in PN and stomatal conductance during drought and a higher recovery capacity than the pre-Mediterranean species. Among the pre-Mediterranean species, P. latifoliahad the best adaptation to long drought periods also by its higher leaf mass per area (LMA) which lowered leaf temperature thus decreasing transpiration rate during drought. Moreover, its leaf longevity determined a more stable leaf biomass during the year. Among the Mediteranean species, R. officinalis was the best adapted species to short drought periods by its ability to rapidly recover. Nevertheless, R. officinalis had the lowest tolerance to high temperatures by its PN dropping below half its maximum value when leaf temperature was over 33.6°C. R. officinalismay be used as a bioindicator species of global change.This revised version was published online in March 2005 with corrections to the page numbers. 相似文献
3.
The morphological, anatomical and physiological variations of leaf traits were analysed during Quercus ilex L. leaf expansion. The leaf water content (LWC), leaf area relative growth rate (RGRl) and leaf dry mass relative growth rate (RGRm) were the highest (76±2 %, 0.413 cm2 cm−2 d−1, 0.709 mg mg−1 d−1, respectively) at the beginning of the leaf expansion process (7 days after bud break). Leaf expansion lasted 84±2 days when
air temperature ranged from 13.3±0.8 to 27.6±0.9 °C. The net photosynthetic rate (P
N), stomatal conductance (g
s), and chlorophyll content per fresh mass (Chl) increased during leaf expansion, having the highest values [12.62±1.64 μmol
(CO2) m−2 s−1, 0.090 mol (H2O) m−2 s−1, and 1.03±0.08 mg g−1, respectively] 56 days after bud break. Chl was directly correlated with leaf dry mass (DM) and P
N. The thickness of palisade parenchyma contributed to the total leaf thickness (263.1±1.5 μm) by 47 %, spongy layer thickness
38 %, adaxial epidermis and cuticle thickness 9 %, and abaxial epidermis and cuticle thickness 6 %. Variation in leaf size
during leaf expansion might be attributed to a combination of cells density and length, and it is confirmed by the significant
(p<0.001) correlations among these traits. Q. ilex leaves reached 90 % of their definitive structure before the most severe drought period (beginning of June — end of August).
The high leaf mass area (LMA, 15.1±0.6 mg cm−2) at full leaf expansion was indicative of compact leaves (2028±100 cells mm−2). Air temperature increasing might shorten the favourable period for leaf expansion, thus changing the final amount of biomass
per unit leaf area of Q. ilex. 相似文献
4.
In consideration of their origin the adaptive strategies of the evergreen species of the Mediterranean maquis were analysed. Rosmarinus officinalis L., Erica arborea L., and Erica multiflora L. had the lowest net photosynthetic rate (PN) in the favourable period [7.8±0.6 μmol(CO2) m?2s?1, mean value], the highest PN decrease (on an average 86 % of the maximum) but the highest recovery capacity (>70 % of the maximum) at the first rainfall in September. Cistus incanus L. and Arbutus unedo L. had the highest PN during the favourable period [15.5±5.2 μmol(CO2) m?2s?1, mean value], 79 % decrease during drought, and a lower recovery capacity (on an average 54 %). Quercus ilex L., Phillyrea latifolia L., and Pistacia lentiscus L. had an intermediate PN in the favourable period [9.2±1.3 μmol(CO2) m?2s?1, mean value], a lower reduction during drought (on an average 63 %), and a range from 62 % (Q. ilex and P. latifolia) to 39 % (P. lentiscus) of recovery capacity. The Mediterranean species had higher decrease in PN and stomatal conductance during drought and a higher recovery capacity than the pre-Mediterranean species. Among the pre-Mediterranean species, P. latifoliahad the best adaptation to long drought periods also by its higher leaf mass per area (LMA) which lowered leaf temperature thus decreasing transpiration rate during drought. Moreover, its leaf longevity determined a more stable leaf biomass during the year. Among the Mediteranean species, R. officinalis was the best adapted species to short drought periods by its ability to rapidly recover. Nevertheless, R. officinalis had the lowest tolerance to high temperatures by its PN dropping below half its maximum value when leaf temperature was over 33.6°C. R. officinalismay be used as a bioindicator species of global change. 相似文献
5.
