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1.
Christoph Scherber David J. Gladbach Karen Stevnbak Rune Juelsborg Karsten Inger Kappel Schmidt Anders Michelsen Kristian Rost Albert Klaus Steenberg Larsen Teis Nørgaard Mikkelsen Claus Beier Søren Christensen 《Ecology and evolution》2013,3(6):1449-1460
The impact of climate change on herbivorous insects can have far‐reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO2, warming, drought) in a Danish heathland ecosystem. The experiment was established in 2005 as a full factorial split‐plot with 6 blocks × 2 levels of CO2 × 2 levels of warming × 2 levels of drought = 48 plots. In 2008, we exposed 432 larvae (n = 9 per plot) of the heather beetle (Lochmaea suturalis Thomson ), an important herbivore on heather, to ambient versus elevated drought, temperature, and CO2 (plus all combinations) for 5 weeks. Larval weight and survival were highest under ambient conditions and decreased significantly with the number of climate change drivers. Weight was lowest under the drought treatment, and there was a three‐way interaction between time, CO2, and drought. Survival was lowest when drought, warming, and elevated CO2 were combined. Effects of climate change drivers depended on other co‐acting factors and were mediated by changes in plant secondary compounds, nitrogen, and water content. Overall, drought was the most important factor for this insect herbivore. Our study shows that weight and survival of insect herbivores may decline under future climate. The complexity of insect herbivore responses increases with the number of combined climate change drivers. 相似文献
2.
Biotic interactions influence the projected distribution of a specialist mammal under climate change
Brooke L. Bateman Jeremy VanDerWal Stephen E. Williams Christopher N. Johnson 《Diversity & distributions》2012,18(9):861-872
Aim
To measure the effects of including biotic interactions on climate‐based species distribution models (SDMs) used to predict distribution shifts under climate change. We evaluated the performance of distribution models for an endangered marsupial, the northern bettong (Bettongia tropica), comparing models that used only climate variables with models that also took into account biotic interactions.Location
North‐east Queensland, Australia.Methods
We developed separate climate‐based distribution models for the northern bettong, its two main resources and a competitor species. We then constructed models for the northern bettong by including climate suitability estimates for the resources and competitor as additional predictor variables to make climate + resource and climate + resource + competition models. We projected these models onto seven future climate scenarios and compared predictions of northern bettong distribution made by these differently structured models, using a ‘global’ metric, the I similarity statistic, to measure overlap in distribution and a ‘local’ metric to identify where predictions differed significantly.Results
Inclusion of food resource biotic interactions improved model performance. Over moderate climate changes, up to 3.0 °C of warming, the climate‐only model for the northern bettong gave similar predictions of distribution to the more complex models including interactions, with differences only at the margins of predicted distributions. For climate changes beyond 3.0 °C, model predictions diverged significantly. The interactive model predicted less contraction of distribution than the simpler climate‐only model.Main conclusions
Distribution models that account for interactions with other species, in particular direct resources, improve model predictions in the present‐day climate. For larger climate changes, shifts in distribution of interacting species cause predictions of interactive models to diverge from climate‐only models. Incorporating interactions with other species in SDMs may be needed for long‐term prediction of changes in distribution of species under climate change, particularly for specialized species strongly dependent on a small number of biotic interactions. 相似文献3.
