scholarly journals The nature and modelling of piospheres: a review

Koedoe ◽  
1999 ◽  
Vol 42 (2) ◽  
Author(s):  
I. Thrash ◽  
J.F. Derry
Keyword(s):  
Plant Density ◽  
Plant Biomass ◽  
Canopy Cover ◽  
Production Plant ◽  
Large Herbivore ◽  
Data Set ◽  
Large Herbivores ◽  
Large Populations ◽  
Herbivore Species ◽  
Artificial Watering

Gradients in utilisation pressure tend to develop around watering points because water dependent herbivores are forced to congregate within a maximum distance of about 10-15 km from water in the dry season. Artificial watering points cause previously migratory or nomadic indigenous large herbivores to become sedentary, so that natural grazing patterns are disrupted. Under this altered grazing pattern, piosphere patterns tend to develop in herbaceous species composition, range condition, grass production, plant biomass, understory cover, standing crop and basal cover. In areas with large populations of elephants the density and canopy cover of trees is directly proportional to distance from watering points. In the absence of elephants an increase in woody plant density and canopy cover tends to occur in a zone just beyond a sacrifice area. Soil erosion, compaction and capping tend to occur at watering points on soils containing clay and silt. Artificial watering points are advantageous to the non-mobile water dependent large herbivore species and disadvantageous to the water independent large herbivore species. The processes underlying piosphere development and maintenance are numerous and diverse. While being parsimonious treatments of a complex system, conceptual models do provide a reasonable basis upon which to design an improved understanding. The logistic curve has been proposed as a convenient tool for estimating piosphere dimensions, but ignoring the 'best-fit' regression model for a piosphere data set may be an inaccurate practice. A large number of gradient models have been developed, each an attempt to shed some light on the behavioural response underlying what appears to be a complex grazing pattern. Several system models that take piosphere effects into account have been constructed. Some of these produce good simulations of herbaceous materi- al dynamics and especially good simulations of bush dynamics.

scholarly journals Varied diets, including broadleaved forage, are important for a large herbivore species inhabiting highly modified landscapes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Annika M. Felton ◽  
Emma Holmström ◽  
Jonas Malmsten ◽  
Adam Felton ◽  
Joris P. G. M. Cromsigt ◽  
...  
Keyword(s):  
Food Availability ◽  
Diet Composition ◽  
Nutritional Composition ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Winter Diet ◽  
Varied Diet ◽  
Survival And Reproduction ◽  
Herbivore Species ◽  
Free Ranging

AbstractDiet quality is an important determinant of animal survival and reproduction, and can be described as the combination of different food items ingested, and their nutritional composition. For large herbivores, human landscape modifications to vegetation can limit such diet-mixing opportunities. Here we use southern Sweden’s modified landscapes to assess winter diet mixtures (as an indicator of quality) and food availability as drivers of body mass (BM) variation in wild moose (Alces alces). We identify plant species found in the rumen of 323 moose harvested in Oct-Feb, and link variation in average calf BM among populations to diets and food availability. Our results show that variation in calf BM correlates with variation in diet composition, diversity, and food availability. A varied diet relatively rich in broadleaves was associated with higher calf BM than a less variable diet dominated by conifers. A diet high in shrubs and sugar/starch rich agricultural crops was associated with intermediate BM. The proportion of young production forest (0–15 yrs) in the landscape, an indicator of food availability, significantly accounted for variation in calf BM. Our findings emphasize the importance of not only diet composition and forage quantity, but also variability in the diets of large free-ranging herbivores.

scholarly journals Collapse of the world’s largest herbivores

2015 ◽  
Vol 1 (4) ◽  
pp. e1400103 ◽  
Author(s):  
William J. Ripple ◽  
Thomas M. Newsome ◽  
Christopher Wolf ◽  
Rodolfo Dirzo ◽  
Kristoffer T. Everatt ◽  
...  
Keyword(s):  
Fire Regimes ◽  
Large Carnivores ◽  
Population Declines ◽  
Resource Depression ◽  
Ecological Processes ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Cascading Effects ◽  
Ecosystem Effects ◽  
Herbivore Species

