Turnover Of Plants Research Articles

Thermal erosion of cratonic lithosphere as a potential trigger for mass-extinction.

The temporal coincidence between large igneous provinces (LIPs) and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here we present a synthesis of ammonite biostratigraphy, isotopic data and high precision U-Pb zircon dates from the Triassic-Jurassic (T-J) and Pliensbachian-Toarcian (Pl-To) boundaries demonstrating that these biotic crises are both associated with rapid change from an initial cool period to greenhouse conditions. We explain these transitions as a result of changing gas species emitted during the progressive thermal erosion of cratonic lithosphere by plume activity or internal heating of the lithosphere. Our petrological model for LIP magmatism argues that initial gas emission was dominated by sulfur liberated from sulfide-bearing cratonic lithosphere before CO2 became the dominant gas. This model offers an explanation of why LIPs erupted through oceanic lithosphere are not associated with climatic and biotic crises comparable to LIPs emitted through cratonic lithosphere.

Assembly mechanisms determining high species turnover in aquatic communities over regional and continental scales

Niche and neutral processes drive community assembly and metacommunity dynamics, but their relative importance might vary with the spatial scale. The contribution of niche processes is generally expected to increase with increasing spatial extent at a higher rate than that of neutral processes. However, the extent to what community composition is limited by dispersal (usually considered a neutral process) over increasing spatial scales might depend on the dispersal capacity of composing species. To investigate the mechanisms underlying the distribution and diversity of species known to have great powers of dispersal (hundreds of kilometres), we analysed the relative importance of niche processes and dispersal limitation in determining beta‐diversity patterns of aquatic plants and cladocerans over regional (up to 300 km) and continental (up to 3300 km) scales. Both taxonomic groups were surveyed in five different European regions and presented extremely high levels of beta‐diversity, both within and among regions. High beta‐diversity was primarily explained by species replacement (turnover) rather than differences in species richness (i.e. nestedness). Abiotic and biotic variables were the main drivers of community composition. Within some regions, small‐scale connectivity and the spatial configuration of sampled communities explained a significant, though smaller, fraction of compositional variation, particularly for aquatic plants. At continental scale (among regions), a significant fraction of compositional variation was explained by a combination of spatial effects (exclusive contribution of regions) and regionally‐structured environmental variables. Our results suggest that, although dispersal limitation might affect species composition in some regions, aquatic plant and cladoceran communities are not generally limited by dispersal at the regional scale (up to 300 km). Species sorting mediated by environmental variation might explain the high species turnover of aquatic plants and cladocerans at regional scale, while biogeographic processes enhanced by dispersal limitation among regions might determine the composition of regional biotas.

Land abandonment and intensification diminish spatial and temporal β‐diversity of grassland plants and herbivorous insects within paddy terraces

Summary Although traditional land‐use and management practices are known to enhance environmental heterogeneity in agricultural lands, loss of heterogeneity resulting from recent land‐use changes can lead to spatiotemporal β‐diversity losses (biotic homogenization). However, patterns and causes of β‐diversity loss, especially at a within‐field scale, have remained unexplored. We examined β‐diversity declines in plants, butterflies and orthopterans resulting from land abandonment and intensification in semi‐natural grasslands on paddy margins at a within‐field scale in relation to changes in disturbance frequency and surrounding landscapes by surveying eight abandoned, thirteen traditional and ten intensive paddy terraces. Three indices, the additive partitioning of species richness (βadd) and the turnover (βtu) and nestedness (βne) components of Jaccard dissimilarity of plants and herbivores, were used to evaluate different aspects of β‐diversity. We hypothesized that biotic homogenization due to abandonment and intensification would be expressed as low spatiotemporal βadd and βtu, low spatial βne and high temporal βne. The spatial and temporal βadd of plants and herbivores were higher in traditional terraces than in others. Changes in mowing frequency caused direct declines in butterfly βadd and indirectly decreased herbivore βadd through diminished plant βadd in abandoned and intensified terraces. Neighbouring forests increased plant spatial and butterfly temporal βadd and βtu. Abandoned terraces had higher orthopteran spatial and plant temporal βtu than traditional terraces. Mowing frequency generally did not influence spatial and temporal βtu of plants and herbivores. In intensive terraces, temporal βne of plants were higher than in traditional terraces, suggesting dominance by plant species sharing similar phenologies. Synthesis and applications. These results suggest that traditional mowing practices are essential for maintaining plant and herbivore βadd, and consequently, species pools within terraces. The higher spatial or temporal species turnover of plants and orthopterans in abandoned terraces and higher temporal plant nestedness in intensive than in traditional terraces were not due to increases in species pools within terraces. Because within‐terrace environmental heterogeneity is thought to remain in abandoned and intensive terraces, we recommend reduction in mowing frequency in intensive terraces and reintroduction of mowing in abandoned terraces for biodiversity restoration.

