Life Sciences Commons^™

Differential Responses Of Yield And Shoot Traits Of Five Tropical Grasses To N And Distance To Trees In Silvopastoral Systems, L. S. Pontes, Emilio A. Laca

IGC Proceedings (1997-2023)

Light intensity and nitrogen (N) availability are important factors influencing the growth of C₄ forage species. Trade-offs may occur in the adaptive responses of species to shading and N inputs, and functional shoot traits can help to explain the consequences of these responses for species performance. Our objective was to gain understanding of the mechanisms between traits of five C₄ perennial grasses determining above-ground dry matter yield (DMY) when both resources, light and N, vary. Forage grasses were grown in six shading conditions (full sunlight vs. five positions between Eucalyptus dunnii rows) with two N levels (0 vs. …

A Herbage Growth Model For Different Types Of Natural Grassland, J. Viégas, M. Duru, P. Cruz, J. P. Theau, P. Ansquer, C. Ducourtieux

IGC Proceedings (1997-2023)

The aim of this work was to extend existing growth models established for pure stands to a wide range of grassland communities. For this purpose we built a simple growth model, including sub-models for radiation interception and use. Parameters for the effect of nutrient rates (N, P) and defoliation regimes were based on a plant trait database. Senescence and reproductive processes were particularly considered because of their importance in late spring growth. The model makes it possible to simulate the daily biomass production as a function of both environmental factors and the functional type of the dominant species in the …

Are Leaf Traits Stable Enough To Rank Native Grasses In Contrasting Growth Conditions?, V. Poozesh, R. Al Haj Khaled, P. Ansquer, J. P. Theau, M. Duru, G. Bertoni, P. Cruz

IGC Proceedings (1997-2023)

The growing interest in classifying species in response groups relating to variations in environmental factors has triggered the search for functional traits that express differences in ecological behaviour among plant species (Lavorel & Garnier, 2002). Specific leaf area (SLA) and leaf dry matter content (LDMC) reflect a fundamental trade-off in plant functioning between a fast growth rate (high SLA, low LDMC species) and nutrient conservation (low SLA, high LDMC species). This study aimed to analyse the stability of ranking native grasses by SLA and LDMC values under different plant growing conditions.

Evidence For Phylogenetic Signal And Correlated Evolution In Plant-Water Relations Traits, Eleinis Ávila-Lovera, Klaus Winter, Gregory R. Goldsmith

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Evolutionary relationships are likely to play a significant role in shaping plant physiological and structural traits observed in contemporary taxa. We review research on phylogenetic signal and correlated evolution in plant-water relations traits, which play important roles in allowing plants to acquire, use and conserve water. We found more evidence for a phylogenetic signal in structural traits (e.g., stomatal length, stomatal density) than in physiological traits (e.g., stomatal conductance, water potential at turgor loss). Although water potential at turgor loss is the most-studied plant-water relations trait in an evolutionary context, it is the only trait consistently found to not have …

Biodiversity Assessment And Conservation Of Threatened Plant Species Belonging To The Unique Steppe With Trees In Tunisian Drylands, Jamila Msadek, Mohamed Tarhouni

IGC Proceedings (1997-2023)

Biodiversity conservation from heavy grazing impacts, through the creation of national parks, is usually considered to sustain higher ecosystem resilience and to protect the natural plant cover as well as the threatened species. The study was carried out in Bou Hedma national park, a biosphere reserve containing the unique Acacia tortilis (Forssk.) Hayne subsp. raddiana (Savi) Brenan steppe with trees in Tunisia. Several functional traits of seven (7) rare and threatened plant species are used to highlight their adaptive strategies in order to understand the evolution of plant communities and the overall ecosystems functioning inside the park. Such results may …

Understanding Patterns And Functional Impacts Of An Invasive Tree And Its Biological Control In A Riparian System, Annie L. Henry

Electronic Theses and Dissertations

Invasive species have become an inextricable part of the landscape, particularly in riparian plant communities, and removal is often a key component of restoration programs. Biological control (biocontrol) is a method of removal that is often both efficient and effective. However, the impact of biocontrol on target species and indirect effects from invasive species removal can be hard to predict. While monitoring the impact of invasive species removal usually involves some species-based assessment such as changes in diversity, historically dominant species or native species, these strategies do not typically provide insight into the mechanisms underlying plant community response to removal. …

Nitrogen Uptake By Two Plants In Response To Plant Competition As Regulated By Neighbor Density, Xuan Jia, Chaohe Huangfu, Dafeng Hui

