Foliage randomness and light interception in 3-D digitized trees: an analysis from multiscale discretization of the canopy

Light models for vegetation canopies based on the turbid medium analogy are usually limited by the basic assumption of random foliage dispersion in the canopy space. The objective of this paper was to assess the effect of three possible sources of non-randomness in tree canopies on light interception properties. For this purpose, four three-dimensional (3-D) digitized trees and four theoretical canopies – one random and three built from fractal rules – were used to compute canopy structure parameters and light interception, namely the sky-vault averaged STAR (Silhouette to Total Area Ratio). STAR values were computed from (1) images of the 3-D plants, and (2) from a 3-D turbid medium model using space discretization at different scales. For all trees, departure from randomness was mainly due to the spatial variations in leaf area density within the canopy volume. Indeed STAR estimations, based on turbid medium assumption, using the finest space discretization were very close to STAR values computed from the plant images. At this finest scale, foliage dispersion was slightly clumped, except one theoretical fractal canopy, which showed a marked regular dispersion. Taking into account a non-infinitely small leaf size, whose effect is theoretically to shorten self-shading, had a minor effect on STAR computations. STAR values computed from the 3-D turbid medium were very sensitive to plant lacunarity, a parameter introduced in the context of fractal studies to characterize the distribution of gaps in porous media at different scales. This study shows that 3-D turbid medium models based on space discretization are able to give correct estimation of light interception by 3-D isolated trees, provided that the 3-D grid is properly defined, that is, discretization maximizes plant lacunarity.     

间伐改形对陇东旱塬密闭苹果园树体冠层结构和发育后期叶片质量的影响

为研究间伐改形对红富士成龄乔化密植果园树体冠层特征、生育后期叶片生理特性、养分积累分配规律、光合生产力和土壤水分时空分布动态的影响,以18年生‘红富士’苹果密闭园为试材,对苹果树单株结构参数、枝量、枝类组成、覆盖率、叶片光合速率等参数进行测定.结果表明: 密闭果园叶片光合作用受非气孔因素限制,导致PSII最大光化学效率、PSII光合潜能、光合性能指数下降了1.2%、11.5%、13.9%.间伐改形后,叶面积指数、树冠覆盖率有所降低,使得冠层直射光透过系数增加了79.0%,树形结构有所改善.苹果园总枝数降低到约1100400条·hm^-2,单株枝量增加了5.0%,短枝比例提高至73.0%.由于冠层光照条件的改善,叶面积、比叶质量、百叶重、叶绿素含量有不同程度的提高.叶片光合速率的提高促进了光合产物的积累,淀粉、蛋白质含量为密闭果园的143.5%、107.8%.叶片的发育质量与其所处的光照辐射环境有着密切联系,密闭果园经间伐、改形后,果园群体结构和冠层光照得以改善,促进了叶片生长发育,提高了叶片光合效能,降低了果园土壤水分的无效消耗,是陇东旱塬苹果产区密闭果园适宜的调整、优化方案.     

Influence of the variation of geometrical and topological traits on light interception efficiency of apple trees: sensitivity analysis and metamodelling for ideotype definition

Background and Aims

The impact of a fruit tree''s architecture on its performance is still under debate, especially with regard to the definition of varietal ideotypes and the selection of architectural traits in breeding programmes. This study aimed at providing proof that a modelling approach can contribute to this debate, by using in silico exploration of different combinations of traits and their consequences on light interception, here considered as one of the key parameters to optimize fruit tree production.

Methods

The variability of organ geometrical traits, previously described in a bi-parental population, was used to simulate 1- to 5-year-old apple trees (Malus × domestica). Branching sequences along trunks observed during the first year of growth of the same hybrid trees were used to initiate the simulations, and hidden semi-Markov chains previously parameterized were used in subsequent years. Tree total leaf area (TLA) and silhouette to total area ratio (STAR) values were estimated, and a sensitivity analysis was performed, based on a metamodelling approach and a generalized additive model (GAM), to analyse the relative impact of organ geometry and lateral shoot types on STAR.

Key Results

A larger increase over years in TLA mean and variance was generated by varying branching along trunks than by varying organ geometry, whereas the inverse was observed for STAR, where mean values stabilized from year 3 to year 5. The internode length and leaf area had the highest impact on STAR, whereas long sylleptic shoots had a more significant effect than proleptic shoots. Although the GAM did not account for interactions, the additive effects of the geometrical factors explained >90% of STAR variation, but much less in the case of branching factors.

