Variation In Fruit Production Research Articles

Intraspecific variation in fruit production of African mahogany (Khaya anthotheca) in a semi‐deciduous East African rainforest

AbstractRestoring valuable timber trees is a necessary part of regaining many ecosystem services and products provided by degraded tropical forests. However, knowledge of seed production, a regeneration prerequisite, is limited for many tropical timber tree species. We studied the fruit production of African mahogany (Khaya anthotheca) in a semi‐deciduous rainforest in East Africa, to provide information for ecological restoration programs. First, we quantified population variability and synchrony in fruit production. Then, we assessed how reproductive status and output were influenced by tree size, neighbourhood crowding, exchangeable cations, liana presence, and crown exposure. We found fruit production at the population level was weakly synchronised, with high interannual variability at the population and individual levels. Tree size determined reproductive status. Individual quantity of fruit produced increased with tree size but decreased with neighbourhood crowding. Our results indicate that K. anthotheca does not meet the criteria for mast fruiting. Our findings suggest that reproductive output in mahogany is regulated by tree size and competition. In addition to active protection, thinning to reduce competition around seed trees may boost fruit production at the individual tree level to provide seed for forest enrichment.

Are seeds of trees with higher fruit production dispersed farther by frugivorous mammals?

ABSTRACT Previous studies have estimated distributions of seed dispersal distance by a variety of methods. But apart from direct observation, these methods cannot clarify the absolute numbers of seeds dispersed by each disperser. Without the ability to calculate absolute spreading volumes, each dispersers’ contribution cannot be quantitatively evaluated. To resolve this problem, we estimated and compared quantities and distances of seed dispersal by mammalian seed dispersers. We focused on the fruits of Cerasus leveilleana and five species of frugivorous mammals that forage on it, central Japan. We tracked wild individuals of each species and gut retention times of seeds in captive individuals. By observing wild C. leveilleana trees for 2 years, we calculated fruit production, visitation frequency, and numbers of fruits removed per visit by each species. The mammal species differed greatly in body size and foraging behavior, and thus in the seed dispersal patterns that they generated: not only in dispersal distance, especially long distance, but also in the number of seeds removed. In particular, total seed removal and long-distance dispersal tended to be greater when fruit production was greater, and they were strongly affected by occasional visitation by bears. Therefore, understanding the relative functional importance of seed dispersers requires direct comparison of their effectiveness at seed dispersal. Large differences in the seed disperser fauna between years due to interannual variation in fruit production suggest that observations of many trees with different amounts of fruit production over multiple years are needed to clarify how fruiting trees and seed dispersers interact.

ESTIMATION OF SHEA TREES (Vitellaria paradoxa C.F. GAERTN.) FRUIT PRODUCTION BY ASSESSING THE CORRELATION BETWEEN YIELD PARAMETERS AND DENDROMETRIC FEATURES IN NORTHERN OF CÔTE D'IVOIRE

Vitellaria paradoxa, commonly known as the shea tree, is a tree of the family Sapotaceae and represents a traditional African food plant. It has been claimed to have the potential to improve nutrition, boost food supply, foster rural development, and support sustainable land care. Despite its multiple potentials, statistical data relating to its production are non-existent and/or unexploited in several African communities. To contrast this tendency, the present study aims to assess the intra-seasonal variation in fruit production of a sample of 115 shea trees and then to establish a correlation between yield parameters and several dendrometric features. Dendrometric (i.e. tree height, trunk girth, and crown basal area) and pomological (i.e. fruit and nut length and width) parameters, as well as yield parameters by monitoring daily fallen fruit from each sampled shea tree, carried out for five years consecutively, were considered for this study. The results showed inter-year fluctuation of shea fruit/nut number and shea fruit/nut weight. In addition, the results showed a significant increase in the annual average of shea fruit/nut yield per tree and as well per girth and/or crown basal area interval class, randomly generated by Sturge and Yule's formula. Interestingly, potentially high producing trees emerged within each considered interval class. Then, observed intraclass variation between trees determining shea yield can be exploited in selecting elite shea trees.

