Positive interactions between large herbivores and grasshoppers, and their consequences for grassland plant diversity

Ecology ◽  
2014 ◽  
Vol 95 (4) ◽  
pp. 1055-1064 ◽  
Author(s):  
Zhiwei Zhong ◽  
Deli Wang ◽  
Hui Zhu ◽  
Ling Wang ◽  
Chao Feng ◽  
...  
Keyword(s):  
Plant Diversity ◽  
Positive Interactions ◽  
Large Herbivores

Effects of grazing by large herbivores on plant diversity and productivity of semi-arid alpine steppe on the Qinghai-Tibetan Plateau

2015 ◽  
Vol 37 (4) ◽  
pp. 389 ◽  
Author(s):  
Hasbagan Ganjurjav ◽  
Min-jie Duan ◽  
Yun-fan Wan ◽  
Wei-na Zhang ◽  
Qing-zhu Gao ◽  
...  
Keyword(s):  
Species Diversity ◽  
Tibetan Plateau ◽  
Plant Community ◽  
Plant Diversity ◽  
Net Primary Productivity ◽  
Strong Impact ◽  
Aboveground Net Primary Productivity ◽  
Large Herbivores ◽  
Alpine Steppe ◽  
Semi Arid

Grazing by large herbivores may have a strong impact on plant diversity and productivity, but the effects are expected to vary with grazing pressure. The changes in productivity and species diversity of Stipa purpurea-dominated semi-arid alpine steppe grassland were measured under four different stocking rates of Tibetan sheep [no grazing, light (2.4 sheep units ha–1), moderate (3.6 sheep units ha–1), and heavy (6.0 sheep units ha–1) grazing] in a 5-year (2006–2010) grazing experiment on the Qinghai-Tibetan Plateau, China. Herbage mass and aboveground net primary productivity of alpine steppe declined significantly with increasing stocking rate (P < 0.05). Over the 5 years of the experiment, the proportion of forbs and sedges increased significantly under light and moderate grazing; the proportion of grasses decreased significantly, whereas the proportion of S. purpurea did not change compared with the no grazing treatment. Species diversity was highest under moderate grazing and was significantly higher than the no grazing treatment in 2 years (2008 and 2010). Moderate grazing enhanced the species diversity of the plant community due to an increase in the proportion of forbs. There were significant positive linear correlations between herbage mass and species diversity under no and light grazing. Species diversity was not related to productivity under moderate and heavy grazing. In conclusion, grazing by sheep reduced plant productivity; plant diversity increased under low and moderate grazing, and was as a result of changes in the composition of the plant community of a semi-arid alpine steppe.

scholarly journals Water availability, bedrock, disturbance by herbivores, and climate determine plant diversity in South-African savanna

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Martin Hejda ◽  
Jan Čuda ◽  
Klára Pyšková ◽  
Guin Zambatis ◽  
Llewellyn C. Foxcroft ◽  
...  
Keyword(s):  
Species Richness ◽  
South African ◽  
Plant Diversity ◽  
Water Availability ◽  
Large Scale ◽  
Woody Species ◽  
Plant Species Richness ◽  
African Savanna ◽  
Shrub Species ◽  
Large Herbivores

AbstractTo identify factors that drive plant species richness in South-African savanna and explore their relative importance, we sampled plant communities across habitats differing in water availability, disturbance, and bedrock, using the Kruger National Park as a model system. We made plant inventories in 60 plots of 50 × 50 m, located in three distinct habitats: (i) at perennial rivers, (ii) at seasonal rivers with water available only during the rainy season, and (iii) on crests, at least ~ 5 km away from any water source. We predicted that large herbivores would utilise seasonal rivers’ habitats less intensely than those along perennial rivers where water is available throughout the year, including dry periods. Plots on granite harboured more herbaceous and shrub species than plots on basalt. The dry crests were poorer in herb species than both seasonal and perennial rivers. Seasonal rivers harboured the highest numbers of shrub species, in accordance with the prediction of the highest species richness at relatively low levels of disturbance and low stress from the lack of water. The crests, exposed to relatively low pressure from grazing but stressed by the lack of water, are important from the conservation perspective because they harbour typical, sometimes rare savanna species, and so are seasonal rivers whose shrub richness is stimulated and maintained by the combination of moderate disturbance imposed by herbivores and position in the middle of the water availability gradient. To capture the complexity of determinants of species richness in KNP, we complemented the analysis of the above local factors by exploring large-scale factors related to climate, vegetation productivity, the character of dominant vegetation, and landscape features. The strongest factor was temperature; areas with the highest temperatures reveal lower species richness. Our results also suggest that Colophospermum mopane, a dominant woody species in the north of KNP is not the ultimate cause of the lower plant diversity in this part of the park.

