Cache sites preferred by small rodents facilitate cache survival in a subtropical primary forest, central China

2013 ◽  
Vol 40 (4) ◽  
pp. 294 ◽  
Author(s):  
Shoujia Sun ◽  
Hongmao Zhang

Context Scatter-hoarding rodents tend to hoard plant seeds in preferred places that facilitate seed survival, resulting in high food rewards for hoarders and a high probability of seedling establishment for plants. Aims To test the hypothesis that caches placed in rodent-preferred microhabitats, nearest-neighbour distances between caches (cache density) or cache depths have an increased chance of survival. Methods Rodent-made caches and observer-established caches of Himalayan hazelnut (Corylus ferox) seeds were tracked in a subtropical primary forest in central China. The survival of caches within rodent-preferred microhabitats, nearest-neighbour distances and cache depths were identified. Key results Rodents preferred to hoard Himalayan hazelnut seeds in microhabitats under and at the edge of shrubs, with the nearest-neighbour distance of <4.0 m, and at 2.1–4.0-cm depth. The survival times of both rodent-made caches and observer-established caches were longer within rodent-preferred microhabitats than in other habitats and increased with an increasing nearest-neighbour distance and cache depth, up to what appeared to be an optimal nearest-neighbour distance and depth. Conclusions Conditions of rodent-preferred cache microhabitats, nearest-neighbour distances and cache depths can facilitate cache survival. Implications Rodents often move plant seeds away from parent trees and bury them in shallow soil, which benefits seed dispersal and establishment of plants. The present study demonstrates that rodent-preferred cache conditions may translate into higher seed survival and a higher tendency of seeds to germinate and establish. Thus, careful management and conservation of rodent-preferred hoarding habitats may benefit seed dispersal and survival.

1993 ◽  
Vol 07 (01n03) ◽  
pp. 207-211
Author(s):  
T. KRAFT ◽  
M. METHFESSEL ◽  
M. VAN SCHILFGAARDE ◽  
M. SCHEFFLER

Using the full-potential linear muffin-tin orbital method within the local spin-density approximation we analyse the influence of the nearest neighbour distance on fcc(111) or hcp(0001) iron layers. The LDA-LSDA error in describing ferromagnetic phases is determined to be at least 15 mRy/atom. As a consequence of this error, our calculations favour paramagnetic ground states. In this sense, the reported results have some model character. However, our analysis of the elastic energy cost under distortions should hold for transition metals in general. Allowing relaxations of the interplanar distance the fcc phase can become energetically favourable over the hcp phase at large lattice mismatches. The main reason for this behaviour is the enhanced stiffness of the hcp interplanar bonds due to the shortening of the axial c/a ratio.


