Spicing up restoration: can chili peppers improve restoration seeding by reducing seed predation?

Seed predation by rodents presents a significant barrier to native plant recruitment and can impede restoration seeding efforts. In nature, some plants contain secondary defense compounds that deter seed predators. If these natural defense compounds can be applied to unprotected seeds to inhibit rodent granivores, this approach could improve restoration seeding. Capsaicin is the active ingredient in chili pepper (Capsicum spp.) seeds that creates the burning sensation associated with human consumption of hot peppers. This compound has a similar effect on other mammals and is believed to have evolved as a deterrent to rodent seed predators. We used seed‐coating techniques to attach powder ground from Bhut Jolokia (Capsicum chinense) peppers to native plant seeds and evaluated the efficacy of these seed coatings for deterring rodent seed predation and enhancing native plant recruitment using laboratory and field experiments. Laboratory feeding trials demonstrated that native deer mice (Peromyscus maniculatus) consumed far fewer pepper‐coated seeds compared to untreated control seeds. Field seed‐addition experiments consistently demonstrated that rodent seed predation reduced native plant recruitment over the 4‐year study. Coating techniques used in the first 3 years were not persistent enough to reduce rodent seed predation effects on plant recruitment. However, a more persistent coating applied in conjunction with late‐winter sowing negated rodent seed predation effects on recruitment in year 4. Our results demonstrate that coating seeds with natural plant defense compounds may provide an effective, economical way to improve the efficacy of plant restoration by deterring seed predation by ubiquitous rodent granivores.     

Effects of supplemental feeding and density of white-tailed deer on rodents

Spatial distribution, population density, and reproductive success of many wildlife species may be altered by changes in vegetation composition, habitat structure, and availability of food. Altered distributions of key herbivores such as white-tailed deer (Odocoileus virginianus) may impact all of these factors. Our objective was to determine the direct and indirect effects of supplemental feeding of deer on rodent populations in south Texas. We modeled effects of supplemental feeding and habitat change due to deer browsing through surveys of rodents. Rodents have a short generation time and populations respond quickly to change, so they are a suitable indicator of changes in habitat structure brought about by deer browsing pressure. We sampled rodent populations near to and far from deer feeders within twelve 81-ha enclosures containing three different densities of deer with and without supplemental feed. The three deer densities were low (8.1 ha/deer), medium (3.2 ha/deer), and high (2 ha/deer). We conducted rodent trapping during March and April of 2007 and 2008. Abundance of rodents was much higher (P < 0.001) in 2008 than in the previous year due to an increase in rainfall. However, we found little effect of deer density, supplemental feeding of deer, or distance from deer feeders on rodent populations. Thus we conclude that supplemental feeding of deer and deer density had little influence on rodent communities in this environment. Rodent species native to semi-arid environments are probably adapted to large changes in vegetative productivity brought about by the highly variable annual rainfall patterns, therefore they can adapt to the less abrupt habitat changes resulting from changing densities of deer. Conservation concerns that providing supplemental feed to deer in semi-arid rangeland will disrupt the ecology of the land through changes in rodent populations were not supported. © 2011 The Wildlife Society.     

High Energy or Protein Concentrations in Food as Possible Offsets for Cyanide Consumption by Specialized Bamboo Lemurs in Madagascar

