Effect of species on dune grass growth

Observations of experimental dunes made over a period of nine years indicate differences in utilizing three different dune species along the North Carolina coast and in the type of dunes produced by them.Ammophila is superior in ease of establishment and rate of sand accumulation but is shortlived. It produces a gently sloping dune.Uniola is difficult to propagate but is an excellent dune builder and eventually dominates the foredune. Grown alone, it produces a steep dune front.Panicum is an excellent companion plant to bothAmmophila andUniola. It is easy to propagate, relatively free of pests and produces dunes intermediate in shape, betweenAmmophila andUniola. Plantings of mixtures of two or more of these species should greatly improve long-term dune stability compared with either planted alone.Presented at the Seventh International Biometeorological Congress, 17–23 August 1975, College Park, Maryland, USA     

In vitro flowering of indica rice (Oryza sativa L. spp. indica)

Nodal explants of rice cultivar Pathumthani 1 (PT1; short-day photoperiod insensitive) were collected, surface-disinfected, and cultured on modified MS medium under in vitro conditions for 90 d. A total of 60% nodal explants generated flowering plantlets (with one inflorescence per cluster). The net photosynthetic rate was greater, and soluble sugars (including glucose, fructose, and sucrose) accumulated to higher levels in the leaves of flowering as compared to non-flowering plants. In contrast, chlorophyll a, chlorophyll b, total chlorophyll, and total carotenoid content were enriched to a greater degree in the leaves of non-flowering as compared to flowering plants. Also, growth performance parameters, including plant height, number of leaves per plant, leaf area, fresh weight, and dry weight of plantlets derived from seedlings were superior to those of plantlets derived from nodal explants. In addition, the protocol proved to successfully induce flowering in KDML 105, a short-day photoperiod-sensitive rice cultivar.     

Effects of sandblasting and salt spray on inland plants transplanted to coastal sand dunes

A transplant experiment was conducted on a sandy beach to elucidate whether salt spray and sandblasting are the major factors inhibiting inland plants from becoming established on coastal sand dunes. Potted inland plants of Miscanthus sinensis and Imperata cylindrica var. koenigii were transplanted in two zones on the beach and in one area far inland from the beach. One zone on the beach (sea side) was located on a front dune that was occupied by native sand-dune plants; the other zone (land side) was located behind the sand dunes, where grassland comprised both sand-dune and inland species. To assess the condition of transplants, we measured changes in the canopy leaf area periodically at all sites. The final dry weight at each site was determined at the end of the experiment. Seasonal changes in sandblasting and salt spray intensities were evaluated periodically at the sites by measurement of the opaqueness of exposed transparent plastic sheets and the amount of sodium trapped in exposed filter papers, respectively. All transplants died in the sea-side zone, where both salt spray and sandblasting were most frequent and intense. The final dry weight was greatest at the inland site, which lacked salt spray and sandblasting. Although salt spray was intense in the land-side zone, the canopy leaf area decreased considerably only in seasons during which salt spray was accompanied by intense sandblasting. We concluded that sandblasting accompanied by salt spray is one of the main factors inhibiting the survival and growth of inland plants on coastal sand dunes.     

Genets of dwarf bamboo do not die after one flowering event: evidence from genetic structure and flowering pattern

Dwarf bamboos in the genus Sasa are believed to be long-lived, synchronously flowering, and monocarpic plants. However, the monocarpy of dwarf bamboo has not been confirmed, because whether all ramets within one genet flower at the same time cannot be determined without differentiating the genetic structure among ramets. This study aims to evaluate the reproductive traits of Sasa pubiculmis by verifying the monocarpy and physiological integration between flowering ramets and non-flowering ramets during a 4-year flowering period. One genotypically identified genet, which covered an area of approximately 3 ha, had both flowering and non-flowering patches of ramets during the 4-year flowering period (2004–2007). A fraction of the flowering genet remained non-flowering during the 4 years of observation, and did not die after mass flowering. Flowering ramets were physically connected to non-flowering ramets via rhizomes, and assimilated ¹³C was allocated from non-flowering ramets to flowering ramets. Consequently, we clarified that this dwarf bamboo potentially has polycarpic reproductive traits rather than monocarpic, and a genet can keep rhizomes and non-flowering patches alive to sustain the organism after mass flowering.     

