Limiting mechanisms in the regeneration of the Chilean matorral – Experiments on seedling establishment in burned and cleared mesic sites

The Chilean matorral is characterized by multispecific shrub clumps in dry areas but has a continuous canopy in wetter sites. It has been hypothesized that this difference is due to easier recolonization of open patches by shrub seedlings under more mesic conditions. Within the mesic range of the matorral we designed a field experiment to compare shrub seedling emergence, growth, and survival under the closed canopy of a secondary forest versus three types of open patches: burned, cleared of shrubs but with a herbaceous layer present, and clear without a herbaceous layer. After the first summer, survival of Quillaja saponaria seedlings was 75% in the burned site, 30% in the cleared patch without herbaceous vegetation, and 15% with herbaceous vegetation present, whereas there was 0% survival under the secondary forest canopy. After eight years, the percentages had dropped to: 22%, 12% and 3%, respectively. These results contrast strongly with the seedling establishment patterns in drier areas of the matorral where early seedling survival is higher under the shade of large shrubs. In the experimental mesic sites, seedlings did best on the burned site, not only in terms of survival, but also in terms of growth. After one year, seedling mean height was 10.2 cm in the burned site, whereas 3.8 cm and 5.3 cm in the cleared patches without and with herbaceous respectively. After eight years, mean height differences between treatments had increased further: 147.7 cm in the burned site, 40.3 cm in the cleared patch without herbaceous cover and 13 cm in the cleared patch with herbs. Our results indicate that the facilitative effect of nurse shrubs on seedling establishment found in dry ranges of the matorral is less important in more mesic sites. This difference may explain the continuous shrub cover in relatively mesic areas as opposed to the characteristic patchy structure of the matorral in its drier range.     

On the Relationship between Herbaceous Cover and Vigilance Activity of Degus (Octodon degus)

A number of studies demonstrate that plant cover provides prey animals with refuges to decrease vulnerability to predators. However, others suggest plant cover to visually obstruct detection of predators or conspecifics. We suggest these seemingly conflicting results can, to some extent, be resolved if overhead vs. lateral cover are distinguished. We recorded seasonal variation in vigilance activity of a natural population of degus (Octodon degus), a diurnal, semi‐subterranean and social rodent from central Chile. We used these data to determine whether cover provided by herbaceous vegetation is mostly obstructive. The height of herbaceous vegetation in the habitat of degus varied seasonally, and the ability of degus (estimated from human observers) to detect potential predators decreased when herbaceous vegetation was high. This effect was more important for degus using quadruped postures and when dealing with terrestrial simulated predators. Accordingly, degus adjusted the quality rather than the quantity of their vigilance activity: male and female degus allocated similarly more time to bipedal vigilance when the height of herbs was high. Such increase in bipedal vigilance seemed to occur at the expense of quadruped vigilance instead of foraging time. Collectively, these results support the hypothesis that cover of herbaceous vegetation is mostly obstructive to degus when active above ground, a finding that contrasts with previous evidence supporting that shrub cover provides refuges against predators. The differential effects of shrubs and herbs on degu vigilance are likely linked to differences in the costs and benefits associated with each cover type. For degus, shrubs may provide more overhead (protective) than lateral (obstructive) cover.     

Leaf traits in Chilean matorral: sclerophylly within,among, and beyond matorral,and its environmental determinants

Studies of leaf traits often focus on tradeoffs between growth and resource conservation, but little is known about variation in the mechanical traits that influence resource conservation. This study investigates how leaf mechanical traits vary across matorral vegetation in central Chile, how they correlate with environmental factors, and how these trends compare at a broader geographic scale. Leaf toughness, strength, stiffness, and associated traits were measured in five matorral types in central Chile, and relationships with soil N and P and climate variables were assessed. Trends with soil and climate were then analyzed across shrubland and woodland in Chile, Western Australia, and New Caledonia. Chilean species varied in leaf mechanics and associated traits, both within and among matorral types, with more species in sclerophyll matorral having strong, tough, and stiff leaves than in arid and littoral matorral. Overall, leaves with high leaf dry mass per area were stiffer, tougher, stronger, thicker, denser, with more fiber, lignin, phenolics and fiber per unit protein and less protein: tannin activity and N and P per mass, forming a broad sclerophylly syndrome. Mechanical traits of matorral species were not correlated with soil N or P, or predictably with climate variables, except flexural stiffness (EI_W) which correlated positively with annual reference evapotranspiration (ET₀). However, soil P made strong independent contributions to variation in leaf mechanics across shrublands and woodlands of Chile, Western Australia, and New Caledonia, either separately (strength) or together with ET₀ (toughness) explaining 46–90% of variation. Hence ET₀ was predictive of EI_W in Chilean matorral, whereas soil P was highly predictive of variation in leaf strength, and combined with ET₀ was highly predictive of toughness, at a broader geographic scale. The biological basis of these relationships, however, may be complex.     

