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1.
There are two important allocation hypotheses in plant biomass allocation: allometric and isometric. We tested these two hypotheses in an alpine steppe using plant biomass allocation under nitrogen (N) addition and precipitation (Precip) changes at a community level. An in situ field manipulation experiment was conducted to examine the two hypotheses and the responses of the biomass to N addition (10 g N m ?2 y ?1) and altered Precip (±50% precipitation) in an alpine steppe on the Qinghai–Tibetan Plateau from 2013 to 2016. We found that the plant community biomass differed in its response to N addition and reduced Precip such that N addition significantly increased aboveground biomass (AGB), while reduced Precip significantly decreased AGB from 2014 to 2016. Moreover, reduced Precip enhanced deep soil belowground biomass (BGB). In the natural alpine steppe, the allocation between AGB and BGB was consistent with the isometric hypotheses. In contrast, N addition or altered Precip enhanced biomass allocation to aboveground, thus leading to allometric growth. More importantly, reduced Precip enhanced biomass allocation into deep soil. Our study provides insight into the responses of alpine steppes to global climate change by linking AGB and BGB allocation. 相似文献
2.
- Mechanisms of shade tolerance in tree seedlings, and thus growth in shade, may differ by leaf habit and vary with ontogeny following seed germination. To examine early responses of seedlings to shade in relation to morphological, physiological and biomass allocation traits, we compared seedlings of 10 temperate species, varying in their leaf habit (broadleaved versus needle‐leaved) and observed tolerance to shade, when growing in two contrasting light treatments – open (about 20% of full sunlight) and shade (about 5% of full sunlight).
- We analyzed biomass allocation and its response to shade using allometric relationships. We also measured leaf gas exchange rates and leaf N in the two light treatments.
- Compared to the open treatment, shading significantly increased traits typically associated with high relative growth rate (RGR) – leaf area ratio (LAR), specific leaf area (SLA), and allocation of biomass into leaves, and reduced seedling mass and allocation to roots, and net assimilation rate (NAR). Interestingly, RGR was not affected by light treatment, likely because of morphological and physiological adjustments in shaded plants that offset reductions of in situ net assimilation of carbon in shade. Leaf area‐based rates of light‐saturated leaf gas exchange differed among species groups, but not between light treatments, as leaf N concentration increased in concert with increased SLA in shade.
- We found little evidence to support the hypothesis of a increased plasticity of broadleaved species compared to needle‐leaved conifers in response to shade. However, an expectation of higher plasticity in shade‐intolerant species than in shade‐tolerant ones, and in leaf and plant morphology than in biomass allocation was supported across species of contrasting leaf habit.
相似文献
3.
Water‐holding soil amendments such as super‐absorbent polymer (SAP) may improve native species establishment in restoration but may also interact with precipitation or invasive species such as Bromus tectorum L. (cheatgrass or downy brome) to influence revegetation outcomes. We implemented an experiment at two sites in Colorado, U.S.A., in which we investigated the interactions of drought (66% reduction of ambient rainfall), B. tectorum seed addition (BRTE, 465 seeds/m 2), and SAP soil amendment (25 g/m 2) on initial plant establishment and 3‐year aboveground and belowground biomass and allocation. At one site, SAP resulted in higher native seeded species establishment but only with ambient precipitation. However, by the third year, we detected no SAP effects on native seeded species biomass. Treatments interacted to influence aboveground and belowground biomass and allocation differently. At one site, a SAP × precipitation interaction resulted in lower belowground biomass in plots with SAP and drought (61.7 ± 7.3 g/m 2) than plots with drought alone (91.6 ± 18.1 g/m 2). At the other site, a SAP × BRTE interaction resulted in higher belowground biomass in plots with SAP and BRTE (56.6 ± 11.2 g/m 2) than BRTE alone (35.0 ± 3.7 g/m 2). These patterns were not reflected in aboveground biomass. SAP should be used with caution in aridland restoration because initial positive effects may not translate to long‐term benefits, SAP may uniquely influence aboveground versus belowground biomass, and SAP can interact with environmental variables to impact developing plant communities in positive and negative ways. 相似文献
4.