Guillermo Gea‐Izquierdo Antoine Nicault Giovanna Battipaglia Isabel Dorado‐Liñán Emilia Gutiérrez Montserrat Ribas Joel Guiot 《Global Change Biology》2017,23(7):2915-2927
Forest performance is challenged by climate change but higher atmospheric [CO2] (ca) could help trees mitigate the negative effect of enhanced water stress. Forest projections using data assimilation with mechanistic models are a valuable tool to assess forest performance. Firstly, we used dendrochronological data from 12 Mediterranean tree species (six conifers and six broadleaves) to calibrate a process‐based vegetation model at 77 sites. Secondly, we conducted simulations of gross primary production (GPP) and radial growth using an ensemble of climate projections for the period 2010–2100 for the high‐emission RCP8.5 and low‐emission RCP2.6 scenarios. GPP and growth projections were simulated using climatic data from the two RCPs combined with (i) expected ca; (ii) constant ca = 390 ppm, to test a purely climate‐driven performance excluding compensation from carbon fertilization. The model accurately mimicked the growth trends since the 1950s when, despite increasing ca, enhanced evaporative demands precluded a global net positive effect on growth. Modeled annual growth and GPP showed similar long‐term trends. Under RCP2.6 (i.e., temperatures below +2 °C with respect to preindustrial values), the forests showed resistance to future climate (as expressed by non‐negative trends in growth and GPP) except for some coniferous sites. Using exponentially growing ca and climate as from RCP8.5, carbon fertilization overrode the negative effect of the highly constraining climatic conditions under that scenario. This effect was particularly evident above 500 ppm (which is already over +2 °C), which seems unrealistic and likely reflects model miss‐performance at high ca above the calibration range. Thus, forest projections under RCP8.5 preventing carbon fertilization displayed very negative forest performance at the regional scale. This suggests that most of western Mediterranean forests would successfully acclimate to the coldest climate change scenario but be vulnerable to a climate warmer than +2 °C unless the trees developed an exaggerated fertilization response to [CO2]. 相似文献
4.
Canopy leaf area of a mature evergreen Eucalyptus woodland does not respond to elevated atmospheric [CO2] but tracks water availability
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Remko A. Duursma Teresa E. Gimeno Matthias M. Boer Kristine Y. Crous Mark G. Tjoelker David S. Ellsworth 《Global Change Biology》2016,22(4):1666-1676
Canopy leaf area, quantified by the leaf area index (L), is a crucial driver of forest productivity, water use and energy balance. Because L responds to environmental drivers, it can represent an important feedback to climate change, but its responses to rising atmospheric [CO2] and water availability of forests have been poorly quantified. We studied canopy leaf area dynamics for 28 months in a native evergreen Eucalyptus woodland exposed to free‐air CO2 enrichment (the EucFACE experiment), in a subtropical climate where water limitation is common. We hypothesized that, because of expected stimulation of productivity and water‐use efficiency, L should increase with elevated [CO2]. We estimated L from diffuse canopy transmittance, and measured monthly leaf litter production. Contrary to expectation, L did not respond to elevated [CO2]. We found that L varied between 1.10 and 2.20 across the study period. The dynamics of L showed a quick increase after heavy rainfall and a steady decrease during periods of low rainfall. Leaf litter production was correlated to changes in L, both during periods of decreasing L (when no leaf growth occurred) and during periods of increasing L (active shedding of old foliage when new leaf growth occurred). Leaf lifespan, estimated from mean L and total annual litter production, was up to 2 months longer under elevated [CO2] (1.18 vs. 1.01 years; P = 0.05). Our main finding that L was not responsive to elevated CO2 is consistent with other forest FACE studies, but contrasts with the positive response of L commonly predicted by many ecosystem models. 相似文献
5.
The interannual net primary production variation and trends of a Picea schrenkiana forest were investigated in the context of historical changes in climate and increased atmospheric CO2 concentration at four sites in the Tianshan Mountain range, China. Historical changes in climate and atmospheric CO2 concentration were used as Biome–BGC model drivers to evaluate the spatial patterns and temporal trends of net primary production
(NPP). The temporal dynamics of NPP of P. schrenkiana forests were different in the western, middle and eastern sites of Tianshan, which showed substantial interannual variation.
