Seeds In Dung Research Articles

Can goats disperse seeds of herbaceous pasture plants in Mediterranean grasslands?

In the Mediterranean region, endozoochorous seed dispersal is a potential alternative for the recovery of degraded or abandoned grasslands and shrublands. The objectives of this study were to quantify the number of seeds that pass through the goat gut and to determine whether this process affects seed germination in six common herbaceous species of the Mediterranean area (Ornithopus compressus L., Biserrula pelecinus L., Medicago polymorpha L., Melilotus officinalis L. Pall, Festuca ovina L. and Dactylis glomerata L). We also examined whether the inclusion of the seeds in dung affected seed germination and seedling establishment and growth. The highest seed recovery rate was obtained 24–72h after ingestion. The amount of retrieved seeds varied among species and was generally low, with significant differences among some leguminous and grass species. With the exception of M. officinalis, the quantity of retrieved legume seeds (1.5–6.8%) was greater than that of the grass seeds (0.9–1.1%). A significant relationship was found between recovery of the seeds and their hardness and volume. In all species, the recovered seeds presented significantly lower germinability than seeds that had not been consumed. In general, all recovered legume seeds showed higher average germination rate values (18–50%) compared to recovered grass seeds (0–14%). Seedling emergence was lower in intact than in crumbled dung pellets and, in most cases, the values of both of these were lower than that of unconsumed (control) seeds. No seedling emergence was recorded for seeds of B. pelecinus and O. compressus contained in intact or crumbled faeces at all sampling times. While the percentages of recovery and subsequent emergence found in this study are low in absolute terms, we can conclude that a significant number of seeds may become established from the dung and could be a potential alternative for the recovery of degraded or abandoned grazing areas.

Cattle as Dispersal Vectors of Invasive and Introduced Plants in a California Annual Grassland

Plant invasions are a threat to rangelands in California. Understanding how seeds of invasive plants are dispersed is critical to developing sound management plans. Domestic livestock can transport seeds long distances by ingesting and passing seeds in dung (endozoochory) or by the attachment of seeds to skin and fur (epizoochory). Our objective was to characterize the role of cattle as seed dispersers of both invasive and noninvasive species via endozoochory and epizoochory in a Sierra foothills rangeland. To quantify endozoochory, we sampled dung from two dry-season grazing periods and evaluated seed content by growing dung for 3 months in a greenhouse. To quantify epizoochory, we collected seeds directly from the fur of 40 cattle. We categorized the invasion status and functional groups of all species found and quantified landscape-scale vegetation composition in order to determine whether dispersal mode was associated with functional group, invasion status, or vegetation composition. Finally, we evaluated the potential for the noxious weed medusahead (Taeniatherum caput-medusae [L.] Nevski) to travel long distances on cattle fur using a detachment experiment with a model cow. We found that forbs were more likely to be dispersed by endozoochory, and invasive species were more likely to be dispersed by epizoochory. Medusahead was dispersed exclusively by epizoochory and was able to travel up to 160 m on a model cow. Our results suggest that cattle may be an important dispersal vector for both invasive and noninvasive plants.

Effects of dung beetles on seedling emergence from herbaceous seeds in the dung of sika deer (Cervus nippon) in a temperate Japanese grassland ecosystem

AbstractThe effects of dung form and condition and of dung beetles on the emergence of seedlings from herbaceous seeds in sika deer dung were examined in a temperate grassland ecosystem dominated by Zoysia japonica and Hydrocotyle maritima. I conducted field experiments to compare seedling emergence between dung exposed to dung beetles and intact dung using both dung pellets and pats during a typical rainy month (June) and the hottest, drier month (August), when large numbers of seeds of the dominant species were present in the dung. The exposed dung was immediately attacked and broken up by dung beetles, whereas dung protected from the beetles remained intact. In June, at least 12 herbaceous species, including Z. japonica, H. maritima, Mazus pumilus, and Plantago asiatica, emerged from the dung, versus at least six species in August. Decomposition rates of the pellets in June and decomposition scores of the pats in June and August were positively correlated with the number of emerging seedlings, suggesting that the acceleration of decomposition by dung beetles can positively affect seed germination. In this system of interactions among sika deer, herbaceous plants, and dung beetles, sika deer dung prevented seeds from germinating, and beetles had an indirect positive effect on seedling emergence by accelerating decomposition of the dung, although the extent of the effect may depend on the dung type, plant species, and environmental factors.