Beyond Surrogacy—A Multi‐taxon Approach to Conservation Biogeography

AbstractBiogeographic analysis of species turnover (β diversity) of plants and animals among regions often yields conflicting results, with regions of high β diversity identified for some taxonomic groups but not others. Such discordance calls into question the use of surrogate taxa to forge conservation plans. This discordance begs for a means of comparing multiple taxa across phyla in a manner that is cost‐effective, considers limitations in computer resources in certain global regions, and is understood by policy makers and land managers. As a test case for a method taking into account these considerations, we used species lists for ten organismal groups (spanning plants, vertebrates, and invertebrates) to identify regions of high β diversity using Monmonier's algorithm, a spatially explicit technique that is readily implemented and interpreted. Data were for montane (>1000 m elevation) species across the Eastern Arc of Tanzania and Kenya and surrounding areas. Our results indicate that surrogacy does not make for the most effective expenditure of conservation efforts. We also show that to use a multi‐taxon approach one need not rely on intensive surveys of areas in order to make conservation decisions, including reserve selection. Our approach also eliminates the need for complex modeling and comparisons common to many GIS‐based complementarity techniques. Additionally, a wide variety of socioeconomic, political, demographic, geological, climatological, and evolutionary factors can be incorporated into the technique to help shape conservation biogeography from a local and regional perspective. This technique can bridge the gap between conservation biogeography theory and application in tropical regions and beyond.

Effects of climate and forest age on plant and caterpillar diversity in the Yucatan, Mexico

Abstract:Understanding patterns in plant and herbivorous insect diversity across spatial and temporal scales is fundamental to ecology, but comparative multi-taxonomic studies in tropical seasonally dry forests remain scarce. In 36 sites, distributed over three forest age classes (5–10 y, 10–30 y, >100 y) and three seasonal forest types (dry, intermediate, humid), we sampled plants of different stem diameter classes while caterpillars were sampled across vertically distributed forest layers during three seasons over the year. We recorded 299 plant species and 485 caterpillar morphospecies. For large woody plants, species numbers showed a gradually increasing trend with forest age in the intermediate and humid forest types, while the main portion of explained variation in overall species turnover was accounted for by the forest type × forest age interaction (21.3–23.1% of 44.4–48.7%). Ordinations and multivariate pairwise comparisons suggested a faster but also very distinct successional development of species diversity of large plants in the driest compared with humid and intermediate forest types. In contrast, highest species numbers of small plants in the undergrowth was often found in the 5–10 y-old vegetation across forest types, whereas forest type was the major factor in overall species turnover (contributing 24.2% of 48.7% explained variation). Caterpillar species turnover was most correlated to species turnover of small plants; however, variation in caterpillar species diversity appears to be mostly regulated by seasonal cues, and to a lesser extent by patterns of regional turnover and local diversity of undergrowth plant species.