Drought and warming induced changes in P and K concentration and accumulation in plant biomass and soil in a Mediterranean shrubland 总被引:3,自引:0,他引:3
A field experiment involving drought and warming manipulation was conducted over a 6-year period in a Mediterranean shrubland
to simulate the climate conditions projected by IPCC models for the coming decades (20% decreased soil moisture and 1°C warming).
We investigated P and K concentration and accumulation in the leaves and stems of the dominant species, and in soil. Drought
decreased P concentration in Globularia alypum leaves (21%) and in Erica multiflora stems (30%) and decreased K concentration in the leaves of both species (20% and 29%, respectively). The general decrease
of P and K concentration in drought plots was due to the reduction of soil water content, soil and root phosphatase activity
and photosynthetic capacity that decreased plant uptake capacity. Warming increased P concentration in Erica multiflora leaves (42%), but decreased it in the stems and leaf litter of Erica multiflora and the leaf litter (33%) of Globularia alypum, thereby demonstrating that warming improved the P retranslocation and allocation from stem to leaves. These results correlate
with the increase in photosynthetic capacity and growth of these two dominant shrub species in warming plots. Drought and
warming had no significant effects on biomass P accumulation in the period 1999–2005, but drought increased K accumulation
in aboveground biomass (10 kg ha−1) in Globularia alypum due to the increase in K concentration in stems. The stoichiometric changes produced by the different responses of the nutrients
led to changes in the P/K concentration ratio in Erica multiflora leaves, stems and litter, and in Globularia alypum stems and litter. This may have implications for the nutritional value of these plant species and plant–herbivore relationships.
The effects of climate change on P and K concentrations and contents in Mediterranean ecosystems will differ depending on
whether the main component of change is drought or warming. 相似文献
6.
Seedlings of Bidens cernua L. emerged when mean air temperature was 17.0±1.3 °C. The highest net photosynthetic rate (P
N), 13.8±0.8 μmol(CO2) m−2 s−1, was monitored during the vegetative period (May–August), decreasing on an average by 50 % during flowering (August–September)
and during fruiting (September–November) phases. The senescence phase (October–November) was characterised by 79, 58, and
18 % decrease of P
N, chlorophyll content, and leaf area (LA), respectively, from the maximum values. The time span from seedling emergence to
the end of fruiting phase was 202 d. The total plant biomass was 1.58±0.05 g of which 81 % was aboveground plant portion.
The total dry mass relative growth rate averaged over the assimilation period was 0.0804±0.0002 kg kg−1 d−1, and it was correlated to both the net assimilation rate (NAR) and the leaf area ratio (LAR). 相似文献
7.
Andrew G. Peterson 《Oecologia》1999,118(2):144-150
The relationship between photosynthetic carbon assimilation (A
max) and leaf nitrogen content (N
leaf) can be expressed on either a leaf area basis (A
area vs N
area) or a leaf mass basis (A
mass vs N
mass). Dimensional analysis shows that the units for the slope of this relationship are the same for both expressions (μmol [CO2] g−1 [N] s−1). Thus the slope measures the change in CO2 assimilation per gram of nitrogen, independent of leaf mass or leaf area. Although they have the same units, large differences
between the area and mass-based slopes have been observed over a broad range of taxonomically diverse species. Some authors
have claimed that regardless of these differences, the fundamental nature of the A
max-N
leaf relationship is independent of the units of expression. In contrast, other authors have claimed that the area-based A
max-N
leaf relationship is fundamentally different from the mass-based relationship because of interactions between A
max, N
leaf, and leaf mass per area (LMA, g [leaf] m−2 [leaf]). In this study we consider the mathematical relationships involved in the transformation from mass- to area-based
expressions (and vice versa), and the implications this transformation has for the slope of the A
max-N
leaf relationship. We then show that the slope of the relationship is independent of the units of expression when the effect of
LMA is controlled statistically using a multiple regression. The validity of this hypothesis is demonstrated using 13 taxonomically
and functionally diverse C3 species. This analysis shows that the slope of the A
max-N
leaf relationship is similar for the mass- and area-based expressions and that significant errors in the estimate of the slope
can arise when the effect of LMA is not controlled.