Climate changes would result in increased NPP at all study sites, but only the change in NPP in the western forest (3.186 gC m−2 year−1, P < 0.05) was statistically significant. Our study also showed a higher increase in the air temperature, precipitation and
NPP during 1987–2000 than 1961–1986. Statistical analysis indicates that changes in NPP are positively correlated with annual
precipitation (R = 0.77–0.92) but that NPP was less sensitive to changes in air temperature. According to the simulation, increases in atmospheric
CO2 increased NPP by improving the water use efficiency. The results of this study show that the Tianshan Mount boreal forest
ecosystem is sensitive to historical changes in climate and increasing atmospheric CO2. The relative impacts of these variations on NPP interact in complex ways and are spatially variable, depending on local
conditions and climate gradients.
W. Sang and H. Su contributed equally to this paper, arranged in alphabetical order by surnames. 相似文献
6.
Kristine Y. Crous Audrey G. Quentin Yan‐Shih Lin Belinda E. Medlyn David G. Williams Craig V. M. Barton David S. Ellsworth 《Global Change Biology》2013,19(12):3790-3807
Eucalyptus species are grown widely outside of their native ranges in plantations on all vegetated continents of the world. We predicted that such a plantation species would show high potential for acclimation of photosynthetic traits across a wide range of growth conditions, including elevated [CO2] and climate warming. To test this prediction, we planted temperate Eucalyptus globulus Labill. seedlings in climate‐controlled chambers in the field located >700 km closer to the equator than the nearest natural occurrence of this species. Trees were grown in a complete factorial combination of elevated CO2 concentration (eC; ambient [CO2] +240 ppm) and air warming treatments (eT; ambient +3 °C) for 15 months until they reached ca. 10 m height. There was little acclimation of photosynthetic capacity to eC and hence the CO2‐induced photosynthetic enhancement was large (ca. 50%) in this treatment during summer. The warming treatment significantly increased rates of both carboxylation capacity (Vcmax) and electron transport (Jmax) (measured at a common temperature of 25 °C) during winter, but decreased them significantly by 20–30% in summer. The photosynthetic CO2 compensation point in the absence of dark respiration (Γ*) was relatively less sensitive to temperature in this temperate eucalypt species than for warm‐season tobacco. The temperature optima for photosynthesis and Jmax significantly changed by about 6 °C between winter and summer, but without further adjustment from early to late summer. These results suggest that there is an upper limit for the photosynthetic capacity of E. globulus ssp. globulus outside its native range to acclimate to growth temperatures above 25 °C. Limitations to temperature acclimation of photosynthesis in summer may be one factor that defines climate zones where E. globulus plantation productivity can be sustained under anticipated global environmental change. 相似文献
7.
Tracy E. Twine Jarod J. Bryant Katherine T. Richter Carl J. Bernacchi Kelly D. McConnaughay Sherri J. Morris Andrew D. B. Leakey 《Global Change Biology》2013,19(9):2838-2852
The physiological response of vegetation to increasing atmospheric carbon dioxide concentration ([CO2]) modifies productivity and surface energy and water fluxes. Quantifying this response is required for assessments of future climate change. Many global climate models account for this response; however, significant uncertainty remains in model simulations of this vegetation response and its impacts. Data from in situ field experiments provide evidence that previous modeling studies may have overestimated the increase in productivity at elevated [CO2], and the impact on large‐scale water cycling is largely unknown. We parameterized the Agro‐IBIS dynamic global vegetation model with observations from the SoyFACE experiment to simulate the response of soybean and maize to an increase in [CO2] from 375 ppm to 550 ppm. The two key model parameters that were found to vary with [CO2] were the maximum carboxylation rate of photosynthesis and specific leaf area. Tests of the model that used SoyFACE parameter values showed a good fit to site‐level data for all variables except latent heat flux over soybean and sensible heat flux over both crops. Simulations driven with historic climate data over the central USA showed that increased [CO2] resulted in decreased latent heat flux and increased sensible heat flux from both crops when averaged over 30 years. Thirty‐year average soybean yield increased everywhere (ca. 10%); however, there was no increase in maize yield except during dry years. Without accounting for CO2 effects on the maximum carboxylation rate of photosynthesis and specific leaf area, soybean simulations at 550 ppm overestimated leaf area and yield. Our results highlight important model parameter values that, if not modified in other models, could result in biases when projecting future crop–climate–water relationships. 相似文献
8.