Potential of endozoochorous seed dispersal by sheep in calcareous grasslands: correlations with seed traits

AbstractQuestions: What is the potential of sheep to serve as seed dispersers via ingestion and defecation in calcareous grasslands? Is the presence of viable seeds from dung correlated with specific seed traits?Location: Calcareous grasslands, South Limburg, the Netherlands/Belgium.Methods: Dung samples (n=24) from sheep were collected between September 2006 and November 2007 from five sites with Mesobromion plant communities, and communities of Nardo‐Galion saxatilis. Germinability and identity of seeds in the dung samples were ascertained from germination of seedlings under glasshouse conditions. Seed traits of species with viable seeds in dung were compared with those present in the local species pool.Results: Seventy‐two plant species from 23 plant families had viable seeds in sheep dung. The plant families encountered most frequently were Gramineae and Compositae. The most abundant and frequently recorded plant species in dung samples was Urtica dioica, accounting for >80% of the total number of seeds. Mean seed density in sheep dung was 0.8 seeds g−1 dry matter. Seeds with low seed mass and a high seed longevity index were over‐represented in dung. Viable seeds >2.5 mg were infrequent in the dung samples.Conclusions: We conclude that sheep are potentially important dispersers of plant species in Dutch calcareous grasslands. Although smaller seeds were relatively abundant in sheep dung, it cannot be excluded that this was mainly caused by differences in seed abundance.

Effects of dung and seed size on secondary dispersal, seed predation, and seedling establishment of rain forest trees.

Seeds dispersed by tropical, arboreal mammals are usually deposited singly and without dung or in clumps of fecal material. After dispersal through defecation by mammals, most seeds are secondarily dispersed by dung beetles or consumed by rodents. These post-dispersal, plant-animal interactions are likely to interact themselves, as seeds buried by dung beetles are less likely to be found by rodents than unburied seeds. In a series of three experiments with seeds of 15 species in central Amazonia (Brazil), we determined (1) how presence and amount of dung associated with seeds influences long-term seed fate and seedling establishment, (2) how deeply dung beetles bury seeds and how burial depth affects seedling establishment, and (3) how seed size affects the interaction between seeds, dung beetles, and rodents. Our overall goal was to understand how post-dispersal plant-animal interactions determine the link between primary seed dispersal and seedling establishment. On average, 43% of seeds surrounded by dung were buried by dung beetles, compared to 0% of seeds not surrounded by dung ( n=2,156). Seeds in dung, however, tended to be more prone than bare seeds to predation by rodents. Of seeds in dung, probability of burial was negatively related to seed size and positively related to amount of dung. Burial of seeds decreased the probability of seed predation by rodents three-fold, and increased the probability of seedling establishment two-fold. Mean burial depth was 4 cm (0.5-20 cm) and was not related to seed size, contrary to previous studies. Probability of seedling establishment was negatively correlated with burial depth and not related to seed size at 5 or 10 cm depths. These results illustrate a complex web of interactions among dung beetles, rodents, and dispersed seeds. These interactions affect the probability of seedling establishment and are themselves strongly tied to how seeds are deposited by primary dispersers. More generally, our results emphasize the importance of looking beyond a single type of plant-animal interaction (e.g., seed dispersal or seed predation) to incorporate potential effects of interacting interactions.

