Ontwerprichtlijnen klimaatbestendig groen in de stad
Klemm, W. ; Lenzholzer, S. ; Brink, A. van den - \ 2017
Wageningen : Wageningen University & Research - 1 p.
air quality - climate - urban areas - plantations - water harvesting - heat stress - shade
How virtual shade sheds light on plant plasticity
Bongers, Franca J. - \ 2017
Wageningen University. Promotor(en): N.P.R. Anten, co-promotor(en): R. Pierik; J.B. Evers. - Wageningen : Wageningen University - ISBN 9789463432047 - 140
planten - fenotypen - fenotypische variatie - modellen - arabidopsis - natuurlijke selectie - schaduw - reacties - concurrentie tussen planten - licht - plants - phenotypes - phenotypic variation - models - arabidopsis - natural selection - shade - responses - plant competition - light
Phenotypic plasticity is the ability of a genotype to express multiple phenotypes in accordance with different environments. Although variation in plasticity has been observed, there is limited knowledge on how this variation results from natural selection. This thesis analyses how variation in the level of plasticity influences light competition between plants and how this variation could result from selection, driven by light competition, in various environments. As an exemplary case of phenotypic plasticity, this thesis focusses on phenotypic responses of the annual rosette plant Arabidopsis thaliana (Brassicaceae) in response to the proximity of neighbour plants, as signalled through the red : far—red (R:FR) ratio, which are responses associated with the shade avoidance syndrome (SAS).
Plant experiments were conducted to measure variation in these plastic responses and a functional-structural plant (FSP) model was created that simulates plant structures in 3D and includes these organ-level plastic responses while simulating explicitly a heterogeneous light environment. Simulating individual plants that explicitly compete for light, while their phenotype changes through plasticity, gave insights in the role of the level of phenotypic plasticity and site of signal perception on plant competitiveness. In addition, an analysis on how natural selection in different environments acts on the level of plasticity was performed by combining FSP simulations and evolutionary game theoretical (EGT) principles.
Primeur op congres: onderzoeksresultaten urban heat effect door kunstgras : WUR-onderzoeker bestudeert op verzoek van vakblad Fieldmanager
Theeuwes, N.E. - \ 2015
Fieldmanager 11 (2015)6. - ISSN 2212-4314 - p. 70 - 71.
sportterreinen - grasveld - kunststoffen - natuurlijke graslanden - voetballen - omgevingstemperatuur - bodemtemperatuur - schaduw - sports grounds - grass sward - plastics - natural grasslands - soccer - environmental temperature - soil temperature - shade
Er bestaat vermoedelijk een groot verschil tussen de temperatuur van kunstgras en die van natuurgras bij hitte. Als kunstgrasvelden hitte-eilandjes vormen, zou dit een groot effect hebben op het stadsklimaat. Natalie Theeuwes van de Wageningen Universiteit deed op verzoek van vakblad Fieldmanager wetenschappelijk onderzoek naar het urban heat effect door kunstgras en geeft de bezoekers van het Nationaal Sportvelden Congres de primeur van haar meetresultaten. Ook geeft zij advies over het minimaliseren van hittestress rónd de velden.
Wheat 2004 outdoor
Evers, J.B. ; Vos, J. ; Andrieu, B. ; Struik, P.C. - \ 2013
Triticum aestivum - wheat - tiller - bud - plant population density - shade - PAR - red:far-red ratio - function-structural model
(Koel)water voor waterbuffels; noodzaak onder NL-omstandigheden?
Bokma, S. ; Poelarends, J.J. - \ 2011
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 550) - 27
buffels - dierenwelzijn - schaduw - diergezondheid - dierhouderij - buffaloes - animal welfare - shade - animal health - animal husbandry
From literature, discussions with buffalo farmers and interviews with experts, no indications were determined that water buffaloes need (cooling) water under Dutch climatological circumstances.
