Mapping and Estimation of Above-ground Grass Biomass using Sentinel 2A Satellite Data

Above-Ground Grass Biomass (AGGB) mapping and estimation is one of the important parameters for environmental ecosystem and grazing-lands management, particularly for livestock farming. However, previous models for estimation of AGGB with satellite imagery has some difficulty in choosing a particular satellite and vegetation index that can build a good estimation model at a higher accuracy. This study explores the potentiality of Sentinel 2A data to derive a satellite-based model for AGGB mapping and estimation. The study area was Skudai, Johor in Malaysia Peninsular. Grass parameters of forty grass sample units were measured in the field and their corresponding AGGB was later measured in the laboratory. The samples were used for modelling and assessment. Four indices were tested for their fitness in modelling AGGB from the satellite data. The result from the grass allometric analysis indicates that grass height and volume demonstrate good relationship with the measured AGGB (R² = 0.852 and 0.837 respectively). Vegetation Index Number (VIN) has the best fit for modeling AGGB (R2 = 0.840) compared to other vegetation indices. The derived satellite AGGB estimate was validated with the assessment field and allometry derived AGGB at RMSE = 15.89g and 44.45g, respectively. This study demonstrate that VIN derived from Sentinel 2A MSI satellite data can be used to model AGGB estimation at a good accuracy. Therefore, it will contribute to providing reliable information on AGGB of grazing lands for sustainable livestock farming.

Savanna Rodents’ Selective Removal of an Encroaching Plant’s Seeds Increased With Grass Biomass

In savannas across the planet, encroaching woody plants are altering ecosystem functions and reshaping communities. Seed predation by rodents may serve to slow the encroachment of woody plants in grasslands and savannas. Our goals for this study were to determine if rodents in an African savanna selectively removed seeds of an encroaching plant and if foraging activity was influenced by the local vegetation structure or by the landscape context. From trials with two species of seeds (encroacher = Dichrostachys cinerea, non-encroaching overstory tree = Senegalia nigrescens) at 64 seed stations, we recorded 1,065 foraging events by seven species of granivorous rodents. We found a strong positive relationship between rodent activity and the number of seeds removed during trials. Foraging events were dominated by rodent seed predators, with <10.6% of events involving a rodent with the potential for secondary dispersal. Rodents selectively removed the seeds of the encroaching species, removing 32.6% more D. cinerea seeds compared to S. nigrescens. Additionally, rodent activity and the number of seeds removed increased at sites with more grass biomass. Our results suggest a potential mechanistic role for rodents in mitigating the spread of woody plants in grass dominated savannas.

Spatial Modeling of Forage Crops for Tiger Prey Species in the Area Surrounding Highway 304 in the Dong Phayayen-Khao Yai Forest Complex

Spatial modeling is an analytical procedure that simulates real-world conditions using remote sensing and geographic information systems. The field data in this study were collected from 318 survey plots in the area surrounding highway 304 in the Dong Phayayen-Khao Yai Forest Complex (DPKY-FC) during the 2019 rainy season. Forage-crop biomass was collected from all plots. We focused on sambar deer (Rusa unicolor) and gaur (Bos gaurus), which are the main prey for tigers in this area. We created spatial models using generalized linear models with stepwise regression. The results indicated that the normalized difference vegetation index (NDVI) varied directly with grass biomass but inversely with shrub biomass (p<0.05). Elevation varied directly with forb biomass but inversely with shrub biomass (p<0.05). The probability of occurrence of sambar deer varied directly with distance from disturbance variables, distance from the stream, and grass biomass (p<0.001), but inversely with NDVI (p<0.05). The occurrence of gaur varied directly with NDVI (p=0.08), but varied inversely with slope, distance from the road, and distance from the stream (p<0.05). Our results demonstrate that spatial modeling can be an effective tool for wildlife habitat management in the area surrounding highway 304.

Short duration overnight cattle kraaling in natural rangelands: does time after kraal use affect their utilization by wildlife and above ground grass parameters?