Impact of cattle dung deposition on the distribution pattern of plant species in an alvar limestone grassland

Abstract. Seed banks in cattle dung, soil under cattle dung and soil under vegetation and growth response of plant species to the changes in soil nitrogen availability were studied in an alvar limestone grassland on Öland, Sweden, in order to analyse the impact of dung deposition and decomposition on the formation of patches of plant species. Results suggest that patches of four plant species could result from cattle dung deposition and decomposition. Impact of dung could proceed in three ways: (1) by changing the relative abundance of species in the soil seed bank under dung, and/or (2) by influencing the deposition of seeds in the dung, and/or (3) by intensifying the growth of some species through nutrient release. Species patches could result from one or more of these aspects. For instance, patches of Arenaria serpyllifolia may be induced by dung deposition because of the dominance of its seeds in dung, while the pattern of Cerastium semidecandrum and Festuca ovina may be due to the abundance of their seeds in the soil seed bank under dung and their positive growth response to increased nitrogen availability.

Post-dispersal predation of Acacia farnesiana seeds by Stator vachelliae (Bruchidae) in Central America.

Post-dispersal seed predation by the bruchid beetle Stator vachelliae was investigated in Santa Rosa National Park, Costa Rica. This insect finds the seeds of the leguminous Acacia farnesiana in the feces of horses, deer, and ctenosaur lizards, the current major dispersers. Patterns of oviposition and pre-adult survival of beetles in the seeds were investigated in a series of experiments using fresh horse dung. S. vachelliae never minded into the dung balls, attacking only those seeds located on the surface. Fresh horse dung did not attract insects more readily than dry dung. The proportion of seeds attacked was not related to their density in a defecation, and was similar in three areas with different densities of the host plant. In a fourth area with no fruiting A. farnesiana shrubs all seeds survived insect predation. Bruchids attacked a greater proportion of seeds at 1 m than at 5 m from the edge of the shrub's crown. Seeds were mainly removed from horse dung by rodents with similar intensity in all areas and at both distances; this seed removal interfered with bruchid oviposition and probably with bruchid survival. S. vachelliae oviposited less frequently on seeds in dung fully exposed to sun. When oviposition on a dung pile was high, the distribution of eggs on the seeds was clumped, suggesting that some seeds were preferred to others. By the end of the dry season, bruchids stopped attacking the seeds. The results show that the fate of both seeds and bruchids is greatly influenced by the location and time of defecation.

Seed Dispersal by Cassowaries (Casuarius casuarius) in North Queensland's Rainforests

Casuarius casuarius inhabits the rainforests of northeastern Australia and some of the islands to the north. It depends on fruit which has fallen from the middle and upper forest canopy. During the two-year study period diaspores of 78 plant species were found in cassowary dung. Although the germination percentage of seeds in dung were variable, some germination was observed for 70 species. The passage of most diaspores through a cassowary does not appear to greatly affect seed germination characteristics. These birds are the only extant frugivores large enough to effectively disperse many of the plant species found in the rainforests of this region. CASSOWARIES ARE LARGE (standing to 1.5 m high), powerfully built, flightless birds which are found in or near rainforests in northeastern Australia, New Guinea, and some adjacent islands (Rand and Gilliard 1967). Of the three extant species recognised, Casuarius casuarius (L.) is the most widespread and is the only species now found in Australia. They are reasonably common in the lowland rainforest north of Ingham where their presence is indicated by tracks and piles of dung. The latter are readily recognisable, consisting of up to one kg of seeds and fruit fragments (Fig. 1). Crome (1976) used these dung components to identify the plant species contributing to their diet. The observation that seeds frequently germinated within the dung piles (Fig. 2) prompted the present study aimed at assessing the role of cassowaries in dispersing rainforest plant species. Although Ridley (1930) provides several reports of cassowaries dispersing seeds of some forest species on Ceram and the Aru Islands, the cassowary was not incduded in Snow's recent world survey of tropical frugivorous birds and their food plants (Snow 1981) and except for the notes of Crome (1976) and Frizelle (in White 1913) very little seems to be known of this bird's biology.