Received: 7 May 1998 / Accepted: 19 October 1998 相似文献
8.
Differences in leaf traits among the dune species developing along the Latium coast were analysed. Cakile maritima Scop. subsp. maritima, Elymus farctus (Viv.) Runemark ex Melderis subsp. farctus, Ammophila arenaria (L.) Link subsp. australis (Mabille) Lainz, Ononis variegata L., Pancratium maritimum L., Eryngium maritimum L., and Anthemis maritima L. were considered. The considered species showed a similar net photosynthetic rate (P
N) and chlorophyll content (Chl) during the year, with a peak from the end of April to the middle of May [13.0±3.6 μmol (CO2) m−2 s−1 and 0.63±0.21 mg g−1, respectively, mean values of the considered species], favoured by air temperature in the range 13.3–17.5°C, and 6% of soil
water availability. In June–July, the increase of air temperature (Tmax = 28.4°C), associated with a lower water availability (42 mm, total rainfall of the period) and a 1% of soil water availability
determined a significant decrease of P
N (59%, mean of the considered species) and Chl (38%), and an increase of the carotenoid (Car)/Chl ratio (59%). The significant
correlation between P
N and stomatal conductance (g
s) (p<0.05) explained 67% of P
N variations. Moreover, the correlation between P
N and leaf temperature (T
l) underlined that the favourable T
l enabling 90–100% of the highest P
N for the considered species was within the range 23.4 to 26.6°C. P
N decreased below half of its maximum value when T
l was over 35.8 and 37.4°C for E. farctus subsp. farctus and A. arenaria subsp. australis, respectively and over 32.2°C for the other considered species (mean value). Leaf mass area (LMA) varied from 6.8 ± 0.7 mg
cm−2 (O. variegata) to 30.6 ± 1.6 mg cm−2 (A. arenaria). PCA (principal component analysis) carried out using the considered morphological and physiological leaf traits underlined
that the co-occurring species were characterised by different adaptive strategies: E. farctus and A. arenaria photosynthesized for a long period also when air temperature was over 35.8 and 37.4°C, respectively, because of their lower
transpiration rates [E, 1.4 ± 0.1 mmol (H2O) m−2 s−1], which seemed to be controlled by the highest LMA. On the contrary, A. maritima and C. maritima subsp. maritima had a higher P
N (on an average 52% higher than the others) in the favourable period, allowed by the highest succulence index (SI, 85.7 ±
9 mg cm−2) and the lower LMA. The results allowed us to hypothesize that A. arenaria and E. farctus might be at a competitive advantage relative to the other considered species with respect to the increase of air temperature,
by their ability to photosynthesize at sufficient rates also during summer. 相似文献
9.
Hidenobu Kunii 《Ecological Research》1988,3(3):305-318
In order to determine the seasonal growth and biomass ofTrapa japonica Flerov, field observations were carried out at Ojaga-ike Pond, Chiba, Japan, during 1979 and 1980. In spring, the plant showed
exponential growth (c. 0.080 g g−1 day−1) and shoot elongation was as rapid as 10 cm day−1. The plant attained its maximum biomass (380.5±35.1 g m−2) in late August, and about 50% of this was concentrated in the topmost 30-cm stratum (645.7±33.1 g m−3); maximum total stem length exceeded 6m. The plant produced large (500–800 mg per fruit), but small numbers of nut-like fruit
(maximum, 5 fruits per rosette). Defoliation occurred almost linearly with time at a rate of 30.6 leaves m−2 day−1; annual net leaf production was estimated to be about twice as large as the seasonal maximum leaf biomass. While the number
of leaves per rosette showed moderate seasonal change, rosette density, rosette area and leaf dry weight changed considerably
during the year. From the negative log-log correlation between mean total leaf dry weight per rosette and rosette density,
density-dependent rosette growth was assumed. The cause of the wide spread of this species in aquatic habitats is briefly
discussed in terms of its seed size and morphology. 相似文献
10.
