Impacts of grazing on ground cover, soil physical properties and soil loss via surface erosion: A novel geospatial modelling approach

Monthly sampling reveals seasonal fine sediment fluctuations and riverine invertebrate community responses

Managing the impacts of anthropogenically enhanced deposited fine sediment levels in lotic ecosystems requires understanding of how catchment land-use changes have altered the natural sediment regime (erosion, transport, deposition) of rivers. Unfortunately, no existing studies have employed an appropriate sampling frequency over a period encompassing the full range of seasonal flow conditions expected to influence in-stream sediment dynamics. We determined the short-term (monthly) dynamics of deposited fine sediment and invertebrate communities over 12-months in 15 fourth- and fifth-order rivers draining catchments of low, medium and high land-use intensity in Southland, New Zealand to determine when and where fine sediment threatens stream health. We compared the Quorer resuspension method (suspendable inorganic sediment, SIS) and the in-stream visual sediment cover assessment method, and evaluated the effectiveness of four commonly-used invertebrate stream health metrics against their newly developed sediment-specific counterparts. Monthly variability in SIS was substantial across all land-use categories, but became more pronounced as land-use intensity increased. All 15 sites experienced a prolonged period of relatively stable flow which coincided with the largest short-term increase in SIS at 14 of the 15 sites. However, variability in SIS was not mirrored in macroinvertebrate metrics. These findings suggest that controlling inputs of fine sediment to rivers and streams will be most effective when targeted at periods of prolonged stable flow, particularly within high land-use intensity catchments. The resuspension method consistently outperformed visual estimates when considering its relationship with macroinvertebrate metrics, while sediment-specific metrics demonstrated a stronger association with fine sediment than commonly employed metrics e.g. (%EPT). We conclude that restoration/mitigation practices cannot be based solely on short-term, or even long-term, reductions in fine sediment, or on physical measures alone, but should be based on long-term recoveries of sediment-impacted invertebrate communities using concurrent measurements of both biotic and abiotic conditions.

Morphometric Characteristics and Genetic Issr Marker Variability in Rhodiola rosea L. (Crassulaceae) in Different Ecological and Geographic Conditions in the Altai Republic

Rhodiola rosea L. is a vulnerable species in the Altai Republic (AR) and Russia in general. For the first time on the territory of AR, studies of the adaptive capabilities of the species and genetic differentiation using ISSR markers were carried out in seven cenopopulations (CP) of R. rosea in 2018 and 2020. The research was founded on the notion of conducting a comparative analysis of the morphogenetic structure of Rhodiola rosea populations in various ecological and geographical conditions of AR. The aim of this work is to evaluate the variability of morphometric traits of sexually mature living female R. rosea plants and to conduct a comparative analysis of genetic variability in cenopopulations (CP) both under undisturbed conditions and under stressful conditions of anthropogenic impact (grazing). Of the 8 primers used, HB12 turned out to be the most informative. The percentage of polymorphic loci in the populations between 0 and 88%. Two populations, located in favorable conditions at relatively low absolute altitudes (2000 m above sea level) (masl) in the undisturbed habitats of the Katun and Altai reserves of AR, were characterized by higher polymorphism. The share of polymorphic loci reached 80%. According to the analysis of statistical data, the highest values of morphometric parameters of the aerial parts of R. rosea plants and the highest potential seed productivity were also recorded in these habitats. Representatives of two high-mountain CPs (2400-2500 masl) in the Sailyugemsky National Park (SNP) were characterized by the lowest genetic polymorphism. Their genetic structure is the most homogeneous, since we have not found polymorphic loci. Due to spatial isolation, these individuals are reliably genetically differentiated. In addition, individuals of one type were subjected to stressful anthropogenic impact (grazing). Therefore, the smallest sizes and lowest potential seed productivity were recorded. Our research shows that alpine populations of R. rosea in AR, under conditions of anthropogenic stress, need protection for their gene pool.

Detrimental Effects of Induced Soil Compaction on Morphological Adaptation and Physiological Plasticity of Selected Multipurpose Tree Species

Soil compaction has become a global problem affecting soil worldwide. With an increased population, more demands for food and wood have resulted in intensive cultivation and increased mechanization of our farmlands and irrigated plantations. The use of heavy machinery results in soil compaction, which affects the entire soil ecosystem. This study was conducted to analyze the impact of compacted soil on germination and initial growth stages of four major agro-forest trees of central Punjab, Pakistan. Morpho-physiological traits of all selected species (Eucalyptus camaldulensis, Albizia lebbeck, Vachellia nilotica, and Zyziphus mauritiana) were measured against soil compaction. Results indicated that the root and shoot length, biomass, root-shoot ratio, diameter at root collar, no. of leaves and branches, leaf area, germination, and survival %, and physiological traits (i.e., photosynthetic rate, transpiration rate, stomatal conductance, internal CO₂ concentration, and photosynthetic water use efficiency) were significantly affected by the induced soil compaction. Eucalyptus camaldulensis Dehnh. performed better and exhibited 96% germination percentage under (1.40 mg m^-3) compaction level and gradually decreased by 11% with the increase of compaction level (1.80 mg m^-3). It shows that the shorter roots developed due to soil compaction decreased water use efficiency, photosynthesis, and whole-plant physiological performance. The findings concluded that judicious use of machinery is highly desired for sustainable and good-quality wood production from farm trees.