Global patterns of leaf mechanical properties
Onoda, Y. ; Westoby, M. ; Adler, N.E. ; Choong, A.M.L. ; Clissold, F.J. ; Cornelissen, J.H.C. ; Diaz, S. ; Dominy, N.J. ; Elgart, A. ; Markesteijn, L. ; Poorter, L. ; Kitajima, K. - \ 2011
Ecology Letters 14 (2011)3. - ISSN 1461-023X - p. 301 - 312.
fracture-toughness - life-span - latitudinal variation - economics spectrum - leaves - plants - traits - shade - photosynthesis - biomechanics
Leaf mechanical properties strongly influence leaf lifespan, plant-herbivore interactions, litter decomposition and nutrient cycling, but global patterns in their interspecific variation and underlying mechanisms remain poorly understood. We synthesize data across the three major measurement methods, permitting the first global analyses of leaf mechanics and associated traits, for 2819 species from 90 sites worldwide. Key measures of leaf mechanical resistance varied c. 500-800-fold among species. Contrary to a long-standing hypothesis, tropical leaves were not mechanically more resistant than temperate leaves. Leaf mechanical resistance was modestly related to rainfall and local light environment. By partitioning leaf mechanical resistance into three different components we discovered that toughness per density contributed a surprisingly large fraction to variation in mechanical resistance, larger than the fractions contributed by lamina thickness and tissue density. Higher toughness per density was associated with long leaf lifespan especially in forest understory. Seldom appreciated in the past, toughness per density is a key factor in leaf mechanical resistance, which itself influences plant-animal interactions and ecosystem functions across the globe
Stress-driven changes in the strength of facilitation on tree seedling establishment in west african woodlands
Biaou, S.S.H. ; Holmgren, M. ; Sterck, F.J. ; Mohren, G.M.J. - \ 2011
Biotropica 43 (2011)1. - ISSN 0006-3606 - p. 23 - 30.
plant-communities - nurse-plants - shrubs - competition - shade - drought - tolerance - survival - savanna - forests
The strength of competitive and facilitative interactions in plant communities is expected to change along resource gradients. Contrasting theoretical models predict that with increasing abiotic stress, facilitative effects are higher, lower, or similar than those found under more productive conditions. While these predictions have been tested in stressful environments such as arid and alpine ecosystems, they have hardly been tested for more productive African woodlands. We experimentally assessed the strength of tree seedling facilitation by nurse trees in mesic and dry woodlands in Benin, West Africa. We planted seedlings of the drought-sensitive Afzelia africana and the drought-tolerant Khaya senegalensis under three microsite conditions (closed woodland, woodland gap, and open fields). Seedling survival was greater within woodlands compared with open fields in both the mesic and dry woodlands. The relative benefits in seedling survival were larger at the dry site, especially for the drought-sensitive species. Nevertheless, plant interactions became neutral or negative during the dry season in the drier woodland, indicating that the net positive effects may be lost under very stressful abiotic conditions. We conclude that facilitation also occurs in the relatively more productive conditions of African woodlands. Our results underscore the role of environmental variation in space and time, and the stress tolerance of species, in explaining competitive and facilitative interactions within plant communities
Genetische modificatie tomaat en chrysant
Angenent, G.C. - \ 2010
[S.l. : S.n. - 18
glastuinbouw - tomaten - genetische modificatie - energiebesparing - lichtdoorlating - genen - chrysanten - schaduw - greenhouse horticulture - tomatoes - genetic engineering - energy saving - light transmission - genes - chrysanthemums - shade
Gedurende 1999 en 2000 zijn in dit project tomaten en chrysanten getransformeerd met genen waarvan kon worden aangenomen dat ze van invloed zijn op de energiehuishouding. Deze aanname berust op effecten die door deze genen in andere planten zijn opgewekt bijv. een andere gewasopbouw en lichtonderschepping. De werkelijke effecten op de energiebehoefte van de genetisch gemodificeerde tomaten en chrysanten worden in het project "Teeltanalyse transgene planten tomaat en crysant" onderzocht. In het vervolg traject "Genetische modificatie van tomaat en chrysant, analyse op plantniveau" zijn de effecten van verhoogde niveaus van phyA, phyB1 en phyB2 op de schaduw-vermijdings-reactie (SAR) onderzocht, door fytochroomgenen in tomaat tot overexpressie te brengen
Selection of native trees for intercropping with coffee in the Atlantic Rainforest biome
Souza, H.N. de; Cardoso, I.M. ; Fernandes, J.M. ; Garcia, F.C.P. ; Bonfim, V.R. ; Santos, A.C. ; Carvalho, A.F. ; Mendonca, E.S. - \ 2010
Agroforestry Systems 80 (2010)1. - ISSN 0167-4366 - p. 1 - 16.