Short duration overnight cattle kraaling in natural rangelands creates nutrients hotspots attractive to a diverse suite of large mammalian herbivores. However, few studies have determined the use of these sites by large mammalian herbivores. We determined the number of animal sightings per day from camera traps and used them as proxies for use of these newly created nutrient hotspots of varying ages (1, 2, 3 and 4 years) and surrounding vegetation. Six mammalian herbivores of different sizes belonging to three feeding guilds viz. grazers (Burchell’s zebra Equus quagga burchelli and warthog Phacochoerus africanus), mixed feeders (impala Aepyceros melampus and African savanna elephant Loxodonta africana africana) and browsers (northern giraffe Giraffa camelopardalis giraffa and greater kudu Tragelaphus strepsiceros) frequently used these nutrient hotspots. The number of sightings per day of mammalian herbivores was determined during three periods of the year (January – wet season; June – early dry season; October – late dry season) to ascertain their use of these nutrient hotspots. In addition, above ground grass biomass and height was measured and related to grazer sightings. Furthermore, we tested if repeated grazing in the newly created nutrient hotspots stimulated grass compensatory growth. All the mammalian herbivores used the newly created nutrient hotspots similarly throughout the year, with impala the most active users. Grazer and browser use of nutrient hotspots was not influenced by their age, while mixed feeders mostly used the one year old sites. Grazer use of nutrient hotspots was not influenced by aboveground grass biomass and height. Repeated clipping (proxy for grazing) resulted in compensatory aboveground grass biomass growth in nutrient hotspots. Impala benefited the most and zebra the least from the creation of nutrient hotspots in natural rangelands. We conclude that creation of nutrients hotspots through short duration overnight kraaling results in rangeland heterogeneity that improves availability of herbivore foraging sites.

Restoration after bush control in selected rangeland areas of semi-arid savannas in South Africa

Background: One of the main causes of land degradation in South Africa is bush thickening (BT) of mainly Senegalia or Vachellia species. Restoration methods are required to control BT, and to improve grass biomass production and soil conditions in South Africa.Objectives: The objectives of this study were to determine the effect of brush packing (BP) as a restoration method to increase grass biomass production, assess soil moisture after BP on different soil types, and document the perceptions of the local communities towards BP.Method: Methods included cutting the stems of woodies with a diameter of at least 10 cm at knee height by chainsaw and manual clipping after which an arborocide was applied to the stumps. A neutron probe was used to measure volumetric moisture content at two different soil depths. The grass biomass was analysed using ANOVA at a confidence level of 95%. Quantitative and qualitative approaches were used to gather information about the perceptions of local communities towards restoration in group discussions.Results: The short-term data showed that the implementation of BP as restoration method increased grass biomass production. The soil texture influenced the volumetric soil moisture. Higher soil moisture content was found in the deeper clayey soils. The local participants’ interpretation towards the restoration project was positive.Conclusion: The project increased the grazing potential and contributed to job creation to improve the well-being of the people in the community.

Factor Analysis of the Parameters of Samples of the Steppe Soil and Grass of Mongolia and Inland Mongolia of China on the Eastern Transsect of the Eurasian Steppe

Regularities of rank distributions and binary relations between nine parameters are given. The most active are the geographical coordinates of 48 test sites. This proves that the geomorphology of the steppes in Mongolia and Inner Mongolia is becoming decisive. Factor analysis showed that the first four places for influencing variables and dependent indicators are the same: in the first place is the northern latitude, the second is the east longitude, the third is the average annual precipitation, and the fourth is the intensity of sheep grazing. The rest of the factors are located in different ways. The density of organic carbon was only in ninth place as an influencing variable, and in seventh place as a dependent indicator. This is based on the fact that organic carbon is an accumulative (cumulative) parameter over many years. The productivity of the biomass of steppe grass as an influencing variable is in sixth place, and as a dependent indicator (criterion) only in ninth place. This parameter is seasonal, therefore, in comparison with organic carbon, it is highly dynamic. The average annual temperature as an influencing variable is in fifth place, but as a dependent indicator only in eighth place. This was influenced by the strong averaging of the parameter (average value for the year). Plants are strongly influenced by the temperature dynamics during the growing season, and even more by the sum of temperatures during the growing season. With the productivity of steppe grass less than 75 g / m2, the intensity of sheep grazing is zero. According to the second term of the trend, an optimum of 270 g / m2 appears with the maximum intensity of sheep grazing on average 65 pcs / km2. The first fluctuation shows that with an increase in grass biomass, there is a loss of stability of the grass cover with an exponential growth of the amplitude. The second oscillation is dangerous in that with an increase in the biomass of the grass, the half-period of the oscillation sharply decreases and this will also lead to the collapse of the steppe grass. From the remnants of the effect of sheep grazing on grass biomass, it can be seen that there are three clusters: 1) from 0 to 30; 2) from 30 to 95; 3) more than 95 pcs / km2. In this case, the variability of the productivity of the grass decreases.