Conclusions

This study demonstrates that the proposed modelling approach could contribute to screening architectural traits and their relative impact on tree performance, here viewed through light interception. Even though trait combinations and antagonism will need further investigation, the approach opens up new perspectives for breeding and genetic selection to be assisted by varietal ideotype definition.     

几个板栗株系的开花结果习性比较分析

采用在美国育成的几个株系,并以常见的本地栽培品种‘桂花香’作对照,对刚进入结果幼树的枝梢开花习性,枝梢生长情况与开花坐果关系,以及树冠不同部位的枝梢开花与坐果进行调查分析。结果表明：对全部参试材料而言,末级梢的长、粗度区间分别以20．0～59．9cm和0．5～1．49cm的雌花量和坐果数较高;株系95—1—26和95—1-9雌花着生部位较其它3个株系或品种的节位高出一倍以上,其平均着生节位与末级梢平均节位基本上相等;从树冠立体分布上看,其外围和树冠上部水平方向中膛结果数较多,但对于每个株系来说,又存在一定的差异。以上研究结果对幼年结果树的枝梢培养、树体的整形修剪,以及达到早期丰产具有实践指导意义。     

Simple equations to estimate light interception by isolated trees from canopy structure features: assessment with three-dimensional digitized apple trees

* Simple models of light interception are useful to identify the key structural parameters involved in light capture. We developed such models for isolated trees and tested them with virtual experiments. Light interception was decomposed into the projection of the crown envelope and the crown porosity. The latter was related to tree structure parameters. * Virtual experiments were conducted with three-dimensional (3-D) digitized apple trees grown in Lebanon and Switzerland, with different cultivars and training. The digitized trees allowed actual values of canopy structure (total leaf area, crown volume, foliage inclination angle, variance of leaf area density) and light interception properties (projected leaf area, silhouette to total area ratio, porosity, dispersion parameters) to be computed, and relationships between structure and interception variables to be derived. * The projected envelope area was related to crown volume with a power function of exponent 2/3. Crown porosity was a negative exponential function of mean optical density, that is, the ratio between total leaf area and the projected envelope area. The leaf dispersion parameter was a negative linear function of the relative variance of leaf area density in the crown volume. * The resulting models were expressed as two single equations. After calibration, model outputs were very close to values computed from the 3-D digitized databases.     

Variation in crown light utilization characteristics among tropical canopy trees

BACKGROUND AND AIMS: Light extinction through crowns of canopy trees determines light availability at lower levels within forests. The goal of this paper is the exploration of foliage distribution and light extinction in crowns of five canopy tree species in relation to their shoot architecture, leaf traits (mean leaf angle, life span, photosynthetic characteristics) and successional status (from pioneers to persistent). METHODS: Light extinction was examined at three hierarchical levels of foliage organization, the whole crown, the outermost canopy and the individual shoots, in a tropical moist forest with direct canopy access with a tower crane. Photon flux density and cumulative leaf area index (LAI) were measured at intervals of 0.25-1 m along multiple vertical transects through three to five mature tree crowns of each species to estimate light extinction coefficients (K). RESULTS: Cecropia longipes, a pioneer species with the shortest leaf life span, had crown LAI <0.5. Among the remaining four species, crown LAI ranged from 2 to 8, and species with orthotropic terminal shoots exhibited lower light extinction coefficients (0.35) than those with plagiotropic shoots (0.53-0.80). Within each type, later successional species exhibited greater maximum LAI and total light extinction. A dense layer of leaves at the outermost crown of a late successional species resulted in an average light extinction of 61% within 0.5 m from the surface. In late successional species, leaf position within individual shoots does not predict the light availability at the individual leaf surface, which may explain their slow decline of photosynthetic capacity with leaf age and weak differentiation of sun and shade leaves. CONCLUSION: Later-successional tree crowns, especially those with orthotropic branches, exhibit lower light extinction coefficients, but greater total LAI and total light extinction, which contribute to their efficient use of light and competitive dominance.     