Biology Faculty Research

Plant species may acquire different forms of nitrogen (N) to reduce competition for the same resource, but how plants respond to neighbors with different densities in their N uptake is still poorly understood. We investigated the effects of competition regime on the uptake of different N forms by two hygrophytes, Carex thunbergii and Polygonum criopolitanum, by conducting a hydroponic test of excised roots and an in situ experiment in a subtropical wetland ecosystem. The two species were grown either in monocultures or mixtures with various neighbor densities. Root functional traits and N uptake rates of different N forms were measured. …

Patterns Of Intraspecific Trait Variation Along An Aridity Gradient Suggest Both Drought Escape And Drought Tolerance Strategies In An Invasive Herb, Shana R. Welles, Jennifer L. Funk

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Background and Aims

In water limited landscapes, some plants build structures that enable them to survive with minimal water (drought resistance). Instead of making structures that allow for survival through times of water limitation, annual plants may invoke a drought escape strategy where they complete growth and reproduction when water is available. Drought escape and resistance each require a unique combination of traits and, therefore, plants are likely to have a suite of trait values that are consistent with a single drought response strategy. In environments where conditions are variable, plants may additionally evolve phenotypically plastic trait responses to water …

Lithological Constraints On Resource Economies Shape The Mycorrhizal Composition Of A Bornean Rain Forest, Monique Weemstra, Kabir G. Peay, Stuart J. Davies, Mohizah Mohamad, Akira Itoh, Sylvester Tan, Sabrina E. Russo

School of Biological Sciences: Faculty Publications

• Arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF) produce contrasting plant–soil feedbacks, but how these feedbacks are constrained by lithology is poorly understood.

• We investigated the hypothesis that lithological drivers of soil fertility filter plant resource economic strategies in ways that influence the relative fitness of trees with AMF or EMF symbioses in a Bornean rain forest containing species with both mycorrhizal strategies.

• Using forest inventory data on 1245 tree species, we found that although AMF-hosting trees had greater relative dominance on all soil types, with declining lithological soil fertility EMF-hosting trees became more dominant. Data on …

The Use Of Functional Traits To Identify Grasses And Fodder Shrubs For Domestication To Suit A Changing Climate, Meredith L. Mitchell, R. D. B. Whalley, Hayley C. Norman

IGC Proceedings (1997-2023)

There is uncertainty about future climatic predictions; however there is little doubt amongst experts that the future will be warmer. Climate change and the associated elevation in atmospheric CO₂ level and temperatures will provide novel challenges and potential opportunities for cultivated plant species. Plant breeding and domestication can contributed to improvements in both yield and quality of grasses and fodder shrubs. A range of key functional traits is required to cope with this changing climate. The main challenges that are discussed are new pests and pathogens; changes in the pattern of nutrient supply and forage quality; challenge associated with …

Landscape Scale: Inter- And Intraspecific Variation In Plant Interactions Along A Stress Gradient In The Sheep Range Of Nevada, Jordan Dowell

UNLV Theses, Dissertations, Professional Papers, and Capstones

Impending threats to shrubland ecosystems, posed by climate change, necessitate niche modeling efforts to project vegetation range shifts. However, efforts often remain unguided by individual-scale interspecific plant interactions. The stress gradient hypothesis posits that facilitation should increase in areas of high abiotic stress, only if the individuals are able to ameliorate the surrounding area via functional traits. The Sheep Range of Nevada was used to assess the role of functional traits as predictors of plant association. Larrea tridentata, Coleogyne ramosissima, and Artemisia nova were selected as shrubs with variable life history strategies and ranges in order to identify general patterns …

Individual-Based Modeling Of Amazon Forests Suggests That Climate Controls Productivity While Traits Control Demography, Sophie Fauset, Manuel Gloor, Nikolaos M. Fyllas, Oliver L. Phillips, Gregory P. Asner, Timothy R. Baker, Lisa Patrick Bentley, Roel J. W. Brienen, Bradley O. Christoffersen, John Del Aguila-Pasquel

Biology Faculty Publications and Presentations

Climate, species composition, and soils are thought to control carbon cycling and forest structure in Amazonian forests. Here, we add a demographics scheme (tree recruitment, growth, and mortality) to a recently developed non-demographic model—the Trait-based Forest Simulator (TFS)—to explore the roles of climate and plant traits in controlling forest productivity and structure. We compared two sites with differing climates (seasonal vs. aseasonal precipitation) and plant traits. Through an initial validation simulation, we assessed whether the model converges on observed forest properties (productivity, demographic and structural variables) using datasets of functional traits, structure, and climate to model the carbon cycle at …

Interactive Effects Of Salinity And Inundation On Native Spartina Foliosa, Invasive S. Densiflora And Their Hybrid From San Francisco Estuary, California, Blanca Gallego-Trevar, Brenda J. Grewell, Caryn J. Futrell, Rebecca E. Drenovsky, Jesus M. Castillo

2019 Faculty Bibliography

Sea level rise (SLR) associated with climate change is intensifying permanent submersion and salinity in salt marshes. In this scenario, hybridization between native and invasive species may result in hybrids having greater tolerance of abiotic stress factors than their parents. Thus, understanding the responses of native and invasive halophytes and their hybrids to interacting physiological stresses imposed by SLR is key to native species conservation. We analysed how salinity, inundation depth and their interaction impact the functional traits of native and invasive cordgrass species and their hybrid (genus Spartina; Poaceae).

