Scholarly Work - Land Resources & Environmental Sciences
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8680
Browse
328 results
Search Results
Item Spring Seeding Integrated with a Spring Glyphosate Application Promotes Establishment ofPseudoroegneria spicata(bluebunch wheatgrass) inBromus tectorum(cheatgrass)-infested Rangelands(University of Wisconsin Press, 2024-08) Majeski, Michelle L.; Simanonok, Stacy C.; Miller, Zachariah; Rew, Lisa J.; Mangold, Jane M.Bromus tectorum invasion and associated impacts have been documented extensively in the western United States. Integrated approaches have been shown to be effective in restoring rangeland impacted by B. tectorum. While integrating herbicide and seeding of native species can be effective, strategic timing of these tools could further improve restoration outcomes. At three B. tectorum-infested rangeland sites in western Montana, we tested the effects of glyphosate application and timing (fall or spring) and five Pseudoroegneria spicata seeding dates (one fall and four spring dates) on density and cover of P. spicata. Pseudoroegneria spicata density was nearly ten times higher with glyphosate applied to B. tectorum compared to none at one site, and P. spicata abundance was generally greater when spring glyphosate application was combined with spring seeding at two other sites where densities ranged from six to 25 plants per m2. Overall, B. tectorum abundance was minimally affected by treatments and fluctuated between years and across study sites. Our results indicate that spring seeding of P. spicata following a spring glyphosate application promoted establishment of P. spicata, increasing its density and cover compared to fall glyphosate application and fall seeding, spring glyphosate following fall seeding, or seeding without any glyphosate. Restoration practitioners have an ecologically-based strategy for timing glyphosate application and seeding P. spicata based on our results, where spring-seeded P. spicata can grow for several months prior to fall emergence of the next B. tectorum cohort.Item Testing the effects of seed pellet composition to aid in semiarid restoration seeding(Wiley, 2024-11) Teichroew, Erin B.; Rew, Lisa J.Restoring and revegetating semiarid regions with native perennial grasses is an extremely difficult task, often unsuccessful due to harsh abiotic conditions. We conducted studies evaluating the use of seed pellets to improve restoration seeding success in controlled and field environments. In a controlled setting, we evaluated the impacts of clay volume, pellet size, and watering rate on seedling establishment and pellet disintegration. The amount of clay, size of pellets, and watering rate were varied in a full factorial design. Seedlings emerged from 40% of the pellets. Clay content did not impact seedling emergence, but larger pellets (2.5 cm) were more likely to produce seedlings. However, when smaller pellets (1.5 cm) produced seedlings, a higher proportion emerged (15 vs. 9%). In the field, we compared seedling establishment monthly, overall summer recruitment, and disintegration of seed pellets made with 10% and 55% clay to broadcast seed and a non-seeded control using a randomized design. Seedling emergence was higher for both the 10% (1.4 seedlings) and 55% clay pellets (1.0 seedling) than the control treatments (0.5 seedlings), and also higher for the 10% clay pellets than broadcast treatments (0.8 seedlings). Additionally, we found that seedling establishment and recruitment were unaffected by pellet disintegration. End-of-season recruitment was higher in 10% clay pellets (2.6 seedlings) than in 55% clay pellets (1.2 seedlings) and control treatments (1.0 seedling). We also found that 2.5 cm pellets had slightly higher recruitment, indicating that larger pellets may be more suited to seedling survival in semiarid environments.Item A New Species of Nemozoma Latreille, 1804 (Coleoptera: Cleroidea: Trogossitidae) from the French Antilles and New Distributional Records for Nemozoma fleutiauxi Lepesme, 1947(Coleopterists Society, 2024-09) Kippenhan, Michael G.Nemozoma lepesmei Kippenhan, new species is described and illustrated from specimens collected from the islands of Montserrat and Guadeloupe in the French Antilles. This new species is compared to other West Indian species and a key to the species known to inhabit the West Indies is provided. Recent distributional records for Nemozoma fleutiauxi Lepesme, 1947 are included.Item Consistent time allocation fraction to vegetation green-up versus senescence across northern ecosystems despite recent climate change(American Association for the Advancement of Science, 2024-06) Meng, Fandong; Felton, Andrew J.; Mao, Jiafu; Cong, Nan; Smith, William K.; Körner, Christian; Hu, Zhongmin; Hong, Songbai; Knott, Jonathan