Three decades of declining natural foods alters bottom-up pressures on American black bears

Wildlife management entails the manipulation of bottom-up and top-down forces that affect populations. For bear management in North America, both food availability (bottom-up) and hunting pressure (top-down) can limit population growth. Whereas seasonal and year-to-year variation in production of fruits and nuts (i.e., primary bear foods) has been widely recognized, long-term trends in natural food production have rarely been reported. Here we compared the current (2015–2019) availability of 18 fruits and nuts representing the main foods of American black bears (Ursus americanus) in north-central Minnesota to what was available three decades earlier (1980s) on the same study area. Timber harvesting was routine in the 1980s but less intensive in recent decades, prompting us to hypothesize that forests matured and consequently produced less fruit for bears due to increased shade. Within each of 12 forest types, we measured the abundance, productivity and biomass (kg/ha) of each fruit-bearing plant species using the same methodology as in the 1980s. Bootstrapped independent two-sample t-tests identified species-specific changes in food availability between the two sampling periods. Generalized linear mixed-effects models were used to quantify changes for groups of fruit-producing species (i.e., summer/fall foods and short/tall shrubs). For all these groups, availability of the fruiting species changed little, but the probability of forest stands producing any fruit at all in the recent time period (~40%) was nearly half what it was in the 1980s (~80%). At the landscape scale, we estimated a ~70% decline in fruit biomass. Our hypothesis that this decline was due to reduced timber harvesting and thus denser canopy was only partially correct, as we observed the same decline in fruit production within forests of the same type and canopy closure, and also along edges of stands with high light penetration. Decline in fruit availability was due more to a complete lack of production in some stands of the same type and age rather than to general forest maturation. We explored three alternate hypotheses to explain this decline: (1) change in weather (which could affect fruiting directly, or cause issues with pollination), (2) increase in invasive earthworms, and (3) increased deer browsing. None of these were completely consistent with our findings, although it appeared from the extreme spatial variability in fruit production that on-the-ground factors were more of a driving force than weather. The magnitude and complexity of this change in bottom-up forces is a serious issue for bear management.

Influence of neighbor competition and tree attributes on the fruit production of Sinomanglietia glauca, an endangered tree species endemic to China

Sinomanglietia glauca is a critically endangered species with limited population and narrow distribution in China. Yet to date, we know surprisingly little about how the characteristics of forests affect the reproduction process of S. glauca individuals. The fruit production of S. glauca individuals was examined in artificial forest (AF), free-encroached deciduous forest (FF), and intensively encroached forest by evergreen trees and moso bamboos (EF) at Mingyueshan Mountain in Jiangxi province. The relationships between the characteristics of fruits and seeds and those of parent trees and neighborhood were analyzed through redundancy analysis. The fruiting indicators (number, weight and volume of fruits/seeds) for S. glauca in AF were significantly higher than those in EF and FF. The fruit production was positively related to the crown radius and the ratio of crown length to tree height, and was negatively linked to neighbor enclosure index. The characteristics of parent trees, neighborhood and their interaction explained the variation of fruit production by 70.6%. Although the competition of neighbors exerted less explanatory power than the characteristics of parent trees, it was negatively correlated with the crown radius and volume. The crown radius and neighbor enclosure were identified as the two dominant causal factors taking the major responsibility to the fruit production. The increasing competition from neighbors bring detrimental impacts on the fruiting of S. glauca. Efficient management strategies were proposed to reduce the interference from neighbors, such as reasonably pruning and thinning adjacent evergreen trees and bamboos.

Does masting scale with plant size? High reproductive variability and low synchrony in small and unproductive individuals

In a range of plant species, the distribution of individual mean fecundity is skewed and dominated by a few highly fecund individuals. Larger plants produce greater seed crops, but the exact nature of the relationship between size and reproductive patterns is poorly understood. This is especially clear in plants that reproduce by exhibiting synchronized quasi-periodic variation in fruit production, a process called masting. We investigated covariation of plant size and fecundity with individual-plant-level masting patterns and seed predation in 12 mast-seeding species: Pinus pinea, Astragalus scaphoides, Sorbus aucuparia, Quercus ilex, Q. humilis, Q. rubra, Q. alba, Q. montana, Chionochloa pallens, C. macra, Celmisia lyallii and Phormium tenax. Fecundity was non-linearly related to masting patterns. Small and unproductive plants frequently failed to produce any seeds, which elevated their annual variation and decreased synchrony. Above a low fecundity threshold, plants had similar variability and synchrony, regardless of their size and productivity. Our study shows that within-species variation in masting patterns is correlated with variation in fecundity, which in turn is related to plant size. Low synchrony of low-fertility plants shows that the failure years were idiosyncratic to each small plant, which in turn implies that the small plants fail to reproduce because of plant-specific factors (e.g. internal resource limits). Thus, the behaviour of these sub-producers is apparently the result of trade-offs in resource allocation and environmental limits with which the small plants cannot cope. Plant size and especially fecundity and propensity for mast failure years play a major role in determining the variability and synchrony of reproduction in plants.

