Botany, genetics and ethnobotany: a crossed investigation on the elusive tapir's diet in French Guiana

While the populations of large herbivores are being depleted in many tropical rainforests, the importance of their trophic role in the ecological functioning and biodiversity of these ecosystems is still not well evaluated. This is due to the outstanding plant diversity that they feed upon and the inherent difficulties involved in observing their elusive behaviour. Classically, the diet of elusive tropical herbivores is studied through the observation of browsing signs and macroscopic analysis of faeces or stomach contents. In this study, we illustrate that the original coupling of classic methods with genetic and ethnobotanical approaches yields information both about the diet diversity, the foraging modalities and the potential impact on vegetation of the largest terrestrial mammal of Amazonia, the lowland tapir. The study was conducted in the Guianan shield, where the ecology of tapirs has been less investigated. We identified 92 new species, 51 new genera and 13 new families of plants eaten by tapirs. We discuss the relative contribution of our different approaches, notably the contribution of genetic barcoding, used for the first time to investigate the diet of a large tropical mammal, and how local traditional ecological knowledge is accredited and valuable for research on the ecology of elusive animals.     

Fruit patch size and frugivory in the lowland tapir (Tapirus terrestris)

Large non-ruminant ungulates consume the more abundant low-quality forage because this gives them the advantage of reducing search effort. However, large-bodied herbivores would be predicted to search for high-quality fruit patches if these patches were of large size and the fruits rich in nutrients. Diets of lowland tapir ( Tapirus terrestris ), a large non-ruminant of the Amazon basin, were examined from animals of north-eastern Peru to investigate this relationship between high-quality fruit, lower-quality browse and searching behaviour. Lowland tapir consumed on average 33% fruit, which is relatively high for a large non-ruminant ungulate. The fruit portion of lowland tapir diets was dominated by the nutritious Mauritia flexuosa (Palmae) drupes, which were selected by tapir more frequently than other fruit types. M. flexuosa palms grow in virtually monotypic stands and occur in larger patches than other fruit trees used by terrestrial herbivores of the Amazon. Lowland tapir encountered fruits more frequently when ranging in M. flexuosa palm forests than in non-palm forests, because they changed their searching behaviour once they entered palm forests by turning more abruptly. It appears that lowland tapir can consume greater proportions of fruit than other large non-ruminant ungulates, because they exploit a nutritious fruit that occurs in large patches and that meets the energy demands of their large body size.     

Local and landscape factors determining occurrence of phyllostomid bats in tropical secondary forests

Neotropical forests are being increasingly replaced by a mosaic of patches of different successional stages, agricultural fields and pasture lands. Consequently, the identification of factors shaping the performance of taxa in anthropogenic landscapes is gaining importance, especially for taxa playing critical roles in ecosystem functioning. As phyllostomid bats provide important ecological services through seed dispersal, pollination and control of animal populations, in this study we assessed the relationships between phyllostomid occurrence and the variation in local and landscape level habitat attributes caused by disturbance. We mist-netted phyllostomids in 12 sites representing 4 successional stages of a tropical dry forest (initial, early, intermediate and late). We also quantitatively characterized the habitat attributes at the local (vegetation structure complexity) and the landscape level (forest cover, area and diversity of patches). Two focal scales were considered for landscape characterization: 500 and 1000 m. During 142 sampling nights, we captured 606 individuals representing 15 species and 4 broad guilds. Variation in phyllostomid assemblages, ensembles and populations was associated with variation in local and landscape habitat attributes, and this association was scale-dependent. Specifically, we found a marked guild-specific response, where the abundance of nectarivores tended to be negatively associated with the mean area of dry forest patches, while the abundance of frugivores was positively associated with the percentage of riparian forest. These results are explained by the prevalence of chiropterophilic species in the dry forest and of chiropterochorous species in the riparian forest. Our results indicate that different vegetation classes, as well as a multi-spatial scale approach must be considered for evaluating bat response to variation in landscape attributes. Moreover, for the long-term conservation of phyllostomids in anthropogenic landscapes, we must realize that the management of the habitat at the landscape level is as important as the conservation of particular forest fragments.     