Components of herbage accumulation in elephant grass cvar Napier subjected to strategies of intermittent stocking management

SUMMARYHerbage accumulation is determined by the tissue turnover of individual plants and by the regulation patterns of the number of individuals in a plant population, which function in conjunction to enable swards to adapt to variations in growth and management conditions. Based on the hypothesis that intermittent grazing strategies change the proportion of basal and aerial tillers and, consequently, sward herbage accumulation, the objective of the current experiment was to evaluate the components of herbage accumulation in elephant grass cvar Napier (Pennisetum purpureum Schum. cvar Napier) from January 2011 to April 2012. The treatments corresponded to combinations of two post-grazing (post-grazing heights of 35 and 45 cm) and two pre-grazing conditions (0·95 and maximum canopy light interception during regrowth – LI0·95 and LIMax) and were allocated to experimental units (850 m2 paddocks) according to a 2×2 factorial arrangement in a complete randomized block design with four replications. The following response variables were evaluated: the population density of basal tillers (TPDb) and the population density of aerial tillers (TPDa), the number of aerial tillers per supporting unit (A/B+VC), growth rates of the leaf (LGR) and stem (SGR), leaf senescence rate, net leaf accumulation rate (LAR), and the contributions of basal and aerial tillers to sward growth and senescence. The swards managed with the LI0·95 target had greater TPDb than those managed with the LIMax target, but no difference was recorded between the LI pre-grazing targets for TPDa. The larger A/B+VC ratio recorded for the swards managed with the LIMax target resulted in a higher contribution of aerial tillers to the growth and senescence of swards. This growth strategy resulted in a higher SGR and lower LGR and LAR for the swards managed with the LIMax target relative to those managed with the LI0·95 target. The post-grazing height targets affected only LGR during winter and the second summer and SGR on average for the experiment, with higher values recorded for the swards managed at 35 cm. The LI pre-grazing targets played a central role in defining the compensatory mechanisms responsible for the competitive ability of the plants, which were primarily expressed in the variation of the proportion of basal and aerial tillers in the tiller population and interfered with the components of herbage accumulation and total herbage yield of the swards.

Do vascular plants and bryophytes respond differently to coniferous invasion of coastal heathlands?

Invasion by non-native conifers may pose a threat to local biodiversity, but knowledge about introduced conifer effects on Northern Hemisphere ecosystems is scarce. The coastal heathlands of north-west Europe are threatened by invasion of native and introduced tree species. We assess how spread of the introduced conifer Sitka spruce (Picea sitchensis (Bong.) Carr.) into European coastal heathlands affect two major functional groups; vascular plants and bryophytes, and how these effects relate to the environmental changes imposed by the developing tree canopies. We compared the impact of introduced Sitka spruce and native Scots pine (Pinus sylvestris L.) by analysing effects on species richness and turnover of vascular plants and bryophytes along fine-scale transects from individual tree stems into open heathland vegetation. Environmental impacts were assessed by measured environmental variables, and the responses of the two species groups were assessed by calculating changes in their respective mean Ellenberg indicator values. Species richness decreased beneath both conifers, related to decreased light and increased nitrogen and pH. Whereas vascular plants responded negatively to poor light conditions beneath dense and low Sitka spruce canopies, bryophytes were more negatively affected by the warmer and drier microclimates beneath Scots pine. Introduced Sitka spruce impacts the sub-canopy environment differently from the native Scots pine, and the two functional plant groups responded differently to these impacts. This suggests that future forests are likely to differ in species richness and composition, depending on whether succession is based on native or introduced coniferous trees.

Plant Invasions in China – Challenges and Chances

Invasive species cause serious environmental and economic harm and threaten global biodiversity. We set out to investigate how quickly invasive plant species are currently spreading in China and how their resulting distribution patterns are linked to socio-economic and environmental conditions. A comparison of the invasive plant species density (log species/log area) reported in 2008 with current data shows that invasive species were originally highly concentrated in the wealthy, southeastern coastal provinces of China, but they are currently rapidly spreading inland. Linear regression models based on the species density and turnover of invasive plants as dependent parameters and principal components representing key socio-economic and environmental parameters as predictors indicate strong positive links between invasive plant density and the overall phytodiversity and associated climatic parameters. Principal components representing socio-economic factors and endemic plant density also show significant positive links with invasive plant density. Urgent control and eradication measures are needed in China's coastal provinces to counteract the rapid inland spread of invasive plants. Strict controls of imports through seaports need to be accompanied by similarly strict controls of the developing horticultural trade and underpinned by awareness campaigns for China's increasingly affluent population to limit the arrival of new invaders. Furthermore, China needs to fully utilize its substantial native phytodiversity, rather than relying on exotics, in current large-scale afforestation projects and in the creation of urban green spaces.