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(CO 2) 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
5.
One of the main drivers of tropical forest loss is their conversion to oil palm, soy or cacao plantations with low biodiversity and greatly reduced carbon storage. Southeast Asian cacao plantations are often established under shade tree cover, but are later converted to non-shaded monocultures to avoid resource competition. We compared three co-occurring cacao cultivation systems (3 replicate stands each) with different shade intensity (non-shaded monoculture, cacao with the legume Gliricidia sepium shade trees, and cacao with several shade tree species) in Sulawesi (Indonesia) with respect to above- and belowground biomass and productivity, and cacao bean yield. Total biomass C stocks (above- and belowground) increased fivefold from the monoculture to the multi-shade tree system (from 11 to 57 Mg ha -1), total net primary production rose twofold (from 9 to 18 Mg C ha -1 yr -1). This increase was associated with a 6fold increase in aboveground biomass, but only a 3.5fold increase in root biomass, indicating a clear shift in C allocation to aboveground tree organs with increasing shade for both cacao and shade trees. Despite a canopy cover increase from 50 to 93%, cacao bean yield remained invariant across the systems (variation: 1.1–1.2 Mg C ha -1 yr -1). The monocultures had a twice as rapid leaf turnover suggesting that shading reduces the exposure of cacao to atmospheric drought, probably resulting in greater leaf longevity. Thus, contrary to general belief, cacao bean yield does not necessarily decrease under shading which seems to reduce physical stress. If planned properly, cacao plantations under a shade tree cover allow combining high yield with benefits for carbon sequestration and storage, production system stability under stress, and higher levels of animal and plant diversity. 相似文献
6.
Plants in nutrient-poor environments typically have low foliar nitrogen (N) concentrations, long-lived tissues with leaf traits
designed to use nutrients efficiently, and low rates of photosynthesis. We postulated that increasing N availability due to
atmospheric deposition would increase photosynthetic capacity, foliar N, and specific leaf area (SLA) of bog shrubs. We measured
photosynthesis, foliar chemistry and leaf morphology in three ericaceous shrubs ( Vaccinium myrtilloides, Ledum groenlandicum and Chamaedaphne calyculata) in a long-term fertilization experiment at Mer Bleue bog, Ontario, Canada, with a background deposition of 0.8 g N m −2 a −1. While biomass and chlorophyll concentrations increased in the highest nutrient treatment for C. calyculata, we found no change in the rates of light-saturated photosynthesis ( A
max), carboxylation ( V
cmax) , or SLA with nutrient (N with and without PK) addition, with the exception of a weak positive correlation between foliar N
and A
max for C. calyculata, and higher V
cmax in L. groenlandicum with low nutrient addition. We found negative correlations between photosynthetic N use efficiency (PNUE) and foliar N, accompanied
by a species-specific increase in one or more amino acids, which may be a sign of excess N availability and/or a mechanism
to reduce ammonium (NH 4) toxicity. We also observed a decrease in foliar soluble Ca and Mg concentrations, essential minerals for plant growth, but
no change in polyamines, indicators of physiological stress under conditions of high N accumulation. These results suggest
that plants adapted to low-nutrient environments do not shift their resource allocation to photosynthetic processes, even
after reaching N sufficiency, but instead store the excess N in organic compounds for future use. In the long term, bog species
may not be able to take advantage of elevated nutrients, resulting in them being replaced by species that are better adapted
to a higher nutrient environment. 相似文献
7.
