Faster Height Growth Research Articles

Correction: Fast height growth is key to non-native conifers invasiveness in temperate forests

Correction: Fast height growth is key to non-native conifers invasiveness in temperate forests

Fast height growth is key to non-native conifers invasiveness in temperate forests

Fast height growth is key to non-native conifers invasiveness in temperate forests

Warming, drought, and disturbances lead to shifts in functional composition: A millennial-scale analysis for Amazonian and Andean sites.

Tropical forests are changing in composition and productivity, probably in response to changes in climate and disturbances. The responses to these multiple environmental drivers, and the mechanisms underlying the changes, remain largely unknown. Here, we use a functional trait approach on timescales of 10,000 years to assess how climate and disturbances influence the community-mean adult height, leaf area, seed mass, and wood density for eight lowland and highland forest landscapes. To do so, we combine data of eight fossil pollen records with functional traits and proxies for climate (temperature, precipitation, and El Niño frequency) and disturbances (fire and general disturbances). We found that temperature and disturbances were the most important drivers of changes in functional composition. Increased water availability (high precipitation and low El Niño frequency) generally led to more acquisitive trait composition (large leaves and soft wood). In lowland forests, warmer climates decreased community-mean height probably because of increased water stress, whereas in highland forests warmer climates increased height probably because of upslope migration of taller species. Disturbance increased the abundance of acquisitive, disturbance-adapted taxa with small seeds for quick colonization of disturbed sites, large leaves for light capture, and soft wood to attain fast height growth. Fire had weak effects on lowland forests but led to more stress-adapted taxa that are tall with fast life cycles and small seeds that can quickly colonize burned sites. Site-specific analyses were largely in line with cross-site analyses, except for varying site-level effects of El Niño frequency and fire activity, possibly because regional patterns in El Niño are not a good predictor of local changes, and charcoal abundances do not reflect fire intensity or severity. With future global changes, tropical Amazonian and Andean forests may transition toward shorter, drought- and disturbance-adapted forests in the lowlands but taller forests in the highlands.

Genotypic traits and tradeoffs of fast growth in silver birch, a pioneer tree

Fast-growing and slow-growing plant species are suggested to show integrated economics spectrums and the tradeoffs of fast growth are predicted to emerge as susceptibility to herbivory and resource competition. We tested if these predictions also hold for fast-growing and slow-growing genotypes within a silver birch, Betula pendula population. We exposed cloned saplings of 17 genotypes with slow, medium or fast height growth to reduced insect herbivory, using an insecticide, and to increasing resource competition, using naturally varying field plot grass cover. We measured shoot and root growth, ectomycorrhizal (EM) fungal production using ergosterol analysis and soil N transfer to leaves using 15N-labelled pulse of NH4+. We found that fast-growing genotypes grew on average 78% faster, produced 56% and 16% more leaf mass and ergosterol, and showed 78% higher leaf N uptake than slow-growing genotypes. The insecticide decreased leaf damage by 83% and increased shoot growth, leaf growth and leaf N uptake by 38%, 52% and 76%, without differences between the responses of fast-growing and slow-growing genotypes, whereas root mass decreased with increasing grass cover. Shoot and leaf growth of fast-growing genotypes decreased and EM fungal production of slow-growing genotypes increased with increasing grass cover. Our results suggest that fast growth is genotypically associated with higher allocation to EM fungi, better soil N capture and greater leaf production, and that the tradeoff of fast growth is sensitivity to competition, but not to insect herbivory. EM fungi may have a dual role: to support growth of fast-growing genotypes under low grass competition and to maintain growth of slow-growing genotypes under intensifying competition.