Plants producing toxic plant secondary metabolites (PSMs) deter folivores from feeding on them. Animals that can cope with noxious PSMs have a niche with a competitive advantage over other species. However, the ability to cope with toxic PSMs incurs the costs of detoxification. To assess possible compensations for the ingestion of toxic PSMs, we compare the chemical quality of plants consumed by bamboo lemurs (genera Hapalemur and Prolemur; strepsirrhine primates of Madagascar) in areas with and without bamboo. Some bamboo lemurs consume bamboo containing concentrations of cyanogenic substances 10–50 times above the average lethal dosage for mammals, and we postulate that animals consuming cyanogenic substances need supplementary protein or readily available energy for detoxification. We compared the chemical composition of food consumed by three species of bamboo lemurs that feed mainly (>80% of their time) on bamboo in the evergreen rainforest of Ranomafana (Madagascar) with published data of the diets of bamboo lemurs at two sites without highly cyanogenic plants (reed beds of Lac Alaotra and the evergreen littoral forest of Mandena) and with food of sympatric folivorous lemur species that do not feed on bamboo. Lemurs feeding on bamboo consumed up to twice as much protein as bamboo lemurs in areas without bamboo and sympatric lemur species that feed on leaves of trees. Concentrations of nonstructural carbohydrates (a source of energy) showed the opposite trend. This result supports the hypothesis that feeding on cyanogenic plants is linked to high protein intake, either as a source of protein or for sulfur-containing amino acids that can be used for detoxification. Owing to the high protein concentrations in bamboo, however, we cannot distinguish between the hypothesis that lemurs that eat bamboo target additional food items with higher protein from the hypothesis that lemurs feeding on bamboo unavoidably obtain higher concentrations of protein than animals feeding on leaves of trees, without an added nutritional benefit.     

The indole alkaloid,hypaphorine and Pterocarpus seed protection

L-Hypaphorine has been isolated as a major constituent of the seeds of Pterocarpus officinalis, seeds which are rejected as a food source by a wide variety of seed-eating rodents dwelling in the same habitat. Incorporation of the isolated hypaphorine into artificial diets of a small seed predator, Liomys salvini (a rodent) supports its role as a feeding deterrent.     

Are rodents a source of biotic resistance to tree invasion in Pampean grasslands? Tree seed consumption under different conditions

Biotic resistance has been invoked as a major barrier to woody species invasion, although the role of resident generalist consumers and their interaction with seed availability in a local community has received little attention. We assessed tree seed consumption by rodents under two different scenarios: (i) We documented in field spatio‐temporal patterns of seed predation by native rodents on two exotic tree species, Gleditsia triacanthos or ‘honey locust’ and Robinia pseudoacacia or ‘white locust’ (family Leguminosae), in five grassland habitats of the Inland Pampa, Argentina. (ii) We conducted laboratory feeding trials to evaluate tree seed consumption in the presence (cafeteria‐style feeding trials) and in the absence (non‐choice feeding trials) of alternative food supplies. Seed predation was generally higher for Robinia than for Gleditsia seeds, both in field and laboratory conditions. For both tree species, seed predation varied between habitats and seasons and was higher in the native tussock grassland than in the remaining studied communities, whereas the crop field showed the lowest levels of consumption along with the absence of captured rodents. Seed consumption of Gleditsia and Robinia among the four grassland communities (which did not differ in rodent abundance) was negatively associated with the availability of alternative food. Laboratory feeding trials showed a higher consumption of Gleditsia seeds in the non‐choice than in the cafeteria‐style feeding trials, while the consumption of Robinia seeds did not differ in the absence or presence of alternative seeds. These patterns indicate that the contribution of resident granivores to invasion resistance might depend on colonizer species identity, recipient community type and season of the year. We suggest that rodent preferences for different invader seeds will interact with the availability of alternative food in the local habitat in influencing the amount of predator‐mediated biotic resistance to invasion.     

Dietary niche differentiation among three species of invasive rodents (Rattus rattus, R. exulans, Mus musculus)

The diets of sympatric rodents partially define their realized niches. Identifying items in stomachs of introduced rodents helps determine rodents’ trophic positions and species most at risk of consumption. In the Hawaiian Islands, which lacked rodents prior to human arrival, three rodents (Rattus rattus or black rat, R. exulans or Pacific rat, Mus musculus or house mouse) commonly coexist in native habitats where they consume a wide range of plants and animals. These three rodent species were trapped in montane forest for 2.5 years; their stomach contents were analyzed to determine short-term diets (n = 12–95 indiv. per species), and isotopic fractions of δ¹⁵N and δ¹³C in their bone collagen were analyzed to further estimate their trophic positions (n = 11–20 indiv. per species). For all three species, >75 % of individuals had plants and >90 % had arthropods in their stomachs, and significant differences in mean relative abundances were found for food items in stomachs among all three rodents. Rodents may be dispersing some native and non-native seeds, including the highly invasive Clidemia hirta. Most identifiable arthropods in rodent stomachs were non-native, and no stomachs contained birds, snails, or lizards. The δ¹⁵N and δ¹³C signatures were consistent with trophic feeding differences revealed from stomach contents. Dietary niche differentiation by coexisting rodent species is evident in this forest, with Pacific rats being intermediate between the mostly carnivorous house mouse and the mostly herbivorous black rat; such findings can help forecast rodent impacts and direct management efforts in ecosystems where these invasive animals coexist.     