agroforestry - shade - biodiversity - conservation - adoption - systems - tropics - growth
A challenge in establishing agroforestry systems is ensuring that farmers are interested in the tree species, and are aware of how to adequately manage these species. This challenge was tackled in the Atlantic Rainforest biome (Brazil), where a participatory trial with agroforestry coffee systems was carried out, followed by a participatory systematisation of the farmers experiences. Our objective was to identify the main tree species used by farmers as well as their criteria for selecting or rejecting tree species. Furthermore, we aimed to present a specific inventory of trees of the Leguminosae family. In order to collect the data, we reviewed the bibliography of the participatory trial, visited and interviewed the farmers and organised workshops with them. The main farmers' criteria for selecting tree species were compatibility with coffee, amount of biomass, production and the labour needed for tree management. The farmers listed 85 tree species; we recorded 28 tree species of the Leguminosae family. Most trees were either native to the biome or exotic fruit trees. In order to design and manage complex agroforestry systems, family farmers need sufficient knowledge and autonomy, which can be reinforced when a participatory methodology is used for developing on-farm agroforestry systems. In the case presented, the farmers learned how to manage, reclaim and conserve their land. The diversification of production, especially with fruit, contributes to food security and to a low cost/benefit ratio of agroforestry systems. The investigated agroforestry systems showed potential to restore the degraded landscape of the Atlantic Rainforest biome.
Monitoring ClimecoVent-systeem in de praktijk - Technisch, teeltkundig en economisch onderzoek naar een energiezuinige kas bij kwekerij Grenspaal B.V.
Raaphorst, M.G.M. ; Voermans, J. - \ 2010
Bleiswijk : Wageningen (Rapporten GTB 1032) - 54
kassen - innovaties - schaduw - kooldioxide - temperatuur - tomaten - glastuinbouw - energiebesparing - greenhouses - innovations - shade - carbon dioxide - temperature - tomatoes - greenhouse horticulture - energy saving
De tomatentelers Noud en Roy Steegh zijn in januari 2009 op kwekerij Grenspaal te Wellerlooi (L) gestart met een nieuwe kas, voorzien van het ClimecoVent-systeem. Met het ClimecoVent-systeem wordt beoogd zodanig energie te besparen dat de warmtevraag bij een tomatenteelt neerkomt op een aardgasverbruik van 25 tot 30 m3/m2. De productiedoelen liggen gelijk aan die van een standaard tomatenteelt. Gezien het innovatieve en energiezuinige karakter van het ClimecoVent-systeem, heeft Wageningen UR in samenwerking met Climeco het systeem bij kwekerij Grenspaal over een tijdsspanne van ruim een jaar gemonitord in opdracht van het programma “Kas als Energiebron”. Doordat minder gas is gebruikt voor de verwarming van de kas is ook minder CO2 beschikbaar. In combinatie met de schaduwwerking van het extra scherm zou hiermee mogen worden verwacht dat het productieniveau achterblijft, maar dat is niet gebleken.