Genetic differentiation of indigenous (Quercus robur L.) and late flushing oak stands (Q. robur L. subsp. slavonica (G\xe1yer) M\xe1ty\xe1s) in western Germany (North Rhine-Westphalia)

Slavonian oaks (Quercus robur subsp. slavonica (Gáyer) Mátyás) originating from Croatia have been cultivated in Germany mainly in the Münsterland region of North Rhine-Westphalia since the second half of the nineteenth century. Compared to indigenous pedunculate oak stands in Germany, they are characterised by their late bud burst, but also by their excellent bole shape and faster height growth. Previously, Slavonian pedunculate oaks (= late flushing oaks) were mainly studied at chloroplast (cp) DNA markers in order to determine their geographical origin. The origin of the material is probably the Sava lowland between Zagreb and Belgrade. In the present study, the aim was to genetically differentiate between indigenous Quercus robur and Slavonian oak stands using nuclear DNA markers. For this purpose, we used 20 nuclear Simple Sequence Repeats (nSSRs). A total of 37 pedunculate oak stands (mean: 18.6 samples per population with an age of 95 to 210 years) were examined, of which 21 were characterized as Slavonian late flushing oaks and three stands for which the Slavonian origin was not clear. Maternally inherited chloroplast markers were analysed earlier in all 37 stands to validate their geographic origin. We found that the stands of native pedunculate oaks and Slavonian pedunculate oaks are represented by two genetic clusters which are weakly differentiated. Slavonian oaks (Na = 9.85, Ar = 8.689, Ho = 0.490, He = 0.540) showed similar levels of genetic variation as native oak stands (Na = 7.850, Ar = 7.846, Ho = 0.484, He = 0.526). Differences in growth and phenology and low but consistent genetic differentiation between groups suggest that both taxa represent different ecotypes with specific local adaptations, which are perhaps separated by less overlapping flowering phenologies. The nuclear microsatellite markers in combination with the cpDNA markers are suitable to differentiate between Slavonian and local oak stands.

Potential of Birch (Betula pendula Roth and B. pubescens Ehrh.) for Forestry and Forest-Based Industry Sector within the Changing Climatic and Socio-Economic Context of Western Europe

Five commercial tree species comprise nearly 80% of the forest standing stock volume in Western Europe. Nowadays, there is a strong need to consider a wider diversity of tree species, as evidenced by the impact of climate change and the forest health crises over the past decades. In this context, this study focuses on the potential of birch (Betula pendula Roth and Betula pubescens Ehrh.), a neglected indigenous species, for forestry and the forest-based industry sector. We have therefore compiled, analyzed, and discussed literature regarding the strengths and weaknesses of the species and the opportunities and threats of its use for this purpose. Among the strengths, birch tolerates various climates and sites, and high genetic variability promotes its adaptability. Birch improves forest resilience by colonizing forest gaps and quickly increasing soil functioning and biodiversity. Birch is also remarkably resistant to game overpopulation-associated damage. Large-sized logs are produced within relatively short periods with proper silvicultural treatment, and the wood characteristics allow versatile and valuable uses, as shown in Northern Europe. However, its weaknesses include high sensitivity to crown competition and to wood rot as challenges for silviculture. Among the opportunities, birch is well-suited to the global changes with its adaptability to climate change and its possible integration in diverse productive mixed tree stands. In the context of societal evolutions and customer perceptions, birch wood could play an increasing role in the building and furniture sectors, and among non-wood forest products. In Western Europe, the main obstacle to birch development is the lack of information on the wood uses and, consequently, the lack of interest among forest managers and wood processing professionals, which have led to a poor quality of the resource and to insufficient demand for its wood. Moreover, its fast height growth can affect the vitality of other species in mixed stands. Our analysis highlighted the potential of birch in the Western European forestry considering societal, ecological, and economic purposes in a changing climatic and socio-economic context and the need to (i) develop opportunities for industrial uses of birch wood, (ii) inform forest owners, managers, and industrial professionals about the potential value of birch, and (iii) define silvicultural guidelines.