Deterring rodent seed‐predation using seed‐coating technologies

With many degraded environments undergoing restoration efforts, there is a growing need for the optimization of direct seeding practices. Seeds planted on wildlands are often consumed by rodents, leading to reduced plant establishment. Coating seeds in rodent aversive products may prevent seed‐predation. We tested 10 seed‐coating formulations containing products expected to deter rodents, namely: ghost and cayenne pepper powders; essential oils from bergamot, neem, and pine; methyl‐nonyl‐ketone, anthraquinone, activated carbon, beta‐cyclodextrin, and a blank coating containing no rodent deterrents to serve as a control treatment. Each treatment was applied to Pseudoroegneria spicata (bluebunch wheatgrass) seeds. These seeds germinated similarly to uncoated control seeds unless the coating contained methyl‐nonyl‐ketone which reduced germination. When seeds were offered to Ord's kangaroo rats (Dipodomys ordii), they strongly avoided the treatments in favor of uncoated control seeds. Notably, the blank coating, lacking active ingredients, still elicited 99% avoidance. However, these results indicated behavior when alternative food sources are readily available, a scenario rare in nature. To address this, a second feeding experiment was conducted to observe D. ordii's behavior under calorie‐restricted conditions. D. ordii were subjected to a fast period, then offered only one treatment. Under these conditions, many subjects chose to consume coated seeds, but to a lesser degree than subjects offered control seeds. Seeds coated in ghost pepper, neem oil, and activated carbon reduced consumption by 47–50%. Given these lab results, we would expect these treatments to increase native plant establishment following the direct seeding of wildlands by protecting seeds from rodent predation.     

Effects of burrow condition and seed handling time on hoarding strategies of Edward's long-tailed rat (Leopoldamys edwardsi)

Many hoarding rodents use burrows not only for dwelling and protection from natural enemies, but also for food storage. However, little is known how burrows used by scatter-hoarding animals influence their foraging behaviors. In addition, handling time for a given food item has a fundamental impact on hoarding strategies of these hoarding animals: food items with longer handling time are more likely to be hoarded due to increasing predation risk because the animals spend more time outside their burrows if they consumed such food. By providing with two types of artificial burrows (aboveground vs. underground) and two types of food items (i.e. seeds) with contrasting handling times, we investigated how burrow condition and handling time co-influence hoarding strategies of a key scatter-hoarding rodent, Edward's long-tailed rat (Leopoldamys edwardsi) in large enclosures in southwest China. We found that only a few animals larder-hoarded fewer seeds when only aboveground burrows were available, while over 80% of the animals preferred to use the underground burrows and hoard significantly more seeds in the burrows when both aboveground and underground burrows were provided simultaneously. We also found that seed handling time significantly affected hoarding strategies of the animals: they consumed and/or scatter-hoarded more Camellia oleifera seeds with shorter handling time outside the burrow, but consumed and larder-hoarded more Lithocarpus harlandii seeds with longer handling time in underground burrows. Our study indicates that both burrow types and seed handling time have important impacts on hoarding strategies of scatter-hoarding animals.     

Insect assemblages on flowering patches of 12 bamboo species

Bamboos are known as long-living monocarpic plants that exhibit synchronous flowering at long intervals. It has been reported that florivory has a critical effect on their seed production in bamboos, especially in small scale flowering patches. In this study, we aimed to determine species composition and life history of florivorous insects in multiple bamboo species. We collected the inflorescences of 12 bamboo species from 15 sites in Japan from 2017 to 2019 and recorded insect assemblages found in the flowers. Five different insect species were observed to feed on the flowers of bamboo species. Among these, the larvae of two Dicraeus species were the most widely observed florivorous insects of the bamboo species. The other insects included the larvae of Cecidomyiidae sp., which was frequently observed on Sasa species, and the other two insects were Epuraea submicrurula, and Dimorphopterus japonicus. These insects were oviposited on the florets during the budding period. In addition, predators and parasitoids were found in the bamboo flowers. Our findings suggest that the bamboos flowers were mainly consumed by dipteran larvae. Insect species composition and frequency varied among bamboo species and sites. Comparing the frequency of the florivorous insects among bamboo flowering patches, including mass flowering patches, in different areas is needed in future studies.     