MICRODISTRIBUTION OF THE BEACH PLANT CAKILE MARITIMA (BRASSICACEAE) AS INFLUENCED BY A RODENT HERBIVORE

The microdistribution of a beach plant, Cakile maritima, was examined relative to patches of an introduced beachgrass, Ammophila arenaria. Sampling was done with belt transects oriented parallel to the beachfront to minimize the influence of physical factors along the land/sea gradient. No Cakile individuals were found within Ammophila patches, and a 3–4 m wide zone of decreased abundance occurred outside of patch borders. I hypothesized that this microdistribution was due to foraging behavior of deer mice, Peromyscus maniculatus, which nest in Ammophila patches and forage outward from them. Manipulative experiments using fruits and seedlings of Cakile confirmed that herbivory was higher inside patches and in border areas. Seedlings protected from herbivory by wire cages survived and grew equally well both inside and outside of Ammophila patches, demonstrating that differences in other habitat factors were not of major importance in determining Cakile microdistribution. Herbivory by mice was concluded to be of primary importance in determining the microdistribution of Cakile relative to Ammophila. Rodent herbivory may influence microdistributions of beach plants along the land/sea gradient, and may also be partly responsible for decreased plant species richness often observed in Ammophila-dominated areas on the West Coast.     

Native and exotic foundation grasses differ in traits and responses to belowground tri-trophic interactions

A plant’s growth and fitness are influenced by species interactions, including those belowground. In primary successional systems, belowground organisms are known to have particularly important control over plant growth. Exotic plant invasions in these and other habitats may in part be explained by altered associations with belowground organisms compared to native plants. We investigated the growth responses of two foundation grasses on Great Lakes sand dunes, the native grass Ammophila breviligulata and the exotic grass Leymus arenarius, to two groups of soil organisms with important roles in dune succession: arbuscular mycorrhizal fungi (AMF) and plant-parasitic nematodes (PPN). We manipulated the presence/absence of two generalist belowground species known to occur in Great Lakes dunes, Rhizophagus intraradices (AMF) and Pratylenchus penetrans (PPN) in a factorial greenhouse experiment and assessed the biomass production and root architectural traits of the plants. There were clear differences in growth and above- and belowground architecture between Ammophila and Leymus, with Leymus plants being bigger, taller, and having longer roots than Ammophila. Inoculation with Rhizophagus increased above- and belowground biomass production by ~32% for both plant species. Inoculation with Pratylenchus decreased aboveground biomass production by ~36% for both plant species. However belowground, the exotic Leymus was significantly more resistant to PPN than the native Ammophila, and gained more benefits from AMF in belowground tri-trophic interactions than Ammophila. Overall, our results indicate that differences in plant architecture coupled with altered belowground interactions with AMF and PPN have the potential to promote exotic plant invasion.     

ECOTYPIC DIFFERENTIATION WITHIN FOUR NORTH AMERICAN PRAIRIE GRASSES. I. MORPHOLOGICAL VARIATION WITHIN TRANSPLANTED COMMUNITY FRACTIONS

Ecological variation within transplanted community fractions, containing Andropogon scoparius Michx., A. gerardi Vitman, Panicum virgatum L. and Sorghastrum nutans (L.) Nash, included broad behavioral and morphological differentiation. In Austin, Texas, during 1958–1962, southern community fractions that contained early spring activity, late flowering and late fall dormancy included taller plants than early-flowering, northern community fractions. The tallest populations in all 4 species originated in Texas. In P. virgatum, size of leaves and panicles showed north-south trends similar to culm height values. Leaf pubescence and leaf glaucousness in all 4 species showed geographic patterning that was not correlated with north-south maturity gradients. Greatest pubescence was on clones in community fractions from pine woods in the Southeast. Glaucousness was concentrated in community fractions from central Texas northward to Nebraska.     