Large wild herbivores are crucial to ecosystems and human societies. We highlight the 74 largest terrestrial herbivore species on Earth (body mass ≥100 kg), the threats they face, their important and often overlooked ecosystem effects, and the conservation efforts needed to save them and their predators from extinction. Large herbivores are generally facing dramatic population declines and range contractions, such that ~60% are threatened with extinction. Nearly all threatened species are in developing countries, where major threats include hunting, land-use change, and resource depression by livestock. Loss of large herbivores can have cascading effects on other species including large carnivores, scavengers, mesoherbivores, small mammals, and ecological processes involving vegetation, hydrology, nutrient cycling, and fire regimes. The rate of large herbivore decline suggests that ever-larger swaths of the world will soon lack many of the vital ecological services these animals provide, resulting in enormous ecological and social costs.

scholarly journals Global large herbivore conservation and international law

2019 ◽  
Vol 28 (14) ◽  
pp. 3891-3914 ◽  
Author(s):  
Arie Trouwborst
Keyword(s):  
International Law ◽  
Biological Diversity ◽  
Legal Framework ◽  
Convention On Biological Diversity ◽  
Migratory Species ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Herbivore Species ◽  
The Many ◽  
Bilateral Treaties

Abstract Large wild herbivore species are important to ecosystems and human societies, but many of them are threatened and in decline. International wildlife treaties have a role to play in arresting and reversing these declines. This paper provides a global overview and analysis of relevant legal instruments and their roles regarding the conservation of the 73 largest terrestrial herbivores, i.e., those with a body mass of ≥ 100 kg. Outcomes reveal both significant positive contributions and shortcomings of the Ramsar Wetlands Convention, the World Heritage Convention, the Convention on International Trade in Endangered Species, the Convention on Migratory Species and its subsidiary instruments, the Convention on Biological Diversity, and a range of regional and bilateral treaties. Maximizing the potential of these treaties, and attaining their objectives regarding the conservation and restoration of large herbivores, requires substantial increases in funding and political will. Even before such game-changing increases occur, however, it remains worthwhile to seek and use the many opportunities that exist within the current international legal framework for enhancing the conservation of the world’s largest herbivores.

Nitrogen Demand of Cut Chrysanthemums in Relation to Shoot Height and Planting Date

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 523c-523
Author(s):  
Siegfried Zerche
Keyword(s):  
Dry Matter ◽  
Plant Density ◽  
Plant Biomass ◽  
N Uptake ◽  
Planting Date ◽  
Dry Matter Accumulation ◽  
Planting Dates ◽  
Shoot Height ◽  
Climate Conditions ◽  
Growing Period

Refined nutrient delivery systems are important for environmentally friendly production of cut flowers in both soil and hydroponic culture. They have to be closely orientated at the actual nutrient demand. To solve current problems, express analysis and nutrient uptake models have been developed in horticulture. However, the necessity of relatively laborious analysis or estimation of model input parameters have prevented their commercial use up to now. For this reason, we studied relationships between easily determinable parameters of plant biomass structure as shoot height, plant density and dry matter production as well as amount of nitrogen removal of hydroponically grown year-round cut chrysanthemums. In four experiments (planting dates 5.11.91; 25.3.92; 4.1.93; 1.7.93) with cultivar `Puma white' and a fixed plant density of 64 m2, shoots were harvested every 14 days from planting until flowering, with dry matter, internal N concentration and shoot height being measured. For each planting date, N uptake (y) was closely (r2 = 0.94; 0.93; 0.84; 0.93, respectively) related to shoot height (x) at the time of cutting and could be characterized by the equation y = a * × b. In the soilless cultivation system, dry matter concentrations of N remained constant over the whole growing period, indicating non-limiting nitrogen supply. In agreement with constant internal N concentrations, N uptake was linearly related (r2 = 0.94 to 0.99) to dry matter accumulation. It is concluded that shoot height is a useful parameter to include in a simple model of N uptake. However, in consideration of fluctuating greenhouse climate conditions needs more sophisticated approaches including processes such as water uptake and photosynthetically active radiation.