Spatial Variation and Dynamics of Flooding,Canopy Openness,and Structure in a Neotropical Swamp Forest

Temporal changes and spatial variation of soil drainage and understory light availability in 2001 and 2002, small stem (5 ≤ dbh (diameter at breast height) < 10 cm) density, forest successional phase and large stem (dbh ≥ 10 cm) spatial distribution were investigated in 1 ha of tropical swamp forest in southeastern Brazil. Building patches and treefall gaps comprised, respectively, 69.75 and 7.5% of the area in 2002. Semivariograms indicated spatial segregation of successional phases, with mature areas predominating in the North and gaps aggregated into the South. Exclusion of outliers showed large unpredictability of background variation in canopy openness, but patches with high canopy openness values concentrated along the South and East plot borders. Overall canopy openness increased from 2001 to 2002, and was locally autocorrelated between years. In 2001, well-drained and flooded sites comprised 46.75 and 38.19% of the study area, respectively, and were not spatially autocorrelated. In the study period, the number of flooded sites decreased by 40.4%. Canopy openness and small stem density were independent from drainage and were not correlated. Large trees aggregated at scales larger than 40 m, while arborescent palms were aggregated at all scales. Our findings suggest that tropical swamp forests have architectural characteristics similar to that of young, secondary forests and treefall gaps in old-growth forests. Patterns at larger scales pointed to the occurrence of widespread forest degradation, which seems to be particularly advanced in some forest sectors.     

Effect of treefall gaps on the patchiness and species richness of Neotropical ant assemblages

Natural formation of treefall gaps plays an integral role in the ecological and evolutionary dynamics of many tropical forests, affecting the spatiotemporal distribution of plants and the animals that interact with them. This study examines the impact of treefall gaps on the spatial and temporal patchiness of ant assemblages in a moist lowland forest in Panama. Using pitfall traps and honey baits, we compared ant assemblages in five 1 to 2-year-old treefall gaps (ca 100 m²) and five adjacent plots (ca 100 m²) in undisturbed forest understory at three different times of year (late wet season, late dry season, and early wet season). We found little evidence that ant assemblages respond dramatically to the formation of treefall gaps and the differences in habitat qualities they produce. Ant abundance, species richness, species composition, and rates of resource discovery did not differ between gaps and forest understory. However, we did find significant differences in numerical abundance related to forest stratum (ground vs vegetation) and resource type in pitfall traps (oil-cockroach vs honey), and significant differences in ant species richness and rates of resource discovery across seasons. While habitat effects by themselves were never statistically significant, habitat and seasonal differences in species richness interacted significantly to produce complex, season-dependent differences among gap and forest habitats. These results suggest that the formation of natural treefall gaps has less of an effect on Neotropical ant assemblages compared to other groups of organisms (e.g., plants, birds) or other causes of patchiness (e.g., ant mosaics, moisture availability, army ant predation). The results of our study also have important implications for the underlying causes of habitat differences in the distribution of ant-defended plants. Received: 3 February 1998 / Accepted: 7 April 1998     

The benefits of being in a bad neighbourhood: plant community composition influences red deer foraging decisions

Diet selection by mammalian herbivores is often influenced by plant community composition, and numerous studies have focused on the relationships between herbivore foraging decisions and food/plant species abundance. However, few have examined the role of neighbour palatability in affecting foraging of a target plant by large mammalian herbivores. We used a large-scale field dataset on diet selection by red deer Cervus elaphus in Fiordland National Park, New Zealand to: (1) estimate the palatability of native forest plant species to introduced deer from observed patterns of browse damage; and (2) examine whether intraspecific variation in browsing of plants can be related to variation in the local abundance of alternative forage species. Overall, 21 of the 53 forest species in our dataset were never browsed by deer. At a community level, plants were more likely to be browsed if they were in a patch of vegetation of high forage quality, containing high abundances of highly palatable species and/or low abundances of less-palatable species. Our findings suggest that deer make foraging decisions at both a coarse-grain level, selecting vegetation patches within a landscape based on the overall patch quality, and at a fine-grain level by choosing among individual plants of different species.     