Long-term trends in fruit production in a tropical forest at Ngogo, Kibale National Park, Uganda.

Fruit production in tropical forests varies considerably in space and time, with important implications for frugivorous consumers. Characterizing temporal variation in forest productivity is thus critical for understanding adaptations of tropical forest frugivores, yet long-term phenology data from the tropics, in particular from African forests, are still scarce. Similarly, as the abiotic factors driving phenology in the tropics are predicted to change with a warming climate, studies documenting the relationship between climatic variables and fruit production are increasingly important. Here we present data from 19 years of monitoring the phenology of 20 tree species at Ngogo in Kibale National Park, Uganda. Our aims were to characterize short- and long-term trends in productivity and to understand the abiotic factors driving temporal variability in fruit production. Short-term (month-to-month) variability in fruiting was relatively low at Ngogo, and overall fruit production increased significantly through the first half of the study. Among the abiotic variables we expected to influence phenology patterns (including rainfall, solar irradiance, and average temperature), only average temperature was a significant predictor of monthly fruit production. We discuss these findings as they relate to the resource base of the frugivorous vertebrate community inhabiting Ngogo.

Impact of environmental conditions on fruit production patterns of shea tree (Vitellaria paradoxa C.F.Gaertn) in West Africa

AbstractA better knowledge of the impact of environmental conditions on shea tree’s fruit production is critical to improve the species management. Fruit production of 237 shea trees was monitored over five successive years (2014–2018) to understand how climatic variables, shea tree population and land use could affect fruit production patterns of the species in Burkina Faso. Data were collected in 12 shea tree populations distributed in three climatic zones with two contrast land use systems. The results showed that fruit production was negatively correlated with mean annual temperature, temperature seasonality, rainfall seasonality and solar radiation, while it was positive with annual rainfall. Therefore, fruiting modelling is needed to predict the impact of future climate change on reproductive ability of the species. In each climatic zone, fruit production was significantly different among shea tree populations (p < 0.05). Within populations, fruit production greatly varies among years with specific patterns of variation. Land use had significant effect on fruit production of shea tree (p < 0.05). Annually, shea trees produced about 12 times more in agroforestry parklands than in protected areas. Interannual variation in fruit production at individual tree level was higher in protected areas. The cultivation of shea tree is recommended to improve its fruit productivity.

Variability and estimating in fruiting of shea tree (Vitellaria paradoxa C.F. Gaertn) associated to climatic conditions in West Africa: implications for sustainable management and development

ABSTRACT Shea tree (Vitellaria paradoxa) is one of the main native oil plants with high economic value in Africa. Its fruits are used for food, medicinal, cultural and exportation purposes. However, the lack of efficient tools to assess annual fruit production of the species limits the sustainable management of its resources. Therefore, production statistics are useful to organize the activities of the shea sector. This study aimed to (i) assess the interannual variation in fruit production along a climatic gradient in Burkina Faso, (ii) examine fruit production patterns according to climatic zones and tree size, (iii) assess the contribution of high-yielding trees in the annual potential production and (iv) develop allometric equations for estimating fruit yields of the species. The yield of 212 trees distributed across three climatic zones was monitored over four successive years. Within each climatic zone, fruit production was significantly different among years. Fruit production was positively and significantly correlated with tree size. The interannual variation in fruit production at tree individual level was higher in drier climatic conditions. The mean interindividual synchrony was less than 50% in each zone, suggesting a large range in fruit production patterns of the species. Annually, more than 55% of the total fruit production was supported by high-yielding trees. The best regression models for estimating fruit yields had R 2 values of 69–73% with prediction errors ranging from −7% to 4%. Our findings are useful tools for the planning of rational exploitation of shea tree’s resources and its sustainable management.