Improved quality of beneath-canopy grass in South African savannas: Local and seasonal variation
Treydte, A.C. ; Looringh van Beeck, F.A. ; Ludwig, F. ; Heitkonig, I.M.A. - \ 2008
Journal of Vegetation Science 19 (2008)5. - ISSN 1100-9233 - p. 663 - 670.
open eucalypt woodlands - species composition - perennial grasses - soil nutrients - forage quality - trees - shade - vegetation - ecosystem - cattle
Questions: Do large trees improve the nutrient content and the structure of the grass layer in savannas? Does the magnitude of this improvement differ with locality ( soil nutrients) and season ( water availability)? Are grass structure and species composition beneath tree canopies influenced by soil fertility and season? Location: South Africa. Methods: We compared grass leaf nutrient contents and grass sward structure beneath and outside tree canopy areas in three savannas of different soil fertility during the dry and the wet seasons. Results: Grass nitrogen contents were twice as high during the wet season as compared to the dry season, being more strongly elevated underneath tree canopies during the wet season. Grasses had significantly less stem material and provided less dead material underneath trees on the high soil fertility site. Grass species composition differed significantly beneath and outside tree canopies, with more nutritious grass species found sub-canopy. Grass species richness was significantly lower beneath than outside of trees at the site of high soil fertility. Conclusions: Trees improve overall quality of savanna grasses by enhancing grass growth and nutrient uptake during the wet season, and by delaying grass wilting in the dry season. The positive effect of trees on the grass layer might attract grazing herbivores in otherwise nutrient-poor savannas. Hence, single standing large trees should be maintained to sustain high grass quality and, consequently, grazer populations in savanna habitats.
Seedling traits determine drought tolerance of tropical tree species
Poorter, L. ; Markesteijn, L. - \ 2008
Biotropica 40 (2008)3. - ISSN 0006-3606 - p. 321 - 331.
phylogenetically independent contrasts - woody-plants - moist forest - dry forest - water-stress - responses - patterns - growth - shade - root
Water availability is the most important factor determining tree species distribution in the tropics, but the underlying mechanisms are still not clear. In this study, we compared functional traits of 38 tropical tree species from dry and moist forest, and quantified their ability to survive drought in a dry-down experiment in which wilting and survival were monitored. We evaluated how seedling traits affect drought survival, and how drought survival determines species distribution along the rainfall gradient. Dry forest species tended to have compound leaves, high stem dry matter content (stem dry mass/fresh mass), and low leaf area ratio, suggesting that reduction of transpiration and avoidance of xylem cavitation are important for their success. Three functional groups were identified based on the seedling traits: (1) drought avoiders with a deciduous leaf habitat and taproots; (2) drought resisters with tough tissues (i.e., a high dry matter content); and (3) light-demanding moist forest species with a large belowground foraging capacity. Dry forest species had a longer drought survival time (62 d) than moist forest species (25 d). Deciduousness explained 69 percent of interspecific variation in drought survival. Among evergreen species, stem density explained 20 percent of the drought survival. Drought survival was not related to species distribution along the rainfall gradient, because it was mainly determined by deciduousness, and species with deciduous seedlings are found in both dry and moist forests. Among evergreen species, drought survival explained 28 percent of the variation in species position along the rainfall gradient. This suggests that, apart from drought tolerance, other factors such as history, dispersal limitation, shade tolerance, and fire shape species distribution patterns along the rainfall gradient.
Impacts of savanna trees on forage quality for a large African herbivore
Ludwig, F. ; Kroon, H. de; Prins, H.H.T. - \ 2008
Oecologia 155 (2008)3. - ISSN 0029-8549 - p. 487 - 496.