Patterns of plant beta‐diversity along elevational and latitudinal gradients in mountain forests of China

Biodiversity patterns and their underlying mechanisms have long been focal topics of study for ecologists and biogeographers. However, compared with spatial variation in species richness (α‐ and γ‐diversity), β‐diversity, or the dissimilarity of species composition between two or more sites has until recently received limited attention. In this study, we explored the large‐scale patterns of altitudinal turnover (β‐diversity) of plants in montane forests of China, based on systematic inventories of 1153 plots from 46 mountains distributed over ˜30 degrees of latitude (21.9–51.7°N) and ˜4100 m of altitude (160–4250 m). The β‐diversity of trees and shrubs declined significantly with increasing latitude. Along the altitudinal gradient, β‐diversity of both trees and shrubs showed non‐significant trends in most mountains. Differences in climate explained ˜30.0% of the variation in tree β‐diversity (27.7, 36.5, and 26.2% for the Jaccard's, βj, Sorenson's, βs, and Simpson's dissimilarity, βsim, respectively), with mean annual temperature being most important, and ≤ 10.0% of that in shrub β‐diversity (10.0, 8.2, and 7.0% for βj, βs, and βsim, respectively), with annual actual evapotranspiration and annual precipitation as the main predictors. However, climatic controls of β‐diversity varied dramatically in different biogeograpical regions. The β‐diversity of trees exhibited stronger, whereas that of shrubs showed weaker, climatic patterns in temperate and arid than subtropical regions. These results suggest that mechanisms causing patterns of β‐diversity may differ between latitudinal and altitudinal gradients, and among biogeographical regions; as a result, caution should be exercised in drawing close parallels between patterns and causes of β‐diversity along latitudinal and altitudinal gradients and among regions.

Effects of geographic distance and climatic dissimilarity on species turnover in alpine meadow communities across a broad spatial extent on the Tibetan Plateau

Understanding the underlying mechanisms that generate species turnover or beta diversity among biological communities is a central theme in ecology. Here, we distinguish the effects of geographic distance and climatic dissimilarity on species turnover of vascular plants in alpine meadow communities on the Tibetan Plateau in China. We calculated species turnover between each pair of 17 sites, using the Jaccard’s and Simpson’s indices. We selected six variables to quantify climate at each site, and subjected values of the climatic variables to a principal component analysis. We applied a variance partitioning approach to disentangle the effects of geographic distance and climatic dissimilarity on species turnover in alpine meadow communities. We also examined the effect of elevation variation on species turnover. Geographic distance and climate dissimilarity together explained 49.1 % of the variation in compositional difference between alpine meadow communities; the amount of the variation explained purely by geographic distance and purely by climatic dissimilarity was 6.8 % and 2.8 %, respectively. When geographic distance, climate dissimilarity, and elevation difference were included in an analysis, they together explained 55 % of the variation in compositional difference between alpine meadow communities; the pure effect of each of the three sets of explanatory variables was 4.8, 4.3, and 3.5 %, respectively. The fact that the vast majority of the variation explained by geographic distance and climatic dissimilarity cannot be independently attributed to either factor suggests that the two factors operate together in determining regional patterns of species composition in alpine meadows on the Tibetan Plateau.