A.; Yan, Yanzi; Guo, Bixi; Deng, Ying; Leisz, Stephen J.; Dorji, Tsechoe; Wang, Shiping; Chen, AnpingExtended growing season lengths under climatic warming suggest increased time for plant growth. However, research has focused on climatic impacts to the timing or duration of distinct phenological events. Comparatively little is known about impacts to the relative time allocation to distinct phenological events, for example, the proportion of time dedicated to leaf growth versus senescence. We use multiple satellite and ground-based observations to show that, despite recent climate change during 2001 to 2020, the ratio of time allocated to vegetation green-up over senescence has remained stable [1.27 (± 0.92)] across more than 83% of northern ecosystems. This stability is independent of changes in growing season lengths and is caused by widespread positive relationships among vegetation phenological events; longer vegetation green-up results in longer vegetation senescence. These empirical observations were also partly reproduced by 13 dynamic global vegetation models. Our work demonstrates an intrinsic biotic control to vegetation phenology that could explain the timing of vegetation senescence under climate change.Item Assessing the effectiveness of satellite and UAV-based remote sensing for delineating alfalfa management zones under heterogeneous rootzone soil salinity(Elsevier BV, 2024-09) Sapkota, Anish; Verdi, Amir; Scudiero, Elia; Montazar, AliSite-specific application of agricultural inputs is crucial for optimizing resource utilization in alfalfa (Medicago sativa L.) production and addressing challenges such as soil salinity. The main objective of this study was to assess the effectiveness of PlanetScope and UAV-based NDVI imagery for delineating alfalfa management zones under heterogeneous rootzone soil salinity. The research was conducted in the alfalfa field located in Imperial Valley, CA. The extent of rootzone soil salinity was assessed using Electromagnetic induction (EMI) technology and deep soil sampling. Reference management zones were then defined using the soil salinity (ECe) map derived from apparent electrical conductivity (ECa) data. Additionally, a time series of NDVI images from PlanetScope imagery and an NDVI image captured using an unmanned aerial vehicle were used to delineate remote sensing-based management zones. Laboratory analysis of disturbed soil samples collected at various depths provided soil physicochemical property data. Soil salinity of the samples ranged from 2.2 to 13.4 dS m−1 with a moderate level of variability (CV = 37.7 %). ECe-based management zones accounted for approximately 83 % of the field's variability and exhibited substantial differentiation among delineated zones concerning diverse soil properties, including ECa, ECe, gravimetric water content, Mg2+, boron, Ca2+, Na+, and Cl−. Notably, NDVI images effectively captured field variability on par with ECe-based zoning. Moreover, NDVI images recommended the same optimal number of zones (i.e., three) to address the field's variability, aligning with the ECe-based zoning approach. Our findings highlight that heterogeneity of soil salinity in the root zone primarily impacts the variability of alfalfa NDVI early in the growing season. Consequently, this early stage emerges as the most opportune timeframe for NDVI-based zoning for rapid assessment of rootzone soil salinity concerns.Item Functional attributes of conifers expanding into temperate semi-arid grasslands modulate carbon and nitrogen fluxes in response to prescribed fire(Springer Science and Business Media LLC, 2024) Gay, Justin D.; Currey, Bryce; Davis, Kimberley T.; Brookshire, E. N. JackFire exclusion is a key factor driving conifer expansion into temperate semi-arid grasslands. However, it remains unclear how reintroducing fire affects the aboveground storage of carbon (C) and nitrogen (N) in the expanding tree species and belowground in soils. To assess the impacts of fire reintroduction C and N pools and fluxes in areas of conifer expansion we targeted a region of the Northern Great Plains that has experienced extensive woody plant expansion (WPE) of two species: ponderosa pine (Pinus ponderosa) and juniper (Juniperus spp). We quantified tree mortality of both species to estimate the amount of dead biomass C and N produced by a recent prescribed fire, in addition to changes in soil C, pyrogenic C (PyC), and N concentrations across a woody-cover gradient using a before/after/control experimental design. Post-fire soil chemical analysis revealed a 2 year increase in mineral soil C, PyC and N, suggesting the return of fire led to the transfer of partially combusted plant organic matter back to the soil. Further, we found that functional trait differences between the two species influenced the distribution of living conifer