The relationship between net photosynthetic (P
N) and leaf respiration (R) rates of Quercus ilex, Phillyrea latifolia, Myrtus communis, Arbutus unedo, and Cistus incanus was monitored in the period February 2006 to February 2007. The species investigated had low R and P
N during winter, increasing from March to May, when mean air temperature reached 19.2 °C. During the favourable period, C. incanus and A. unedo had a higher mean P
N (16.4±2.4 μmol m−2 s−1) than P. latifolia, Q. ilex, and M. communis (10.0±1.3 μmol m−2 s−1). The highest R (1.89±0.30 μmol m−2 s−1, mean of the species), associated to a significant P
N decrease (62 % of the maximum, mean value of the species), was measured in July (mean R/P
N ratio 0.447±0.091). Q10, indicating the respiration sensitivity to short-term temperature increase, was in the range 1.49 to 2.21. Global change
might modify R/P
N determining differences in dry matter accumulation among the species, and Q. ilex and P. latifolia might be the most favoured species by their ability to maintain sufficiently higher P
N and lower R during stress periods. 相似文献
11.
Many studies have shown that similarly aged plants within a species or population can vary markedly in the concentration of
defence compounds they deploy to protect themselves from herbivores. Some studies have also shown that the concentration of
these compounds can change with development, but no empirical research has mapped such an ontogenetic trajectory in detail.
To do this, we grew cyanogenic Eucalyptus yarraensis seedlings from three half-sibling families under constant glasshouse conditions, and followed their foliar cyanogenic glycoside
(prunasin) concentration over time for 338 days after sowing (DAS). Plants in all families followed a similar temporal pattern.
Plants increased in foliar prunasin concentration from a very low level (10 μg cyanide (CN) equivalents g−1) in their first leaves, to a maximum of, on average, 1.2 mg CN g−1 at about 240 DAS. From 240 to 338 DAS, prunasin concentration gradually decreased to around 0.7 mg CN g−1. Significant differences between families in maximum prunasin concentration were detected, but none were detected in the
time at which this maximum occurred. In parallel with these changes in prunasin concentration, we detected an approximately
linear increase in leaf mass per unit leaf area (LMA) with time, which reflected a change from juvenile to adult-like leaf
anatomy. When ontogenetic trajectories of prunasin against LMA were constructed, we failed to detect a significant difference
between families in the LMA at which maximum prunasin concentration occurred. This remarkable similarity in the temporal and
ontogenetic trajectories between individuals, even from geographically remote families, is discussed in relation to a theoretical
model for ontogenetic changes in plant defence. Our results show that ontogeny can constrain the expression of plant chemical
defense and that chemical defense changes in a nonlinear fashion with ontogeny. 相似文献
12.