Masting synchrony in northern hardwood forests: super‐producers govern population fruit production

Summary Trees commonly reproduce via masting cycles, which involves synchronized inter‐annual variability in fruit crop size. A few individuals in a population will commonly produce much more fruit than others. If these trees produce fruit more frequently, as indicated by a lower inter‐annual variability in fruit production, they may dominate fruit production over time. By measuring fruit production of 1635 individuals of 10 temperate tree species across 4 years in northern lower Michigan, we estimated the inter‐annual variability and synchrony in each species. We compared fruit production estimates with measurements of tree size, soil nutrient availability and neighbourhood crowding to investigate the source of inter‐individual variation in number of fruit produced. We found that trees’ fruit production increased with tree size. The trees that accounted for the largest proportion of total fruit production had lower inter‐annual variability and higher synchrony in fruit production. These ‘super‐producer’ trees tended to have high nutrient availability and few neighbouring trees, but there were no effects of nutrient availability or neighbourhood crowding on fruit production in the population as a whole. Synthesis. Masting is a population‐level phenomenon, and is typically studied at this level. However, when we apply individual tree observations of fruit production to this phenomenon, it reveals super‐producers which produce fruit more consistently than the rest of the population. By reducing inter‐annual variability in fruit production, but increasing synchrony and making large numbers of fruit, super‐producers may be able to reap the benefits of masting while governing population fruit production over time.

Climate and herbivore influence on Vaccinium myrtillus over the last 40 years in northwest Lapland, Finland

AbstractAnnual fluctuations in the abundance of wild berries have repercussions on animals and humans who depend on this important resource. Although studies have tried to disentangle the effect of climate and herbivores on inter‐annual berry yield, there are still many uncertainties as to which factors are driving productivity. In this research, we evaluated the effect of climate and predation by rodents and moths on the abundance of bilberry (Vaccinium myrtillus) flowers and berries at the Kilpisjärvi Biological Station in northwest Finnish Lapland. The data were collected from 1973 to 2014 in a forest and an alpine site, both undisturbed by human activities. This dataset is unique due to the length of the sampling period, the availability of flower, berry, and rodent abundance data as well as the undisturbed nature of the habitat. Previous summer temperatures, the abundance of rodents, and the presence of a moth outbreak were complementary factors explaining the abundance of flowers. Herbivores had a larger impact on flower production than climate, but both variables were important to understand reproductive effort. Contrary to results from experimental studies, warmer winters did not significantly influence reproductive success. The abundance of fruits was strongly correlated with pollinator activity; the forest site, with a larger pollinator network, had a higher reproductive success and spring conditions were linked to inter‐annual variability in fruit production. Our results illustrate the importance of the location of the population within the species distribution range to understand plant sensitivity to climatic fluctuations with fruit production only influenced by current‐year summer temperatures at the alpine site. Finally, we observed a general increase in flower and fruit production at the alpine site, which was driven by large yields since the early 1990s. Fruit production at the forest site was comparatively stable throughout the study period.

Population structure and fruit production of Pyrus bourgaeana D. are affected by land-use

The Iberian wild pear (Pyrus bourgaeana D.) is a rare, fleshy-fruited tree restricted to dehesas and evergreen sclerophyllous Mediterranean forests in the southwestern Iberian Peninsula. It produces palatable fruits and leaves attractive to different species groups, playing an important trophic role in the ecological networks of Mediterranean ecosystems. However, the intensification in the traditional land-use linked to these areas could threaten the stability of the wild pear populations in the short/medium-term. In order to determine the population dynamics of this relevant species in relation to the land-use history, we selected two populations (southern Spain) subjected to different land-use management, dehesa (D) and abandoned olive grove (AOG). An analysis of 122 adult trees reported an overall density of 0.6 trees ha−1. The tree age was estimated by tree-rings analysis in all adult trees. Dendrometric parameters, reproductive features, and germination rates were also measured. Regeneration was clearly biased, as evidenced by the truncated age structure. A low correlation (R2 = 34%) between age and DBH (diameter at breast height) (244 cores analysed) showed that diameter seems not to be a reliable predictor of tree age. Trees from AOG populations had significantly-higher values of DBH, height and crown diameter, but were less productive in terms of fruits and seeds. Nested analysis of variance showed significant variation in fruit production, fruit size, dry mass, water content and seed viability. There were also significant differences in masting. No evidence was found to demonstrate that fruit production, seed viability, or germination rate influence the low natural recruitment of this species. These findings indicate that the traditional agrosilvopastoral practices carried out in the study area for decades, and its subsequent intensification, have strongly influenced the ecological structure of the Iberian wild pear populations at the local scale, which could compromise its stability in the near future.

