Principles and procedures

Grasslands are globally extensive; they exist in many different climates, at high and low elevations, on nutrient-rich and nutrient-poor soils. Grassland distributions today are closely linked to human activities, herbivores, and fire, but many have been converted to urban areas, forests, or agriculture fields. Roughly 80% of fires globally occur in grasslands each year, making fire a critical process in grassland dynamics. Yet, little is known about the long-term history of fire in grasslands. Here, we analyze sedimentary archives to reconstruct grassland fire histories during the Holocene. Given that grassland locations change over time, we compare several charcoal-based fire reconstructions based on alternative classification schemes: (a) sites from modern grassland locations; (b) sites that were likely grasslands during the mid-Holocene; and (c) sites based on author-derived classifications. We also compare fire histories from grassland sites, forested sites, and all sites globally over the past 12,000 years. Forested versus grassland sites show different trends: grassland burning increased from the early to mid-Holocene, reaching a maximum about 8000-6000 years ago, and subsequently declined, reaching a minimum around 4000 years ago. In contrast, biomass burning in forests increased during the Holocene until about 2000 years ago. Continental grassland fire history reconstructions show opposing Holocene trends in North versus South America, whereas grassland burning in Australia was highly variable in the early Holocene and much more stable after the mid-Holocene. The sharp differences in continental as well as forest versus grassland Holocene fire history trajectories have important implications for our understanding of global biomass burning and its emissions, the global carbon cycle, biodiversity, conservation, and land management.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.4394

Global fire history of grassland biomes

Most species of Tamarix originate in Eurasia and at least five species have become invasive around the world, including South Africa. However, T. usneoides is indigenous to southern Africa, where the potential for biological control of the invasive species is being investigated. Recent research on the invasive species is reviewed here with particular reference to these South African biocontrol efforts. The successful biological control programme against invasive Tamarix in the USA, using several species of “Tamarisk beetle”, is being used as a guide for the South African research. The South African programme is complicated by firstly, the presence of the indigenous T. usneoides which raises the precision of host-specificity required, and secondly, the introduced and indigenous Tamarix have a high intrinsic value for phytoremediation of mine tailings dams in South Africa. The phylogenetic proximity of these Tamarix species to each other has contributed to this challenge, which has nevertheless been successfully addressed by molecular techniques used to separate the species. In addition, classical morphological techniques have been used to separate the Tamarisk beetles, so that now they can generally be matched to Tamarix tree species. Overall, it is concluded that given the broad knowledge now available on the ecology and identity of both the trees and their biocontrol agents, the prospects for successful biological control of Tamarix in South Africa are good.

Invasive Tamarix (Tamaricaceae) in South Africa: current research and the potential for biological control

1 BACKGROUND AND HISTORY Over the last century, many agricultural producers have become specialized and highly efficient at producing specific crops or livestock to meet the demand of global population growth (MacDonald and McBride, 2009). Societal and population changes are continuing to increase food demand, necessitating intensification of existing crops and livestock production systems (Godfray et al., 2010). However, intensification can result in soil and ecosystem degradation, unsustainable resource use, and agrochemical, antibiotic, and hormone contamination (Herrero et al., 2009; Reganold et al., 2011; Tilman et al., 2001). Integrated crop–livestock systems can provide an alternative management strategy that purportedly sustainably intensifies food production while benefiting producer income, soil, and the environment (Franzluebbers, 2007). An agricultural system that manages crop and livestock production on a single farm or among farms such that products are used to support each other is an ICLS (Franzluebbers et al., 2014; Hilimire, 2011; Russelle et al., 2007; Sulc and Franzluebbers, 2014). Recently, a special report by the International Panel on Climate Change (IPCC) highlighted that ICLSs are resourceefficient and cost-effective agricultural adaptation strategies to sustainably maintain or increase food production (IPCC, 2018). These systems recycle nutrients from livestock waste (feces and urine) back to croplands and through fodder production and use and also improve or sustain soil organic matter and fertility (Franzluebbers et al., 2014). Although farming systems that integrate crops and livestock have existed historically (Halstead, 1996; Smith, 1995), the ICLS concept re-emerged globally in 2007 and was documented through a series of international conferences and publications (Franzluebbers et al., 2014). Facilitating Crop–Livestock Reintegration in the Northern Great Plains