Ecological Predictors of Range Areas and Use of Burrow Systems in the Diurnal Rodent, Octodon degus

Variation in animal space use patterns may be linked to numerous ecological factors affecting survival and reproduction. We examined the relationship between ecology and above‐ and below‐ground components of space use by Octodon degus, a semi‐fossorial rodent in Chile. We monitored the daytime minimum convex polygon and adaptive kernel range areas of 26 individuals and determined the number of burrow systems used by degus during night‐time radiotelemetry and trapping of burrow systems on two study grids at Rinconada de Maipú, a semi‐arid Matorral in central Chile. We quantified food biomass, soil hardness, distance to overhead vegetative cover, and density of burrow openings at putative nest burrows. Degus living on the grid with more shrub cover had larger range areas than degus living on the grid with less cover. The range areas of degus decreased with increasing distance from overhead vegetative cover. There was a weak (but statistically significant) negative relationship between the number of burrow systems used by degus and the distance to vegetative cover and density of burrow openings at burrow systems. Male and female degus had similar range areas. Our results suggest that overhead cover decreases the risk of predation to male and female degus. Degus probably balance the benefits of numerous burrow openings (reduced predation risk) with time and energy requirements of burrow construction and maintenance. Models of space use that consider the effect of multiple ecological variables should measure different dimensions of space use.     

Shrub clumps of the Chilean matorral vegetation: structure and possible maintenance mechanisms

Summary Previous studies have claimed that the Chilean matorral is more open than the Califonia chaparral, and have attributed this dissimilarity largely to the role of man in Chile. In this paper we show that in general the Chilean matorral has a structure better described as shrub clumps that merge to form a continuous vegetation matrix only in very mesic habitats, where it is comparable to the Califonia chaparral. We also present evidence that these clumps have been present for at least the last 26 years and that even without human disturbance they are likely to maintain themselves. Evidence for the latter pertains to seed dispersal, seed germination and establishment, seedling survival, and the diameter size structure of shrub clumps. Finally, we propose that differences between the California chaparral and Chilean matorral are more profound than previously thought and are due not only to different degrees of human disturbance, but also to the presence of periodical natural fires in California and not in Chile, and to different shrub recruitment patterns and mammalian herbivore activity in the two areas.     

The influence of habitat on travel speed, intermittent locomotion, and vigilance in a diurnal rodent

We studied effects of habitat structure on routine travel velocities, intermittent locomotion, and vigilance by the degu (Octodondegus), a diurnal rodent of central Chile. We predicted thattravel speed, pauses during locomotion, and vigilance wouldbe greater in open (riskier) than in shrub (safer) habitats.Video recordings of marked individuals in the wild were used to measure speed and other variables of spontaneous locomotionnot triggered by predatory attack or any other noticeable stimulusduring nonforaging periods. Time spent vigilant while foragingwas also measured. Because degus use bare-ground runways fordistant movements (e.g., between burrow openings and/or foodpatches), data on locomotion decisions were not confounded by effects of obstructive vegetation cover and/or resource abundance.When moving across the habitat between different feeding places,degus showed an intermittent pattern of locomotion, interruptingrunning events with short pauses. As predicted, travel speedand the duration of pauses between locomotion bursts were significantlygreater in open habitats. Further, the duration of locomotionbursts between feeding sites or between feeding sites and burrowswas significantly longer in open habitats. Our assumption that pauses and velocities are independent decisions was supportedby the lack of correlation between pauses and speeds duringlocomotion events. During foraging, degus devoted more timeto vigilance in open than in shrub habitats. The static positionadopted by degus during pauses, the speeds attained during movements, and the concordance between pausing behavior andvigilance across habitats suggest that pausing has an antipredatoryrole and is not limited to orientation and/or physiologicalrecovery. Our results support the view that degus perceivehigher predation risk in open areas and that flexible movement behavior reflects an adaptive antipredator response.     