The North Atlantic Oscillation synchronises fruit production in western European forests

Weather and its lagged effects have been associated with interannual variability and synchrony of fruit production for several tree species. Such relationships are used often in hypotheses relating interannual variability in fruit production with tree resources or favourable pollinating conditions and with synchrony in fruit production among sites through the Moran effect (the synchronisation of biological processes among populations driven by meteorological variability) or the local availability of pollen. Climatic teleconnections, such as the North Atlantic Oscillation (NAO), representing weather packages, however, have rarely been correlated with fruit production, despite often being better predictors of ecological processes than is local weather. The aim of this study was to test the utility of seasonal NAO indices for predicting interannual variability and synchrony in fruit production using data from 76 forests of Abies alba, Fagus sylvatica, Picea abies, Pseudotsuga menziesii, Quercus petraea, and Q. robur distributed across central Europe. Interannual variability in fruit production for all species was significantly correlated with seasonal NAO indices, which were more prominently important predictors than local meteorological variables. The relationships identified by these analyses indicated that proximal causes were mostly responsible for the interannual variability in fruit production, supporting the premise that local tree resources and favourable pollinating conditions are needed to produce large fruit crops. Synchrony in fruit production between forests was mainly associated with weather and geographical distance among sites. Also, fruit production for a given year was less variable among sites during warm and dry springs (negative spring NAO phases). Our results identify the Moran effect as the most likely mechanism for synchronisation of fruit production at large geographical scales and the possibility that pollen availability plays a role in synchronising fruit production at local scales. Our results highlight the influence of the NAO on the patterns of fruit production across western Europe.

Muster und treibende Kräfte der Samenproduktion bei Waldbäumen

Patterns and driving forces for seed production in forest tree species Why is the annual fruit production in forest tree species not constant, and which factors cause massive fruit production (seed mast year)? These and other related questions were already posed more than 100 years ago when tree breeding was economically beneficial. The questions have not been fully answered, yet. Rather, the same questions are studied again today as the climate is changing and the uncertainty about the continuation of forests at their current locations is growing. A 25 year long observation series on the variation of fruit production in Switzerland revealed a mean frequency of three years for mast seeding (full and medium mast) at low elevation on the Central Plateau in European beech (Fagus sylvatica), oak (Quercus petraea, Q. robur) and silver fir (Abies alba). In contrast, mast seed years of Norway spruce (Picea abies) occurred, on average, every sixth year. In 1992 and 2011, all four species synchronously showed mast seeding. The results are discussed in the light of different theories and new research findings. From the state of the current know ledge, we derive the need for long-term and fine-scale baseline data and present the new reporting and information webpage «mast web.ch». Here, volunteers can report observations on the fruit production of main tree species following a few simple criteria (citizen science approach). With this data, distribution maps on mass fructification levels will be made available and will serve for spatio-temporal fine-scale studies on mast seeding phenomena.

Neotropical primate communities: Effects of disturbance, resource production and forest type heterogeneity.