Fallen leaves and unpalatable plants as alternative foods for sika deer under food limitation

Feeding behavior and rumen contents of sika deer (Cervus nippon Temminck) under food limitation were studied on Nakanoshima Island, Hokkaido. During the phase of population growth, the deer subsisted on tree bark and twigs, deciduous leaves and dwarf bamboos (Sasa spp.) in the winter. After a crash in population, the deer began feeding on the fallen leaves of deciduous trees and continued to do so throughout the year. They also ate unpalatable plants Cephalotaxus harringtonia var. nana Rehd., Senecio cannabifolius Less. and Cynanchum caudatum Maxim. as winter foods, which used to remain untouched by deer, and had accordingly expanded their distributions, following a decrease in the amount of dwarf bamboos available. These facts suggest that sika deer drastically shift their foods and exploit alternative foods under conditions of food limitation.     

Deer feeding selectivity for invasive plants

Native generalist herbivores might limit plant invasion by consuming invading plants or enhance plant invasion by selectively avoiding them. The role of herbivores in plant invasion has been investigated in relation to plant native/introduced status, however, a knowledge gap exists about whether food selection occurs according to native/introduced status or to species. We tested preference of the native herbivore white-tailed deer (Odocoileus virginianus) for widespread and frequently occurring invasive introduced and native plants in the northeastern United States. Multiple-choice deer preference trials were conducted for the species and relative preference was determined using biomass consumption and feeding behavior. While more native than introduced plant biomass was consumed overall, deer food selection varied strongly by plant species. Results show consistent deer avoidance of several invasive introduced plants (Alliaria petiolata, Berberis thunbergii, and Microstegium vimineum) and a native plant (Dennstaedtia punctilobula). Other invasive introduced plants (Celastrus orbiculatus, Ligustrum vulgare, and Lonicera morrowii) and a native plant (Acer rubrum) were highly preferred. These results provide evidence that herbivore impacts on plant invaders depend on plant species palatability. Consequently, herbivore selectivity likely plays an important role in the invasion process. To the extent that herbivory impacts population demographics, these results suggest that native generalist herbivores promote enemy release of some plant invaders by avoiding them and contribute to biotic resistance of others by consuming them.     

Fecal Shedding of Zoonotic Food-Borne Pathogens by Wild Rodents in a Major Agricultural Region of the Central California Coast

Recent outbreaks of food-borne illness associated with the consumption of produce have increased concern over wildlife reservoirs of food-borne pathogens. Wild rodents are ubiquitous, and those living close to agricultural farms may pose a food safety risk should they shed zoonotic microorganisms in their feces near or on agricultural commodities. Fecal samples from wild rodents trapped on 13 agricultural farms (9 produce, 3 cow-calf operations, and 1 beef cattle feedlot) in Monterey and San Benito Counties, CA, were screened to determine the prevalence and risk factors for shedding of several food-borne pathogens. Deer mice (Peromyscus maniculatus) were the most abundant rodent species trapped (72.5%). Cryptosporidium species (26.0%) and Giardia species (24.2%) were the predominant isolates from rodent feces, followed by Salmonella enterica serovars (2.9%) and Escherichia coli O157:H7 (0.2%). Rodent trap success was significantly associated with detection of Salmonella in rodent feces, while farm type was associated with fecal shedding of Cryptosporidium and Giardia. Seasonal shedding patterns were evident, with rodents trapped during the spring and summer months being significantly less likely to be shedding Cryptosporidium oocysts than those trapped during autumn. Higher rodent species diversity tended to correlate with lower fecal microbial prevalence, and most spatiotemporal pathogen clusters involved deer mice. Rodents in the study area posed a minimal risk as environmental reservoirs of E. coli O157:H7, but they may play a role in environmental dissemination of Salmonella and protozoa. Rodent control efforts that potentially reduce biodiversity may increase pathogen shedding, possibly through promotion of intraspecific microbial transmission.     