Exotic Herbivores as Drivers of Plant Invasion and Switch to Ecosystem Alternative States

This paper discusses the evidence of the way in which coupled herbivore and plant invasions altered the structure and functioning of ecosystems in central Chile, and compares these patterns to results from other Mediterranean ecosystems around the world. In pre-Columbian times, sclerophyllous matorral forests largely covered mediterranean Chile. Remnants of the original, continuous matorral can now be found only on relatively humid slopes of the Coastal Range. In the Intermediate Depression, a long central valley, it has been replaced by extensive savannas dominated by the exotic Acacia caven, whereas the matorral remains on dry slopes as isolated shrub clumps. Experimental work suggests that introduced cattle have played a major role in promoting the shift to Acacia savanna, whereas introduced European rabbits prevent the recolonization of clearings by matorral on the slopes. As in other regions of the world, the loss of woodlands in Chile is likely to have resulted in reduced carbon storage capacity and nutrient recycling, and in increased erosion and climatic aridity within the region. Numerous exotic herbs and grasses now dominate the open areas, and experiments indicate that the dry conditions in the absence of woodland cover in combination with loss of soil fertility and severe grazing by introduced mammals has pushed the competitive balance from native to exotic species. These changes are probably very difficult to reverse. Even if grazing is drastically reduced, drought may prevent the recovery of matorral species in much of the region. However, recent theoretical work suggests that if such grazer reduction is timed to coincide with wet El Niño episodes, recovery of the original woodlands may be triggered.     

THE ANNUAL RHYTHM OF CAMBIAL ACTIVITY IN TWO WOODY SPECIES OF THE CHILEAN “MATORRAL”

The annual rhythm of cambial activity is compared in Proustia cuneifolia and Acacia caven, two typical shrubs of the “matorral” in the semiarid region of central Chile. Proustia, a drought deciduous shrub, shows a typical desert cambial rhythm, highly sensitive to rainfall. The growth activity of this species is limited to the periods of adequate moisture. Acacia is an evergreen whose cambial activity is observed almost throughout the year; it is not synchronous with rainfall. Adaptation in this species seems to consist in developing long roots able to tap underground water. These results indicate that both shrubs, although growing together, have different adaptive strategies to the same xerophytic conditions.     

Importance of the soil seed bank of disturbed sites in Chilean matorral in early secondary succession

Abstract. The dynamics of the seed bank may provide clues to the process of recovery of the vegetation of disturbed sites. The role of the seed bank may be more important in areas with a seasonal climate than in areas where seedling recruitment is not limited to one season. We studied the seed bank and the seed rain in three sites of the Chilean mediterranean-climate region (33° 48'S) which differed in the degree of anthropic disturbance: a closed-canopy, second-growth forest; an open matorral; and an old-field. Additionally, we tested the germination of seeds from the soil and from the current-year seed crop. The seed bank varied considerably between the two years of study, although no change in the vegetation could be observed. Seed density and species richness were lower in 1989 than in 1988. The seed bank of the second-growth forest changed less between years, while the old-field showed the largest change. The highest seed rain occurred under shrub patches in the open matorral, while few seeds fell in the spaces between shrub clumps or in the old-field. In the forest, seed rain was low and correlated with species cover. Germination was low (0 - 15%) in tests using either soil samples or fresh seeds. These results indicate that matorral succession is a very slow process, limited mainly by low germination and low arrival of propagules to open areas. Most woody species have animal-disseminated fleshy propagules. The presence of established shrubs which may serve as perches or refuges for animals increases species richness in the seed rain and the seed bank.     

Grouping increases the ability of the social rodent,Octodon degus,to detect predators when using exposed microhabitats

We examined the hypothesis that a main benefit of group‐living in the hystricognath rodent, Octodon degus (common degu), is to decrease individual risk of predation. During a first series of field observations, we contrasted group size of degus when using covered microhabitats with that of degus using exposed patches. During a second set of field observations, we assessed how distance to detection and to escape by degus varied with group size upon the approach of a potential human predator. Degus in exposed patches formed larger groups than degus in covered microhabitats. After excluding the influence of nearest burrow to focal subjects, we found that degus of larger groups detected an approaching human predator at a greater distance than degus of smaller groups. Likewise, degus of larger groups escaped to nearby burrows at a greater distance from the approaching predator than degus of smaller groups. All these pieces of evidence support the predatory risk hypothesis according to which group‐living in degus functions to reduce the risk of predation.     