Stable carbon isotopes in tree rings indicate improved water use efficiency and drought responses of a tropical dry forest tree species 总被引:1,自引:0,他引:1
Understanding the responses of tropical trees to increasing [CO2] and climate change is important as tropical forests play an important role in carbon and hydrological cycles. We used stable
carbon isotopes (δ13C) in tree rings to study the physiological responses of a tropical dry forest tree species in southern Mexico, Mimosa acantholoba to changes in atmospheric [CO2] and variation in climate. Based on annual records of tree ring δ13C, we calculated intrinsic water use efficiency (W
i) and intercellular [CO2] (c
i). Our results showed that trees responded strongly to the increase in atmospheric [CO2] over the last four decades; W
i increased dramatically by 40%, while c
i remained largely constant. The maintenance of a constant c
i indicates that photosynthetic rates are unlikely to have increased in response to higher [CO2], and that improvements in W
i are probably due to a reduction in stomatal conductance. This may have large consequences for the hydrological cycle. Inter-annual
variation in c
i was strongly correlated with total annual rainfall (r = 0.70), and not influenced by temperature, solar radiation or cloud cover. Our results show that δ13C in tree rings of tropical dry forest trees may be a powerful tool to evaluate long-term responses of trees to increasing
[CO2] and to variation in climate. 相似文献
9.
Hedwig Selma Eugenia Tietze Jasmin Joshi Francisco Ignacio Pugnaire Michele de S Dechoum 《Austral ecology》2019,44(8):1351-1358
Increasing air temperature and atmospheric CO2 levels may affect the distribution of invasive species. Whereas there is wide knowledge on the effect of global change on temperate species, responses of tropical invasive species to these two global change drivers are largely unknown. We conducted a greenhouse experiment on Terminalia catappa L. (Combretaceae), an invasive tree species on Brazilian coastal areas, to evaluate the effects of increased air temperature and CO2 concentration on seed germination and seedling growth on the island of Santa Catarina (Florianópolis, Brazil). Seeds of the invasive tree were subjected to two temperature levels (ambient and +1.6 °C) and two CO2 levels (ambient and ~650 ppmv) with a factorial design. Increased temperature enhanced germination rate and shortened germination time of T. catappa seeds. It also increased plant height, number of leaves and above‐ground biomass. By contrast, increased atmospheric CO2 concentration had no significant effects, and the interaction between temperature and CO2 concentration did not affect any of the measured traits. Terminalia catappa adapts to a relatively broad range of environmental conditions, being able to tolerate cooler temperatures in its invasive range. As T. catappa is native to tropical areas, global warming might favour its establishment along the coast of subtropical South America, while increased CO2 levels seem not to have significant effects on seed germination or seedling growth. 相似文献
10.
Are whooping cranes destined for extinction? Climate change imperils recruitment and population growth
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Identifying climatic drivers of an animal population's vital rates and locating where they operate steers conservation efforts to optimize species recovery. The population growth of endangered whooping cranes (Grus americana) hinges on juvenile recruitment. Therefore, we identify climatic drivers (solar activity [sunspots] and weather) of whooping crane recruitment throughout the species’ life cycle (breeding, migration, wintering). Our method uses a repeated cross‐validated absolute shrinkage and selection operator approach to identify drivers of recruitment. We model effects of climate change on those drivers to predict whooping crane population growth given alternative scenarios of climate change and solar activity. Years with fewer sunspots indicated greater recruitment. Increased precipitation during autumn migration signified less recruitment. On the breeding grounds, fewer days below freezing during winter and more precipitation during breeding suggested less recruitment. We predicted whooping crane recruitment and population growth may fall below long‐term averages during all solar cycles when atmospheric CO2 concentration increases, as expected, to 500 ppm by 2050. Species recovery during a typical solar cycle with 500 ppm may require eight times longer than conditions without climate change and the chance of population decline increases to 31%. Although this whooping crane population is growing and may appear secure, long‐term threats imposed by climate change and increased solar activity may jeopardize its persistence. Weather on the breeding grounds likely affects recruitment through hydrological processes and predation risk, whereas precipitation during autumn migration may influence juvenile mortality. Mitigating threats or abating climate change should occur within ≈30 years or this wild population of whooping cranes may begin declining. 相似文献
11.