scholarly journals Continuous presence of proto-cereals in Anatolia since 2.3 Ma, and their possible co-evolution with large herbivores and hominins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Valérie Andrieu-Ponel ◽  
Pierre Rochette ◽  
François Demory ◽  
Hülya Alçiçek ◽  
Nicolas Boulbes ◽  
...  
Keyword(s):  
Large Herbivore ◽  
Large Lakes ◽  
Coprophilous Fungi ◽  
Large Herbivores ◽  
Genetic Modifications ◽  
Bioclimatic Zone ◽  
Central Resource ◽  
Sedimentary Core ◽  
Continuous Presence ◽  
Lake Acıgöl

AbstractCereals are a central resource for the human diet and are traditionally assumed to have evolved from wild grasses at the onset of the Neolithic under the pressure of agriculture. Here we demonstrate that cereals may have a significantly longer and more diverse lineage, based on the study of a 0–2.3 Ma, 601 m long sedimentary core from Lake Acıgöl (South-West Anatolia). Pollen characteristic of cereals is abundant throughout the sedimentary sequence. The presence of large lakes within this arid bioclimatic zone led to the concentration of large herbivore herds, as indicated by the continuous occurrence of coprophilous fungi spores in the record. Our hypothesis is that the effects of overgrazing on soils and herbaceous stratum, during this long period, led to genetic modifications of the Poaceae taxa and to the appearance of proto-cereals. The simultaneous presence of hominins is attested as early as about 1.4 Ma in the lake vicinity, and 1.8 Ma in Georgia and Levant. These ancient hominins probably benefited from the availability of these proto-cereals, rich in nutrients, as well as various other edible plants, opening the way, in this region of the Middle East, to a process of domestication, which reached its full development during the Neolithic.

Population structure, density and biomass of large herbivores in the tropical forests of Nagarahole, India

1992 ◽  
Vol 8 (01) ◽  
pp. 21-35 ◽  
Author(s):  
K. Ullas Karanth ◽  
Melvin E. Sunquist
Keyword(s):  
Population Structure ◽  
Tropical Forests ◽  
Primate Species ◽  
Line Transect ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Transect Sampling ◽  
Structure Density ◽  
Density And Biomass ◽  
Turn Over

ABSTRACTWe studied the population structure, density and biomass of seven ungulate and two primate species in the tropical forests of Nagarahole, southern India, using line transect sampling and roadside/platform counts, during 1986–87. The estimated ecological densities of large herbivore species in the study area are: 4.2 muntjac km−2, 50.6 chital km−2, 5.5 sambar km−2, 0.8 four-horned antelope km−2, 9.6 gaur km−2, 4.2 wild pig km−2, 3.3 elephant km−2, 23.8 hanuman langur km−2and 0.6 bonnet macaque km−2. Most ungulates have female-biased adult sex ratios. Among common ungulate species, yearlings and young of the year comprise about a third of the population, suggesting relatively high turn-over rates. Three species (muntjac, sambar and four-horned antelope) are solitary, while others form groups. The study area supports a wild herbivore biomass density of 14,744 kg km−2. Among the three habitat types within the study area, biomass is lower in dry deciduous forests when compared with moist deciduous or teak plantation dominant forests. Using our results, we have examined the factors that may contribute towards maintenance of high ungulate biomass in tropical forests.