Dynamic coupling of allometric ratios to a process-based forest growth model for estimating the impacts of stand density changes

Abstract Process-based models are increasingly applied for simulating long-term forest developments in order to capture climate change impacts and to investigate suitable management responses. Regarding dimensional development, however, allometric relations such as the height/diameter ratio, branch and coarse root fractions or the dependency of crown dimension on stem diameter often do not account for environmental influences. While this may be appropriate for even-aged, monospecific forests, serious biases can be expected if stand density or forest structure changes rapidly. Such events occur in particular when forests experience disturbances such as intensive thinning or during early development stages of planted or naturally regenerated trees. We therefore suggest a calculation of allometric relationships that depends primarily on neighbourhood competition. Respective equations have been implemented into a physiology-based ecosystem model that considers asymmetric competition by explicit simulation of resource acquisition and depletion per canopy layer. The new implementation has been tested at two sites in Germany where beech (Fagus sylvatica) saplings have either been planted below a shelterwood of old spruces (Picea abies) or grown under clear-cut conditions. We show that the modified model is able to realistically describe tree development in response to stand density changes and is able to represent regeneration growth beneath a gradually decreasing overstorey of mature trees. In particular, the model could represent the faster crown size development in saplings until full ground coverage is established and a faster height growth afterwards. The effect enhances leaf area and thus assimilation per tree and increases carbon availability for stem growth at early development stages. Finally, the necessity to consider dynamic allometric relations with respect to climate change impacts is discussed, and further improvements are suggested.

Comparing morphology and physiology of southeastern US Pinus seedlings: implications for adaptation to surface fire regimes

The suite of traits expressed as seedlings by coastal and mountain longleaf pine and south Florida slash pine suggest they can survive fire in the seedling stage. In contrast, loblolly pine and typical slash pine tolerate fire when mature but do not exhibit traits that allow them to survive fire when young, representing a different strategy for survival in frequently burned communities. Fire is an important driver in the distribution and abundance of southern US pine species, and seedling fire tolerance often determines individual survival under frequent fire regimes. We investigated seedling growth, biomass allocation, needle distribution, bark thickness, and total non-structural carbohydrate (TNC) storage in taproots and related them to the expression of fire-tolerance for five species or types, including loblolly pine (Pinus taeda L.), two longleaf pine (P. palustris Mill.) types representing two distinct ecological communities (coastal and mountain) and two slash pine (P. elliottii Englem.) varieties. We analyzed the relationship of seedling growth, biomass characteristics, and total non-structural carbohydrate storage between species by using analysis of variance. Both coastal and mountain longleaf pines had thick bark, long, densely arranged needles, and a grass-stage. South Florida slash pine shared the same suite of traits but, contrary to previous reports, displayed reduced height growth rather than a grass-stage. In contrast, loblolly pine and typical slash pine had faster height growth, more branching, lower needle density, and thinner bark. Both longleaf pines and south Florida slash pine also had higher TNC storage in taproots than either loblolly or typical slash pines. The relative strength of expression of these fire-adaptation traits among the five species types generally matches the fire-return intervals associated with each species’ habitat, suggesting the importance of fire regimes in determining the distribution and abundance of the studied species.

Low Habitual Dietary Calcium and Linear Growth from Adolescence to Young Adulthood: results from the China Health and Nutrition Survey

Evidences from clinical trials and meta-analyses of calcium supplementation in linear growth have given conflicting results, and few longitudinal studies have investigated the long-term associations between dietary calcium and linear growth, especially in the population with low-calcium plant-based diets. We investigated the prospective associations of low habitual dietary calcium with adult height and height-for-age z-score (HAZ) from adolescence to adulthood among 2019 adolescents from the China Health and Nutrition Survey (CHNS). The average dietary calcium intakes were 426(standard deviation: 158) mg/d in boys and 355(134) mg/d in girls during adolescence. During a median follow-up of 7.0 (interquartile range: 5.9–9.0) years, boys reached an average of 169.0(6.7) cm and girls reached 158.4(5.8) cm in adulthood. After adjusting for other potential confounders, non-linear regression found that boys with dietary calcium intakes below 327 mg/d had shorter adult stature, and those taking over 566 mg/d had faster height growth whether adjusting for physical exercises level or not. No significant associations were found in girls. Our study suggests that in boys with plant-based diets, higher dietary calcium intake during adolescence is associated with faster height growth, but not with adult height; calcium intake below 300 mg/d may result in shorter adult stature.