Contrasting acclimation abilities of two dominant boreal conifers to elevated CO2 and temperature
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Alexander G. Ivanov Vi Bui Marin Mema Norman P.A. Hüner Gunnar Öquist Danielle Way Vaughan Hurry 《Plant, cell & environment》2018,41(6):1331-1345
High latitude forests will experience large changes in temperature and CO2 concentrations this century. We evaluated the effects of future climate conditions on 2 dominant boreal tree species, Pinus sylvestris L. and Picea abies (L.) H. Karst, exposing seedlings to 3 seasons of ambient (430 ppm) or elevated CO2 (750 ppm) and ambient temperatures, a + 4 °C warming or a + 8 °C warming. Pinus sylvestris responded positively to warming: seedlings developed a larger canopy, maintained high net CO2 assimilation rates (Anet), and acclimated dark respiration (Rdark). In contrast, carbon fluxes in Picea abies were negatively impacted by warming: maximum rates of Anet decreased, electron transport was redirected to alternative electron acceptors, and thermal acclimation of Rdark was weak. Elevated CO2 tended to exacerbate these effects in warm‐grown Picea abies, and by the end of the experiment Picea abies from the +8 °C, high CO2 treatment produced fewer buds than they had 3 years earlier. Treatments had little effect on leaf and wood anatomy. Our results highlight that species within the same plant functional type may show opposite responses to warming and imply that Picea abies may be particularly vulnerable to warming due to low plasticity in photosynthetic and respiratory metabolism. 相似文献
12.
Remy R. Okazaki Erica K. Towle Ruben van Hooidonk Carolina Mor Rivah N. Winter Alan M. Piggot Ross Cunning Andrew C. Baker James S. Klaus Peter K. Swart Chris Langdon 《Global Change Biology》2017,23(3):1023-1035
Anthropogenic climate change compromises reef growth as a result of increasing temperatures and ocean acidification. Scleractinian corals vary in their sensitivity to these variables, suggesting species composition will influence how reef communities respond to future climate change. Because data are lacking for many species, most studies that model future reef growth rely on uniform scleractinian calcification sensitivities to temperature and ocean acidification. To address this knowledge gap, calcification of twelve common and understudied Caribbean coral species was measured for two months under crossed temperatures (27, 30.3 °C) and CO2 partial pressures (pCO2) (400, 900, 1300 μatm). Mixed‐effects models of calcification for each species were then used to project community‐level scleractinian calcification using Florida Keys reef composition data and IPCC AR5 ensemble climate model data. Three of the four most abundant species, Orbicella faveolata, Montastraea cavernosa, and Porites astreoides, had negative calcification responses to both elevated temperature and pCO2. In the business‐as‐usual CO2 emissions scenario, reefs with high abundances of these species had projected end‐of‐century declines in scleractinian calcification of >50% relative to present‐day rates. Siderastrea siderea, the other most common species, was insensitive to both temperature and pCO2 within the levels tested here. Reefs dominated by this species had the most stable end‐of‐century growth. Under more optimistic scenarios of reduced CO2 emissions, calcification rates throughout the Florida Keys declined <20% by 2100. Under the most extreme emissions scenario, projected declines were highly variable among reefs, ranging 10–100%. Without considering bleaching, reef growth will likely decline on most reefs, especially where resistant species like S. siderea are not already dominant. This study demonstrates how species composition influences reef community responses to climate change and how reduced CO2 emissions can limit future declines in reef calcification. 相似文献
13.