scholarly journals Positive interactions between herbivores and plant diversity shape forest regeneration

2014 ◽  
Vol 281 (1783) ◽  
pp. 20140261 ◽  
Author(s):  
Susan C. Cook-Patton ◽  
Marina LaForgia ◽  
John D. Parker
Keyword(s):  
Plant Diversity ◽  
Forest Regeneration ◽  
Plant Density ◽  
Interspecific Interactions ◽  
Trophic Levels ◽  
Positive Interactions ◽  
Tree Seedling ◽  
Positive Interaction ◽  
Intraspecific Interactions ◽  
Palatable Species

The effects of herbivores and diversity on plant communities have been studied separately but rarely in combination. We conducted two concurrent experiments over 3 years to examine how tree seedling diversity, density and herbivory affected forest regeneration. One experiment factorially manipulated plant diversity (one versus 15 species) and the presence/absence of deer ( Odocoileus virginianus ). We found that mixtures outperformed monocultures only in the presence of deer. Selective browsing on competitive dominants and associational protection from less palatable species appear responsible for this herbivore-driven diversity effect. The other experiment manipulated monospecific plant density and found little evidence for negative density dependence. Combined, these experiments suggest that the higher performance in mixture was owing to the acquisition of positive interspecific interactions rather than the loss of negative intraspecific interactions. Overall, we emphasize that realistic predictions about the consequences of changing biodiversity will require a deeper understanding of the interaction between plant diversity and higher trophic levels. If we had manipulated only plant diversity, we would have missed an important positive interaction across trophic levels: diverse seedling communities better resist herbivores, and herbivores help to maintain seedling diversity.

Grazing as a management tool in dune grasslands: Evidence of soil and scale dependence of the effect of large herbivores on plant diversity

2008 ◽  
Vol 141 (6) ◽  
pp. 1687-1694 ◽  
Author(s):  
Pejman Tahmasebi Kohyani ◽  
Beatrijs Bossuyt ◽  
Dries Bonte ◽  
Maurice Hoffmann
Keyword(s):  
Plant Diversity ◽  
Scale Dependence ◽  
Management Tool ◽  
Large Herbivores

scholarly journals Reciprocal facilitation between large herbivores and ants in a semi-arid grassland

2018 ◽  
Vol 285 (1888) ◽  
pp. 20181665 ◽  
Author(s):  
Xiaofei Li ◽  
Zhiwei Zhong ◽  
Dirk Sanders ◽  
Christian Smit ◽  
Deli Wang ◽  
...  
Keyword(s):  
Species Coexistence ◽  
Plant Biomass ◽  
Soil Surface ◽  
Plant Litter ◽  
Positive Interactions ◽  
Large Herbivores ◽  
Litter Accumulation ◽  
Positive Effects ◽  
Animal Communities ◽  
Semi Arid

While positive interactions have been well documented in plant and sessile benthic marine communities, their role in structuring mobile animal communities and underlying mechanisms has been less explored. Using field removal experiments, we demonstrated that a large vertebrate herbivore (cattle; Bos tarurs ) and a much smaller invertebrate (ants; Lasius spp.), the two dominant animal taxa in a semi-arid grassland in Northeast China, facilitate each other. Cattle grazing led to higher ant mound abundance compared with ungrazed sites, while the presence of ant mounds increased the foraging of cattle during the peak of the growing season. Mechanistically, these reciprocal positive effects were driven by habitat amelioration and resource (food) enhancement by cattle and ants (respectively). Cattle facilitated ants, probably by decreasing plant litter accumulation by herbivory and trampling, allowing more light to reach the soil surface leading to microclimatic conditions that favour ants. Ants facilitated cattle probably by increasing soil nutrients via bioturbation, increasing food (plant) biomass and quality (nitrogen content) for cattle. Our study demonstrates reciprocal facilitative interactions between two animal species from phylogenetically very distant taxa. Such reciprocal positive interactions may be more common in animal communities than so far assumed, and they should receive more attention to improve our understanding of species coexistence and animal community assembly.

scholarly journals Plant diversity with species drilled in the same or alternate rows enhanced pasture yield and quality over 4 years