Resource allocation and storage relative to resprouting ability in wind disturbed coastal forest trees

Many plants persist by resprouting after disturbance. However, the benefits of resprouting (survival) may be traded off against height growth and reproduction. Resources (total non-structural carbohydrates—TNC) that could be allocated to growth or reproduction are stored or mobilised to support resprouting. TNC may either be stored by accumulation where availability exceeds the requirements for growth, or by reserve formation when storage is at the expense of growth. Thus, the mechanism of storage and resource allocation may differ between good (R+) and poor (R−) resprouters in response to nutrient availability and disturbance regime. R+ species typically reserve resources to ensure a rapid resprouting response to disturbance. We test whether R+ and R− species in coastal forest, under chronic wind disturbance, differ in growth rates, biomass allocation, leaf traits, water relations and storage of TNC. Seedlings from three confamilial pairs of R+ and R− tree species were subjected to nitrogen addition, water stress and clipping (simulating herbivory) treatments under greenhouse conditions. R− species had greater height growth rates, larger specific leaf area, lower root mass ratio and lower root TNC than R+ species. These differences between R+ and R− species were maintained irrespective of the levels of nitrogen, water and clipping treatments. R+ species did not increase their TNC concentration under nutrient and water stress, indicating that TNC is stored by reserve formation. R+ species appeared to trade-off growth against storage, while R− species did not. In R+ species, reserve formation is likely a bet-hedging strategy against occasional strong selection events in addition to chronic wind stress. By trading off height growth for better resprouting ability, good resprouters may be able to persist at more frequently disturbed sites (e.g., dune crests and windward slopes), while poor resprouters that have faster height growth can dominate less disturbed sites.

Major litterfall manipulation affects seedling growth and nutrient status in one of two species in a lowland forest in Panama

Abstract:Leaf litter is an important source of nutrients to tropical forest trees, but its importance for understorey seedling growth is not well understood. Seedlings of Licania platypus (n = 190) and Coussarea curvigemmia (n = 304) were transplanted into deeply shaded forest plots in Panama having received 2 y of litter addition or removal and 7 y of fertilization with nitrogen, phosphorus and potassium combined, and their growth and foliar nutrients measured after 13 and 6 mo respectively. Licania platypus growing in litter addition and removal plots had faster height growth and slower leaf growth respectively than in control plots; C. curvigemmia showed no significant effects apart from lower survival in litter addition plots. These effects may be driven by soil nutrients, as suggested by differences in foliar nitrogen and potassium (but not phosphorus) concentrations, and by a pot experiment in a shadehouse using Ochroma pyramidale seedlings, which showed higher leaf area in soils from litter-addition plots, although seedling dry weight was higher only in fertilized soils. Overall, these results show that for one of two species, understorey seedling growth was increased by 2 y of doubled litterfall, and thus that they were probably nutrient limited even in the relatively fertile soils of this semi-deciduous tropical forest.

Costs and benefits of relative bark thickness in relation to fire damage: a savanna/forest contrast

Summary In fire‐prone ecosystems, bark protects the stem bud bank from fire. Absolute bark thickness is a good indicator of this protective function, but it depends on stem size as well as inherent differences between species. Relative bark thickness (i.e. relative to stem diameter) takes the latter into account. We argue that relative bark thickness is an important functional trait offering insights to the evolution of species persistence in fire‐prone habitats. During growth ontogeny different species can acquire absolutely thick bark through having: (i) relatively thick bark (i.e. an early commitment to thick bark) or (ii) relatively thin bark but fast stem diameter growth rates. We test the hypothesis that the most effective way of protecting tree stems from frequent fire is by having relatively thick‐barked small stems. We predict that species with higher relative bark thickness are more common in fire‐prone habitats. In habitats with long fire‐free intervals such as rainforest, delayed investment in bark thickness results in thin bark. We examined the relative bark thickness of woody congeners from Australian non‐fire‐prone forest and fire‐prone savanna and in other tree‐dominated systems world‐wide. We determined the relative cost of acquiring absolute bark thickness of 0.5 cm for different rates of bark allocation. The insulating benefits of bark were considered a linear function of bark thickness. Synthesis. We suggest that relatively thick bark minimizes the costs of acquiring absolutely thick bark, and it confers greater protection to smaller stems. The cost of acquiring thick bark prevents small trees from merely accumulating bark as a consequence of fast height or stem diameter growth. Accordingly, our field survey indicated that forest species had relatively thin bark and acquired thick bark only as a consequence of very large size, while fire‐prone savanna species had relatively thick‐barked small stems. Based on this, relative bark thickness appears to be a good predictor of local fire regimes and is a useful plant functional trait.