hydraulic lift - national-park - grass interactions - tropical savannas - panicum-maximum - light-intensity - vegetation - shade - woodlands - tanzania
Recently, cover of large trees in African savannas has rapidly declined due to elephant pressure, frequent fires and charcoal production. The reduction in large trees could have consequences for large herbivores through a change in forage quality. In Tarangire National Park, in Northern Tanzania, we studied the impact of large savanna trees on forage quality for wildebeest by collecting samples of dominant grass species in open grassland and under and around large Acacia tortilis trees. Grasses growing under trees had a much higher forage quality than grasses from the open field indicated by a more favourable leaf/stem ratio and higher protein and lower fibre concentrations. Analysing the grass leaf data with a linear programming model indicated that large savanna trees could be essential for the survival of wildebeest, the dominant herbivore in Tarangire. Due to the high fibre content and low nutrient and protein concentrations of grasses from the open field, maximum fibre intake is reached before nutrient requirements are satisfied. All requirements can only be satisfied by combining forage from open grassland with either forage from under or around tree canopies. Forage quality was also higher around dead trees than in the open field. So forage quality does not reduce immediately after trees die which explains why negative effects of reduced tree numbers probably go initially unnoticed. In conclusion our results suggest that continued destruction of large trees could affect future numbers of large herbivores in African savannas and better protection of large trees is probably necessary to sustain high animal densities in these ecosystems.
Plant neurobiology and green plant intelligence : science, metaphors and nonsense
Struik, P.C. ; Yin, X. ; Meinke, H.B. - \ 2008
Journal of the Science of Food and Agriculture 88 (2008)3. - ISSN 0022-5142 - p. 363 - 370.
alpi et-al - transport - photosynthesis - acclimation - shade - wheat - model - gain
This paper analyses the recent debates on the emerging science of plant neurobiology, which claims that the individual green plant should be considered as an intelligent organism. Plant neurobiology tries to use elements from animal physiology as elegant metaphors to trigger the imagination in solving complex plant physiological elements of signalling, internal and external plant communication and whole-plant organisation. Plant neurobiology proposes useful concepts that stimulate discussions on plant behaviour. To be considered a new science, its added value to existing plant biology needs to be presented and critically evaluated. A general, scientific approach is to follow the so-called `parsimony principle', which calls for simplest ideas and the least number of assumptions for plausible explanation of scientific phenomena. The extent to which plant neurobiology agrees with or violates this general principle needs to be examined. Nevertheless, innovative ideas on the complex mechanisms of signalling, communication, patterning and organisation in higher plants are badly needed. We present current views on these mechanisms and the specific role of auxins in regulating them.
Seed-mass effects in four Mediterranean Quercus species (Fagaceae) growing in contrasting light environments.
Quero, J.L. ; Villar, R. ; Marañon, T. ; Zamora, R. ; Poorter, L. - \ 2007
American Journal of Botany 94 (2007). - ISSN 0002-9122 - p. 1795 - 1803.
tropical rain-forest - relative growth-rate - trait correlations - moist forest - acorn size - seedlings - shade - responses - survival - drought
Three hypotheses have been proposed to explain the functional relationship between seed mass and seedling performance: the reserve effect (larger seeds retain a larger proportion of reserves after germinating), the metabolic effect (seedlings from larger seeds have slower relative growth rates), and the seedling-size effect (larger seeds produce larger seedlings). We tested these hypotheses by growing four Mediterranean Quercus species under different light conditions (3, 27, and 100% of available radiation). We found evidence for two of the three hypotheses, but none of the four species complied with all three hypotheses at the same time. The reserve effect was not found in any species, the metabolic effect was found in three species (Q. ilex, Q. pyrenaica, and Q. suber), and the seedling-size effect in all species. Light availability significantly affected the relationships between seed size and seedling traits. For Q. ilex and Q. canariensis, a seedling-size effect was found under all three light conditions, but only under the lowest light (3%) for Q. suber and Q. pyrenaica. In all species, the correlation between seed mass and seedling mass increased with a decrease in light, suggesting that seedlings growing in low light depend more upon their seed reserves. A causal model integrates the three hypotheses, suggesting that larger seeds generally produced larger seedlings
Submergence-induced leaf acclimation in terrestrial species varying in flooding tolerance
Mommer, L. ; Wolters-Arts, M. ; Andersen, C. ; Visser, E.J.W. ; Pedersen, O. - \ 2007
New Phytologist 176 (2007)2. - ISSN 0028-646X - p. 337 - 345.