M. A. Sobrado 《Trees - Structure and Function》2009,23(2):429-437
This study estimated the construction const (CC) and maintenance cost (MC) of leaf tissue on the basis of dry mass (CCMass, MCMass) and leaf area (CCArea, MCArea), as well as the maximum leaf gas exchange capacity, so as to examine leaf cost:benefit relationship in six dominant species
of the ‘Bana’ vegetation. Minimum and maximum CCMass averaged 1.71 ± 0.03 and 1.78 ± 0.03 g glucose g−1. The CCMass showed a statistically significant positive correlation with crude fibre, and tended to decline as leaves were larger. Thus,
smaller leaves tended to be built out of a more expensive material than that found in species bearing larger leaves. The average
CCArea of the ‘Bana’ species was 376 ± 15 g glucose m−2. A robust correlation was found between CCArea with leaf dry mass to leaf area ratio, as well as with leaf thickness, but not with leaf density. MCMass (g glucose g−1 day−1) and MCArea (g glucose m−2 day−1) were positively correlated. Maximum and minimum MCMass increased significantly with protein and lipid content, respectively. Maximum carbon assimilation (A
max) was positively correlated with CCArea. All the species operated at high stomatal conductance (g
s) and C
i/C
a which suggested low short-term water use efficiency. Potential nitrogen use efficiency (PNUE = A
max/N) averaged 35.4 ± 1.8 mmol CO2 mol−1 N. As the sclerophylly index (g crude fibre g−1 protein) increased, the ratio of CCArea to A
max increased significantly. This result suggests a trade-off between investments in an expensive resistant sclerophyllous leaf
which should maximize carbon gain in the long term. 相似文献
13.
Increase in isoprene and monoterpene emissions after re-watering of droughted Quercus ilex seedlings
We followed the diurnal cycles of isoprenoid emissions from Quercus ilex seedlings under drought and after re-watering. We found that Quercus ilex, generally considered a non-isoprene emitter, also emitted isoprene although at low rates. The emission rates of isoprene
reached 0.37 ± 0.02 nmol m−2 s−1 in controls, 0.15 ± 0.03 nmol m−2 s−1 under drought and 0.35 ± 0.04 nmol m−2 s−1 after re-watering, while emission rates of monoterpenes reached 11.0 ± 3.0, 7.0 ± 1.0 and 23.0 ± 5.0 nmol m−2 s−1, respectively. Emission rates recovered faster after re-watering than photosynthetic rate and followed diurnal changes in
irradiance in controls and under drought, but in leaf temperature after re-watering. 相似文献
14.
A broad regional understanding of tropical forest leaf photosynthesis has long been a goal for tropical forest ecologists,
but it has remained elusive due to difficult canopy access and high species diversity. Here we develop an empirical model
to predict sunlit, light-saturated, tropical leaf photosynthesis using leaf and simulated canopy spectra. To develop this
model, we used partial least squares (PLS) analysis on three tropical forest datasets (159 species), two in Hawaii and one
at the biosphere 2 laboratory (B2L). For each species, we measured light-saturated photosynthesis (A), light and CO2 saturated photosynthesis (A
max), respiration (R), leaf transmittance and reflectance spectra (400–2,500 nm), leaf nitrogen, chlorophyll a and b, carotenoids, and leaf mass per area (LMA). The model best predicted A [r
2
= 0.74, root mean square error (RMSE) = 2.9 μmol m−2 s−1)] followed by R (r
2
= 0.48), and A
max (r
2
= 0.47). We combined leaf reflectance and transmittance with a canopy radiative transfer model to simulate top-of-canopy
reflectance and found that canopy spectra are a better predictor of A (RMSE = 2.5 ± 0.07 μmol m−2 s−1) than are leaf spectra. The results indicate the potential for this technique to be used with high-fidelity imaging spectrometers
to remotely sense tropical forest canopy photosynthesis. 相似文献
15.
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
16.