Undisturbed primate communities in the Neotropics are bottom-up structured as their biomass and species richness can be predicted from fruit production. However, the effects of fruit scarcity and the availability of forest types have not been fully analyzed, and seasonality is expected to differently affect small and large monkeys. The first aim of this study was to examine the effect of contrasting forest types within a location on the temporal variation in fruit production. The second was to assess the relative roles of disturbance, climate, patterns of fruit and leaf production, and plant composition on determining Neotropical primate communities. I compiled population density data for diurnal primate species from 154 sites to calculate species richness and assemblage biomass. Fruit abundance in the study sites was estimated from fruit trap data and phenology transects, and fruit variability was calculated as the monthly coefficient of variation (CV) and the length of the fruit scarcity period (LFSP). The results indicate that fruit production in floodplain forests is generally more variable than in terra firme forests, and this variation decreases in habitats with mixed forest types. Endozoochorous fruit production (based on fruit traps) and litter productivity were good predictors of the biomass of Neotropical primates (R2 = 0.83 and R2 = 0.59, respectively), but neither CV nor LFSP were good predictors. The biomass of large primates was independent of rainfall variation, but the biomass of small and medium sized monkeys was negatively correlated with temporal rainfall variability. Varzea forests tended to show higher biomass than those from terra firme and igapó. These results suggest that the production of fleshy fruits is the best predictor of the structure of primate assemblages in the Neotropics, but the effect of leaf quality and productivity remains to be investigated. Am. J. Primatol. 78:391-401, 2016. © 2015 Wiley Periodicals, Inc.

Mast fruiting in a hawkmoth-pollinated orchid Habenaria glaucifolia: an 8-year survey

The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants. It considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual. Orchids produce huge numbers of seeds per fruit and rarely experience seed predation. It remains unclear which factors may affect fluctuating fruit production in orchids, which generally suffer a widespread pollen limitation. To explore the temporal pattern of fruiting and potential factors related to fluctuation in fruit production, we investigated reproductive success of a long-spurred orchid (Habenaria glaucifolia) in an alpine meadow with thousands of individuals over 8 years. To estimate reproductive success, pollinator observation was conducted by day and at night, and pollinia removal and receipt were recorded in the field population for 8 years. To examine whether fruit set and seed set are pollen limited, we conducted supplementary pollination experiments and compared fruit set, seed set and pollinia movement of open-pollinated flowers from 2011 to 2013. We measured lengths of spurs and pollinator proboscises, and nectar volume and concentration, to identify potential pollinators. Hawkmoths were seen to be effective pollinators for H. glaucifolia in 3 years, whereas in the remaining 5 years no pollinators were observed, and consequently pollinia were rarely transferred. Numerous pollinia movements were observed in 2012, 2013 and 2014 (pollinia removal: 48, 59 and 85%; pollinia receipt 51, 70 and 80%), and correspondingly fruit set was significantly higher in 2012 and 2013 (59 and 46%) than in 2011 (25%). It was fruit set, rather than seed set, that was pollen limited in this orchid in the 3 years, in that supplementary pollination increased fruit set but did not increase seed set per fruit compared to natural. Three species of hawkmoths had proboscis lengths that matched the spur length of H. glaucifolia. Fruit set in this long spurred orchid depends on the activity of long-tongued hawkmoths, resulting in significant temporal variation in fruit production. Mast fruiting in this alpine orchid could be attributed to a ‘sit and wait’ strategy, awaiting an abundance of effective pollinators.

Variation in growth and fruit yield of populations of Sclerocarya birrea (A. Rich.) Hochst.

Sclerocarya birrea (A. Rich.) Hochst. (marula) is one of the most important indigenous fruit tree species in southern Africa, where it plays a significant role in the diet, tradition and culture of many indigenous people. The species has in the past decade been the subject of domestication to enhance its wider scale cultivation and conservation to preserve its genetic diversity. In this study, we report on the performance of 21 geographic populations of marula (20 of S. birrea ssp. caffra and one of S. birrea ssp. birrea) planted in Mangochi, Malawi (14°28′S, 35°14’E and 469 m elevation). The trial was assessed for tree height, bole height, root collar diameter (RCD), diameter at breast height (DBH), crown width and depth, and fruiting at 7 years after out-planting. There were significant differences between the populations for most of the traits. Differences between the top and bottom ranked populations were often up to three-fold, reflecting wide genetic variation in the germplasm. The Marracuene population from Mozambique, was ranked top for height, RCD, DBH, crown width and crown depth. Only eight populations had fruits of which Marracuene population had the highest fruit yield. Although the average fruit load per tree ranged from one to 274 among the fruiting populations, tree-to-tree variation in fruit production was very wide ranging from one to 1,228 fruits per tree. Phenotypic correlations among the growth and crown size (height, RCD, DBH and crown depth) traits were large, positive and significant (P < 0.001). Correlations between fruit yield and growth and crown size traits although significant and positive, were mostly moderate. The implication of this large genetic variation in growth and fruit production detected among the marula populations is discussed in relation to conservation, breeding and choice of seed source for planting.