Quantifying ecological memory during forest succession: A case study from lower subtropical forest ecosystems in South China

The concept of ecological memory provides a new perspective for research on forest succession by including historical factors and the initial state of ecological processes. However, there are still significant gaps between the concept and its application. We selected nine proxy indicators (plant species, soil seed banks, soil microbes, soil animals, birds, soil age, soil pollen, soil mineral distribution, and light environment) and developed a method to quantify ecological memory and succession in a subtropical forest succession in South China. Taking the climax-monsoon evergreen broad-leaved forest as the reference ecosystem, we found that ecological memory increased nonlinearly and accumulated following a specific assembly rule during succession. Memory concerning major soil microbes and soil animals, which improve the soil substrate, mainly accumulated from the initial to the early successional stage. Memory concerning the number of bird species and the availability of light, which ensure a source of regenerative seeds and the survival of understory seedlings, mainly accumulated from the early to middle successional stages. Memory concerning vegetation and soil seed banks mainly accumulated late in succession, guaranteeing that the ecosystem would reach the regional climax stage. Prospective memory was greater than retrospective memory in every successional stage except the late stage, which indicated that all stages but the late stage were undergoing progressive succession. Our study demonstrates that the concept of ecological memory and the proposed evaluation framework are useful for guiding research on succession and restoration, and especially for assessing how “far” a restored ecosystem is from a reference ecosystem or how far a restored ecosystem has deviated from its natural succession trajectory.     

The key role of the largest extant Neotropical frugivore (Tapirus terrestris) in promoting admixture of plant genotypes across the landscape

The historical and contemporary loss of large‐bodied frugivores has disrupted many plant‐disperser mutualisms, with potentially profound consequences for plants. Although several aspects of seed dispersal by megafrugivores have already been examined, the role of these species in promoting seed‐mediated gene flow has remained unexplored. We evaluated the role of the Amazonian tapir (Tapirus terrestris), the largest Neotropical frugivore, in shaping plant genetic structure through seed‐mediated gene flow. We used microsatellites to analyze the genetic patterns of Syagrus romanzoffiana seedlings recruited in tapir latrines and around conspecific adult palms, the two sites where seeds and seedlings are most frequently found in this species. While the genetic diversity of seedlings was rather similar in both sites, the kinship structure was substantially weaker in latrines. Most seedlings recruited around adult palms were half‐ or full‐sibs originating from those adults. In contrast, seedlings recruited in latrines came from several (>5, on average) contributing mothers other than the nearest adult (95%) and were mostly non‐sibs (72%). Kinship patterns indicated that tapir‐mediated dispersal promotes the admixture of genotypes across space. Also, our results suggested that genetic diversity and the number of contributing mothers in latrines increase with the number of fruiting adults visited by tapirs before defecating and with the accumulation of feces over time. We provide evidence of the relevance of tapirs in mobilizing maternal progenies (and genotypes) across the landscape and recruiting clusters of unrelated seedlings. This study suggests a key role for plant–megafrugivore interactions in seed‐mediated gene flow and emphasizes the importance of preserving such mutualisms.     

Experimentelle Untersuchungen zur optischen Kommunikation bei im Zoo gehaltenen Schabracken- und Flachlandtapiren (Tapirus indicus und Tapirus terrestris)

Until now, unlike their relatives, rhinos and horses tapirs have received considerably less attention in studies about communication. Therefore, it was the aim of this study to test which stimuli contain optical information for tapirs. For this purpose, the reactions of tapirs on optical stimuli (posters with edited tapir silhouettes) were examined. Research visits took place at the zoos of Berlin, Dortmund, Heidelberg, Munich, Nuremberg and Osnabrück during the year 2006. A total of 23 individuals, thereof 8 (5.3) Malayan tapirs (Tapirus indicus) and 15 (5.10) Lowland tapirs (Tapirus terrestris) attended the experiment. The results of the optical test with variously intense edited tapir silhouettes speak for the importance of the white ear rims as a family specific key stimulus. But that effect could not be amplified by adding a greater extent of white to the silhouette. Tapirs of both species reacted most strongly to the normal tapir silhouette followed by a silhouette without proboscis.     