Consequences of the Elimination of Old Leaves upon Spring Phenological Events and the New Leaves Nutrient Concentration in a Wintergreen Woody Species in the Southern Hemisphere

Previous studies analyzed the importance of old leaves conservancy for wintergreen species plant growth only after early spring old leaves elimination. However, carbon and nutrient resources for growth could have already been translocated from old leaves to shoots during autumn. In this work, the effect of old leaves absence on the leaf mass per area (LMA, g m⁻²) and nutrient concentration of new spring leaves, shoot growth, and flowering was studied in Aristotelia chilensis, an Andean Patagonic woody wintergreen species of Argentina. Plants were studied after autumn defoliation (AD) or late winter defoliation (WD) and results were compared to those of undamaged control plants (CO). The new leaves LMA and mineral nutrient (N, P, K, and Mg) concentration values did not decrease in AD or WD compared to CO plants. Conversely, CO plants showed higher flowering intensity and shoot lengthening compared to AD or WD plants. There were not remarkable differences regarding the defoliation time, though non-flowering shoots grew in a lesser degree than the flowering shoots in WD plants. It was concluded that A. chilensis old leaves cohort is an important source to shoot growth and flowering but their absence does not affect the new leaves structure or nutritional status from early spring in either AD or in WD plants. New leaves formation probably is guaranteed by resources (carbon and nutrients) previously stored in stems or even in the buds containing the preformed leaves since March, by the end of summer. Provided the availability of complete resources for the new leaf flush independently of the old leaves A. chilensis would restore the carbon balance as soon as possible to resume the growth of heterotrophic tissues at normal rates. Endogenous response to counterbalance the old leaves absence on non-flowering shoots was more effective when there was greater lag time between defoliation and shoot growth resume. Flowering and non-flowering shoots compete for the available resources when A. chilensis have not yet expanded leaves and shoots supporting reproductive structures were stronger sinks compared to non-flowering shoots in WD plants.     

Inheritance of a Mutation which Suppresses Flowering in Red Clover

A spontaneous mutation isolated from stocks of red clover (cultivarS123) prevents flower initiation unless plants are suppliedexogenously with gibberellin. Mutant plants are also more uprightand densely tillering in their growth habit. Inheritance ofthe non-flowering character was analysed in a series of crossesbetween wild-type S123 and mutant plants. Hybridity followingintercrossing was confirmed using electrophoretic variants ofcytoplasmic phosphoglucose isomerase coded by a- and b-allelesof the nuclear gene Pgi-2. All F₁ plants flowered normally andwere heterozygous at the Pgi-2 locus. However, F₂ segregationsdid not provide the expected ratios, with flowering plants exceedingpredicted levels. One back-cross involving an F₁ plant and themutant parent gave flowering:non flowering and ab:aa Pgi-2 ratiosof 2:1 rather than the expected 1:1. The results are consistentwith the existence of a zygotic lethal factor, originally presentin heterozygous (non-lethal) form in the mutant (non-flowering)parent and tightly linked to the mutated gene. Segregants whichwere non-flowering always displayed the characteristic mutantgrowth form and seeds borne on these plants were lighter incolour than those borne on normal plants. Thus, there existsin red clover a gene designated ‘dig’ (developmentinfluencing gibberellin) which has several pleiotropic effectsincluding suppressing the initiation of flowering in normallyflorally-inductive environments. There are at least two allelicforms of the gene, F (flowering) and f (non-flowering).     

孝顺竹开花过程中DNA甲基化水平动态研究

以孝顺竹为材料,利用HPLC和MSAP技术在其未开花至开花的生长过程中进行甲基化水平的检测,分析竹子开花过程中基因组DNA甲基化的动态,以揭示DNA甲基化水平与竹子开花现象的相关性。结果显示:(1)孝顺竹基因组DNA甲基化率在不同的时间处于动态变化中,进入开花状态的孝顺竹植株其甲基化水平极显著低于开花竹丛中未开花植株和未开花竹丛;开花和未开花植株的总甲基化率分别为9.00%和12.42%,全甲基化率分别为5.06%和7.53%。(2)MSAP位点中有66.83%的位点在开花和未开花材料中甲基化状态保持一致,33.17%的位点在开花和未开花植株中发生甲基化变化:其中22.28%的位点在开花植株中发生完全的去甲基化,1.98%的谱带在开花植株中发生甲基化,8.91%的位点在开花和未开花材料中甲基化水平呈现上升或降低的趋势。研究表明,开花的孝顺竹同时发生甲基化和去甲基化,但发生去甲基化的概率明显大于发生甲基化的概率,最终导致其甲基化水平极显著降低。     

Patterns in the Distribution of American Beachgrass (<Emphasis Type="Italic">Ammophila breviligulata</Emphasis>) and the Density and Reproduction of Annual Plants on a Coastal Beach