2005 ◽  
Vol 21 (3) ◽  
pp. 243-253 ◽  
Author(s):  
Sabrina E. Russo

Natural seed deposition patterns and their effects on post-dispersal seed fate are critical in tropical tree recruitment. Previous research showed that the key dispersal agent of the neotropical tree, Virola calophylla, is the spider monkey (Ateles paniscus). Spider monkeys generate a heterogeneous seed deposition pattern because they scatter-disperse seeds diurnally, whereas they clump-disperse seeds at their sleeping sites. The recruitment consequences of this pattern were investigated using manipulative experiments and observations. Scatter-hoarding by spiny rats (Proechimys spp.) caused little rearrangement of the initial seed deposition pattern because they moved seeds only short distances. Seed survival to the seedling stage depended negatively on conspecific seed density and positively on the distance from the nearest adult V. calophylla female. These effects were likely mediated by two important seed predators, spiny rats and beetles (Scolytidae). Furthermore, spider monkeys' seed deposition patterns influenced seed survival. Scatter-dispersed and experimentally dispersed seeds had the highest survival. Conversely, clump-dispersed seeds at sleeping sites, which are far from V. calophylla females, and non-dispersed seeds had equally low survival, suggesting that conspecific density- and distance-dependence acted independently and did not explain all variation in seed survival. Instead, other characteristics of the seed deposition pattern, such as the multi-specific assemblage of seeds at sleeping sites, also affected post-dispersal seed fates.Resumen: La conexión entre el patrón natural de dispersión de semillas con el destino después de la dispersión es clave para el reclutamiento de árboles tropicales. Mediante experimentos y observaciones se investigó esta conexión utilizando el árbol neotropical Virola calophylla (Myristicaceae). Ateles paniscus (maquisapa), el principal dispersor de sus semillas, genera un patrón de deposición heterogéneo. Durante el día las semillas son depositadas de manera esparcida mientras que en los dormitorios las semillas son depositadas de manera agregada. En este estudio se encontró que los roedores espinosos (Proechimys spp.) almacenaron semillas individuales debajo de la hojarasca, sin embargo estos no alteraron el patrón de dispersión ya que las semillas fueron transportadas distancias cortas y la tasa de predación fue alta. Se encontró que la tasa de sobrevivencia hasta la etapa de plántula tuve una relación negativa con la densidad de las semillas y una relación positiva con la distancia al árbol hembra de V. calophylla mas cercano. Estos efectos sucedieron por medio de roedores espinosos y coleópteros (Scolytidae), predadores importantes de las semillas de V. callophylla. Adicionalemente, el patrón de deposición de los maquisapas influenció la sobrevivencia de las semillas. Tanto las semillas dispersadas por los maquisapas como las dispersadas experimentalmente tuvieron la tasa de sobrevivencia más alta. Por el contrario, tanto las semillas depositadas en los dormitorios, usualmente lejos de hembras de V. calophylla, como las semillas que cayeron debajo del árbol hembra tuvieron bajos niveles de sobrevivencia. Estos reultados sugieren que tanto la densidad como la distancia tuvieron efectos independientes y no explicaron toda la variación observada en la sobrevivencia de semillas. Por el contrario, otras características de la deposición de semillas tales como la riqueza de especies de la comunidad de semillas en los dormitorios también afectaron el destino de las semillas después de dispersadas.


2022 ◽  
Vol 507 ◽  
pp. 120016
Author(s):  
Jie Chen ◽  
Wenwen Chen ◽  
Zhiyun Lu ◽  
Bo Wang

Weed Science ◽  
2007 ◽  
Vol 55 (6) ◽  
pp. 626-630 ◽  
Author(s):  
Kirk W. Davies ◽  
Roger L. Sheley

Controlling invasive plant infestations is very costly and often unsuccessful. Preventing invasions is more cost-effective than controlling invasive plants after they are established. Because prevention guidelines do not suggest any tools or methods to limit wind dispersal of invasive plant seeds, we investigated the influence of neighboring vegetation height on seed dispersal of a wind-dispersed (yellow salsify) and nonwind-dispersed (medusahead) species. To examine the influence of neighboring vegetation height on dispersal, seeds of both species were released in front of an artificial stand of desert wheatgrass in a modified wind tunnel. Treatments were a complete factorial design with two species, four vegetation heights (10, 30, 40, and 60 cm), three wind speeds (3, 5.5, and 10 km h−1), and three release distances from the neighboring vegetation (0, 15, and 30 cm). The ability of medusahead and yellow salsify seeds to disperse was influenced by the height of neighboring vegetation. Increasing height of neighboring vegetation decreased the number of yellow salsify seeds dispersing across neighboring vegetation. The greatest percentage of medusahead seeds dispersed across the neighboring vegetation was at the shortest height. Based on these results, we suggest that maintaining or promoting tall vegetation neighboring invasive plant infestations may reduce wind dispersal of seeds. More research is needed to investigate the influence of varying heights, densities, structural attributes, and composition of vegetation neighboring infestations and the dispersal of invasive plants.


2020 ◽  
Vol 91 (6) ◽  
pp. 711-720
Author(s):  
Yamato Tsuji ◽  
Risma Yanti ◽  
Atsushi Takizawa ◽  
Toshio Hagiwara