Effects of disturbance caused by traditional Spanish rural land use on the regeneration of Cytisus multiflorus

Abstract. Cytisus multiflorus is a leguminous matorral shrub native to the NW Iberian Peninsula, where it is one of the most important species in the extension of matorral at the expense of set-aside agricultural land. Dehesas have traditionally been used for extensive livestock raising and matorral was periodically burnt, cut or pulled out. The two latter practices are now out of use. However, burning is more frequent than in the past. The effects of fire, cutting, and pulling out of C. multiflorus on its regeneration was studied in order to ascertain whether the presently increasing distribution of the species relates to fire-stimulated regeneration or to the reduction of other traditional practices. Three years after treatment two sets of parameters were determined: 1. Plant origin: seedlings and different ramet types (ramets=resprout clumps), density, weight, and biomass as well as the percentage of resprouting. 2. Seed persistence at various soil depths. The possible mechanisms of breaking dormancy and plant emergence in different years after fire were studied in other experiments. The results suggest that the regeneration mechanism in C. multiflorus is stimulated by fire, but it is not an exclusive relationship. Stimulation occurs also after other disturbances leading to the total elimination of aerial biomass. The present expansion of the species does not appear to result from the abandonment of some traditional practices, such as cutting or pulling out, but from frequent fires (resulting in aerial-biomass elimination).     

SPRING GROWTH OF SHOOTS AND ROOTS IN SHRUBS OF AN ALASKAN MUSKEG

Early spring shoot and fine-root development of four evergreen and three deciduous shrub species were analyzed in a subarctic muskeg at Fairbanks, Alaska. The overwintered foliage of the evergreen shrubs regreened earlier than new leaves developed on the deciduous species. Likewise, the evergreen shrubs produced new fine roots earlier than the deciduous species. The total nonstructural carbohydrate (TNC) concentration did not decline in the evergreen shrub Ledum palustre during the spring development. This contrasted with the deciduous shrub Betula glandulosa, where a significant TNC reduction in stem tissue coincided with bud break and fine-root growth flush.     

Structure and genetic diversity in Colliguaja odorifera Mol. (Euphorbiaceae), a shrub subjected to Pleisto-Holocenic natural perturbations in a mediterranean South American region

Aim Colliguaja odorifera Mol., a Euphorbiaceous shrub of central Chile, inhabits the matorral formation, growing at low altitudes on both Andean and coastal mountain range slopes. In the recent geological past, this region was subjected to climatic changes and geological disturbances that most probably caused population shrinkages on the Andean mountain slopes. This study tested the hypothesis that under such a scenario, existing populations should show lower genetic diversity in the Andean than in the coastal areas; these coastal populations being the potential source populations for recolonization. Location The study was carried out in central Chile by comparing the genetic diversity between the Andean and coastal areas, each represented by five localities distributed from 32°30′ S to 34° S. Methods Genetic diversity was estimated by DNA analysis using 18 dominant multilocus Random Amplified Polymorphic DNA (RAPD) loci, characterizing 73 genetic phenotypes. Results The comparison of the two matorral areas showed that Andean populations of C. odorifera have a subset of the genetic diversity found in the coastal populations. Andean populations also show a consistently lower genetic diversity, lower genetic distances and higher genetic structure, coincident with expectations based on the Pleisto‐Holocenic perturbation regime. Main conclusions This first genetic analysis for South American mediterranean populations confirms the findings of previous floristic and palynological studies that identified refuge zones in the coastal mountain range of central Chile, a situation analogous with that occurring during periods of inter‐glacial northward migration in Southern Europe.     

Afforestation causes changes in post‐fire regeneration in native shrubland communities of northwestern Patagonia,Argentina

Question: What are the effects of fire in native shrubland communities and in pine plantations established in these shrublands? Location: Northern Patagonia, Argentina. Methods: We surveyed four sites in Chall‐Huaco valley, located in northwest Patagonia. Each site was a vegetation mosaic composed of an unburned Pinus ponderosa plantation, a plantation burned in 1996, and an unburned matorral and a matorral burned by the same fire. We recorded the cover of all vascular plant species. We also analysed species richness, total cover, proportion of exotic species, abundance of woody species and herb species, cover of exotic species, abundance of woody and herb species and differences in composition of species. For both shrubs and tree species we recorded the main strategy of regeneration (by resprouting or by seed). Results: We found that fire had different effects on native matorral and pine plantations. Five years after fire, plantations came to be dominated by herbs and exotic species, showing differences in floristic composition. In contrast, matorral communities remained very similar to unburned matorral in terms of species richness, proportion of woody species, and herb species and proportion of exotics. Also, pine plantations were primarily colonized by seedlings, while matorrals were primarily colonized by resprouting. Conclusions: Matorrals are highly fire resilient communities, and the practice of establishing plantations on matorrals produces a strong reduction in the capacity of matorral to return to its original state. The elimination of shrubs owing to the effect of plantations can hinder regeneration of native ecosystems. Burned plantations may slowly develop into ecosystems similar to the native ones, or they may produce a new ecosystem dominated by exotic herbs. This study shows that plantations of exotic conifers affect native vegetation even after they have been removed, as in this case by fire.     