14.
Soil moisture profiles can affect species composition and ecosystem processes, but the effects of increased concentrations of atmospheric carbon dioxide ([CO2]) on the vertical distribution of plant water uptake have not been studied. Because plant species composition affects soil moisture profiles, and is likely to shift under elevated [CO2], it is also important to test whether the indirect effects of [CO2] on soil water content may depend on species composition. We examined the effects of elevated [CO2] and species composition on soil moisture profiles in an annual grassland of California. We grew monocultures and a mixture of Avena barbata and Hemizonia congesta– the dominant species of two phenological groups – in microcosms exposed to ambient (~370 μmol mol?1) and elevated (~700 μmol mol?1) [CO2]. Both species increased intrinsic and yield‐based water use efficiency under elevated [CO2], but soil moisture increased only in communities with A. barbata, the dominant early‐season annual grass. In A. barbata monocultures, the [CO2] treatment did not affect the depth distribution of soil water loss. In contrast to communities with A. barbata, monocultures of H. congesta, a late‐season annual forb, did not conserve water under elevated [CO2], reflecting the increased growth of these plants. In late spring, elevated [CO2] also increased the efficiency of deep roots in H. congesta monocultures. Under ambient [CO2], roots below 60 cm accounted for 22% of total root biomass and were associated with 9% of total water loss, whereas in elevated [CO2], 16% of total belowground biomass was associated with 34% of total water loss. Both soil moisture and isotope data showed that H. congesta monocultures grown under elevated [CO2] began extracting water from deep soils 2 weeks earlier than plants in ambient [CO2]. 相似文献
15.
Xiaohong Liu Xuemei Shao Eryuan Liang Liangju Zhao Tuo Chen Dahe Qin Jiawen Ren 《Plant Ecology》2007,193(2):195-209
Qilian juniper (Sabina przewalskii Kom.) and Qinghai spruce (Picea crassifolia Kom.) represent different tree functional types, which can be found extensively in northwestern China. The former is drought-tolerant,
whereas the latter is hygrophilous and shade-tolerant. We compared their intrinsic water-use efficiency (iWUE, inferred from
carbon isotopic discrimination, δ13C, in their wood) as a function of atmospheric CO2 concentration, [CO2], and climate. δ13C of spruce was consistently about higher than that of juniper in semi-arid areas but was lower in arid areas. This difference was stable over time and demonstrated
strong cross-correlations between species, although some subtle high-frequency (2 or 3 years) variations existed in both species,
suggesting that regional climate may control carbon isotope discrimination. The ratio (the [CO2] values in leaf intercellular and the atmosphere, respectively) of the juniper increased steadily over time, whereas that
of the spruce showed a long-term downward trend. IWUE increased at all sites over the 150-year study period, mainly caused
by increasing [CO2]. The relationship between iWUE and [CO2] reveals that the spruce was more sensitive than the juniper to increasing [CO2], suggesting a species-specific adaptation to long-term environmental changes. Correlations between the high-frequency variations
in stable carbon discrimination (Δ) and climate indicate similar intra-site responses to climate in both species, but different
response strengths. Overall, complex interactions of temperature and moisture on stable carbon discrimination during current
growth seasons of both species were environmental-determined. Regulation of gas exchange and reduced transpiration may influence
water and energy budgets directly; therefore species-dependent responses of trees to elevated CO2 should be considered in future research on global plant physiological ecology. 相似文献
16.