Seasonal and habitat differences affect the impact of food and predation on herbivores: a comparison between gaps and understory of a tropical forest

Herbivore populations are influenced by a combination of food availability and predator pressure, the relative contribution of which is hypothesized to vary across a productivity gradient. In tropical forests, treefall gaps are pockets of high productivity in the otherwise less productive forest understory. Thus, we hypothesize that higher light availability in gaps will increase plant resources, thereby decreasing resource limitation of herbivores relative to the understory. As a result, predators should regulate herbivore populations in gaps, whereas food should limit herbivores in the understory. We quantified potential food availability and compared arthropod herbivore and predator densities in large forest light gaps and in the intact understory in Panama. Plants, young leaves, herbivores and predators were significantly more abundant per ground area in gaps than in the understory. This pattern was similar when we focused on seven gap specialist plant species and 15 shade-tolerant species growing in gaps and understory. Consistent with the hypothesis, herbivory rates were higher in gaps than the understory. Per capita predation rates on artificial caterpillars indicated higher predation pressure in gaps in both the dry and late wet seasons. These diverse lines of evidence all suggest that herbivores experience higher predator pressure in gaps and more food limitation in the understory.     

千岛湖生态保护与建设对景观格局的影响研究

生态保护和生态建设过程对景观格局产生影响并使之发生变化,这种变化又会影响景观的生态过程。应用3s技术和景观指数分析了39年(1964-2003年)内千岛湖库区土地利用和土地覆盖格局的变化。结果显示,斑块总数和景观破碎度基本保持不变,但是各斑块类型的斑块数量、面积和优势度变化非常显著。最优势斑块类型由荒山(占陆地面积的47．44％)演变为马尾松( Pinus massoniana)林(占陆地面积的52．8l％),研究区域内森林植被覆盖率增加。研究还发现景观多样性指数略微下降。景观多样性是对土地利用和覆盖类型丰富度和均匀度的概要度量,并不一定总是和景观功能呈正相关关系。上述变化归因于多项生态保护措施的实施使得自然演替得以实现。景观格局的优化使生态系统的生态功能得到提高,包括生境恢复、生物多样性增加、水土流失减少。森林植被恢复以后,马尾松林斑块的单一化趋势应在今后的生物多样性保护、生态规划和可持续发展中得到重视。     

Herbivore and detritivore effects on rainforest plant production are altered by disturbance

Consumer effects on rainforest primary production are often considered negligible because herbivores and macrodetritivores usually consume a small fraction of annual plant and litter production, even though consumers are known to have effects on plant production and composition in nontropical systems. Disturbances, such as treefall gaps, however, often increase resources to understory food webs, thereby increasing herbivory and feeding rates of detritivores. This increase in consumption could lead to more prominent ecosystem‐level effects of consumers after disturbances, such as storms that cause light gaps. We determined how the effects of invertebrate herbivores (walking sticks) and detritivores (litter snails) on understory plant growth may be altered by disturbances in a Puerto Rican rainforest using an enclosure experiment. Consumers had significant effects on plant growth, but only in light gaps. Specifically, herbivores increased plant growth by 60%, and there was a trend for detritivores to reduce plant growth. Additionally, plant biomass tended to be 50% higher with both consumers in combination, suggesting that herbivores may mediate the effects of detritivores by altering the resources available to detritivore food webs. This study demonstrates that disturbance alters the effects of rainforest consumers, and, furthermore, that consumer activity has the potential to change rainforest successional processes.     

Ecological consequences of Late Quaternary extinctions of megafauna

Large herbivorous vertebrates have strong interactions with vegetation, affecting the structure, composition and dynamics of plant communities in many ways. Living large herbivores are a small remnant of the assemblages of giants that existed in most terrestrial ecosystems 50 000 years ago. The extinction of so many large herbivores may well have triggered large changes in plant communities. In several parts of the world, palaeoecological studies suggest that extinct megafauna once maintained vegetation openness, and in wooded landscapes created mosaics of different structural types of vegetation with high habitat and species diversity. Following megafaunal extinction, these habitats reverted to more dense and uniform formations. Megafaunal extinction also led to changes in fire regimes and increased fire frequency due to accumulation of uncropped plant material, but there is a great deal of variation in post-extinction changes in fire. Plant communities that once interacted with extinct large herbivores still contain many species with obsolete defences against browsing and non-functional adaptations for seed dispersal. Such plants may be in decline, and, as a result, many plant communities may be in various stages of a process of relaxation from megafauna-conditioned to megafauna-naive states. Understanding the past role of giant herbivores provides fundamental insight into the history, dynamics and conservation of contemporary plant communities.     