Functional Traits Explain Variation In Chaparral Shrub Sensitivity To Altered Water And Nutrient Availability, Reina L. Nielsen, Jeremy J. James, Rebecca E. Drenovsky

2019 Faculty Bibliography

Worldwide drylands are threatened by changes in resource availability associated with global environmental change. Functional traits may help predict which species will be most responsive to these alterations in nutrient and water availability. Current functional trait work focuses on tissue construction and nutrient concentrations, but plant performance in low resource environments also may be strongly influenced by traits related to nutrient budgets and allocation. Our overall objective was to compare trait responses in a suite of serpentine and nonserpentine congener pairs from the California chaparral, a biodiverse region facing nutrient deposition and future changes in precipitation. In a common garden …

Functional Traits Explain Variation In Chaparral Shrub Sensitivity To Altered Water And Nutrient Availability, Reina Lee Nielsen, Jeremy James, Rebecca E. Drenovsky

2019 Faculty Bibliography

Worldwide drylands are threatened by changes in resource availability associated with global environmental change. Functional traits may help predict which species will be most responsive to these alterations in nutrient and water availability. Current functional trait work focuses on tissue construction and nutrient concentrations, but plant performance in low resource environments also may be strongly influenced by traits related to nutrient budgets and allocation. Our overall objective was to compare trait responses in a suite of serpentine and nonserpentine congener pairs from the California chaparral, a biodiverse region facing nutrient deposition and future changes in precipitation. In a common garden …

Diversity And Functional Traits Of Spontaneous Plant Species In Algerian Rangelands Rehabilitated With Prickly Pear (Opuntia Ficus-Indica L.) Plantations, Souad Neffar, Taha Menasria, Haroun Chenchouni

Turkish Journal of Botany

The prickly pear (Opuntia ficus-indica L. Miller) is a xerophytic cactus species widely cultivated in arid and semiarid regions worldwide and used in rehabilitation programs of rangelands in Algeria since 1990. This study analyzed the diversity and functional traits of plant species established in prickly pear plantations growing under arid and semiarid climates. A 3-year plant assessment (2008-2010) was carried out using ecological descriptors (abundance, species richness, diversity indices, disturbance index, and Jaccard index) and plant functional traits (life forms, chorological types, dispersal types, Grime's, Noy-Meir's strategies, and morphological types). The results revealed 36 and 31 species in arid and …

Effects Of Management On Functional Diversity In Restored Tallgrass Prairie Plant Communities, Anna K. Farrell

Graduate Research Theses & Dissertations

While recent studies have embraced evaluating ecosystems through functional diversity, the focus on interspecific trait changes may limit their usefulness and application. Functional traits (traits that explain species’ responses to environmental conditions and their ecosystem roles) can provide a more nuanced understanding of how disturbances shape plant communities and the functions they perform. Further, the inclusion of intraspecific trait responses can explain a significant portion of these relationships. In ecosystem restorations, management strategies can act as environmental drivers and disturbances that affect community structure. This study examined how three environmental drivers (grazer presence, prescribed fire, and age) in restored grasslands …

Influence Of Topography And Moisture And Nutrient Availability On Green Alder Function On The Low Arctic Tundra, Nt, Katherine Louise Black Ms., Jennifer Lynn Baltzer Dr.

Theses and Dissertations (Comprehensive)

The Arctic has warmed by at least 3^°C over the past 50 years and this rapid warming is expected to continue. Climate warming is driving the proliferation of shrubs across the tundra biome with implications for energy balance, climate, hydrology, nutrient cycling, and biodiversity. Changes in tundra plant water use attributable to shrub expansion are predicted to increase evapotranspirative water loss which may amplify local warming and reduce run-off. However, little is known about the extent to which shrubs will enhance evapotranspirative water loss in these systems. Direct measures of shrub water use are needed to accurately predict …

Short-Term Effects Of Nutrients On A Barrier Island Grassland Community, Ashley Moulton

Theses and Dissertations

Increased nutrient availability globally has the potential to affect community functional composition of plants in nutrient limited environments, such as coastal grassland systems. Stability of these systems are threatened worldwide by urbanization, as well as effects of sea level rise and increased frequency and intensity of storms, and atmospheric N deposition, associated with climate change. Annual net primary productivity (ANPP), species composition, and functional traits (community weighted specific leaf area (CWSLA), leaf area index (LAI), growth form and photosynthetic pathway) were measured across four treatments to assess multiple resource limitation of nitrogen (N) and phosphorus (P) and functional community response …