Vegetative responses to defoliation of two Chilean matorral shrubs

Summary This paper reports the results of experimental defoliation of two common matorral species: Lithraea caustica and Colliguaya odorifera. L. caustica and C. odorifera are the matorral species previously shown to exhibit the highest and lowest levels of natural defoliation by browsing. Experimental defoliation was performed at four levels: 0% (controls), 25%, 66%, and 100%. C. odorifera exhibited vegetative responses stronger than controls only in the two highest levels of defoliation (66% and 100%), whereas L. caustica responded vigorously at the 25% and 100% levels. The results are related to the observed position of both species in the matorral community and their relative defoliation risks by natural and introduced herbivores.     

Do birch-feeding caterpillars make the right feeding choices?

Summary The effects of leaf quality on caterpillar performance are frequently investigated, as are the feeding preferences of caterpillars, but rarely are the two considered together to see how preferences match performance. I looked at the preferences and performance of the specialist feeder Achlya flavicornis and the generalist Spilosoma luteum on Betula pendula leaves which were artificially damaged, mined or left undamaged, and on leaves of different ages. Often feeding preferences were not for the leaf types that gave faster development, larger pupae or greater survival. A. flavicornis preferred medium aged to older leaves though medium aged leaves produced smaller pupae. They did not discriminate between young and medium aged leaves, though larvae fed young leaves developed more slowly, and had lower survival and lower adult emergence. S. luteum larvae did not discriminate between damaged and undamaged leaves, though feeding on damaged leaves gave smaller pupae and lower adult emergence. I suggest that generalists like S. luteum might be unable to make feeding choices between leaves that are on the same tree and vary only slightly because populations are exposed to much greater variation across the wide range of potential food plants individuals may encounter. Possible differences in within-plant feeding selectivity between generalists and specialists should be investigated. A. flavicornis is a leaftier for which selection of a suitable leaf for tying could be more important in the first instance than feeding considerations. Larvae preferred younger to older leaves for tying, and larvae tended to feed on the tied leaves, so tying preferences explain the initial feeding preferences.     

Temporal fluctuation in shrub species preferences of two native rodents: The effect of infection status on habitat use

Small mammals use plant species for gathering food resources and for shelter. Preferences for certain plant species are related to nutritional restrictions and behavioural patterns, which could be altered in the presence of an infectious disease. Several native small mammals are part of the wild cycle of the protozoan Trypanosoma cruzi, responsible for Chagas disease in humans. This is a vector‐borne disease transmitted by insects of the subfamily Triatominae. We examined the effect of T. cruzi infection status on the use and preference patterns of shrub species by two native rodent species: Octodon degus and Phyllotis darwini. This study was conducted during four sampling years (2010–2013) in a hyper‐endemic zone of Chagas disease located in a semiarid Mediterranean ecosystem. We captured individuals of 599 O. degus and 575 P. darwini (89% of the total captures), which were related to nine shrub species and examined for T. cruzi infection. In a community‐level analysis, infected and non‐infected O. degus used individual shrub species within the shrub community significantly non‐randomly relative to their availability; the same pattern was detected for non‐infected P. darwini individuals, whereas infected individuals used the shrub community according to the abundance of each shrub species. Examining individual preferences, both rodents showed a strong preference for Flourensia thurifera and Colliguaja odorifera regardless of their infection status. Preferences for specific shrub species were variable among years, showing a ‘core’ of preferred shrub species and variable levels of use of the remaining ones. Our results show that T. cruzi infection in wild small mammals can modify habitat use patterns and preferences for certain shrub species, probably affecting processes acting at community level.     