Leaf damage and functional traits along a successional gradient in Brazilian tropical dry forests

Herbivory has significant impacts on individual plants and plant communities, both at ecological and evolutionary time scales. In this context, this study aims to evaluate herbivore damage and its relationship with leaf chemical and structural traits, nutritional status, and forest structural complexity along a successional gradient. We predicted that trees in early successional stages support conservative traits related to drought tolerance (high specific leaf mass and phenolics), whereas trees in light-limited, late successional stages tend to enhance light acquisition strategies (high nitrogen content). We sampled 261 trees from 26 species in 15 plots (50 × 20 m; five per successional stage). From each tree, twenty leaves were collected for leaf trait measures. Phenolic content increased whereas specific leaf mass and nitrogen content decreased from early to late stages. However, leaf damage did not differ among successional stages. Our results partially corroborate the hypothesis that early successional plants in tropical dry forests exhibit leaf traits involved in the conservative use of water. The unexpected decrease in nitrogen content along the chronosequence is likely related to the fact that thinner leaves with low specific leaf mass could have less nitrogen-containing mesophyll per unit area. Mechanisms affecting herbivory intensity varied across scales: at the species level, leaf damage was negatively correlated with tannin concentration and specific leaf mass; at the plot level, leaf damage was positively affected by forest structural complexity. Herbivory patterns in tropical forests are difficult to detect because abiotic factors and multiple top-down and bottom-up forces directly and indirectly affect herbivores.     

Spatiotemporal patterns and dynamics of species richness and abundance of woody plant functional groups in a tropical forest landscape of Hainan Island, South China

Tropical forests are among the most species-diverse ecosystems on Earth. Their structures and ecological functions are complex to understand. Functional group is defined as a group of species that play similar roles in an ecosystem. The functional group approach has been regarded as an effective way of linking the compositions of complex ecosystems with their ecological functions. To understand the variation of functional groups in species-rich ecosystems after disturbance, the present study investigated the spatial pattern and temporal dynamics of woody plants in a typically fragmented natural forest landscape of Hainan Island in South China. The study area was classified into eight landscape types based on vegetation type, disturbance manner and the time of recovery. The woody plant species were aggregated into seven functional groups based on the growth form, successional status and plant size. The results gained from the present study showed that all functional groups, except for the emergent and canopy tree species, were present in all eight landscape types. Each landscape type had different numbers of dominant functional groups. There are similar species richness and stem abundance structure among functional groups between mid-successional clear cut lowland rainforest and old growth tropical coniferous forest. This similarity exists in selective logged lowland rainforest and old-growth lowland rainforest, as well as among landscape types of montane rainforest. The functional groups with the same successional status had similar patterns of species richness and stem abundance ratios among different landscape types. The variation patterns of functional groups along the successional stages in terms of species richness and stem abundance among the tropical lowland rainforest landscape types were more similar to each other than those in the tropical montane reinforest landscape types. This study provides further support for the competition-colonization tradeoff and successional niche theory as opposed to models of neutrality and ecological equivalence.     

Managing open habitats by wild ungulate browsing and grazing: A case‐study in North‐Eastern Germany

Question: Can wild ungulates efficiently maintain and restore open habitats? Location: Brandenburg, NE Germany. Methods: The effect of wild ungulate grazing and browsing was studied in three successional stages: (1) Corynephorus canescens‐dominated grassland; (2) ruderal tall forb vegetation dominated by Tanacetum vulgare; and (3) Pinus sylvestris‐pioneer forest. The study was conducted over 3 yr. In each successional stage, six paired 4 m²‐monitoring plots of permanently grazed versus ungrazed plots were arranged in three random blocks. Removal of grazing was introduced de novo for the study. In each plot, percentage cover of each plant and lichen species and total cover of woody plants was recorded. Results: Wild ungulates considerably affected successional pathways and species composition in open habitats but this influence became evident in alteration of abundances of only a few species. Grazing effects differed considerably between successional stages: species richness was higher in grazed versus ungrazed ruderal and pioneer forest plots, but not in the Corynephorus sites. Herbivory affected woody plant cover only in the Pioneer forest sites. Although the study period was too short to observe drastic changes in species richness and woody plant cover, notable changes in species composition were still detected in all successional stages. Conclusion: Wild ungulate browsing is a useful tool to inhibit encroachment of woody vegetation and to conserve a species‐rich, open landscape.     