Large herbivores suppress liana infestation in an African savanna

2021 ◽  
Vol 118 (41) ◽  
pp. e2101676118
Author(s):  
Tyler C. Coverdale ◽  
Ryan D. O’Connell ◽  
Matthew C. Hutchinson ◽  
Amanda Savagian ◽  
Tyler R. Kartzinel ◽  
...  
Keyword(s):  
Stable State ◽  
Life Forms ◽  
Tree Canopy ◽  
Alternative Stable State ◽  
African Savanna ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Woody Vines ◽  
Plant Life Forms ◽  
Canopy Area

African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages—declining wildlife populations and their displacement by livestock—may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 y (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-y-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana–tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.

scholarly journals On the correspondence of electrical and optical physiology in in vivo population-scale two-photon calcium imaging

2019 ◽  
Author(s):  
Peter Ledochowitsch ◽  
Lawrence Huang ◽  
Ulf Knoblich ◽  
Michael Oliver ◽  
Jerome Lecoq ◽  
...  
Keyword(s):  
Calcium Imaging ◽  
Biophysical Model ◽  
Data Set ◽  
Two Photon ◽  
Simultaneous Imaging ◽  
Fluorescence Measurements ◽  
Large Populations ◽  
Intractable Problem ◽  
Mouse Lines

AbstractMultiphoton calcium imaging is commonly used to monitor the spiking of large populations of neurons. Recovering action potentials from fluorescence necessitates calibration experiments, often with simultaneous imaging and cell-attached recording. Here we performed calibration for imaging conditions matching those of the Allen Brain Observatory. We developed a novel crowd-sourced, algorithmic approach to quality control. Our final data set was 50 recordings from 35 neurons in 3 mouse lines. Our calibration indicated that 3 or more spikes were required to produce consistent changes in fluorescence. Moreover, neither a simple linear model nor a more complex biophysical model accurately predicted fluorescence for small numbers of spikes (1-3). We observed increases in fluorescence corresponding to prolonged depolarizations, particularly in Emx1-IRES-Cre mouse line crosses. Our results indicate that deriving spike times from fluorescence measurements may be an intractable problem in some mouse lines.

scholarly journals Using Canopy Measurements to Predict Soybean Seed Yield

2021 ◽  
Vol 13 (16) ◽  
pp. 3260
Author(s):  
Peder K. Schmitz ◽  
Hans J. Kandel
Keyword(s):  
Seed Yield ◽  
Prediction Models ◽  
Plant Density ◽  
Soybean Seed ◽  
Canopy Cover ◽  
Growing Season ◽  
Practical Method ◽  
Coefficient Of Determination ◽  
Planting Dates ◽  
The Individual

Predicting soybean [Glycine max (L.) Merr.] seed yield is of interest for crop producers to make important agronomic and economic decisions. Evaluating the soybean canopy across a range of common agronomic practices, using canopy measurements, provides a large inference for soybean producers. The individual and synergistic relationships between fractional green canopy cover (FGCC), photosynthetically active radiation (PAR) interception, and a normalized difference vegetative index (NDVI) measurements taken throughout the growing season to predict soybean seed yield in North Dakota, USA, were investigated in 12 environments. Canopy measurements were evaluated across early and late planting dates, 407,000 and 457,000 seeds ha−1 seeding rates, 0.5 and 0.8 relative maturities, and 30.5 and 61 cm row spacings. The single best yield predictor was an NDVI measurement at R5 (beginning of seed development) with a coefficient of determination of 0.65 followed by an FGCC measurement at R5 (R2 = 0.52). Stepwise and Lasso multiple regression methods were used to select the best prediction models using the canopy measurements explaining 69% and 67% of the variation in yield, respectively. Including plant density, which can be easily measured by a producer, with an individual canopy measurement did not improve the explanation in yield. Using FGCC to estimate yield across the growing season explained a range of 49% to 56% of yield variation, and a single FGCC measurement at R5 (R2 = 0.52) being the most efficient and practical method for a soybean producer to estimate yield.

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