Avian gut-passage effects on seed germination of shrubland species in Mediterranean central Chile

Effects of avian gut-passage on seed germination are important to assess the effectiveness of frugivores in woodland regeneration, particularly in biodiversity hotspots that have a high incidence of avian frugivory. We examined the effect of avian gut-passage on seed germination in contrast to seeds that remain uneaten in five shrub species in Mediterranean central Chile and sought to determine the physiological mechanism(s) by which seed germinability is modified. Germination assays were conducted in a glasshouse for five common shrub species of the sub-Andean matorral: Azara dentata (Flacourtiaceae), Schinus polygamus and Schinus molle (Anacardiaceae), Cestrum parqui (Solanaceae), and Maytenus boaria (Celastraceae). We estimated germinability (final percent germination), dormancy length (time from sowing to first germination), mean length of dormancy of all germinated seeds, and contrasted germination rates of defecated versus manually extracted and pulp-enclosed seeds. Avian gut-passage increased seed germinability in four of the five shrub species studied—primarily through deinhibition via pulp removal. Minimum dormancy length was not modified by avian gut-passage for A. dentata, but was significantly shorter for S. molle and C. parqui. Mean dormancy length was significantly shorter in gut-passed seeds of A. dentata, S. molle and M. boaria. Avian gut-passage greatly enhanced the seed germination rates of three species, A. dentata, S. molle and C. parqui. We conclude that the positive effects of birds on seed germination facilitate the regeneration of sub-Andean shrublands, and that bird declines due to landscape change may impair recovery rates of successional or restored areas due to dispersal limitation.     

Geographic variation in fruit colour is associated with contrasting seed disperser assemblages in a south‐Andean mistletoe

Fruit colour influences fruit choice by seed dispersers. The mistletoe Tristerix corymbosus (Loranthaceae) produces mature fruits of two different colours in two different biomes: yellow in the Chilean matorral and green in the temperate forest of southern South America. We conducted field surveys to establish the association between fruit colour and disperser identity throughout the entire geographical range of T. corymbosus. We selected 22 populations, eight of which were located in the Chilean matorral and 14 in the temperate forest south of the matorral. To identify the seed dispersers of the mistletoe we used direct observation, camera traps, and live‐trapping of small mammals. We also report experiments to assess fruit selection by seed dispersers based on differences in colour. The assemblages of dispersers of T. corymbosus differ between the two biomes: yellow fruits in Chilean matorral are exclusively dispersed by three bird species while green fruits in the temperate forest are exclusively dispersed by a marsupial. The differences in the assemblages of seed dispersers can be explained by differences in food‐finding strategies between the two assemblages. Green fruits in temperate forest are not easily detected by birds, while colour might not be an important cue for the marsupial because it is nocturnal and uses other senses to locate food. We propose that the association between the marsupial and the green‐fruited mistletoe constitutes an ecological fitting rather than the outcome of a co‐evolutionary process. The marsupial might have allowed the mistletoe T. corymbosus to retain green coloration in mature fruit, a condition to which it is preadapted by a slower ripening process in temperate forest populations.     

Florivores on the dioecious shrub Eurya japonica and the preferences and performances of two polyphagous geometrid moths on male and female plants

Flowers of dioecious plants have sexually dimorphic traits that may affect florivore performances, and florivores may have preferences to plant sex that are correlated with their performance on different plant sexes. We investigated the florivory on a polygamodioecious evergreen shrub Eurya japonica in Japan to reveal florivores and their feeding patterns involved in sexually biased florivory on E. japonica flowers. Flowers of E. japonica were infested by lepidopteran and dipteran larvae and hemipteran insects. Lepidopteran larvae were chewers, dipteran larvae were gall makers and hemipteran insects were suckers. Chewed flowers were most frequent among infested flowers. Of florivores, lepidopteran larvae, mostly of Geometridae, were the important florivore that damaged flowers by chewing. Florivores infested male flower buds more often than female flower buds, but only a geometrid larvae Chloroclystis excise, which exclusively uses flower buds, showed the biased infection on male flowers. Rearing experiments for two other geometrid moths which use both leaves and flowers showed that the preference and performance of Ourapteryx nivea that fed mainly leaves did not differ between the plant sexes, whereas the development of Alcis angulifera larvae which fed both leaves and flowers was slower when they fed female than male leaves and flower buds. In addition, A. angulifera larvae fed fewer flower buds on female than on male plants. These results show that the male‐biased florivory on E. japonica trees is attributed mainly to the specialist florivore and also feeding preference for male flowers in an opportunistic florivore that feed both leaves and flowers.