Carbon storage in aboveground tree biomass and soil organic matter (in depth of A layer development i.e., up to 20 cm) was
studied in 22–32 year-old post-mining sites in the northwest of the Czech Republic. Four replicated sites afforested with
different tree species (spruce, pine, larch, oak, lime or alder) were compared with sites left to natural regeneration which
were dominated by aspen, birch and willow. No topsoil was applied at the sites; hence carbon accumulation resulted from in
situ soil development on alkaline tertiary clays that were dumped on the heaps. In aboveground tree biomass, carbon storage
ranged from 17.0 ± 5.9 (mean ± SEM) to 67.6 ± 5.9 t ha −1 and the rate of C accumulation increased from 0.60 ± 0.09 to 2.31 ± 0.23 t ha −1 year −1 (natural regeneration < pine < spruce < oak < lime < alder < larch). Carbon storage in soil organic matter varied from 4.5 ± 3.7
to 38.0 ± 7.1 t ha −1 and the rate of C accumulation in soil organic matter increased from 0.15 ± 0.05 to 1.28 ± 0.34 t ha −1 year −1 at sites in the order: natural regeneration < spruce < pine, oak < larch < alder < lime. Carbon storage in the soil was positively
correlated with aboveground tree biomass. Soil carbon was equivalent to 98.1% of the carbon found in aboveground tree biomass
at lime dominated sites, but only 21.8% at sites with natural regeneration. No significant correlation was found between C
storage in soil and aboveground litter input. Total soil carbon storage was correlated positively and significantly with earthworm
density, and occurrence of earthworm cast in topsoil, which indicated that bioturbation could play an important role in soil
carbon storage. Hence, not only restoring of wood production, but also restoring of soil community is critical for C storage
in soil and whole ecosystem. 相似文献
8.
基于2006—2015年青海海北站10年生物量及气候因子监测数据,分析了青藏高原高寒矮嵩草草甸生物量的季节及年际动态,并探讨了气候因子对其影响。结果表明:(1)季节尺度上,高寒矮嵩草草甸地上生物量表现为单峰变化曲线,8月为其峰值点,为(345.72±27.01) g/m~2,代表了高寒草甸的地上净初级生产力。而地下根系的现存量变化较为复杂,其中5—7月呈现持续上升趋势,8月快速下降,之后9月份急剧,且各月份之间未达到显著水平(P0.05);年际尺度上,10年间高寒矮嵩草草甸地上生物量整体呈现波动增加趋势,2014年为其峰值点,达(437.12±32.01) g/m~2。地下生物量呈现波动性变化,变异较大,10年间平均值为(2566.99±138.11) g/m~2;(2)高寒草甸光合产物分配主要分布在地下,80%地下根系生物量分布于地表0—10 cm土层,且不同土层根系生物量占总地下生物量的比值在不同月份较为稳定。(3)气候因子中,大气相对湿度是影响高寒草甸地上生物量大小的主要因素;而气候因子对地下根系生物量的影响极为微弱。研究表明,高寒嵩草草甸对环境变化具有较高的自我调节能力,且高寒草甸的演化受制于人类干扰,而非气候变化。 相似文献
9.
The chromium (Cr III and Cr VI) removal capability of Rhizobium leguminosarum was checked by estimating the amount of chromium in the medium before and after inoculation. To determine the efficiency
of R. leguminosarum in removal of chromium, the influence of physical and chemical parameters such as temperature, pH and different concentrations
(0.1–1.0 mM) of trivalent (Cr III) and hexavalent (Cr VI) chromium were studied. The chromium removal in aqueous solution by different size of active and inactivated biomass and
immobilized cells of R. leguminosarum in a packed-bed column was also carried out. Results showed that in a medium containing up to 0.5 mM concentration of both
Cr III and Cr VI, R. leguminosarum showed optimal growth. The maximum chromium removal was at pH 7.0 and 35°C. Active biomass removed 84.4 ± 3.6% of Cr III and 77.3 ± 4.3% of Cr VI in 24 h of incubation time. However, inactivated biomass removed maximum chromium after 36 h of incubation. Immobilized bacterial
cells in a packed-bed column removed 86.4 ± 1.7% of Cr III and 83.8 ± 2.2% of Cr VI in 16 and 20 h of incubation time, respectively. 相似文献
10.