Chengzhang Liao Yiqi Luo Lifen Jiang Xuhui Zhou Xiaowen Wu Changming Fang Jiakuan Chen Bo Li 《Ecosystems》2007,10(8):1351-1361
Whether plant invasion increases ecosystem carbon (C) stocks is controversial largely due to the lack of knowledge about differences
in ecophysiological properties between invasive and native species. We conducted a field experiment in which we measured ecophysiological
properties to explore the response of the ecosystem C stocks to the invasion of Spartina alterniflora (Spartina) in wetlands dominated by native Scirpus mariqueter (Scirpus) and Phragmites australis (Phragmites) in the Yangtze Estuary, China. We measured growing season length, leaf area index (LAI), net photosynthetic rate (Pn), root
biomass, net primary production (NPP), litter quality and litter decomposition, plant and soil C and nitrogen (N) stocks in
ecosystems dominated by the three species. Our results showed that Spartina had a longer growing season, higher LAI, higher Pn, and greater root biomass than Scirpus and Phragmites. Net primary production (NPP) was 2.16 kg C m−2 y−1 in Spartina ecosystems, which was, on average, 1.44 and 0.47 kg C m−2 y−1 greater than that in Scirpus and Phragmites ecosystems, respectively. The litter decomposition rate, particularly the belowground decomposition rate, was lower for Spartina than Scirpus and Phragmites due to the lower litter quality of Spartina. The ecosystem C stock (20.94 kg m−2) for Spartina was greater than that for Scirpus (17.07 kg m−2), Phragmites (19.51 kg m−2) and the mudflats (15.12 kg m−2). Additionally, Spartina ecosystems had a significantly greater N stock (698.8 g m−2) than Scirpus (597.1 g m−2), Phragmites ecosystems (578.2 g m−2) and the mudflats (375.1 g m−2). Our results suggest that Spartina invasion altered ecophysiological processes, resulted in changes in NPP and litter decomposition, and ultimately led to enhanced
ecosystem C and N stocks in the invaded ecosystems in comparison to the ecosystems with native species. 相似文献
17.
We compared variation in sun-canopy leaf anatomy, morphology and photosynthetic rates of coexisting woody species (trees and
lianas) in an 8-year-old secondary forest (SF) and mature forest (MF) in the wet season in Xishuangbanna, SW China. Variability
of leaf traits of 66 species within growth-form groups in each forest was quantified using coefficients of variation (CV).
For the mean values, the woody species in the SF had significantly higher leaf thickness and stomatal density, but lower nonmesophyll/mesophyll
ratios than those in the MF. The average leaf area and leaf mass area (LMA) in the studied woody species did not change greatly
during the successional process, but differed significantly between the growth forms, with trees having higher values than
lianas. The light-saturated photosynthetic rate per unit leaf area (A
a) of the woody species in the SF ranged from 11.2 to 34.5 μmol m−2 s−1, similarly to pioneer tree species from literature data in southeast Asia. The A
a and photosynthetic nitrogen-use efficiency (PNUE) were significantly higher than those in the MF; whereas A
a in the MF ranged between 9 to 21 μmol m−2 s−1, with similar values between lianas and trees. For all woody species in both SF and MF, there were no significant differences
in the average values of the CV of all measured variables for both lianas and trees. However, considerable variation in leaf
anatomy, morphology, and photosynthetic rates within both growth forms and forests existed, as well as substantial variation
in leaf size and stomatal density. We concluded that the tropical woody species formed a heterogeneous functional group in
terms of leaf morphology and physiology in both secondary and mature forests. 相似文献
18.
Recovery of Aboveground Plant Biomass and Productivity After Fire in Mesic and Dry Black Spruce Forests of Interior Alaska 总被引:1,自引:0,他引:1
Michelle C. Mack Kathleen K. Treseder Kristen L. Manies Jennifer W. Harden Edward A. G. Schuur Jason G. Vogel James T. Randerson F. Stuart Chapin III 《Ecosystems》2008,11(2):209-225
Plant biomass accumulation and productivity are important determinants of ecosystem carbon (C) balance during post-fire succession.