Facilitating Crop–Livestock Reintegration in the Northern Great Plains

Habitat restoration is considered critical for maintaining and restoring biodiversity of many species groups. A better understanding of how species respond to the restoration process is imperative to identifying practices that benefit the target organisms. Using survey responses from land managers about the restoration process in tallgrass prairie habitat, we identify common restoration and management techniques. These responses are then combined with current literature on bee and plant responses to these methods in tallgrass prairie habitat. While some widely used methods, such as burning, are believed to be fairly benign to bees, there are still many knowledge gaps about how bees may respond to many common practices such as tillage, pesticides, and grazing in tallgrass prairie. Other commonly used methods, such as broadcasting of seeds, are known to significantly affect plant diversity, which could hinder bee conservation efforts. The variability in bee and plant response to commonly used meth...

https://bioone.org/journals/natural-areas-journal/volume-36/issue-4/043.036.0407/Common-Methods-for-Tallgrass-Prairie-Restoration-and-Their-Potential-Effects/10.3375/043.036.0407.pdf

Common Methods for Tallgrass Prairie Restoration and Their Potential Effects on Bee Diversity

https://openprairie.sdstate.edu/cgi/viewcontent.cgi?article=1024&context=plant_faculty_pubs

Spring Clipping, Fire, and Simulated Increased Atmospheric Nitrogen Deposition Effects on Tallgrass Prairie Vegetation

Fire and grazing are commonly used to manage nonnative grasses in the Northern Great Plains, but the effects of fire frequency and management between fire events on fire behavior in this region are poorly understood. We examined temperature and duration of prescribed spring fires at two locations where plots were treated with two fire frequencies (annual or biennial), simulated grazing (1 mo of weekly clipping in spring) and no simulated grazing. In May 2011 and 2013, soil surface fire temperatures and heat duration were monitored in treatment plots using thermocouples. Probes also were placed at 1, 2, and 3 cm depths to measure soil heat transfer. Lethal heat duration (>60 C) at the surface tended to be longer in plots treated with biennial fires compared to plots treated with annual fires. Fires in 2011 had higher maximum temperatures than 2013. Cooler fires in 2013 were characterized by longer durations of lethal heat. However, simulated grazing increased residence time of lethal temperatures ...

Surface Temperatures and Durations Associated with Spring Prescribed Fires in Eastern South Dakota Tallgrass Prairies

Tamarix spp. (saltcedar) were introduced from Asia to the southern United States as windbreak and ornamental plants and have spread into natural areas. This study determined differential gene expression responses to water deficit (WD) in seedlings of T. chinensis and T. ramosissima from established invasive stands in New Mexico and Montana, respectively. A reference de novo transcriptome was developed using RNA sequences from WD and well-watered samples. Blast2GO analysis of the resulting 271,872 transcripts yielded 89,389 homologs. The reference Tamarix (Tamaricaceae, Carophyllales order) transcriptome showed homology with 14,247 predicted genes of the Beta vulgaris subsp. vulgaris (Amaranthaceae, Carophyllales order) genome assembly. T. ramosissima took longer to show water stress symptoms than T. chinensis. There were 2068 and 669 differentially expressed genes (DEG) in T. chinensis and T. ramosissima, respectively; 332 were DEG in common between the two species. Network analysis showed large biological process networks of similar gene content for each of the species under water deficit. Two distinct molecular function gene ontology networks (binding and transcription factor-related) encompassing multiple up-regulated transcription factors (MYB, NAC, and WRKY) and a cellular components network containing many down-regulated photosynthesis-related genes were identified in T. chinensis, in contrast to one small molecular function network in T. ramosissima.

/pdf/water-deficit-transcriptomic-responses-differ-in-the-187j2yfu1j.pdf

Water Deficit Transcriptomic Responses Differ in the Invasive Tamarix chinensis and T. ramosissima Established in the Southern and Northern United States.