Quantifying plant carbon (C) allocation among different pools is critical for understanding and predicting how C turnover responds to global climate change in terrestrial ecosystems. A field experiment with increasing warming and nitrogen (N) was established to investigate interactive effects on plant C allocation in alpine meadows. Open-top chambers (OTCs) were used to simulate warming. In OTCs, daytime air and soil temperature at 5 cm depth increased by 2.0 and 1.6 °C, respectively, compared with ambient conditions, but soil moisture at 5 cm depth decreased by 4.95% (v/v) from 2012 to 2014. Warming reduced aboveground biomass by 38, 36, and 43% in 2012, 2013, and 2014, respectively, and increased belowground biomass by 64% and 29% in 2013 and 2014, respectively, and the root-to-shoot ratio was significantly increased. Specifically, warming increased the proportion of plant roots in the deep layers (10–20 cm). Both N addition and its combination with warming substantially enhanced belowground biomass. Pulse-labeling experiments for 13C revealed that warming reduced the translocation of assimilated C to shoots by 8.8% (38.7% in warming, and 47.5% in the control [CK]), and increased the allocation to root by 12.2% (55.5% in warming, and 43.3% in CK) after 28 days labeling. However, N addition increased the proportion of assimilated C allocated to shoots by 6.5% (54.0% in N addition, and 47.5% in CK), whereas warming combined with N addition reduced this proportion by 10.9%. A decline in soil water content in the surface layer may be the main cause of plants allocating more newly fixed photosynthate to roots. Therefore, plants promoted root growth to draw water from deeper soil layers (10–20 cm). We concluded that climate warming will change the allocation patterns of plant photosynthates by affecting soil water availability, whereas N addition will increase plant photosynthates aboveground in alpine meadows and thus will significantly affect C turnover under future climate change scenarios. 相似文献
11.
Sugar beet cv. Rizor was grown for five growing seasons (2002–2006) in field conditions in Thessaly, central Greece. A total
of 55 samplings took place during the growing seasons and allometric growth of the leaves was monitored. Highly significant
( p<0.001) quadratic relationships were found between individual leaf mass (LM), individual leaf area (LA), aboveground dry biomass
(ADB), and leaf area index (LAI). Only the LM-LA relationship (LA = 43.444 LM 2 − 10.693 LM + 118.34) showed a relatively high r
2 (0.63) and thus could be used for prediction of LA. Specific leaf area (SLA) was significantly related with leaf water content
(LWC) (SLA = 26 279 LWC 2 − 44 498 LWC + 18 951, r
2 = 0.91, p<0.001) and thus LWC could be a good indirect predictor of SLA in this cultivar. 相似文献
12.
A total of 244 plants from two species, Lythrum salicaria and Epilobium glandulosum, were grown individually in hydroponic sand culture from seed for 36 d. Until day 27 all plants experienced an irradiance of 550 μmol m ?2 s ?1 PFD and on day 27 half of the plants were subjected to a neutral shade treatment in which irradiance was reduced to 100 μmol m ?2 s ?1 photon fluy density (PFD). Measures of relative growth rate, net assimilation rate, specific leaf area, biomass partitioning to leaves, roots, structural tissues (i.e. stems, petioles and inflorescences) and tissue density were obtained from intensive harvests three or four times per day. The shade treatment caused an immediate decrease in relative growth rate and net assimilation rate. Within hours the specific leaf area of the shaded plants increased and leaf tissue density decreased, thus partially offsetting the decrease in relative growth rate. Biomass partitioning was not affected. 相似文献
13.