We compared the characteristics of seeds within faeces between semi-terrestrial Japanese macaques (<i>Macaca fuscata</i>) and sympatric arboreal Japanese martens (<i>Martes melampus</i>) in Shiga Heights, central Japan. We collected faecal samples of the two mammalian species for 1 year (<i>n</i> = 229 for macaques and <i>n</i> = 22 for martens). We then compared the proportion of seed occurrence, life-form composition, number of seeds and species richness within single faecal samples, and the seed intact ratio between the two mammalian species. We detected seeds from 20 and 7 species from macaque and marten faeces, respectively. Macaque faeces contained seeds of multiple strata, while marten faeces contained no herbaceous plant seeds. Seed sizes within faeces showed no interspecific difference. For macaques, seeds were found within faecal samples collected in late spring to late fall, while for martens, seeds were found between summer and winter. The proportion of seed occurrence was greater in summer (both species) and fall (macaques), which implied that the seed dispersal roles of macaques and martens was greater in these seasons. The mean seed number (across species), intact ratio of seeds (high for both species) and seed species richness within single faecal samples of macaques and martens showed no significant differences, but for several species, martens defecated more seeds than macaques and showed higher intact ratio. Our study indicates that sympatric mammals in the temperate regions of Japan contribute differently to seed dispersal in forest ecosystems.


1995 ◽  
Vol 407 ◽  
Author(s):  
Y. Kogure ◽  
H. Masuyama ◽  
M. Doyama

ABSTRACTMolecular dynamics simulations on the solid-liquid transition of copper crystals have been performed. The configulation and the motion of atoms are monitored by RDF. It is seen that the height of the first peak in the RDF, which located at the nearest neighbour distance, decreased drastically as the temperature is increased.


1990 ◽  
Vol 6 (4) ◽  
pp. 459-468 ◽  
Author(s):  
Pierre-Michel Forget

ABSTRACTA possible mutualistic dispersal system between a large-seeded tree of French Guiana, Vouacapoua americana (Caesalpiniaceae), and caviomorph rodents, Myoprocta exilis and Dasyprocta leporina, is described. Mast fruiting of Vouacapoua at the beginning of the wet season coincides with scatter-hoarding seed dispersal. During the wet season, almost 100% of marked seeds on three sites were removed: nearly 70% were buried and the rest were eaten by mammals. Unburied seeds were attacked by insects and/or lost their ability to germinate. Rodents preferred ungerminated seeds, and had no interest in germinated seeds. Seeds were buried individually near natural objects such as palms, branches, logs, lianas, roots and trees. After predation by rodents, seedling distribution did not differ from seed distribution. Most seeds were transported less than 5 m from the feeding plots but some were carried as far as 22.4 m. Between 40 and 85% of dispersed seeds were retrieved during the following month by rodents and eaten. The disinterest of caviomorph rodents in germinated seeds, because of rapid exhaustion of endosperm reserves, prevents feeding from hoarded Vouacapoua during the long dry season when resources are scarce. Seedlings emerging from forgotten or abandoned cached seeds appear to increase the recruitment of Vouacapoua americana.


1976 ◽  
Vol 31 (1) ◽  
pp. 90-101 ◽  
Author(s):  
Peter Lamparter ◽  
Siegfried Steeb ◽  
Walter Knoll

Neutron diffraction work (λ = 0.695 Å) was done with molten Bi-Sb-alloys in the temperature range between 550 and 750 °C. Furthermore molten Bi was investigated at 300 °C. The interference functions show subsidiary maxima especially for alloys with higher Sb-concentrations. Evaluation yields, that the melts contain two different kinds of structure:a) The one kind shows coordination number 9 and a statistical distribution of the atoms of two components. This kind is more inetal-like.b) The other kind shows coordination number 3, consists of non-centered tetrahedra with smaller nearest neighbour distance. It shows covalent binding.In molten Sb the nearest neighbour distance amounts up to 3.16 - 3.19 Å for theo ne kind and up to 2.64 -2.78 Å fort he other kind, which yields an mean distance of 2.99 Å, which was observed. The dependence of the concentration of the statistical kind of meld, of the (Sb)4-, and the (Bi)4-kind from the concentration of the whole melt is given.By the model described the run of the measured mean coordination number and the mean distance versus concentration can be well explained.


Oikos ◽  
2014 ◽  
Vol 124 (7) ◽  
pp. 899-907 ◽  
Author(s):  
Erik Kleyheeg ◽  
Casper H. A. van Leeuwen ◽  
Mary A. Morison ◽  
Bart A. Nolet ◽  
Merel B. Soons

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