Maternal smoking during pregnancy and offspring trajectories of height and adiposity: comparing maternal and paternal associations

Background Maternal smoking during pregnancy is associated with reduced offspring birth length and has been postulated as a risk factor for obesity. Causality for obesity is not established. Causality is well-supported for birth length, but evidence on persistence of height deficits is inconsistent.Methods We examined the association between maternal smoking during pregnancy and trajectories of offspring height (0–10 years, N = 9424), ponderal index (PI) (0–2 years, N = 9321) and body mass index (BMI) (2–10 years, N = 8887) in the Avon Longitudinal Study of Parents and Children. To strengthen inference, measured confounders were controlled for, maternal and partner smoking associations were compared, dose–response and associations with post-natal smoking were examined.Results Maternal smoking during pregnancy was associated with shorter birth length, faster height growth in infancy and slower growth in later childhood. By 10 years, daughters of women who smoke during pregnancy are on average 1.11 cm (SE = 0.27) shorter after adjustment for confounders and partner smoking; the difference is 0.22 cm (SE = 0.22) for partner's smoking. Maternal smoking was associated with lower PI at birth, faster PI increase in infancy, but not with BMI changes 2–10 years. Associations were stronger for maternal than partner smoking for PI at birth and PI changes in infancy, but not for BMI changes after 2 years. A similar dose–response in both maternal and partner smoking was seen for BMI change 2–10 years.Conclusion Maternal smoking during pregnancy has an intrauterine effect on birth length, and possibly on adiposity at birth and changes in height and adiposity in infancy. We do not find evidence of a specific intrauterine effect on height or adiposity changes after the age of 2 years.

Influence of growth trajectories on risk of overweight during early childhood among a population‐based longitudinal cohort in China

To assess the nutritional status of preschool children aged under 5 in China and to examine the influence of early growth patterns on later adiposity and overweight risks (assessed using body mass index, BMI), we followed 131,215 children born during 2000–2005 in Zhejiang Province, south China. Z scores and prevalence of overweight were calculated using the 2006 WHO growth charts. The association was explored using linear and logistic models. From age 1 to 5, the prevalence (%) of overweight (BMI z‐score<2) decreased from 7.2, to 5.3, 3.1, 2.1, and 2.1, respectively. In the 21,711 participants with repeated anthropometric measures between birth and ages of 4–5, prevalence of overweight at ages 4–5 was 2.1%, while 11.8% had a BMI z‐score<1. Elevated risk for overweight at age 4–5 was associated with faster weight gain (100 g/month) during infancy (OR=2.41; 95% CI: 2.13–2.72) and 1‐3 years of life (OR=11.39 (9.10–14.26)) adjusted for covariates, while the risk was negatively associated with faster height growth (P<0.05). Other factors such as gender, urban/rural residence, birth weight, access to health care, maternal BMI and weight gain during pregnancy were also associated with overweight risk (P<0.05). In conclusion, prospective data from a large birth cohort in China show that rapid weight gain during early years of life and other pre‐ and postnatal factors predict increased risk for overweight at age 4‐5 years.