Effect of dietary history and algal traits on feeding rate and food preference in the green sea urchin Strongylocentrotus droebachiensis

Feeding behaviour is influenced by a variety of factors, including nutritional requirements, the quality of available foods, and environmental conditions. We examined the effect of two factors, food morphology and dietary history, on the feeding rate and preference of the sea urchin Strongylocentrotus droebachiensis. Standardizing food shape and structure did not alter urchins' expected preference for the native kelp Laminaria longicruris over the invasive alga Codium fragile ssp. tomentosoides. However, when foods containing L. longicuris were shaped to mimic the algae, the C. fragile mimic was consumed more rapidly than the kelp mimic. Dietary history had no effect on single diet feeding rate. Urchins feeding on C. fragile consistently consumed twice as much (by mass) as those fed kelp, regardless of their previous diet. Despite higher feeding rates on C. fragile, urchins feeding on this alga were unable to compensate for its low energetic content and ingested less energy. Dietary history had a short-term effect on food preference, with urchins tending to prefer less familiar foods. Our findings suggest that urchins feed on C. fragile at a high rate, due to ease of handling and/or compensatory feeding, and that they do not a have strict preference hierarchy. Rather, food choice appears to reflect active maintenance of a mixed diet.     

Sin Nombre Virus and Rodent Species Diversity: A Test of the Dilution and Amplification Hypotheses

Background

Species diversity is proposed to greatly impact the prevalence of pathogens. Two predominant hypotheses, the “Dilution Effect” and the “Amplification Effect”, predict divergent outcomes with respect to the impact of species diversity. The Dilution Effect predicts that pathogen prevalence will be negatively correlated with increased species diversity, while the Amplification Effect predicts that pathogen prevalence will be positively correlated with diversity. For many host-pathogen systems, the relationship between diversity and pathogen prevalence has not be empirically examined.

Methodology/Principal Findings

We tested the Dilution and Amplification Effect hypotheses by examining the prevalence of Sin Nombre virus (SNV) with respect to diversity of the nocturnal rodent community. SNV is directly transmitted primarily between deer mice (Peromyscus maniculatus). Using mark-recapture sampling in the Spring and Fall of 2003–2005, we measured SNV prevalence in deer mice at 16 landscape level sites (3.1 hectares each) that varied in rodent species diversity. We explored several mechanisms by which species diversity may affect SNV prevalence, including reduced host density, reduced host persistence, the presence of secondary reservoirs and community composition. We found a negative relationship between species diversity and SNV prevalence in deer mice, thereby supporting the Dilution Effect hypothesis. Deer mouse density and persistence were lower at sites with greater species diversity; however, only deer mouse persistence was positively correlated with SNV prevalence. Pinyon mice (P. truei) may serve as dilution agents, having a negative effect on prevalence, while kangaroo rats (Dipodomys ordii), may have a positive effect on the prevalence of SNV, perhaps through effects on deer mouse behavior.

Conclusions/Significance

While previous studies on host-pathogen systems have found patterns of diversity consistent with either the Dilution or Amplification Effects, the mechanisms by which species diversity influences prevalence have not been investigated. Our study indicates that changes in host persistence, coupled with interspecific interactions, are important mechanisms through which diversity may influence patterns of pathogens. Our results reveal the complexity of rodent community interactions with respect to SNV dynamics.     