In boreal black spruce (Picea mariana) forests near Delta Junction, Alaska, we quantified aboveground plant biomass and net primary productivity (ANPP) for 4 years
after a 1999 wildfire in a well-drained (dry) site, and also across a dry and a moderately well-drained (mesic) chronosequence
of sites that varied in time since fire (2 to ∼116 years). Four years after fire, total biomass at the 1999 burn site had
increased exponentially to 160 ± 21 g m−2 (mean ± 1SE) and vascular ANPP had recovered to 138 ± 32 g m−2 y−1, which was not different than that of a nearby unburned stand (160 ± 48 g m−2 y−1) that had similar pre-fire stand structure and understory composition. Production in the young site was dominated by re-sprouting
graminoids, whereas production in the unburned site was dominated by black spruce. On the dry and mesic chronosequences, total
biomass pools, including overstory and understory vascular and non-vascular plants, and lichens, increased logarithmically
(dry) or linearly (mesic) with increasing site age, reaching a maximum of 2469 ± 180 (dry) and 4008 ± 233 g m−2 (mesic) in mature stands. Biomass differences were primarily due to higher tree density in the mesic sites because mass per
tree was similar between sites. ANPP of vascular and non-vascular plants increased linearly over time in the mesic chronosequence
to 335 ± 68 g m−2 y−1 in the mature site, but in the dry chronosequence it peaked at 410 ± 43 g m−2 y−1 in a 15-year-old stand dominated by deciduous trees and shrubs. Key factors regulating biomass accumulation and production
in these ecosystems appear to be the abundance and composition of re-sprouting species early in succession, the abundance
of deciduous trees and shrubs in intermediate aged stands, and the density of black spruce across all stand ages. A better
understanding of the controls over these factors will help predict how changes in climate and fire regime will affect the
carbon balance of Interior Alaska.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Daily sap flow rate as an indicator of drought avoidance mechanisms in five Mediterranean perennial species in semi-arid southeastern Spain 总被引:1,自引:0,他引:1
Daily sap flow rate was determined in five Mediterranean species (Pinus halepensis, Quercus coccifera,
Pistacia lentiscus, Erica multiflora, and Stipa tenacissima) under two slope aspects (north- and south-facing) in a semi-arid area (Alicante, SE Spain). Sap flow velocity was measured
in January, May, August and October of two consecutive years (1998 and 1999) using the stem heat balance (SHB) method. Our
results have demonstrated the effects of global radiation (R
g), vapour pressure deficit (VPD) on the sap flow velocity per unit of leaf area. Mean daily sap flow rates (Q
md) showed values between 0.001 and 0.202 g H2O cm−2 leaf area day−1. Q
md values were higher on the south-facing slope than on the north-facing slope. In most species, the Q
md was higher in 1998 than in 1999 due to the higher soil water content, temperature and VPD in 1998. In all five species, a
decrease in predawn leaf water potential was accompanied by a decrease in mean daily sap flow rates; nevertheless, the responses
of the five species to water deficit conditions were different. In this context, we have linked the drought avoidance mechanisms
of the different species through the combined use of daily sap flow rate and predawn leaf water potential under different
water deficit conditions. We conclude that Pinus halepensis, Pistacia lentiscus and Erica multiflora show water-savers mechanisms to cope with drought, while Quercus coccifera and Stipa tenacissima show water-spenders mechanisms. 相似文献
20.
The relationships between dark respiration rate (R
D) and net photosynthetic rate (P
N) in Quercus ilex L. shrubs growing at the Botanical Garden in Rome were analysed. Correlation analysis of the data sets collected in the year
2006 confirmed the dependence among the considered leaf traits, in particular, R
D was significantly (p<0.05) correlated with P
N (r = 0.40). R
D and P
N increased from March to May [1.40±0.10 and 10.1±1.8 μmol(CO2) m−2 s−1 mean values of the period, respectively], when air temperature was in the range 14.8–25.2 °C, underlining the highest metabolic
activity in the period of the maximum vegetative activity that favoured biomass accumulation. On the contrary, the highest
R
D [1.60±0.02 μmol(CO2) m−2 s−1], associated to the lowest P
N rates (44 % of the maximum) and carbon use efficiency (CUE) in July underlined the mobilization of stored material during
drought stress by a higher air temperature (32.7 °C). 相似文献