biomass-N prior to fire. Despite junipers having 41% less total aboveground biomass than ponderosa, they contained two times more aboveground N. Prescribed fire resulted in 88% mortality of all mature juniper stems and increased fire severity correlated with greater pre-fire juniper cover. Ponderosa mortality varied by size class, with > 40 cm stem diameter class having only 28% mortality. High mortality and greater aboveground N storage in juniper biomass, compared to ponderosa, led to 77% of the total conifer biomass N lost. Consequently, the functional attributes of expanding trees differentially contribute to fluxes of C and N after the return of fire, with junipers acting as conduits for N movement due to their relatively higher N content in less fire-resistant tissues and ponderosa serving as important and more stable storage pools for C. Together, these findings highlight the importance of considering species-specific traits when planning WPE management strrategies at landscape-scales, particularly when goals include C storage or soil nutrient status.Item Optimizing crop seeding rates on organic grain farms using on farm precision experimentation(Elsevier BV, 2024-09) Loewen, Sasha; Maxwell, Bruce D.Organic agriculture is often regarded as less damaging to the environment than conventional agriculture, though at the expense of lower yields. Field-specific precision agriculture may benefit organic production practices given the inherent need of organic farmers to understand spatiotemporal variation on large-scale fields. Here the primary research question is whether on-farm precision experimentation (OFPE) can be used as an adaptive management methodology to efficiently maximize farmer net returns using variable cover crop and cash crop seeding rates. Inputs of cash crop seed and previous-year green manure cover crop seed were experimentally varied on five different farms across the Northern Great Plains from 2019 to 2022. Experiments provided data to model the crop yield response, and subsequently net return, in response to input (seeding) rates plus a suite of other spatially explicit data from satellite sources. New, field-specific spatially explicit optimum input rates were generated to maximize net return including temporal variation in economic variables. Inputs were spatially optimized and using simulations it was found that the optimization strategies consistently out-performed other strategies by reducing inputs and increasing yields, particularly for non-tillering crops. By adopting site specific management, the average increase in net return for all fields was $50 ha−1. These results showed that precision agriculture technologies and remote sensing can be utilized to provide organic farmers powerful adaptive management tools with a focus on within-field spatial variability in response to primary input drivers of economic return. Continued OFPE for seeding rate optimization will allow quantification of temporal variability and subsequent probabilistic recommendations.Item Multitemporal Hyperspectral Characterization of Wheat Infested by Wheat Stem Sawfly, Cephus cinctus Norton(MDPI AG, 2024-09) Ermatinger, Lochlin S.; Powell, Scott L.; Peterson, Robert K.D.; Weaver, David K.Wheat (Triticum aestivum L.) production in the Northern Great Plains of North America has been challenged by wheat stem sawfly (WSS), Cephus cinctus Norton, for a century. Damaging WSS populations have increased, highlighting the need for reliable surveys. Remote sensing (RS) can be used to correlate reflectance measurements with nuanced phenomena like cryptic insect infestations within plants, yet little has been done with WSS. To evaluate interactions between WSS-infested wheat and spectral reflectance, we grew wheat plants in a controlled environment, experimentally infested them with WSS and recorded weekly hyperspectral measurements (350–2500 nm) of the canopies from prior to the introduction of WSS to full senescence. To assess the relationships between WSS infestation and wheat reflectance, we employed sparse multiway partial least squares regression (N-PLS), which models multidimensional covariance structures inherent in multitemporal hyperspectral datasets. Multitemporal hyperspectral measurements of wheat canopies modeled with sparse N-PLS accurately estimated the proportion of WSS-infested stems (R2 = 0.683, RMSE = 13.5%). The shortwave-infrared (1289–1380 nm) and near-infrared (942–979 nm) spectral regions were the most important in estimating infestation, likely due to internal feeding that decreases plant-water content. Measurements from all time points were important, suggesting aerial RS of WSS in the field should incorporate the visible through shortwave spectra collected from the beginning of WSS emergence at least weekly until the crop reaches senescence.Item Microbial