Variation In Leaf Wettability Traits Along A Tropical Montane Elevation Gradient, Gregory R. Goldsmith, Lisa Patrick Bentley, Alexander Shenkin, Norma Salinas, Benjamin Blonder, Roberta E. Martin, Rosa Castro-Ccossco, Percy Chambi-Porroa, Sandra Diaz, Brian J. Enquist, Gregory P. Asner, Yadvinder Malhi

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

• Leaf wetting is often considered to have negative effects on plant function, such that wet environments may select for leaves with certain leaf surface, morphological, and architectural traits that reduce leaf wettability. However, there is growing recognition that leaf wetting can have positive effects.
• We measured variation in two traits, leaf drip tips and leaf water repellency, in a series of nine tropical forest communities occurring along a 3300-m elevation gradient in southern Peru. To extend this climatic gradient, we also assembled published leaf water repellency values from 17 additional sites. We then tested hypotheses for how these traits should …

The Non-Native Plant Rosa Multifl Ora Expresses Shade Avoidance Traits Under Low Light Availability, Rebecca E. Drenovsky, Daniel M. Dlugos, Hillary Collins, Elise M. Bartelme

Biology

PREMISE OF THE STUDY: Shade tolerance is a key trait promoting invasive plant performance in forest interiors. Rosa multifl ora is a problematic invasive shrub in the northeastern United States, occurring in edge habitats and encroaching into forests. Our objective was to evaluate the shade tolerance of R. multifl ora to assess how ecophysiological traits may facilitate its spread into forest interiors. METHODS: In the fi eld, we documented shrub and seed bank density, fecundity, phenology, and seasonal photosynthetic rates of R. multifl ora in contrasting light environments. In the greenhouse, we exposed seedlings to simulated canopy treatments by altering …

A New Perspective On Trait Differences Between Native And Invasive Exotic Plants, A. Joshua Leffler, Jeremy J. James, Thomas A. Monaco, Roger L. Sheley

Natural Resource Management Faculty Publications

Functional differences between native and exotic species potentially constitute one factor responsible for plant invasion. Differences in trait values between native and exotic invasive species, however, should not be considered fixed and may depend on the context of the comparison. Furthermore, the magnitude of difference between native and exotic species necessary to trigger invasion is unknown. We propose a criterion that differences in trait values between a native and exotic invasive species must be greater than differences between co-occurring natives for this difference to be ecologically meaningful and a contributing factor to plant invasion. We used a meta-analysis to quantify …

A Functional Trait Perspective On Plant Invasion, Rebecca E. Drenovsky, Brenda J. Grewell, Carla M. D'Antonio

Biology

Global environmental change will affect non-native plant invasions, with profound potential impacts on native plant populations, communities and ecosystems. In this context, we review plant functional traits, particularly those that drive invader abundance (invasiveness) and impacts, as well as the integration of these traitsacross multiple ecological scales, and as a basis for restoration and management.
We review the concepts and terminology surrounding functional traits and how functional traits influence processes at the individual level. We explore how phenotypic plasticity may lead to rapid evolution of novel traits facilitating invasiveness in changing environments and then oscale up' to evaluate the relative …

Can Resource-Use Traits Predict Native Vs. Exotic Plant Success In Carbon Amended Soils?, Robert J. Steers, Jennifer L. Funk, Edith B. Allen

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Productivity in desert ecosystems is primarily limited by water followed by nitrogen availability. In the deserts of southern California, nitrogen additions have increased invasive annual plant abundance. Similar findings from other ecosystems have led to a general acceptance that invasive plants, especially annual grasses, are nitrophilous. Consequently, reductions of soil nitrogen via carbon amendments have been conducted by many researchers in a variety of ecosystems in order to disproportionately lower invasive species abundance, but with mixed success. Recent studies suggest that resource-use traits may predict the efficacy of such resource manipulations; however, this theory remains largely untested. We report findings …

Seed Dispersal And Reproduction Patterns Among Everglades Plants, Ronald E. Mossman

FIU Electronic Theses and Dissertations

In this study three aspects of sexual reproduction in Everglades plants were examined to more clearly understand seed dispersal and the allocation of resources to sexual reproduction— spatial dispersal process, temporal dispersal of seeds (seedbank), and germination patterns in the dominant species, sawgrass (Cladium jamaicense). Community assembly rules for fruit dispersal were deduced by analysis of functional traits associated with this process. Seedbank ecology was investigated by monitoring emergence of germinants from sawgrass soil samples held under varying water depths to determine the fate of dispersed seeds. Fine-scale study of sawgrass fruits yielded information on contributions to variation in sexually …