Feeding Habits of Introduced Black Rats,Rattus rattus,in Nesting Colonies of Galapagos Petrel on San Cristóbal Island,Galapagos

Introduced rodents are responsible for ecosystem changes in islands around the world. In the Galapagos archipelago, their effects on the native flora and fauna are adverse, including the extinction of endemic rodents in some islands and the reduction in the reproductive success of the Galapagos petrel (Pterodroma phaeopygia) in its nesting zones. Understanding the feeding behavior of introduced rodents and their trophic interactions with native and non-native species on islands, can assist in the design of management strategies and conservation plans of invasive and endemic species respectively. Four petrel nesting colonies were monitored during June 2013 on San Cristóbal Island (El Plátano, El Junco, San Joaquín, and La Comuna). The feeding habits of black rats were evaluated by analyzing stomach contents and stable isotopes in hair. Three species of introduced rodents were captured. R. rattus was the most abundant at all sites (n=43, capture success (CS) = 55.8%), followed by the house mouse, Mus musculus (n = 17, CS = 37.8%), and the Norwegian rat, R. norvegicus (n = 4, CS = 4.5%), captured only at La Comuna. The omnivorous black rat ate mostly plants (98%) and arthropods (2%). Intact seeds of Miconia robinsoniana were the main food at all sites (relative abundance=72.1%, present in 95% of the analyzed stomachs), showing the black rats’ possible role in the archipelago as endemic seed dispersers. There was no evidence of petrel’s intake; however, its possible consumption is not discarded at all. The δ¹⁵N and δ¹³C analysis corroborated the primarily herbivorous diet of black rats. The isotopic signatures of the three rodent species reflect the inter- and intra-specific differential use of food resources. Black rat showed a wider diet in La Comuna, which was related to a lower availability of its primary prey and its ability to adapt to the available resources in its habitat.     

Black bears Ursus americanus are effective seed dispersers,with a little help from their friends

Black bears Ursus americanus are generally considered effective seed dispersal agents for fleshy‐fruited plants because they can consume hundreds of fruits at once and have large home ranges. Although seedlings can emerge from faecal piles, establishment of such seedlings seems to be infrequent. Removal of seeds from faeces by rodents is often considered seed predation. We show that removal of seeds from bear faeces by seed‐caching rodents in the Sierra Nevada, USA, represents a second phase of seed dispersal that benefits some fleshy‐fruited plants. Using Trail Master infrared cameras to photograph animals and scandium‐46, a gamma‐emitting radionuclide, to track seeds, we determined that deer mice Peromyscus maniculatus removed seeds from bear faeces and cached them in soil. Caches typically contained 1–3 seeds buried 5–10 mm deep. These seeds escaped several sources of mortality by being moved to relatively safe locations, but deer mice also eventually eat many of the cached seeds. A field germination study confirmed that seed burial increased seedling emergence. Rodents removed seeds in bear faeces more quickly than those in bird faeces in one year, but seeds in bird faeces were removed faster in another year. Results varied across two years, probably because of availability of alternative food sources or changes in deer mice population sizes. The two‐phase seed dispersal syndrome described here may be important in understanding seed dispersal by carnivores and large ungulates that produce large faecal deposits containing many relatively large seeds.     

Shade tolerance of temperate Asian bamboos: a harbinger of their naturalization in Pacific Northwest coniferous forests?

Bamboos native to temperate East Asian coniferous forests arrive with increasing frequency in the United States as horticultural imports, and some are becoming naturalized locally. Given the strong floristic and physiognomic similarities between East Asian and western North American coniferous forests, we asked whether these introduced bamboos could tolerate the varied light regimes within coniferous forests in their new range. Seven temperate Asian bamboos and one North American bamboo (Arundinaria gigantea) were grown within shade structures in an experimental garden; these structures reduced ambient light to three light levels (50, 70, 90 % shade) that occur routinely within coniferous forests in the Pacific Northwest. Species’ responses under these light levels were measured by their light response curves to photosynthesis, resource allocation to light or carbon harvesting centers inferred by CO₂ response curves, and shifts amongst forms of leaf Chlorophyll. Bashania fargesii has lower chlorophyll content and photosynthetic rates under high shade (90 %) relative to other Asian species and to B. fargesii grown in 50 and 70 % shade. Bashania fargesii, Sasa kurilensis and A. gigantea also displayed lower photosynthetic rates under 90 % shade compared to plants grown in 50 and 70 % shade and lower electron transport capacity under 70 and 90 % shade compared to plants grown in 50 % shade. In contrast, Pleioblastus chino, Pleioblastus distichus, Pseudosasa japonica, Sasa palmata and Sasaella ramosa display strong tolerance of low light. Our results indicate these five Asian bamboos (and others yet to be introduced) could skirt a major environmental barrier to new species establishment in these North American forests. Measuring a species’ light response curve offers a reliable, rapid means to assess an immigrant species’ potential to tolerate forests’ varied light regimes.     