贵州省普定县不同植被演替阶段的物种组成与群落结构特征

通过对贵州省普定县喀斯特地区不同植被演替阶段群落的调查, 研究了植被演替过程中群落物种组成和群落结构的变化。结果表明, 该地区的植被主要处于5个演替阶段, 即次生乔木林、乔灌过渡林、藤刺灌丛、稀灌草丛以及火烧干扰后的蕨类植物群落。本次调查共记录到植物365种, 隶属89科218属。其中, 蕨类植物31种, 隶属14科23属; 种子植物334种, 隶属75科195属。物种分布较多的科主要有蔷薇科、菊科、禾本科、百合科、忍冬科、唇形科、莎草科、樟科、葡萄科和水龙骨科。随着正向演替的推进, 物种丰富度增加, 群落结构趋于复杂化。藤刺灌丛与乔灌过渡林群落层次不明显, 次生乔木林分层明显。从藤刺灌丛向次生乔木林演替的过程中, 小径级个体所占比例明显降低, 高于1.3 m植物的总密度、乔木密度和藤本密度都先升高后降低, 而灌木密度呈逐渐降低的趋势。对喀斯特地区植被的恢复提出了参考措施。     

Threatened vascular plant species in spontaneously revegetated post‐mining sites

The occurrence of threatened vascular plant species has been occasionally reported from some disturbed sites. Nevertheless, almost nothing is known about the conservation potential of post‐mining habitats for vascular plant species at a landscape scale. We asked how much threatened species occur in the artificial habitats, and if the participation of particular threatened species categories differ over the course of succession. We studied 10 successional series running in 321 post‐mining sites across the Czech Republic, Central Europe. In total, 2,597 vegetation samples comprising 935 vascular plant species were analyzed. We found 235 threatened species (14% of the country's threatened flora). The majority of the threatened plants, namely 223, avoided plots overgrown by woody species, in which only 48 species occurred. The importance of spontaneously revegetated habitats for nature conservation differed among successional stages formed by discontinuous vegetation cover (not fully developed and still open, up to approximately 25 years since site abandonment), which harbored especially critically endangered species of open habitats, and continuous vegetation cover (fully developed and closed, over approximately 25 years), which was suitable for specialized threatened species typical of fully established vegetation. A mosaic of various successional stages comprising both categories of vegetation cover should be applied as an effective restoration solution to maintain a variety of habitats for threatened species.     

Small mammalian herbivore determines vegetation response to patchy nutrient inputs

Nutrient inputs to plant communities are often spatially heterogeneous, for example those deriving from the dung and urine of large grazing animals. The effect of such localised elevation of nutrients on plant growth and composition has been shown to be modified by the grazing of large herbivores. However, there has been little work on interactions between small mammalian herbivores and such patchy nutrient inputs, even though these interactions are potentially of major significance for plant performance and community structure.
We examined the effect of simulated cattle urine deposition on the vegetation structure, above-ground biomass and species composition of chalk grassland within enriched patches. Short-term exclosures were used to determine whether a small herbivore (rabbit) would preferentially graze the vegetation in enriched patches and what impact this interaction would have on the performance of plants in such patches. Rabbit grazing pressure determined whether nutrient inputs had a negative or positive effect on plant biomass. Nutrients increased plant biomass in the absence of grazing, but when exposed to grazing, plants in nutrient-rich patches had more biomass consumed by herbivores than neighbouring plants. Further, nutrients increased the relative palatability of a less preferred forage species ( Brachypodium pinnatum ), contributing to changes in plant community composition. We conclude that a small herbivore can drive plant responses to patchily distributed nutrients.