assemblages and associated biogeochemical processes in Lake Bonney, a permanently ice-covered lake in the McMurdo Dry Valleys, Antarctica(Springer Science and Business Media LLC, 2024-08) Lee, Hanbyul; Hwang, Kyuin; Cho, Ahnna; Kim, Soyeon; Kim, Minkyung; Morgan-Kiss, Rachael; Priscu, John C.; Mo Kim, Kyung; Kim, Ok-SunBackground. Lake Bonney, which is divided into a west lobe (WLB) and an east lobe (ELB), is a perennially ice-covered lake located in the McMurdo Dry Valleys of Antarctica. Despite previous reports on the microbial community dynamics of ice-covered lakes in this region, there is a paucity of information on the relationship between microbial genomic diversity and associated nutrient cycling. Here, we applied gene- and genome-centric approaches to investigate the microbial ecology and reconstruct microbial metabolic potential along the depth gradient in Lake Bonney. Results. Lake Bonney is strongly chemically stratified with three distinct redox zones, yielding different microbial niches. Our genome enabled approach revealed that in the sunlit and relatively freshwater epilimnion, oxygenic photosynthetic production by the cyanobacterium Pseudanabaena and a diversity of protists and microalgae may provide new organic carbon to the environment. CO-oxidizing bacteria, such as Acidimicrobiales, Nanopelagicales, and Burkholderiaceae were also prominent in the epilimnion and their ability to oxidize carbon monoxide to carbon dioxide may serve as a supplementary energy conservation strategy. In the more saline metalimnion of ELB, an accumulation of inorganic nitrogen and phosphorus supports photosynthesis despite relatively low light levels. Conversely, in WLB the release of organic rich subglacial discharge from Taylor Glacier into WLB would be implicated in the possible high abundance of heterotrophs supported by increased potential for glycolysis, beta-oxidation, and glycoside hydrolase and may contribute to the growth of iron reducers in the dark and extremely saline hypolimnion of WLB. The suboxic and subzero temperature zones beneath the metalimnia in both lobes supported microorganisms capable of utilizing reduced nitrogens and sulfurs as electron donors. Heterotrophs, including nitrate reducing sulfur oxidizing bacteria, such as Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), and denitrifying bacteria, such as Gracilimonas (MAG7), Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), dominated the hypolimnion of WLB, whereas the environmental harshness of the hypolimnion of ELB was supported by the relatively low in metabolic potential, as well as the abundance of halophile Halomonas and endospore-forming Virgibacillus. Conclusions. The vertical distribution of microbially driven C, N and S cycling genes/pathways in Lake Bonney reveals the importance of geochemical gradients to microbial diversity and biogeochemical cycles with the vertical water column.Item Divergent metabolism estimates from dissolved oxygen and inorganic carbon: Implications for river carbon cycling(Wiley, 2024-08) Shangguan, Qipei; Payn, Robert A.; Hall Jr., Robert O.; Young, Fischer L.; Valett, H. Maurice; DeGrandpre, Michael D.Rivers efficiently collect, process, and transport terrestrial-derived carbon. River ecosystem metabolism is the primary mechanism for processing carbon. Diel cycles of dissolved oxygen (DO) have been used for decades to infer river ecosystem metabolic rates, which are routinely used to predict metabolism of carbon dioxide (CO2) with uncertainties of the assumed stoichiometry ranging by a factor of 4. Dissolved inorganic carbon (DIC) has been less used to directly infer metabolism because it is more difficult to quantify, involves the complexity of inorganic carbon speciation, and as shown in this study, likely requires a two-station approach. Here, we developed DIC metabolism models using single- and two-station approaches. We compared metabolism estimates based on simultaneous DO and DIC monitoring in the Upper Clark Fork River (USA), which also allowed us to estimate ecosystem-level photosynthetic and respiratory quotients (PQE and RQE). We observed that metabolism estimates from DIC varied more between single- and two-station approaches than estimates from DO. Due to carbonate buffering, CO2 is slower to equilibrate with the atmosphere compared to DO, likely incorporating a longer distance of upstream heterogeneity. Reach-averaged PQE ranged from 1.5 to 2.0, while RQE ranged from 0.8 to 1.5. Gross primary production from DO was larger than that from DIC, as was net ecosystem production by . The river was autotrophic based on DO but heterotrophic based on DIC, complicating our understanding of how metabolism regulated CO2 production. We suggest future studies simultaneously model metabolism from DO and DIC to understand carbon processing in rivers.