Endophytic fungi and silica content of different bamboo species in giant panda diet

The giant panda (Ailuropoda melanoleuca), one of the most threatened mammalian species in the world, has adapted to herbivorous diet consisting mainly of bamboo (Poaceae: Bambusoidea). The most acute threats to the survival of the giant panda are habitat loss and fragmentation. However, changes in habitat may influence also the quality of giant panda diet through the bamboo species composition as well as their symbiotic leaf endophytes and plant chemical properties. Here we explore species composition and frequency of endophytic fungi and silica content in different bamboo species in the range of giant panda habitat in relation to panda food preference. Silica content of the bamboos varied from 3.7 g/kg to 45.7 g/kg and did not correlate with panda preference and altitudinal gradient. Systemic and vertically in seeds transmitted fungal endophytes or bacterial endophytes were not detected in bamboo leaves. Nearly half of the identified endophytic fungi belonged to genus Arthrinium. Pandas preferred bamboo species naturally occurring in higher altitudes. Furthermore, the total amount of endophytes tended to be lower in samples collected from bamboos in higher altitudes. This draws attention to the importance of more detailed studies on the endophytic fungi-bamboo-panda trophic interactions and the effect of land use and climate change on conservation programs of giant panda.     

Bamboo thickets alter the demographic structure of Euterpe edulis population: A keystone,threatened palm species of the Atlantic forest

The rapid spread of bamboos can strongly affect forest structure by interfering plant regeneration and reducing local biodiversity. Considering that bamboos exert a negative influence on the plant community, our main goal was to investigate how this influence manifests at the population level. We compared the demographic structure of the threatened palm Euterpe edulis between bamboo and non-bamboo dominated patches within the Atlantic forest. In the study site, the native bamboo Guadua tagoara has created a marked patchiness and heterogeneity in the vegetation. Plots were set up randomly in bamboo and non-bamboo patches and the heights of all E. edulis individuals were measured. Data from canopy openness and litter depth were collected for both patches. Greater number of E. edulis was recorded in bamboo patches. However, frequency distribution of the height classes differed between patches revealing a predominance of seedling and sapling I classes in bamboo patches, in comparison to a more evenly distribution of height classes in non-bamboo patches. The canopy in bamboo patches was more open and the litter depth was thicker. Our analyses evidenced G. tagoara is functioning as a demographic bottleneck of natural population of E. edulis by arresting its later stages of regeneration and in high densities that bamboos may limit recruitment of this palm species.     

秦岭森林鼠类对华山松种子捕食及其扩散的影响

森林鼠类的种子贮藏行为对植物的扩散和自然更新有着非常重要的影响。通过塑料片标记法,2008和2009年的9月—11月分别在秦岭南坡的佛坪国家级自然保护区内调查了森林鼠类对华山松(Pinus armandii)种子的捕食和扩散,结果显示:森林鼠类对华山松种子有着非常大的捕食压力。在2008年,几乎所有的种子(96.4%)在第3天后就被全部取食,而在2009年,也有将近一半的种子(49.6%)在第3天后被取食。但与此同时,鼠类对华山松种子的扩散也起着非常重要的作用。尤其在2009年,第3天时鼠类最高分散贮藏了17.75%的种子,而且直到第19天后仍然有12.25%被贮藏的种子存活下来。华山松种子在两个年份间的扩散历程有很大差异。在2008年,几乎所有的种子都被鼠类取食,贮藏量非常小;而在2009年,种子被贮藏的比例显著的增加。这个结果可能与种子大小年现象有着十分紧密的联系。2008年是华山松种子的小年,产量非常低。鼠类为了满足其日常的能量需求,只能大量的取食有限的种子,而减少其贮藏量。而2009年是华山松种子的大年,产量非常高。鼠类在满足其日常能量需求的同时,还有大量剩余的种子供其贮藏。