2021 ◽  
Vol 17 ◽  
Author(s):  
Alistair Black ◽  
Thinzar Myint ◽  
Arulmageswaran Shampasivam ◽  
Shuo Yang
Keyword(s):  
Plant Diversity ◽  
Total Yield ◽  
Red Clover ◽  
Weed Suppression ◽  
Positive Interactions ◽  
Pasture Production ◽  
Yield And Quality ◽  
Relative Abundances ◽  
Total Seed ◽  
Pasture Yield

This paper reports on the effects of plant species diversity and sowing method on pasture yield and quality. Nineteen seed mixtures of perennial ryegrass (PR), plantain (Pl), white clover (WC) and red clover (RC) were sown on 26 March 2015 at Lincoln University. Four mixtures of PR, Pl and WC were repeated with species separated in alternate drill rows. Plots were grazed by sheep and irrigated. After 4 years, a mixture with 25% of each species based on seed count – equivalent to 7.5 kg PR, 5.6 kg Pl, 1.9 kg WC and 4.4 kg RC (19.4 kg total seed)/ha – produced an optimal balance of increased total yield (17.44 t DM/ha/yr), weed suppression (0% of total yield), metabolisable energy (11.4 MJ/kg DM) and crude protein (19% of DM). Sowing method had no effect. Plant diversity enhanced pasture production through positive interactions and identity effects among the legumes (WC and RC) and non-legumes (PR and Pl). The strength of interactions between species depended on the identity and relative abundances of the species involved. The diversity effects occurred alongside shifts in species relative abundances over time. This study demonstrated an experimental basis for the evaluation of multi-species pasture mixtures.

scholarly journals Living at the Edge: Increasing Stress for Plants 2–13 Years After the Retreat of a Tropical Glacier

2021 ◽  
Vol 9 ◽  
Author(s):  
Fabien Anthelme ◽  
Sophie Cauvy-Fraunié ◽  
Bernard Francou ◽  
Bolívar Cáceres ◽  
Olivier Dangles
Keyword(s):  
Species Richness ◽  
Abiotic Stress ◽  
Plant Diversity ◽  
Plant Succession ◽  
Positive Interactions ◽  
Plant Colonization ◽  
Tropical Andes ◽  
Glacial Retreat ◽  
Distribution Study ◽  
Grain Distribution

Rapid warming is a major threat for the alpine biodiversity but, at the same time, accelerated glacial retreat constitutes an opportunity for taxa and communities to escape range contraction or extinction. We explored the first steps of plant primary succession after accelerated glacial retreat under the assumption that the first few years are critical for the success of plant establishment. To this end, we examined plant succession along a very short post-glacial chronosequence in the tropical Andes of Ecuador (2–13 years after glacial retreat). We recorded the location of all plant individuals within an area of 4,200 m2 divided into plots of 1 m2. This sampling made it possible to measure the responses of the microenvironment, plant diversity and plants traits to time since the glacial retreat. It also made it possible to produce species-area curves and to estimate positive interactions between species. Decreases in soil temperature, soil moisture, and soil macronutrients revealed increasing abiotic stress for plants between two and 13 years after glacial retreat. This increasing stress seemingly explained the lack of positive correlation between plant diversity and time since the glacial retreat. It might explain the decreasing performance of plants at both the population (lower plant height) and the community levels (lower species richness and lower accumulation of species per area). Meanwhile, infrequent spatial associations among plants indicated a facilitation deficit and animal-dispersed plants were almost absent. Although the presence of 21 species on such a small sampled area seven years after glacial retreat could look like a colonization success in the first place, the increasing abiotic stress may partly erase this success, reducing species richness to 13 species after 13 years and increasing the frequency of patches without vegetation. This fine-grain distribution study sheds new light on nature's responses to the effects of climate change in cold biomes, suggesting that faster glacial retreat would not necessarily result in accelerated plant colonization. Results are exploratory and require site replications for generalization.

Communication/Interaction Development at Mealtimes for the Multiply Handicapped Child

1981 ◽  
Vol 12 (4) ◽  
pp. 216-232 ◽  
Author(s):  
Suzanne Evans Morris
Keyword(s):  
Handicapped Child ◽  
Positive Interactions ◽  
Speech Language Pathologist ◽  
Specific Program ◽  
Communication Interaction

The mealtime setting can be creatively used by the speech-language pathologist to increase the positive interactions between the child and caregiver and to establish the basic prerequisites for the development of communication. Specific program suggestions are provided to enable the speech-language pathologist to utilize the mealtime setting to integrate both vocal and nonvocal communicative objectives. The roots of interaction and communication which underly both vocal and nonvocal systems are described.

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