In Loquat (Eriobotrya japonica Lindl.) Return Bloom Depends on the Time the Fruit Remains on the Tree

In loquat (Eriobotrya japonica Lindl.), the comparison of fruiting trees and defruited trees carried out covering a range of developmental fruit stages reveals a significant reduction in flowering due to fruit from its early stage of development, being higher when it changes color and becomes senescent, which coincides with the floral bud inductive period. This effect occurred both at the tree and at the shoot level. Furthermore, although current shoots almost always develop into panicles, those from fruiting trees develop fewer flowers, suggesting that fruit also affects at the floral bud level. In our experiment, the gibberellin concentration at the floral bud inductive period was significantly higher in bark tissues (periderm, cortex and phloem tissues) of fruiting trees, compared with defruited trees that tend to flower more. The lower concentration of IAA in the bark tissues of defruited trees also contributes to increase their flowering intensity. On the contrary, the zeatin concentration was higher. Accordingly, at bud burst, the IAA/zeatin ratio, an indication of effect on flowering, was significantly higher for fruiting trees. Some disruption in the nitrate reduction process in fruiting tree was also observed. The process of floral bud induction and differentiation was not associated with either reducing or translocating and reserve carbohydrate concentration. Hence, loquat flower intensity depends on the time the fruit is maintained on the tree. The intensity is affected indirectly, by reducing the number of shoots, and directly, by reducing the number of flowers per panicle, and these effects are linked to endogenous plant hormone contents.     

Modeling the vertical foliage distribution of an individual <Emphasis Type="Italic">Castanopsis cuspidata</Emphasis> (Thunb.) Schottky,a dominant broad-leaved tree in Japanese warm-temperate forest

The vertical foliage distribution of Castanopsis cuspidata (Thunb.) Schottky was examined in trees of various sizes to clarify its variation in relation to tree size and the light environment in a stand. As indices of these parameters, we analyzed crown social position (CSP: percent of stand height) and specific leaf area (SLA). The vertical foliage distribution of trees was expressed by a Weibull function. The variation in the vertical foliage distribution of C. cuspidata could be categorized into three types using crown social position and light environment. In the first type, leaves were concentrated to the top 20% of the tree; such trees are canopy trees that can receive full sunlight. The second type had a large relative crown depth and an asymmetric distribution with the maximum foliage located near the top of the tree; such trees are suppressed trees whose crowns do not receive sufficient light. The third type had a large relative crown depth and a symmetric distribution; such trees occur in high light environments, although their crowns are in the understory layer. The differences in the vertical foliage distribution are related to the strategies used to capture light. Multiple regression analysis showed that CSP and SLA at the top layer of the tree explained successive changes in the vertical foliage distribution. These results will contribute to scaling-up the vertical foliage distribution to the community level in pure stands of C. cuspidata using an individual-based model.     

Plant growth-form alters the relationship between foliar morphology and species shade-tolerance ranking in temperate woody taxa

Variation in leaf size (area per leaf) and leaf dry weight per area (LWA) in relation to species shade- and drought-tolerance, characterised by Ellenberg's light (ELD) and water demand (EWD) values, respectively, were examined in 60 temperate woody taxa at constant relative irradiance. LWA was independent of plant size, but leaf size increased with total plant height at constant ELD. Canopy position also affected leaf morphology: leaves from the upper crown third had higher LWA and were larger than leaves from the lower third. Leaf size and LWA were negatively correlated, and leaf size decreased and LWA increased with decreasing species shade-tolerance. Mean LWA was similar for trees and shrubs, but trees had larger leaves than shrubs. Furthermore, all relationships were altered by plant growth-form: none of the qualitative tendencies was significant for trees. This implies the considerably lower plasticity of foliar parameters in trees than those in shrubs. Accordingly, shade-tolerance of trees, having relatively constant leaf structure, may be most affected by the variability in biomass partitioning and crown geometry which influence foliage distribution and spacing and finally determine canopy light absorptance. Alteration of leaf form and investment pattern for construction of unit foliar surface area which change the efficiency of light interception per unit biomass investment in leaves, is a competitive strategy inherent to shrubs. EWD as well as wood anatomy did not control LWA and leaf size, though there was a trend of ring-porous tree species to be more shade-tolerant than diffuse-porous trees. Since ring-porous species are more vulnerable to cavitation than diffuse-porous species, they may be constrained to environments where irradiances and consequently evaporative demand is lower.     