Beach communities of eastern North America are commonly dominated by the native perennial grass Ammophila breviligulata. It typically co-occurs with a variety of annual grasses and herbs in the pioneer zone. To determine the potential significance of this vigorous clonal species to the annual community, density, spatial distribution, seed production and potential seed rain were quantified for three focus species (Triplasis purpurea, Cenchrus tribuloides, and Heterotheca subaxillaris) in a 45×40 m section of coastal beach on Staten Island, New York, USA. During autumn 2000, five 40 m transects (10 m apart) were established perpendicular to shore; ramet density for Ammophila, and densities and per capita seed production for the three species, were estimated in 150 contiguous quadrats (35 cm × 30 cm) per transect. Both Triplasis and Cenchrus were more likely to occur in quadrats without Ammophila. Per capita seed production of Cenchrus and Heterotheca showed a curvilinear decrease with increasing numbers of Ammophila ramets. Mean seed rain per m² was significantly reduced in the presence of Ammophila for all three focus annuals. In this beach community, Ammophila acts as an ecosystem engineer, but has a mostly negative influence on the distribution, density, and reproduction of the co-occurring annuals. Results suggest that continual, deliberate planting of A. breviligulata could be detrimental to the abundance and diversity of native annual herbs on the eastern coasts of North America.     

Barrier Island Morphology and Sediment Characteristics Affect the Recovery of Dune Building Grasses following Storm-Induced Overwash

Barrier islands are complex and dynamic systems that provide critical ecosystem services to coastal populations. Stability of these systems is threatened by rising sea level and the potential for coastal storms to increase in frequency and intensity. Recovery of dune-building grasses following storms is an important process that promotes topographic heterogeneity and long-term stability of barrier islands, yet factors that drive dune recovery are poorly understood. We examined vegetation recovery in overwash zones on two geomorphically distinct (undisturbed vs. frequently overwashed) barrier islands on the Virginia coast, USA. We hypothesized that vegetation recovery in overwash zones would be driven primarily by environmental characteristics, especially elevation and beach width. We sampled species composition and environmental characteristics along a continuum of disturbance from active overwash zones to relict overwash zones and in adjacent undisturbed environments. We compared species assemblages along the disturbance chronosequence and between islands and we analyzed species composition data and environmental measurements with Canonical Correspondence Analysis to link community composition with environmental characteristics. Recovering and geomorphically stable dunes were dominated by Ammophila breviligulata Fernaud (Poaceae) on both islands while active overwash zones were dominated by Spartina patens (Aiton) Muhl. (Poaceae) on the frequently disturbed island and bare sand on the less disturbed island. Species composition was associated with environmental characteristics only on the frequently disturbed island (p = 0.005) where A. breviligulata was associated with higher elevation and greater beach width. Spartina patens, the second most abundant species, was associated with larger sediment grain size and greater sediment size distribution. On the less frequently disturbed island, time since disturbance was the only factor that affected community composition. Thus, factors driving the abundance of dune-building grasses and subsequent recovery of dunes varied between the two geomorphically distinct islands.     

Biotic soil factors affecting the growth and development of Ammophila arenaria

Summary To study the origin of replant disease of Ammophila arenaria (L.) Link the growth and development in sand originating from the rhizosphere of a natural Ammophila vegetation was compared with the growth in sand from the sea-floor. In a greenhouse experiment, the growth of Ammophila seedlings in rhizosphere sand, when compared with that in sea sand, was significantly reduced. As sterilization by means of gamma-irradiation increased the biomass production of Ammophila seedlings significantly, it was concluded that the rhizosphere sand contained biotic factors that were harmful to Ammophila. In rhizosphere sand the roots of Ammophila were brown and poorly developed, and the specific uptake rates of N, P and K were reduced. The shoot weight proportion of the total plant dry matter was hardly influenced. In an outdoor experiment with Ammophila seedlings and cuttings, using both sands, the mortality was high and the plants were feeble in rhizosphere sand whereas plants in sea sand grew vigorously. It seems plausible that the plants in rhizophere sand were dessicated because the root system was shallow and badly developed. In the greenhouse experiments, Ammophila cuttings were less sensitive to the inhibiting factors in the rhizosphere than seedlings. This was confirmed in the outdoor experiment. Calammophila baltica (Fluegge ex Schrader) Brand, however, was hardly affected by the harmful biotic factors in the greenhouse. These results are discussed with reference to the ecology of Ammophila. It is assumed that the catching of fresh windblown sand provides Ammophila with a way to escape from harmful biotic soil factors, and it was concluded that degeneration of Ammophila is caused mainly by self-intolerance due to these biotic soil factors.     