Sophie J. McCoy Alex Santillán-Sarmiento Murray T. Brown Stephen Widdicombe Glen L. Wheeler 《Journal of phycology》2020,56(1):85-96
Seaweeds are important components of near-shore ecosystems as primary producers, foundation species, and biogeochemical engineers. Seaweed communities are likely to alter under predicted climate change scenarios. We tested the physiological responses of three perennial, turf-building, intertidal rhodophytes, Mastocarpus stellatus, Osmundea pinnatifida, and the calcified Ellisolandia elongata, to elevated pCO2 over 6 weeks. Responses varied between these three species. E. elongata was strongly affected by high pCO2, whereas non-calcified species were not. Elevated pCO2 did not induce consistent responses of photosynthesis and respiration across these three species. While baseline photophysiology differed significantly between species, we found few clear effects of elevated pCO2 on this aspect of macroalgal physiology. We found effects of within-species variation in elevated pCO2 response in M. stellatus, but not in the other species. Overall, our data confirm the sensitivity of calcified macroalgae to elevated pCO2, but we found no evidence suggesting that elevated pCO2 conditions will have a strong positive or negative impact on photosynthetic parameters in non-calcified macroalgae. 相似文献
17.
Cuticular penetration of five different 14C-labeled chemicals (benzoic acid, bitertanole, carbaryl, epoxiconazole and 4-nitrophenol) into Arabidopsis thaliana leaves was measured and permeances P (ms−1) were calculated. Thus, cuticular barrier properties of A. thaliana leaves have been characterized quantitatively. Epoxiconazole permeance of A. thaliana was 2.79 × 10−8 ms−1. When compared with cuticular permeances measured with intact stomatous and astomatous leaf sides of Prunus
laurocerasus, frequently used in the past as a model species studying cuticular permeability, A. thaliana has a 48- to 66-fold higher permeance. When compared with epoxiconazole permeability of isolated cuticles of different species
(Citrus aurantium, Hedera helix and P. laurocerasus) A. thaliana permeability is between 17- to 199-fold higher. Co-permeability experiments, simultaneously measuring 14C-epoxiconazole and 3H2O permeability of isolated cuticles of three species (C. aurantium, H. helix and P. laurocerasus) showed that 3H2O permeability was highly correlated with epoxiconazole permeability. The regression equation of this correlation can be used
predicting cuticular transpiration of intact stomatous leaves of A. thaliana, where a direct measurement of cuticular permeation using 3H2O is impossible. Water permeance estimated for A. thaliana was 4.55 × 10−8 ms−1, which is between 12- and 91-fold higher than water permeances measured with isolated cuticles of C. aurantium, H. helix and P. laurocerasus. This indicates that cuticular water permeability of the intact stomatous leaves of the annual species A. thaliana is fairly high and in the upper range compared with most P values of perennial species published in the past. 相似文献
18.
Pieter A. Zuidema Ingo Heinrich Mizanur Rahman Mart Vlam Sophie A. Zwartsenberg Peter van der Sleen 《Global Change Biology》2020,26(7):4028-4041
Atmospheric CO2 (ca) rise changes the physiology and possibly growth of tropical trees, but these effects are likely modified by climate. Such ca × climate interactions importantly drive CO2 fertilization effects of tropical forests predicted by global vegetation models, but have not been tested empirically. Here we use tree‐ring analyses to quantify how ca rise has shifted the sensitivity of tree stem growth to annual fluctuations in rainfall and temperature. We hypothesized that ca rise reduces drought sensitivity and increases temperature sensitivity of growth, by reducing transpiration and increasing leaf temperature. These responses were expected for cooler sites. At warmer sites, ca rise may cause leaf temperatures to frequently exceed the optimum for photosynthesis, and thus induce increased drought sensitivity and stronger negative effects of temperature. We tested these hypotheses using measurements of 5,318 annual rings from 129 trees of the widely distributed (sub‐)tropical tree species, Toona ciliata. We studied growth responses during 1950–2014, a period during which ca rose by 28%. Tree‐ring data were obtained from two cooler (mean annual temperature: 20.5–20.7°C) and two warmer (23.5–24.8°C) sites. We tested ca × climate interactions, using mixed‐effect models of ring‐width measurements. Our statistical models revealed several significant and robust ca × climate interactions. At cooler sites (and seasons), ca × climate interactions showed good agreement with hypothesized growth responses of reduced drought sensitivity and increased temperature sensitivity. At warmer sites, drought sensitivity increased with increasing ca, as predicted, and hot years caused stronger growth reduction at high ca. Overall, ca rise has significantly modified sensitivity of Toona stem growth to climatic variation, but these changes depended on mean climate. Our study suggests that effects of ca rise on tropical tree growth may be more complex and less stimulatory than commonly assumed and require a better representation in global vegetation models. 相似文献
19.