Grazing is an important modulator of both plant productivity and biodiversity in grassland community, yet how to determine a suitable grazing intensity in alpine grassland is still controversy. Here, we explore the effects of different grazing intensities on plant biomass and species composition, both at community level and functional group level, and examines the productivity–species richness relationship under four grazing patterns: no grazing (CK), light grazing (LG), moderate grazing, (MG) and heavy grazing (HG), attempt to determine a suitable grazing intensity in alpine grassland. The results were as follows. The total aboveground biomass (AGB) reduced with increasing grazing intensity, and the response of plant functional groups was different. AGB of both sedges and legumes increased from MG to HG, while the AGB of forbs reduced sharply and the grass AGB remained steady. There was a significant positive relationship between productivity and species richness both at community level and functional group level. In contrast, the belowground biomass (BGB) showed a unimodal relationship from CK to HG, peaking in MG (8,297.72 ± 621.29 g/m 2). Interestingly, the grassland community tends to allocate more root biomass to the upper soil layer under increasing grazing intensities. Our results suggesting that moderate levels of disturbance may be the optimal grassland management strategy for alpine meadow in terms of root production. 相似文献
14.
选取南方重要的造林树种杉木(Cunninghamia lanceolata(Lamb.)Hook)幼苗为研究对象,通过搭建遮荫棚设置5个光照强度(分别为自然光照的100%、60%、40%、15%和5%),研究了幼苗在不同光照强度下的生长形态、生物量积累及分配、叶片的非结构性碳含量(NSC)特征。结果显示:(1)叶长、叶宽和叶面积在40%光照强度下最大,而比叶面积和叶片相对含水量随着光照强度的降低呈递增趋势;(2)随着光照强度的降低,杉木幼苗各器官生物量下降,根生物量比和根冠比降低,茎和叶生物量比增加;(3)杉木幼苗在60%光照强度下叶片非结构性碳含量最高,5%光照强度下含量最低;(4)杉木幼苗比叶面积与叶生物量以及与非结构性碳含量之间存在极显著的负相关关系(P0.01),叶生物量与非结构性碳含量之间存在极显著的正相关关系(P0.01)。杉木幼苗能够通过形态学上的可塑性来适应不同的光强环境,提高光竞争能力和生存适合度,但在5%光照强度下,由于较难维持碳收支平衡而不利于其生长和存活。 相似文献
15.
植物叶功能性状是连接植物与外界环境的重要桥梁,是探索植物适应环境、进行全球气候变化研究的指标,也是生态水文模型重要的输入参数。通过高时间分辨率样品的采集结合图像处理技术,对祁连山中部优势物种金露梅(Dasiphora fruticosa)和鬼箭锦鸡儿(Caragana jubata)叶功能性状变化特征进行研究,结果表明:叶面积(LA)从生长初期到生长末期发生明显变化,且2020年6—7月初灌木叶面积变化最为明显;比叶面积(SLA)分别在76—157 cm 2/g之间和120—217 cm 2/g之间,金露梅SLA平均值(123 cm 2/g)<鬼箭锦锦鸡儿SLA平均值(176 cm 2/g);在生长初期金露梅的叶面积指数(LAI)明显大于鬼箭锦鸡儿,金露梅和鬼箭锦鸡儿的叶面积指数随时间的变化都符合三次函数;生物量与基径和高度的乘积呈显著性相关,最优回归模型均为幂函数;地上生物量与叶功能性状参数在不同阶段的模拟方程均不同,地上总生物量与叶生物量在生长期的最优选择模型分别呈S型函数和幂函数,金露梅的单株地... 相似文献
16.