deep-water rice - amphibious plants - photosynthesis - plasticity - responses - elongation - shade - environments - communities - performance
Earlier work on the submergence-tolerant species Rumex palustris revealed that leaf anatomical and morphological changes induced by submergence enhance underwater gas exchange considerably. Here, the hypothesis is tested that these plastic responses are typical properties of submergence-tolerant species. ¿ Submergence-induced plasticity in leaf mass area (LMA) and leaf, cell wall and cuticle thickness was investigated in nine plant species differing considerably in tolerance to complete submergence. The functionality of the responses for underwater gas exchange was evaluated by recording oxygen partial pressures inside the petioles when plants were submerged. ¿ Acclimation to submergence resulted in a decrease in all leaf parameters, including cuticle thickness, in all species irrespective of flooding tolerance. Consequently, internal oxygen partial pressures (pO2) increased significantly in all species until values were close to air saturation. Only in nonacclimated leaves in darkness did intolerant species have a significantly lower pO2 than tolerant species. ¿ These results suggest that submergence-induced leaf plasticity, albeit a prerequisite for underwater survival, does not discriminate tolerant from intolerant species. It is hypothesized that these plastic leaf responses may be induced in all species by several signals present during submergence; for example, low LMA may be a response to low photosynthate concentrations and a thin cuticle may be a response to high relative humidity.
Trees improve grass quality for herbivores in African savannas
Treydte, A.C. ; Heitkonig, I.M.A. ; Prins, H.H.T. ; Ludwig, F. - \ 2007
Perspectives in plant ecology, evolution and systematics 8 (2007)4. - ISSN 1433-8319 - p. 197 - 205.
biological nitrogen-fixation - shade - nutrients - cattle - dynamics - availability - productivity - communities - vegetation - woodlands
The tree-grass interactions of African savannas are mainly determined by varying rainfall patterns and soil fertility. Large savanna trees are known to modify soil nutrient conditions, but whether this has an impact on the quality of herbaceous vegetation is unclear. However, if this were the case, then the removal of trees might also affect the structure and quality of the grass layer. We studied the impact of large nitrogen- and non-nitrogen fixing trees on the sub-canopy (SC) grass layer in low- and high-rainfall areas of differing soil fertility in eastern and southern Africa. We compared the structure and nutrient levels of SC grasses with those outside the canopy. Grass leaf nitrogen and phosphorus contents beneath tree canopies were elevated at all study sites and were up to 25% higher than those outside the canopy in the site of lowest rainfall and soil fertility. Grass leaf fibre and organic matter (OM) contents were slightly enhanced beneath tree canopies. At the site of highest rainfall and soil fertility, grasses beneath the canopy had significantly lower ratios of stem:leaf biomass and dead:living leaf material. Grass species composition differed significantly, with the highly nutritious Panicum spp. being most abundant underneath tree crowns. In the two drier study sites, soil nitrogen and OM contents were enhanced by 30% beneath trees. N-fixation capacity of trees did not contribute to the improved quality of grass under the canopy. We conclude that trees improve grass quality, especially in dry savannas. In otherwise nutrient-poor savanna grasslands, the greater abundance of high-quality grass species with higher contents of N and P and favourable grass structure beneath trees could attract grazing ungulates. As these benefits may be lost with tree clearance, trees should be protected in low fertility savannas and their benefits for grazing wildlife recognised in conservation strategies.