Inter-annual variation in characteristics of endozoochory by wild Japanese macaques.

Endozoochory is important to the dynamics and regeneration of forest ecosystems. Despite the universality of inter-annual variation in fruit production, few studies have addressed the sign (seed predation versus seed dispersal) and strength (frequency and quantity) of fruit-frugivore interaction and the effectiveness of endozoochory in response to the long-term temporal context. In this study I evaluated the characteristics of endozoochorous dispersal by wild Japanese macaques Macaca fuscata inhabiting deciduous forest in northern Japan for five different years. I collected 378 fecal samples from the macaques in fall (September to November) and quantified the proportion of feces containing seeds, number of seeds per fecal sample, ratio of intact seeds, and seed diversity. The proportion of feces containing seeds of any species (five-year mean: 85.9%, range: 78–97%) did not show significant inter-annual variation, while species-level proportions did. The intact ratio of seeds (mean: 83%, range: 61–98%) varied significantly both between years and between months, and this varied among dominant plant species. The number of seeds per fecal sample (mean: 78, range: 32–102) varied monthly but did not between years, and the seed diversity (mean: 0.66, range: 0.57–0.81) did not show significant inter-annual variation, both of which were attributed to longer duration of macaques’ gastro-intestinal passage time of seeds exceed their feeding bouts. This study demonstrated that frequency and success of seed dispersal over seed predation of macaque endozoochory showed inter-annual variation, indicating low specificity across the seed–macaque network. The temporal variability in the quality of seed dispersal may provide evidence of high resilience in response to fluctuating environmental conditions in the temperate forests.

Thermal requirements for flowering and fruit yield attainment in advance lines of okra

The field experiment comprising 12 advance lines of okra was carried out to assess thermal requirement for flowering and total fruit yield during rainy seasons at CCS Haryana Agricultural University, Hisar. The results revealed that okra crop required 762.4 dayoC accumulated heat units for flowering and 1600.5 dayoC accumulated heat units for total fruit yield production. Advance line HRB 108-2 required minimum for flowering (664.4 dayoC) and highest 1644.8 dayoC for total fruit production with better thermal use efficiency (9.1 kg ha-1 ºD) indicating its suitability for early and more fruits availability for longer period. Fruit yield production showed significant positive association with heat unit requirement in all the years. The R2 values of regression equation could explain the variation between 63-87% of the total variation in fruit production in okra.

What makes a good neighborhood? Interaction of spatial scale and fruit density in the predator satiation dynamics of a masting juniper tree

Spatio-temporal variability in fruit production (masting) has been regarded as a key mechanism to increase plant fitness by reducing seed predation. However, considerably more effort has been devoted into understanding the consequences of temporal rather than spatial variations in fruit crop for plant fitness. In order to simultaneously evaluate both components, we quantify fruit production and pre-dispersal damage by three arthropod species (mites, chalcid wasps and moths) in the Spanish juniper (Juniperus thurifera) during 3 years in a spatially explicit context. Our aims were to assess (1) the interaction between fruit production and pre-dispersal fruit damage by arthropods, (2) the potential interference or competition between arthropods, and (3) the form of the phenotypic selection exerted by arthropods on fruit traits considering the spatial context. Arthropods damaged a substantial fraction of fruits produced by Spanish juniper with levels of damage showing sharp inter-annual variations. Fruit damage by mites was negatively related to yearly fruit crop and positively correlated at individual trees fruiting in consecutive years. Increased interspecific interference was an additional consequence of reduced fruit availability during small crop years. During a masting year, fruit damage by less mobile species such as mites was negatively affected by tree crop size, and no spatial structure was observed for mite damage. The incidence of chalcid wasps was low, so the spatial pattern of seed predation was unclear, and no preferences for fruit or seed traits were detected. Conversely, moths selected larger fruits and their incidence on trees was spatially aggregated up to 20 m, with predation levels being negatively affected by fruit abundance at the patch level, suggesting a positive density-dependent effect of neighbors on fruit output. These results highlight the importance of including the spatial component to understand complex species interactions at local scales.