Wood density (WD) is not only an important parameter to estimate aboveground biomass but also an indicator of timber quality and plant adaptation strategies to stressful conditions (i.e., windthrow, pests, and pathogens). This study had three objectives: (1) to compare WD among seven subtropical tree species; (2) to determine how tree growth traits may influence possible differences in WD between the pioneer and shade‐tolerant species; and (3) to examine whether or not WD differs by tree social status (dominant vs. suppressed trees) within species. To do this, 70 trees were destructively harvested. From each tree, disks at different stem heights were obtained and subjected to a method of stem analysis to measure whole tree level WD. The results showed that WD differed significantly among the seven species ( p < .001). Their average WD was 0.537 g/cm 3, ranging from 0.409 g/cm 3 for Choerospondias axillaris to 0.691 g/cm 3 for Cyclobalanopsis glauca. The average WD of the four pioneer species (0.497 ± 0.13 g/cm 3) was significantly lower ( p < .01) than that of the three shade‐tolerant species (0.589 ± 0.12 g/cm 3). The WD of the pioneers had a significant positive correlation with their stem diameter at breast height (DBH), tree height ( H), and tree age, but WD had a significant negative correlation with relative growth rate (RGR). In contrast, the WD of the shade‐tolerant tree species had no significant relationships with DBH, H, tree age, or RGR. The dominant trees of the pioneer species had a higher WD than the suppressed trees, whereas the shade‐tolerant species had a lower WD for dominant trees than the suppressed trees. However, the differences in WD between dominant and suppressed trees were not significant. Taken together, the results suggest that classifying species into pioneer and shade‐tolerant groups to examine the effects of tree growth traits and social status could improve our understanding of intra‐ and interspecific variation in WD among subtropical tree species. 相似文献
17.
Studies on the relationship between soil fertility and aboveground biomass in lowland tropical forests have yielded conflicting
results, reporting positive, negative and no effect of soil nutrients on aboveground biomass. Here, we quantify the impact
of soil variation on the stand structure of mature Bornean forest throughout a lowland watershed (8–196 m a.s.l.) with uniform
climate and heterogeneous soils. Categorical and bivariate methods were used to quantify the effects of (1) parent material
differing in nutrient content (alluvium > sedimentary > granite) and (2) 27 soil parameters on tree density, size distribution,
basal area and aboveground biomass. Trees ≥10 cm (diameter at breast height, dbh) were enumerated in 30 (0.16 ha) plots (sample
area = 4.8 ha). Six soil samples (0–20 cm) per plot were analyzed for physiochemical properties. Aboveground biomass was estimated
using allometric equations. Across all plots, stem density averaged 521 ± 13 stems ha −1, basal area 39.6 ± 1.4 m 2 ha −1 and aboveground biomass 518 ± 28 Mg ha −1 (mean ± SE). Adjusted forest-wide aboveground biomass to account for apparent overestimation of large tree density (based
on 69 0.3-ha transects; sample area = 20.7 ha) was 430 ± 25 Mg ha −1. Stand structure did not vary significantly among substrates, but it did show a clear trend toward larger stature on nutrient-rich
alluvium, with a higher density and larger maximum size of emergent trees. Across all plots, surface soil phosphorus (P),
potassium, magnesium and percentage sand content were significantly related to stem density and/or aboveground biomass ( R
Pearson = 0.368–0.416). In multiple linear regression, extractable P and percentage sand combined explained 31% of the aboveground
biomass variance. Regression analyses on size classes showed that the abundance of emergent trees >120 cm dbh was positively
related to soil P and exchangeable bases, whereas trees 60–90 cm dbh were negatively related to these factors. Soil fertility
thus had a significant effect on both total aboveground biomass and its distribution among size classes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
Increased drought severity is expected in the Mediterranean Basin over the twenty-first century, but our understanding of
the potential of most forest tree species to cope with it remains uncertain. In this study, (1) we examined the potential
effects of long-term selection and the capacity to respond to future changes in selective pressures in three populations of
cork oak ( Quercus suber L.). For this purpose, we evaluated the response to dry conditions of 45 open-pollinated trees originating from populations
in Morocco, Portugal, and Spain. Growth, leaf size, specific leaf area (SLA), carbon isotope discrimination (Δ 13C), leaf nitrogen content (N mass), and total chlorophyll content (Chl mass) were measured in 9-year-old plants. (2) We also investigated the relationships between functional traits and aboveground
growth by regression models. Plants presenting larger and more sclerophyllous leaves (low SLA and high leaf thickness) exhibited
higher growths, with results suggesting that these traits are subjected to divergent selection in this species. Heritability
estimates were moderately high for Δ 13C (0.43 ± 0.25–0.83 ± 0.31) and stem diameter (0.40 ± 0.15–0.71 ± 0.28) for the tree populations. For the rest of the traits
(except for annual growth), heritability values varied among populations, particularly for height, leaf size, leaf thickness,
and N mass. Our results suggest that natural selection has led to local adaptations and has also affected the genetic variance intrapopulation
in these cork oak populations, although studies with a higher number of populations should be carried out across different
years. Additionally, the absence of significant genetic correlations and the fact that correlated traits did not undergo opposing
selection provided little evidence for constraints on evolution caused by genetic correlations. 相似文献
19.