Warming leads to divergent responses but similarly improved performance of two invasive thistles

Plants’ responses to climate change are complex. Even the same net performance changes may involve different responses of multiple life history traits. Here we show that two congeneric thistles, Carduus nutans and Carduus acanthoides, both grew taller under increased temperature, albeit following divergent response patterns. For C. nutans, warming advanced bolting more than flowering, leading to a longer growing period before flowering and ultimately taller plant height at the end of the growing season. Carduus acanthoides maintained the same length of growing period because of equally shifted events in the phenological sequence, however, post-flowering growth rate was increased, which also led to enhanced final plant height. As seeds from taller plants disperse farther, their responses imply that future invasion spread rates of these two species will increase. Similar consequences due to divergent responses in life history traits, as demonstrated in this study, suggest that considering only ultimate performance outcomes, and not the underlying processes generating such outcomes, is not enough to understand the impacts of climate change.     

Parasitoid Preference for Host-Infested Plants Is Affected by the Risk of Intraguild Predation

Flowering Rorippa indicaplants are attended by ants that collect nectar and, at the same time, prey on herbivorous insects, including larvae of the diamondback moth, Plutella xylostella.Here, we showed that P. xylostellalarvae suffered higher predation on R. indicawhose flowers were accessible by ants than on plants those whose flowers were inaccessible. Ants showed equal predation preference between unparasitized and larvae parasitized by Cotesia plutellae,a dominant specialist parasitic wasp of P. xylostellalarvae. C. plutellaepreferred non-flowering, host-infested R. indicato flowering, host infested R. indica.Based on these results, we infer that the preference of C. plutellaefor non-flowering, host-infested plants is in part explained by the avoidance of intraguild predation by attending ants.     

Relationship between gibberellin and cytokinin activity and flowering in Rosa damascena Mill.

Kinetin at 10 mg l^–1 increased the number of flowers produced on Rosa damascena plants while GA₃ inhibited flowering. In the leaves of non-flowering plants GA-like activity was high while specific cytokinin activity (fraction-II) was significantly higher in flowering plants. A novel compound 10- methyldihydrozeatin riboside and isopentenyl-adenine were identified from TLC fraction-II while TLC fraction-I yielded zeatin and 2-hydroxy-6-methylaminopurine.Abbreviations TLC thin layer chromatography - BA N⁶-benzyladenine - GA₃ gibberellic acid CIMAP communication No. 92-40J     

Prevention of the flowering of a tree,silver birch

Genetic modification of trees presents great advantages but it is hampered by the possible spread of introduced genes to native populations. However, the spread would be prevented if the modified trees would be sterile. We have previously shown that the induction of sterility by the prevention of flowering is possible in tobacco and Arabidopsis by introducing a gene construct composed of the ribonuclease gene BARNASE ligated to the flower-specific promoter of the birch gene BpMADS1. In the present study, we test this gene construct in silver birch (Betula pendula Roth). When this gene construct was introduced into very early-flowering birch clones, 81 kanamycin resistant lines were obtained. In 38 lines, the vegetative development was disturbed, e.g., the leaves were small and the plants were short and bushy or the growth of plants was weak. More importantly, in 7 other lines no male inflorescences formed or they aborted early. If male inflorescences were formed, they did not contain any stamens. The initial growth of these lines was similar to the non-transgenic control lines. Later, however, the growth of the non-flowering lines differed from that of the controls in showing some dichotomic branching and a reduced number of branches. Preliminary results showed that the gene construct can prevent the development of female inflorescences as well. The results show clearly that BpMADS1::BARNASE can prevent the flowering in a tree but the prevention of flowering may cause some side effects. Studies with ordinary birch clones will show whether the side effects are a property of the early flowering clones or all birches.     