Agronomy Journa l • Volume 109, I s sue 4 • 2017 Collaborative projects between farmers/ranchers and scientists can be very rewarding, as well as produce lasting positive impacts on the environment (Smart et al., 2015). However, success requires the development of trust between the farmer and the scientists, and ability to use shortterm fi eld experiments to produce results that can be communicated to the farming community in a timely manner. In projects addressing soil health, this may involve conducting demonstration or targeted experiments focused on one or two questions. Th is project is focused on the question, what is the fate of the C and N in cattle feces? Carbon and N budgets are based on accurate measurements of the C and N additions and losses. Additions represent the C or N that is added through photosynthesis or fertilizer or manure applications, whereas losses represent leaching, erosion, and gaseous emissions. Research has shown that management, soils, and climatic conditions interact to infl uence both additions and losses in ecological systems. To accurately measure nutrient additions and losses, sampling approaches must be tested and modifi ed for each unique problem (Clay et al., 1996, 2006; Chang et al., 2016b). Th ree basic approaches have been used to determine CO2 emissions in grassland systems (Fynn et al., 2009). Th e fi rst approach measures CO2–C or NH3 emission in the laboratory (Murwira et al., 1990; Van Kessel et al., 2000; Kyvsgaard et al., 2000; Powell et al., 2006; Ayadi et al., 2015). Laboratory experiment are most useful for measuring mineralization potential (Franzluebbers et al., 2000; Van Kessel et al., 2000), evaluating responses mechanisms (Adu and Oades, 1978), or determining the impact of a specifi c treatment on many factors including biological activity (Clay et al., 1990). However, the removal of the samples from the fi eld or drying and grinding the samples can change the soils physical and biological characteristics (De Nobili et al., 2006). In the second approach, soil organic carbon (SOC) losses are determined by diff erence. In this approach, changes in SOC and net aboveground and belowground productivity are measured at the beginning and completion of an experiment (Schuman et al., 1999; Franzluebbers et al., 2000; Tate et al., 2003; Chang et al., 2004, 2016b; Clay et al., 2005, 2006, 2015; Derner et al., 2006; Derner and Schuman, 2007; Smart et al., 2010a, 2010b; Dunn et A Rapid Method for Measuring Feces Ammonia-Nitrogen and Carbon Dioxide-Carbon Emissions and Decomposition Rate Constants

/pdf/a-rapid-method-for-measuring-feces-ammonia-nitrogen-and-4hxry6rrbk.pdf

A Rapid Method for Measuring Feces Ammonia‐Nitrogen and Carbon Dioxide‐Carbon Emissions and Decomposition Rate Constants

Controlled burns and grazing are being tested to manage invasive grasses in the Prairie Pothole region of the Northern Great Plains. These practices, however, may inadvertently promote saltcedar infestations from seed by opening the vegetative canopy. Saltcedar seedling establishment was investigated in greenhouse experiments using intact soil cores from one summit and three footslope sites in eastern South Dakota. Establishment tests were conducted in soil cores collected from treatment and control plots immediately after spring fire treatment (postburn) and in cores that contained peak cool- or peak warm-season vegetation, with or without clipping (simulated grazing treatment), to simulate vegetation conditions typical of saltcedar seed-shed in northern regions. Cores were seeded with 100 saltcedar seeds and subirrigated to maintain high soil water conditions, characteristic of the environment near potholes during late spring/early summer. Seedlings were counted during the first 3 wk to estimat...

https://bioone.org/journals/invasive-plant-science-and-management/volume-4/issue-4/IPSM-D-11-00012.1/Preventing-Saltcedar-Tamarix-spp-Seedling-Establishment-in-the-Northern-Prairie/10.1614/IPSM-D-11-00012.1.pdf

Michelle K. Ohrtman

Papers

Spring Clipping, Fire, and Simulated Increased Atmospheric Nitrogen Deposition Effects on Tallgrass Prairie Vegetation

Surface Temperatures and Durations Associated with Spring Prescribed Fires in Eastern South Dakota Tallgrass Prairies

Water Deficit Transcriptomic Responses Differ in the Invasive Tamarix chinensis and T. ramosissima Established in the Southern and Northern United States.

A Rapid Method for Measuring Feces Ammonia‐Nitrogen and Carbon Dioxide‐Carbon Emissions and Decomposition Rate Constants

Preventing Saltcedar (Tamarix spp.) Seedling Establishment in the Northern Prairie Pothole Region