Aggregations of dead wood after wildfire act as browsing refugia for seedlings of Populus tremula and Salix caprea

In the European boreal forest, early successional tree species in the genera Salix and Populus are among the most favoured by browsers, often causing poor regeneration. It is frequently assumed that the fast height growth rate of these species on favourable sites can increase their chances to outgrow browsers. Spatial or temporal variation in browsing pressure could be important mechanisms for escape too, but there are few examples of this. In 1999 a large area of old-growth mixed Pinus sylvestris L. and Picea abies L. Karst. forest burned in Tyresta National Park in central Sweden. In the following year, an abundance of Populus tremula L. and Salix caprea L. seedlings regenerated naturally. Four years later we analyzed seedling height and browsing history for the tallest seedlings inside and outside natural aggregations of dead wood formed by windthrow of fire-killed trees. All seedlings outside the aggregations had been browsed (on average three times) and average height was 60 ± 9 cm for P. tremula and 54 ± 12 cm for S. caprea. Inside aggregations, only 33% of the tallest seedlings had any evidence of browsing, and in most cases only from one episode. Average height for P. tremula was 153 ± 41 cm and for S. caprea 167 ± 27 cm. Stem base diameter was also wider for seedlings growing in dead wood aggregations than in open areas. Droppings of moose, roe deer, and hare were abundant in the area, but judging from bite marks, most browsing damage was due to the ungulates. For seedlings inside dead wood aggregations, backward regression analysis showed that both the structure of the aggregations and the spatial position of seedlings influenced seedling height: for P. tremula seedlings, there was a significant association with increasing height of the dead wood aggregation, increasing distance to the edge of the aggregation, and decreasing distance to the nearest dead wood stem. For S. caprea seedlings there was a significant association only with the height of the aggregation. The results show that the legacy of the pre-fire tree stand can allow seedlings of palatable early successional trees to escape browsers. The effectiveness of this mechanism depends on both the quality of the pre-fire stand and on the fire behaviour generating the dead wood. A fire regime of long fire-intervals (allowing for wide-crowned trees to develop) followed by a stand-replacing fire (allowing for large aggregates of dead wood) would be optimal.

Selection for improved growth and wood quality in lodgepole pine: effects on phenology, hydraulic architecture and growth of seedlings

Selection for both growth and wood quality is the primary goal of many tree breeding programs. In order to investigate the impacts of such selection on adaptive traits, observations were made on phenology, drought resistance, xylem conductance and xylem vulnerability to cavitation of 2-year-old seedlings of lodgepole pine (Pinus contorta Dougl. Ex Loud var. latifolia Engelm) from four subpopulations: (1) fast height growth and high wood density (FH); (2) slow height growth and high density (SH); (3) fast height growth and low density (FL); and (4) slow height growth and low density (SL). Results showed that the impact of the selection on phenology was minor; differences in growth among subpopulations were mainly attributable to maximal growth rate and the duration of the period of rapid growth. The FL subpopulation showed a significantly stronger productivity decline in response to moderate drought compared to the two slower-growing subpopulations. The FH subpopulation showed significantly higher xylem specific conductivity than the two slower-growing subpopulations, and greater resistance to cavitation than the other three subpopulations, suggesting the possibility of selecting families that combine fast growth, high wood density and drought tolerance.

Light environment and tree strategies in a Bolivian tropical moist forest: an evaluation of the light partitioning hypothesis

Light partitioning is thought to contribute to the coexistence of rain forest tree species. This study evaluates the three premises underlying the light partitioning hypothesis; 1) there is a gradient in light availability at the forest floor, 2) tree species show a differential distribution with respect to light, and 3) there is a trade-off in species performance that explains their different positions along the light gradient. To address these premises, we studied the light environment, growth, and survival of saplings of ten non-pioneer tree species in a Bolivian moist forest. Light availability in the understorey was relatively high, with a mean canopy openness of 3.5% and a mean direct site factor of 6.8%. Saplings of two light demanding species occurred at significantly higher light levels than the shade tolerant species. The proportion of saplings in low-light conditions was negatively correlated with the successional position of the species. Light-demanding species were characterised by a low share of their saplings in low-light conditions, a high sapling mortality, a fast height growth and a strong growth response to light. These data show that all three premises for light partitioning are met. There is a clear gradient in shade-tolerance within the group of non-pioneer species leading to a tight packing of species along the small range of light environments found in the understorey.