Management of below-ground biomass of <Emphasis Type="Italic">Typha angustifolia</Emphasis> by harvesting shoots above the water surface on different summer days

A dynamic model of regrowth in Typha angustifolia after cutting shoots above the water surface was formulated by characterizing the phenology and mobilization of resources from below-ground to above-ground organs after the cutting. The model parameters were determined by two cutting experiments to investigate the different strategies with flowering and non-flowering shoots after cutting in 2001 and by four cutting experiments to elucidate the regrowth characteristics after cutting on different days from June to September in 2002. A difference was evident both for flowering and non-flowering shoots and for each cutting day. From June to August, non-flowering shoots regrew immediately after cutting, but flowering shoots did not. The shoot regrowth height, number of leaves and shoot biomass were higher with the earlier cutting. The model was validated using the below-ground biomass observed in December 2002 and below-ground dynamics observed in 2003. In the low-flowering shoot zone of the stands, in which the percentage of flowering shoots was small (around 10%), the decrease in below-ground biomass became larger from June (20%) to August (60%). Cutting the high-flowering shoot zone (flowering shoots: 78%) in July 2001, just 1 week after peduncle formation, decreased the below-ground biomass by about 50%. In the low-flowering shoot zone, cutting just before senescence is better for decreasing below-ground biomass with a smaller rate of flowering shoots. The difference of below-ground biomass reduction in non-flowering shoots is mainly due to the decrease in downward translocation (DWT) of above-ground material to below-ground organs during senescence, because of the decrease in regrowth biomass. As for flowering shoots, the decrease in the photosynthate transportation from above-ground to below-ground organs and that of DWT are closely related because they cannot grow again within the season.     

Uprooting and Burial of Invasive Alien Plants: A New Tool in Coastal Restoration?

Invasive alien plants are a problem for conservation management, and control of these species can be combined with habitat restoration. Subsoil burial of uprooted plants is a new method of mechanical control, which might be suitable in disturbed habitats. The method was tested in Rosa rugosa (Japanese Rose), an invasive shrub in north‐western Europe with negative effects on coastal biodiversity. Two months after uprooting and burial in dunes of north‐eastern Denmark, 89% of the 58 shrubs resprouted from roots and rhizomes; on average 41 resprouts per shrub. Resprout density was twice as high at former shrub margins compared with the center; resprouts were taller and originated from more superficial soil layers at the margin than in the center. Resprouting was negatively correlated with fragment depth, and no resprouts were observed from greater than 15 cm depth. The number of resprouts increased with fragment dry mass (0.5–168.5 g). After 18 months with harrowing the species was still resprouting, flowering, and fruiting, albeit with no difference between shrub margin and center. Resprouts were taller (26 cm) and coverage was higher (0–4%) after two compared with three times harrowing, whereas no difference was found in cover of native dune species (1–5%). The results show that even small fragments of R. rugosa resprout, and that resprouting persists despite repeated harrowing. Thus, careful subsoil burial of all fragments is necessary, special attention should be paid to the shrub margin, and follow‐up treatments are needed. The effectiveness of the burial method is discussed for restoration of coastal dunes.     

Light partitioning among species and species replacement in early successional grasslands

Abstract. We studied canopy structure, shoot architecture and light harvesting efficiencies of the species (photon flux captured per unit above‐ground plant mass) in a series of exclosures of different age (up to 4.5 yr) in originally heavily grazed grassland in N Japan.Vegetation height and Leaf Area Index (LAI) increased in the series and Zoysia japonica, the dominant in the beginning, was replaced by the much taller Miscanthus sinensis. We showed how this displacement in dominance can be explained by inherent constraints on the above‐ground architecture of these two species. In all stands light capture of plants increased with their above‐ground biomass but taller species were not necessarily more efficient in light harvesting. Some subordinate species grew disproportionally large leaf areas and persisted in the shady undergrowth. Some other species first grew taller and managed to stay in the better‐lit parts of the canopy, but ultimately failed to match the height growth of their neighbours in this early successional series. Their light harvesting efficiencies declined and this probably led to their exclusion. By contrast, species that maintained their position high in the canopy managed to persist in the vegetation despite their relatively low light harvesting efficiencies. In the tallest stands ‘later successional’ species had higher light harvesting efficiencies for the same plant height than ‘early successional’ species which was mostly the result of the greater area to mass ratio (specific leaf area, SLA) of their leaves. This shows how plant stature, plasticity in above‐ground biomass partitioning, and architectural constraints determine the ability of plants to efficiently capture light, which helps to explain species replacement in this early successional series.