The Earth has undergone a significant climate switch from greenhouse to icehouse during the Plio–Pleistocene transition (PPT) around 2.7–2.4 million years ago (Ma), marked by the intensification of the Northern Hemisphere glaciation (NHG) ~2.7 Ma. Evidence based on oceanic CO2 [(CO2)aq], supposed to be in close equilibrium with the atmospheric CO2 [(CO2)atm], suggests that the CO2 decline might drive such climate cooling. However, the rarity of direct evidence from [CO2]atm during the interval prevents determination of the atmospheric CO2 level and further assessment on the impact of its fluctuation. Here, we reconstruct the [CO2]atm level during 2.77–2.52 Ma based on a new developed proxy of stomatal index on Typha orientalis leaves from Shanxi, North China, and depict the first [CO2]atm curve over the past 5 Ma by using stomata‐based [CO2]atm data. Comparisons of the terrestrial‐based [CO2]atm and the existed marine‐based [CO2]aq curves show a similar general trend but with different intensity of fluctuations. Our data reveal that the high peak of [CO2]atm occurred at 2.77–2.52 Ma with a lower [CO2]aq background. The subsequent sharp fall in [CO2]atm level might be responsible for the intensification of the NHG based on their general temporal synchronism. These findings shed a significant light for our understanding toward the [CO2]atm changes and its ecological impact since 5 Ma. 相似文献
20.
Dongsu Choi Kobayashi Makoto Ali M. Quoreshi Laiye Qu 《Landscape and Ecological Engineering》2009,5(2):107-113
We investigated the effect of ectomycorrhizal colonization, charcoal and CO2 levels on the germination of seeds of Larix kaempferi and Pinus densiflora, and also their subsequent physiological activity and growth. The seeds were sown in brown forest soil or brown forest soil
mixed with charcoal, at ambient CO2 (360 μmol mol−1) or elevated CO2 (720 μmol mol−1), with or without ectomycorrhiza. The proportions of both conifer seeds that germinated in forest soil mixed with charcoal
were significantly greater than for seeds sown in forest soil grown at each CO2 level (P < 0.05; t-test). However, the ectomycorrhizal colonization rate of each species grown in brown forest soil mixed with charcoal was
significantly lower than in forest soil at each CO2 treatment [CO2] (P < 0.01; t-test). The phosphorus concentrations in needles of each seedling colonized with ectomycorrhiza and grown in forest soil were
greater than in nonectomycorrhizal seedlings at each CO2 level, especially for L. kaempferi seedlings (P < 0.05; t-test), but the concentrations in seedlings grown in brown forest soil mixed with charcoal were not increased at any CO2 level. Moreover, the maximum net photosynthetic rate of each seedling for light and CO2 saturation (P
max) increased when the seedlings were grown with ectomycorrhiza at 720 μmol mol−1 [CO2]. Ectomycorrhizal colonization led to an increase in the stem diameter of each species grown in each soil treatment at each
CO2 level. However, charcoal slowed the initial growth of both species of seedling, constraining ectomycorrhizal development.
These results indicate that charcoal strongly assists seed germination and physiological activity. 相似文献