Woody Plant Encroachment into Grasslands: Spatial Patterns of Functional Group Distribution and Community Development

Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant functional types (PFTs) better suited to invade grasslands than others? To what extent do local patterns of distribution and abundance of woody PFTs invading grasslands reflect intrinsic topoedaphic properties versus plant-induced changes in soil properties? We addressed these questions in the Southern Great Plains, United States at a subtropical grassland known to have been encroached upon by woody species over the past 50-100 years. A total of 20 woody species (9 tree-statured; 11 shrub-statured) were encountered along a transect extending from an upland into a playa basin. About half of the encroaching woody plants were potential N(2)-fixers (55% of species), but they contributed only 7% to 16 % of the total basal area. Most species and the PFTs they represent were ubiquitously distributed along the topoedaphic gradient, but with varying abundances. Overstory-understory comparisons suggest that while future species composition of these woody communities is likely to change, PFT composition is not. Canonical correspondence analysis (CCA) ordination and variance partitioning (Partial CCA) indicated that woody species and PFT composition in developing woody communities was primarily influenced by intrinsic landscape location variables (e.g., soil texture) and secondarily by plant-induced changes in soil organic carbon and total nitrogen content. The ubiquitous distribution of species and PFTs suggests that woody plants are generally well-suited to a broad range of grassland topoedaphic settings. However, here we only examined categorical and non-quantitative functional traits. Although intrinsic soil properties exerted more control over the floristics of grassland-to-woodland succession did plant modifications of soil carbon and nitrogen concentrations, the latter are likely to influence productivity and nutrient cycling and may, over longer time-frames, feed back to influence PFT distributions

Aggregation-Induced Emission (AIE), Life and Health

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health

CCA Ordination (canonical correspondence analysis) results ordered in multivariate space along the first two canonical axes, separately depicting relationships among (A) tree-stature species (Table 1) and soil variables; and (B) communities in each 6 m × 6 m sample plot (symbols indicate community type) along a hill-slope transect.

<p>Species centroids (+) indicate center of distribution among sample plots for each tree species coded as follows: acf = <i>Acacia farnesiana</i>; acr = <i>Acacia rigidula</i>; cel = <i>Celtis pallida</i>; con = <i>Condalia hookeri</i>; dio <i>= Diospyros texana</i>; kar = <i>Karwinskia humboltiana</i>; pro = <i>Prosopis glandulosa</i>; zan = Zanthoxylum <i>fagara</i>. Lines are vectors indicating direction of increasing value (from center outward) for soil variables as follows: BD = bulk density; Sand and clay = soil particle percentages; SOC = soil organic carbon; TN = total nitrogen. </p

Variation decomposition shown as a percentage of total variation explained (TVE) for separate analyses of tree (Figure 3) and shrub (Figure 4) plots, that were uniquely related to variable groupings that included (a) soil organic carbon and total nitrogen, (b) % sand and % clay; or (c) an equal sharing by a and b.

<p>Variation decomposition shown as a percentage of total variation explained (TVE) for separate analyses of tree (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084364#pone-0084364-g003" target="_blank">Figure 3</a>) and shrub (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084364#pone-0084364-g004" target="_blank">Figure 4</a>) plots, that were uniquely related to variable groupings that included (a) soil organic carbon and total nitrogen, (b) % sand and % clay; or (c) an equal sharing by a and b.</p

CCA Ordination (canonical correspondence analysis) results ordered in multivariate space along the first two canonical axes, separately depicting relationships among (A) shrub-stature species and soil variables (Table 1); and (B) 2 m × 2 m sample plots (symbols indicate community type) along a hill-slope transect.

<p>Species centroids (+) indicate center of distribution among sample plots for each shrub species coded as follows: acf = <i>Acacia farnesiana; acg = A. greggeii</i>; acr = <i>A. rigidula</i>; alo = <i>Aloysia gratissima</i>; bem = <i>Bernardia myricaefolia</i>; ber <i>= Bernardia myricaefolia</i>; cel <i>= Celtis pallida</i>; col = <i>Colubrina texensis</i>; con <i>= Condalia hookeri</i>; dio <i>= Diospyros texana</i>; eph = Ephedra <i>antisyphilitica</i>; eys = <i>Eysenhardtia texana</i>; for = <i>Forestiera angustifolia</i>; gym = <i>Gymnosperma</i> spp.; kar <i>= Karwinskia humboltiana</i>; par <i>= Parkinsonia aculeata</i>; pro <i>= Prosopis glandulosa</i>; sch = <i>Schaefferia cuneifolia</i>; zan = Zanthoxylum <i>fagara</i>; ziz = <i>Ziziphus obtusifolia</i>. Lines are vectors indicating direction of increasing value (from center outward) for soil variables coded as follows: BD = bulk density; Sand and clay = soil particle percentages; SOC = soil organic carbon; TN = total nitrogen.</p

Topoedaphic variations based on sampling at 1-m intervals along a transect extending from plant communities in a savanna parkland upland (grassland, shrub cluster, grove), through intermittent drainage woodlands and into a playa savanna community.

<p>VWC = soil volumetric water content; SOC = soil organic carbon. </p

Aggregation-Induced Emission (AIE), Life and Health.

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health