Comparative height crown allometry and mechanical design in 22 tree species of Kuala Belalong rainforest, Brunei, Borneo

In rainforests, trunk size, strength, crown position, and geometry of a tree affect light interception and the likelihood of mechanical failure. Allometric relationships of tree diameter, wood density, and crown architecture vs. height are described for a diverse range of rainforest trees in Brunei, northern Borneo. The understory species follow a geometric model in their diameter-height relationship (slope, β = 1.08), while the stress-elasticity models prevail (β = 1.27-1.61) for the midcanopy and canopy/emergent species. These relationships changed with ontogeny, especially for the understory species. Within species, the tree stability safety factor (SSF) and relative crown width decreased exponentially with increasing tree height. These trends failed to emerge in across-species comparisons and were reversed at a common (low) height. Across species, the relative crown depth decreased with maximum potential height and was indistinguishable at a common (low) height. Crown architectural traits influence SSF more than structural property of wood density. These findings emphasize the importance of applying a common reference size in comparative studies and suggest that forest trees (especially the understory group) may adapt to low light by having deeper rather than wider crowns due to an efficient distribution and geometry of their foliage.     

Changes in foliage distribution with relative irradiance and tree size: Differences between the saplings ofAcer platanoides andQuercus robur

Dependencies of foliage arrangement and structure on relative irradiance and total height (TH) were studied in saplings ofAcer platanoides andQuercus robur. The distribution of relative foliar area and dry weight (leaf area and weight in a crown layer per total tree leaf area and weight, respectively) were examined with respect to relative height (RH, height in the crown per TH) and characterized by the Weibull function. The distributions of relative area and weight were nearly identical, and the differences between them were attributable to a systematic decline in leaf dry weight per area with increasing crown depth. Foliage distribution was similarly altered by tree size in both species; RH at foliage maximum was lower and relative canopy size (RCS, length of live crown per TH) greater in taller trees. However, the distribution was more uniform inA. platanoides than inQ. robur. Apart from the size effects, relative irradiance also influenced canopy structure; RCS increased inQ. platanoides and decreased inQ. robur with increasing irradiance. As crown architecture was modified by irradiance, foliage distribution was shifted upwards with decreasing irradiance inA. platanoides, but it was independent of irradiance inQ. robur. Higher foliage maximum at lower irradiance in more shade-tolerantA. platanoides is likely to contribute towards more efficient foliar display for light interception and increase the competitive ability of this species in light-limited environments. Consequently, these differences in crown architecture and foliage distribution may partly explain the superior behavior ofA. platanoides in understory.     

Relationship between reproductive behavior and new shoot development in 5-year-old branches of olive trees (Olea europaea L.)

The development of new shoots plays a central role in the complex interactions determining vegetative and reproductive growth in woody plants. To explore this role we evaluated the new shoots in the olive tree, Olea europaea L., and the effect of fruiting on new shoot growth and subsequent flowering. Five-year-old branches served as canopy subunits in order to obtain a global, whole-tree view of new shoot number, size and morphological origin. The non-bearing trees had many more shoots than the fruit-bearing trees, and a greater number of longer shoots. In both bearing conditions, however, the majority of shoots were less than 4 cm long, with shoots of progressively longer lengths present in successively decreasing frequencies. Six major shoot types were defined on the basis of apical or lateral bud origin and of parent shoot age. On fruit-bearing trees, the new shoots originated predominantly from the shoot apex, while on non-fruiting trees, they formed mainly from axillary buds, but in both cases, they tended to develop on younger parent shoots. The previous bearing condition of the tree was the main determinant for subsequent inflorescence development, which was independent of both shoot type and length. Thus, reproductive behavior strongly affected both the amount and type of new branching, but subsequent flowering level was more influenced by previous bearing than by the potential flowering sites on new shoots.     

Shoot structure, canopy openness, and light interception in Norway spruce

We analysed changes in shoot structure with canopy openness in control (C) and irrigated–fertilized (IL) Picea abies trees. Canopy openness, which was used to characterize light availability, varied between 0·23 and 0·90 for C shoots and 0·07 to 0·75 for IL shoots. Needle width and thickness increased with canopy openness, but were similar for C and IL needles. The ratio of needle thickness to width remained fairly close to one throughout the canopy. This resulted in large values (3·0–4·0) of the ratio of total to projected needle area. The ratio of total to projected needle area did not correlate with canopy openness. Shoot silhouette to total needle area ratio (STAR) and specific needle area decreased with canopy openness. As a result, shoot silhouette area per unit needle mass was up to three times larger in shade shoots than in sun shoots. STAR and specific needle area were similar for C and IL shoots and needles. Needle nitrogen concentration varied between 0·7 and 1·1% (C), and between 1·0 and 1·6% (IL). On both plots, nitrogen content was linearly related to estimated relative light interceptance (RLI) (both expressed per needle area), but the ratio of nitrogen content to RLI increased with decreasing canopy openness.     