- Domestication might affect plant size. We investigated whether herbaceous crops are larger than their wild progenitors, and the traits that influence size variation.
- We grew six crop plants and their wild progenitors under common garden conditions. We measured the aboveground biomass gain by individual plants during the vegetative stage. We then tested whether photosynthesis rate, biomass allocation to leaves, leaf size and specific leaf area (SLA) accounted for variations in whole‐plant photosynthesis, and ultimately in aboveground biomass.
- Despite variations among crops, domestication generally increased the aboveground biomass (average effect +1.38, Cohen's d effect size). Domesticated plants invested less in leaves and more in stems than their wild progenitors. Photosynthesis rates remained similar after domestication. Variations in whole‐plant C gains could not be explained by changes in leaf photosynthesis. Leaves were larger after domestication, which provided the main contribution to increases in leaf area per plant and plant‐level C gain, and ultimately to larger aboveground biomass.
- In general, cultivated plants have become larger since domestication. In our six crops, this occurred despite lower investment in leaves, comparable leaf‐level photosynthesis and similar biomass costs of leaf area (i.e. SLA) than their wild progenitors. Increased leaf size was the main driver of increases in aboveground size. Thus, we suggest that large seeds, which are also typical of crops, might produce individuals with larger organs (i.e. leaves) via cascading effects throughout ontogeny. Larger leaves would then scale into larger whole plants, which might partly explain the increases in size that accompanied domestication.
相似文献
20.
Tropospheric O 3 and deposition of reactive N threaten the composition and function of natural and semi-natural vegetation even in remote
regions. However, little is known about effects of these pollutants individually or in combination on plant species in alpine
habitats. We analyzed 11 frequent plant species of a subalpine Geo-Montani-Nardetum pasture exposed at 2,000 m a.s.l. in the Swiss Alps during 3 years using a factorial free-air exposure system with three
concentrations of O 3 and five rates of N application. The aim was to detect subtle effects on leaf chlorophyll and N concentrations, leaf weight,
specific leaf area (SLA), and δ 18O and δ 13C as proxies for gas exchange. We expected that the species’ responsiveness to O 3 and N would be related to their functional traits and that N-induced changes in these traits would modify the species’ response
to O 3 via increased growth and higher leaf conductance ( g
s). Most species reacted to N supply with the accumulation of N and chlorophyll, but with no change in SLA, g
s, and growth, except Carex sempervirens which showed increased water use efficiency and leaf weight. Elevated O 3 reduced g
s
in most species, but this was not related to a reduction in leaf weight, which was recorded in half of the species . Contrary to our expectation, the magnitude of the response to both O 3 and N was not related to species-specific traits such as SLA or g
s. No pronounced O 3 × N interactions were observed. In conclusion, since for most species neither N nor gas exchange limited growth, their short-term
response to O 3 and N and to their combination was small. O 3 × N interactive effects are expected to be more pronounced in habitats where species are more responsive to N due to favorable
growth conditions in terms of nutrient availability and temperature.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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