Kauri trees (Agathis australis) affect nutrient, water and light availability for their seedlings
Verkaik, E. ; Braakhekke, W.G. - \ 2007
New Zealand Journal of Ecology 31 (2007)1. - ISSN 0110-6465 - p. 39 - 46.
don lindl kauri - new-zealand - population-dynamics - soil interactions - forest remnants - litter - growth - decomposition - biology - shade
Plants can change the soil that they grow on, for example by producing litter. If litter characteristics are such that their effect on the soil increases a plant's fitness, a positive feedback can develop between the plant and the soil. Several studies indicate that New Zealand kauri trees (Agathis australis) lower the availability of nutrients in the soil beneath their crown. Low nutrient availability would be positive for the survival of kauri seedlings as they are known to use nutrients more efficiently than angiosperm species. We tested the hypotheses that nutrient availability is lower and light availability is higher beneath kauri trees than beneath the surrounding angiosperm vegetation. We determined the availability of nutrients (using leaf nutrient concentrations as a proxy), soil moisture, and light in both situations. As a reference we did the same measurements in tea tree vegetation (Leptospermum scoparium and Kunzea ericoides) where kauri seedlings were abundant. The availability of nitrogen, phosphorus and calcium was lower under kauri than in the surrounding vegetation. Further, in a dry period the availability of water in the organic layer surrounding the kauri trunk was lower than in the mineral soil further away from the kauri trunk. We suggest that periodic drought explains why the density of kauri seedlings under mature kauri trees is less than in tea tree vegetation. Kauri seedlings are more tolerant of drought and low nutrient availability than other tree seedlings and we conclude that the conditions under mature kauri give kauri seedlings an advantage over seedlings of other tree species. The low nutrient availability under mature kauri trees supports the idea of a positive soil¿plant feedback driven by poor decomposability of kauri litter.
Carbohydrate storage and light requirements of tropical moist and dry forest tree species
Poorter, L. ; Kitajima, K. - \ 2007
Ecology 88 (2007)4. - ISSN 0012-9658 - p. 1000 - 1011.
seedling survival - leaf traits - growth-rate - shade - allocation - patterns - ecology - size - acclimatization - regeneration
In many plant communities, there is a negative interspecific correlation between relative growth rates and survival of juveniles. This negative correlation is most likely caused by a trade-off between carbon allocation to growth vs. allocation to defense and storage. Nonstructural carbohydrates (NSC) stored in stems allow plants to overcome periods of stress and should enhance survival. In order to assess how species differ in carbohydrate storage in relation to juvenile light requirements, growth, and survival, we quantified NSC concentrations and pool sizes in sapling stems of 85 woody species in moist semi-evergreen and dry deciduous tropical forests in the rainy season in Bolivia. Moist forest species averaged higher NSC concentrations than dry forest species. Carbohydrate concentrations and pool sizes decreased with the light requirements of juveniles of the species in the moist forest but not in the dry forest. Combined, these results suggest that storage is especially important for species that regenerate in persistently shady habitats, as in the understory of moist evergreen forests. For moist forest species, sapling survival rates increased with NSC concentrations and pool sizes while growth rates declined with the NSC concentrations and pool sizes. No relationships were found for dry forest species. Carbon allocation to storage contributes to the growth¿ survival trade-off through its positive effect on survival. And, a continuum in carbon storage strategies contributes to a continuum in light requirements among species. The link between storage and light requirements is especially strong in moist evergreen forest where species sort out along a light gradient, but disappears in dry deciduous forest where light is a less limiting resource and species sort out along drought and fire gradients. Key words: Bolivia; growth¿survival trade-off; shade tolerance; starch; sugar; total nonstructural carbohydrates (NSC); tropical forest.
Genetic modification of shade-avoidance: overexpression of homologous phytochrome genes in tomato
Husaineid, S.H. - \ 2007
Wageningen University. Promotor(en): Linus van der Plas, co-promotor(en): Sander van der Krol. - [S.l.] : S.n. - ISBN 9789085045120 - 152
solanum lycopersicum - tomaten - schaduw - fytochroom - genen - transgene planten - licht - groei - gewasdichtheid - solanum lycopersicum - tomatoes - shade - phytochrome - genes - transgenic plants - light - growth - crop density