An increase in canopy cover leads to masting in Quercus ilex

Masting is the intermittent and synchronous production of large crops, but its relation to tree growth remains elusive despite the ecological relevance of mast seeding. The production of huge fruit crops has been linked to the accumulation and consumption of resources as nutrients and carbohydrates, but no conclusive assessment has supported this assumption. To evaluate if masting takes place once trees’ canopies reach maximum foliage, changes in canopy cover were measured in Quercus ilex susbp. ballota stands before and after a masting event using the normalized difference vegetation index (NDVI). The results on the whole underline that masting in Q. ilex occurred once maximum levels of NDVI and canopy cover were reached. After the masting event, NDVI dropped, leaf shedding increased and trees produced shorter shoots, narrower tree rings and fewer acorns than before the masting event. These findings support our contention that an increase in canopy cover precedes masting.     

Plant competition for light analyzed with a multispecies canopy model

Summary Competition for light among species in a mixed canopy can be assessed quantitatively by a simulation model which evaluates the importance of different morphological and photosynthetic characteristics of each species. A model was developed that simulates how the foliage of all species attenuate radiation in the canopy and how much radiation is received by foliage of each species. The model can account for different kinds of foliage (leaf blades, stems, etc.) for each species. The photosynthesis and transpiration for sunlit and shaded foliage of each species is also computed for different layers in the canopy. The model is an extension of previously described single-species canopy photosynthesis simulation models. Model predictions of the fraction of foliage sunlit and interception of light by sunlit and shaded foliage for monoculture and mixed canopies of wheat (Triticum aestivum) and wild oat (Avena fatua) in the field compared very well with measured values. The model was used to calculate light interception and canopy photosynthesis for both species of wheat/wild oat mixtures grown under normal solar and enhanced ultraviolet-B (290–320 nm) radiation (UV-B) in a glasshouse experiment with no root competition. In these experiments, measurements showed that the mixtures receiving enhanced UV-B radiation had a greater proportion of the total foliage area composed of wheat compared to mixtures in the control treatments. The difference in species foliage area and its position in the canopy resulted in a calculated increase in the portion of total canopy radiation interception and photosynthesis by wheat. This, in turn, is consistent with greater canopy biomass of wheat reported in canopies irradiated with supplemental UV-B.     

A three-dimensional statistical reconstruction model of grapevine (Vitis vinifera) simulating canopy structure variability within and between cultivar/training system pairs

Background and Aims

In grapevine, canopy-structure-related variations in light interception and distribution affect productivity, yield and the quality of the harvested product. A simple statistical model for reconstructing three-dimensional (3D) canopy structures for various cultivar–training system (C × T) pairs has been implemented with special attention paid to balance the time required for model parameterization and accuracy of the representations from organ to stand scales. Such an approach particularly aims at overcoming the weak integration of interplant variability using the usual direct 3D measurement methods.

Model

This model is original in combining a turbid-medium-like envelope enclosing the volume occupied by vine shoots with the use of discrete geometric polygons representing leaves randomly located within this volume to represent plant structure. Reconstruction rules were adapted to capture the main determinants of grapevine shoot architecture and their variability. Using a simplified set of parameters, it was possible to describe (1) the 3D path of the main shoot, (2) the volume occupied by the foliage around this path and (3) the orientation of individual leaf surfaces. Model parameterization (estimation of the probability distribution for each parameter) was carried out for eight contrasting C × T pairs.

Key Results and Conclusions

The parameter values obtained in each situation were consistent with our knowledge of grapevine architecture. Quantitative assessments for the generated virtual scenes were carried out at the canopy and plant scales. Light interception efficiency and local variations of light transmittance within and between experimental plots were correctly simulated for all canopies studied. The approach predicted these key ecophysiological variables significantly more accurately than the classical complete digitization method with a limited number of plants. In addition, this model accurately reproduced the characteristics of a wide range of individual digitized plants. Simulated leaf area density and the distribution of light interception among leaves were consistent with measurements. However, at the level of individual organs, the model tended to underestimate light interception.Key words: Canopy, architecture, hemispherical, picture, light interception, radiative, balance, stochastic, modelling, virtual, plants     

Light capture efficiency decreases with increasing tree age and size in the southern hemisphere gymnosperm Agathis australis