Architecture and neighbourhood competition of understorey saplings in a subalpine forest in central Japan

We investigated the effects of both overstorey shading and understorey sapling competition on the sapling architecture of three conifers, Abies mariesii, A. veitchii, and Picea jezoensis var. hondoensis, in a subalpine forest in central Japan. With increased overstorey shading, the two Abies species tended to have flatter crowns than P. jezoensis var. hondoensis. Because a flattened crown enhances the efficiency of light interception under low light availability, both Abies species appear more adapted to shading. Conversely, P. jezoensis var. hondoensis seems better adapted to canopy gaps, because its conical crown provides an advantage for faster height growth. Unlike A. veitchii, A. mariesii increased its stem volume to support the greater snow-loading resulting from its flattened crown. Therefore, A. mariesii seems better designed for enduring shading under snowy conditions. However, A. veitchii showed faster height growth and thus presents regeneration traits intermediate between those of A. mariesii and P. jezoensis var. hondoensis. Because sapling competition is intense in sapling-crowded microsites conditions under less crowded overstorey conditions, saplings need faster height increase to escape from other sapling competition. Conversely, because sapling competition is weaker and more space is available under a closed understorey, saplings need to have flatter crowns to compensate for overstorey shading. Species-specific architecture in response to such living conditions is closely associated with the regeneration characteristics of the three conifers studied.

Fugitive and possessive establishment strategies in Amazonian floodplain pioneers

Summary Two pioneer woody plant species with differential growth habits, Cecropia latiloba and Senna reticulata , form monospecific stands during secondary succession in Amazonian floodplains. The ‘fugitive strategy’ of Cecropia latiloba enables vertical evasion from competition by continuous height growth without branching. This establishment strategy is aided by high submergence tolerance. In contrast to this, the ‘possessive’ Senna reticulata shows fast height growth only in the first non-flooded period, with extreme lateral branching and effective shading of competitors. This strategy is efficient only on higher elevations in the flooding gradient where complete submergence does not occur and on sites with supposedly high nutrient availability. The present study describes the two establishment strategies for floodplain pioneers based on structural, physiological and reproductive characteristics of the two species, measured in the lower Rio Solimoes/Amazon River, Brazil, and in experiments performed at the INPA (Amazon Research Institute, Manaus). Despite several traits shared by the two species (many small seeds, high germination rates, high CO 2 -assimilation, fast initial growth, low maximum age, wood with high increments and low density), most physiognomic, structural and reproductive traits indicate two distinct establishment strategies which represent two extremes within a continuum of possible growth habits, and emphasize that also in ecosystems which have adverse growth conditions with prolonged flooding of up to 230 days every year and a water column of more than 10 m, the guild of pioneer trees does not necessarily form a homogeneous group.

Selection for height growth and Pilodyn pin penetration in lodgepole pine: effects on growth traits, wood properties, and their relationships

The effects of selection using indices of height growth and wood density based on Pilodyn pin penetration (PIN) and the relationships among growth traits and wood properties were investigated in lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.). Four subpopulations were constructed by selecting 10 open-pollinated families in each of four categories: (i) fast height growth and high wood density, (ii) slow height growth and high density, (iii) fast height growth and low density, and (iv) slow height growth and low density. Eleven-year growth, PIN, and wood-density traits generated from X-ray densitometry were analyzed. We found that selection of subpopulations using indices of height and PIN resulted in significant differences among subpopulations in most growth and wood-density parameters. However, PIN underestimated the wood density of families with large diameter. Disk density was found to be moderately negatively correlated with diameter growth, weakly negatively correlated with stem volume, but not significantly correlated with height. Selection for latewood proportion to improve wood density in lodgepole pine is likely to result in a reduction in growth and biomass production; however, selection for total latewood volume or simply height has the potential to increase both growth and wood density.