Patterns of species turnover in plant‐pollinator communities along a precipitation gradient in Patagonia (Argentina)

AbstractRecent studies have assessed the influence of different types of gradients (e.g. altitudinal, latitudinal and temporal, among others) on the structure and function of community‐level plant‐pollinator webs. Although the importance of humidity as a major driver of species‐richness gradients worldwide has been stressed by recent reviews, no studies have been specifically designed to address the influence of precipitation gradients on pollination webs. In the present paper we describe for the first time the turnover of species of plants and their associated flower visitors between eight communities located along a steep precipitation gradient in north‐west Patagonia, Argentina. Our results show that: (i) there is a high spatial turnover of plant communities and their associated pollinators; (ii) this turnover is strongly related to precipitation changes across the region; and (iii) the turnover rate is similar for plants and pollinators. Our results support the view that the precipitation gradient is a significant factor associated with the regional turnover of plants and their pollinators in the temperate forests of southern South America.

Why red‐dominated autumn leaves in America and yellow‐dominated autumn leaves in Northern Europe?

Why red‐dominated autumn leaves in America and yellow‐dominated autumn leaves in Northern Europe?

The beauties of calorimetry

This paper gives a short overview of direct and indirect calorimetric experiments to determine the heat production or at least the metabolic turnover of whole plants or their blossoms. A special emphasis is placed on thermogenic plants because of their high specific heat production rates equal to those of mammals or birds and sometimes even surpassing them.

ORIGINAL ARTICLE: Turnover of plants on small islets of the eastern Aegean Sea within two decades

AbstractAim To estimate species turnover of plants on 32 small islands within a 20‐year period and to assess possible changes in community composition and properties, such as species richness and factors affecting it, nestedness, species co‐occurrence and overall community similarity. Additionally, to assess the possible effects of grazing, gull colonies and fire on turnover values.Location Thirty‐two islets in the eastern Aegean Sea (Greece).Methods Complete sampling of plants was performed in 1974 and in 1990–94 (mostly in 1994, which was used as the reference year). Species turnover rates were estimated using both per island and per species approaches. Multiple regression was used to evaluate factors affecting species richness. Chi‐square tests were applied to compare community composition among sampling periods. The effects of various factors on turnover rates and species richness were examined using one‐way anova and ancova. Mann–Whitney tests were applied in order to check for differences between frequencies of occurrence of extinct, immigrant and persisting species. Community nestedness was calculated using bitmatnest and the C‐score index for co‐occurrence was estimated using EcoSim7. Species similarities among islands in each of the 1974 and 1994 data sets were assessed using Jaccard’s index and the two similarity matrices were compared using a Mantel test.Results Of 391 species recorded on the islets, 334 were present in 1974, 301 in 1994 and 244 were common to both these periods. Species richness in the 1974 and 1994 data sets was significantly correlated with elevation and area, but not with distance from the nearest large island. Richness was positively affected by grazing, but not by fire or gull colonies. The slopes of species–area and species–elevation regressions were almost identical in 1974 and 1994. Mean relative turnover was 2.06 (species per islet) and 3.26 (islets per species). Turnover was not correlated with area, elevation or distance from the nearest large island. Nestedness and co‐occurrence levels were very similar. Tables of islet by islet floral similarity (Jaccard’s index) did not differ between the 1974 and 1994 data sets.Main conclusions The turnover rates found are among the highest recorded for plants; at the same time the islet communities exhibit notable stability in overall properties. Our results provide evidence for rapid shifts in species number that may nonetheless be considered as equilibrial dynamics, as these islets are able to respond rapidly to environmental change and disturbance. Human activities, notably the application of grazing, have a significant complicating effect on community dynamics, enhancing observed turnover rates.

Evolution in closely adjacent plant populations X: long-term persistence of prereproductive isolation at a mine boundary

Flowering time differences between metal-tolerant and nontolerant populations of the grass Anthoxanthum odoratum growing across a mine boundary have persisted for over 40 years. These flowering time differences result in a high degree of prezygotic genetic isolation (isolation index=0.43) between the tolerant mine populations and nontolerant pasture populations. Previous work showing genetic determination of flowering time and a high turnover of individual plants argues strongly for the selective maintenance of this difference.