We investigated leaf and shoot architecture in relation to growth irradiance (Q_int) in young and mature trees of a New Zealand native gymnosperm Agathis australis (D. Don) Lindl. to determine tree size-dependent and age-dependent controls on light interception efficiency. A binomial 3-D turbid medium model was constructed to distinguish between differences in shoot light interception efficiency due to variations in leaf area density, angular distribution and leaf aggregation. Because of the positive effect of light on leaf dry mass per area (M_A), nitrogen content per area (N_A) increased with increasing irradiance in both young and mature trees. At a common irradiance, N_A, M_A and the components of M_A, density and thickness, were larger in mature trees, indicating a greater accumulation of photosynthetic biomass per unit area, but also a larger fraction of support biomass in older trees. In both young and mature trees, shoot inclination angle relative to horizontal, and leaf number per unit stem length decreased, and silhouette to total leaf area ratio (S_S) increased with decreasing irradiance, demonstrating more efficient light harvesting in low light. The shoots of young trees were more horizontal and less densely leafed with a larger S_S than those of mature trees, signifying greater light interception efficiency in young plants. Superior light harvesting in young trees resulted from more planar leaf arrangement and less clumped foliage. These results suggest that the age-dependent and/or size-dependent decreases in stand productivity may partly result from reduced light interception efficiency in larger mature relative to smaller and younger plants.     

苹果园光能截获率的数学模型

应用气象学原理推导了不同纬度、不同栽植行向、不同树形的苹果园光能截获率的数学模型,给出在保证树冠基部外围日照时间大于25％总日照时间的条件下,生长季中充分截获光能的最佳树形、行距、冠高、冠径的优化组合方案。实例分析表明,计算结果与专家经验基本一致。本研究为果园合理栽植,充分利用光能,合理整形修剪提供理论依据与参考方案。     

The ecology of tree reproduction in an African medium altitude rain forest

The occurrence of flowering and fruiting in tropical trees will be affected by a variety of factors, linked to availability of resources and suitable climatic triggers, that may be affected by increasing global temperatures. Community‐wide flowering and fruiting of 2526 trees in 206 plots were monitored over 24 years in the Budongo Forest Reserve (BFR), Uganda. Factors that were assessed included the size of the tree, access to light, the impacts of liana load, effects of tree growth, and variation between guilds of trees. Most flowering occurs at the end of the long dry season from February to April. Trees that had access to more light flowered and fruited more frequently. Pioneer and non‐pioneer light‐demanding species tended to reproduce more frequently than shade‐bearing species. Trees that grew faster between 1993 and 2011 also fruited more frequently. When examining all factors, growth rate, tree size, and crown position were all important for fruiting, while liana load but not growth rate was important in reducing flowering. Trees in BFR show a large decline in fruiting over 24 years, particularly in non‐pioneer light demanders, shade‐bearers, and species that produce fleshy fruits eaten by primates. The decline in fruit production is of concern and is having impacts on primate diets and potential recruitment of mahogany trees. Whether climate change is responsible is unclear, but flowering of the guilds/dispersal types which show declines is correlated with months with the coolest maximum temperatures and we show temperature has been increasing in BFR since the early 1990s.     

Phenology of Tree Species in Bolivian Dry Forests

Phenological characteristics of 453 individuals representing 39 tree species were investigated in two dry forests of the Lomerío region, Department of Santa Cruz, Bolivia. The leaf, flower, and fruit production of canopy and sub–canopy forest tree species were recorded monthly over a two–year period. Most canopy species lost their leaves during the dry season, whereas nearly all sub–canopy species retained their leaves. Peak leaf fall for canopy trees coincided with the peak of the dry season in July and August. Flushing of new leaves was complete by November in the early rainy season. Flowering and fruiting were bimodal, with a major peak occurring at the end of the dry season (August–October) and a minor peak during the rainy season (January). Fruit development was sufficiently long in this forest that fruiting peaks actually tended to precede flowering peaks by one month. A scarcity of fruit was observed in May, corresponding to the end of the rainy season. With the exception of figs (Ficus), most species had fairly synchronous fruit production. Most canopy trees had small, wind dispersed seeds or fruits that matured during the latter part of the dry season, whereas many sub–canopy tree species produced larger animal– or gravity–dispersed fruits that matured during the peak of the rainy season. Most species produced fruit annually. Lomerio received less rainfall than other tropical dry forests in which phenological studies have been conducted, but rainfall can be plentiful during the dry season in association with the passage of Antarctic cold fronts. Still, phenological patterns in Bolivian dry forests appear to be similar to those of other Neotropical dry forests.