Creating a Design Framework to Diagnose and Enhance Grassland Health under Pastoral Livestock Production Systems

Grasslands and ecosystem services are under threat due to common practices adopted by modern livestock farming systems. Design theory has been an alternative to promote changes and develop more sustainable strategies that allow pastoral livestock production systems to evolve continually within grasslands by enhancing their health and enabling the continuous delivery of multiple ecosystem services. To create a design framework to design alternative and more sustainable pastoral livestock production systems, a better comprehension of grassland complexity and dynamism for a diagnostic assessment of its health is needed, from which the systems thinking theory could be an important approach. By using systems thinking theory, the key components of grasslands-soil, plant, ruminant-can be reviewed and better understood from a holistic perspective. The description of soil, plant and ruminant individually is already complex itself, so understanding these components, their interactions, their response to grazing management and herbivory and how they contribute to grassland health under different climatic and topographic conditions is paramount to designing more sustainable pastoral livestock production systems. Therefore, by taking a systems thinking approach, we aim to review the literature to better understand the role of soil, plant, and ruminant on grassland health to build a design framework to diagnose and enhance grassland health under pastoral livestock production systems.

Effects of Grazing on Water Erosion, Compaction and Infiltration on Grasslands

Seventy-seven percent of all agricultural land is related to livestock, meat and dairy, including grazing land and arable fields used for animal feed production. The effect of livestock on the natural environment is well documented. Many types of research describe these effects on biodiversity. The surface runoff and soil erosion on grasslands and pastures are investigated with smaller intensity since grasslands are one of the two major land uses that are considered as natural or at least semi-natural lands. Still, mainly due to overuse, grazing on sloping pasture lands can cause severe soil damage, the trampling can cause compaction, compaction decrease infiltration and thus increase runoff and, consequently, soil loss. There are several consequences of the grazing pressure that cause water erosion and surface runoff above the acceptable limit, such as a dramatic decrease in grass densities and/or above-ground bio-mass, compaction, animal tracks, etc. Related research started as early as 1911 and continues until today. There are several methods to analyse the consequences of grazing pressure, e.g., in situ rainfall simulations, infiltration and soil resilience measurements, modelling of runoff, soil loss and infiltration, calculation of ecological costs, etc. Furthermore, most importantly, scientists are investigating the possibilities for improvement of the achieved unstable grazing system due to bad management. Numerous publications have been publishing results on positive changes with the removal of grazing livestock from the grasslands. However, since the socio-economic situation is changing on Earth, more people requiring the products of the pastures, an optimal grazing solution is greatly needed. One of the solutions can be the planning of the optimal animal unit per area, based on the expected grass yields. However, due to the big differences in yields, caused by the greatly unreliable weather, the solution for the future must be a multifunctional agriculture and a flexible land use.

Mapping bare ground in New Zealand hill-country agriculture and forestry for soil erosion risk assessment: An automated satellite remote-sensing method

Removing vegetation cover from hill-slope land increases risk for soil erosion and delivery of sediment to waterways. In New Zealand's productive landscapes, clear-fell harvesting of forestry blocks and winter forage grazing by agricultural livestock are two significant causes of vegetation removal. Bare ground exposed by these activities varies annually and seasonally in location and spatial extent. Modelling soil erosion therefore requires temporally and spatially explicit mapping of this bare ground. We have developed an automated mapping method using time-series satellite imagery, thereby enabling wide-area coverage and ease of updating. The temporal analysis identifies land use along with the period of vegetation removal. It produces results per land parcel (in vector format) for use in a Geographic Information System. We present a description of our method, national maps and statistics of bare ground extent in New Zealand's hill-country forestry and winter forage grazing land in 2018, and an assessment of accuracy. The attributes of the mapped land parcels are designed for input into a soil erosion estimation model such as the New Zealand Universal Soil Loss Equation.

Applying Spatial Analysis to Create Modern Rich Pictures for Grassland Health Analysis

Grasslands are complex and heterogeneous ecosystems, and their health can be defined by the cumulative ability of their components to evolve, adapt, and maintain their integrity in the presence of stress/disturbance and provide ecosystem services. Herein, a design approach is used to generate alternative and multifunctional pastoral livestock production systems that enhance grassland health. As a way of understanding the complexity of grasslands and initiating the design process using systems thinking, rich pictures emerge as a useful method. As rich pictures are subjective views, geographic information systems (GIS) could be applied to improve the veracity of their outcomes, as both techniques are forms of an analytical process. This paper reports the application of GIS to a case study of a high-country farm to generate and combine different thematic maps to create a modern rich picture. The rich picture is a combination of remote sensing data (altitude, slope, aspects, and the Normalized Difference Vegetation Index (NDVI)), and on-the-ground data (plant species distribution and diversity and soil chemical, biological, and physical parameters). Layers were combined using a multi-criteria evaluation (MCE) based on the analytical hierarchy process (AHP) to create a final rich picture. The results highlight dissimilarities in perceptions of what underpins ‘grassland health’ between researchers in different fields and with different perspectives. The use of GIS produced a modern rich picture that enhanced the understanding of grassland health and allowed for the identification of gaps, values, and possibilities for future research work.