FDI and the Dynamics of Productivity in Indonesian Manufacturing

This article examines productivity growth in the Indonesian manufacturing sector. We use a longitudinal data set to calculate the effects on aggregate manufacturing productivity growth from improvements within establishments, from reallocation of market shares, and from the turnover of plants. Productivity growth is mainly explained by reallocation of market shares and from turnover of plants. Moreover, the foreign contribution to productivity growth is unclear and depends on the choice of productivity measure. A cautious conclusion is that the foreign contribution is about the same size as the foreign share of manufacturing output. Finally, there is a difference in the causes of productivity growth between foreign and domestic plants.

Industry Dynamics in the Swedish Textile and Wearing Apparel Sector

This paper analyses the adjustment process within the Swedish textile and wearing apparel sector and finds results that support the notion of Schumpeter’s ‘creative’ destruction. The turnover of plants and jobs seems to ‘improve’ the industries from within due to an exit (entry) of less (more) productive plants, exit (entry) of old (new) incumbents, a destruction (creation) of less (more) human-capital intensive jobs, and a supply of new products on the world market. The econometric analysis of the probability of exit with plant, firm and industry characteristics supports the idea of a rationalisation from within.

Automated calibration aids smooth turnover of new plants

Accurate documentation of instrument calibration saves time and money in the completion of construction projects. There are thousands of newly arrived instruments that must be checked and calibrated and then documented prior to installation in new plants. Such an extended effort was not necessary at the recently completed Front Range Power Station, a 480-MVV combined cycle power plant constructed by The Industrial Company (TIC) near Colorado Springs, Colorado. Instead, one technician printed out calibration certificates in an orderly fashion for more than 60 turnover packages. Ultimately, more than 1,200 HART (highway addressable remote transducer) and conventional devices were documented, and not a single calibration document was subsequently questioned or returned. Even better, no additional costs were incurred for recalibrating the instruments or reworking the documentation, providing an estimated savings of up to US$50,000 in avoided costs. These savings - and the accurate documentation that made them possible - were accomplished through the use of a software tool, the AMS Suite: Intelligent Device Manager software created by Emerson Process Management. This package was originally designed to help end users reduce instrument startup and maintenance costs by accessing diagnostic information from smart field instruments. The database that functions as an integral part of this predictive maintenance technology is also suitable for use by instrument technicians, making instrument calibration easier by saving them time before and after the actual testing and calibration. Furthermore, a record is automatically generated every time an instrument is calibrated or a configuration parameter is changed. Loaded into a PC in a control room or maintenance shop, this software communicates with smart field instruments on the control network, capturing diagnostic information generated by those devices. The massive amount of data obtained in this way is integrated into a single database, organized, processed, and presented on the PC monitor for use by engineers and technicians to streamline and simplify their work.

Kinetic analysis of histone acetylation turnover and Trichostatin A induced hyper- and hypoacetylation in alfalfa.

Dynamic histone acetylation is a characteristic of chromatin transcription. The first estimates for the rate of acetylation turnover of plants are reported, measured in alfalfa cells by pulse, pulse-chase, and steady-state acetylation labeling. Acetylation turnover half-lives of about 0.5 h were observed by all methods used for histones H3, H4, and H2B. This is consistent with the rate at which changes in gene expression occur in plants. Treatment with histone deacetylase inhibitor Trichostatin A (TSA) induced hyperacetylation at a similar rate. Replacement histone variant H3.2, preferentially localized in highly acetylated chromatin, displayed faster acetyl turnover. Histone H2A with a low level of acetylation was not subject to rapid turnover or hyperacetylation. Patterns of acetate labeling revealed fundamental differences between histone H3 versus histones H4 and H2B. In H3, acetylation of all molecules, limited by lysine methylation, had similar rates, independent of the level of lysine acetylation. Acetylation of histones H4 and H2B was seen in only a fraction of all molecules and involved multiacetylation. Acetylation turnover rates increased from mono- to penta- and hexaacetylated forms, respectively. TSA was an effective inhibitor of alfalfa histone deacetylases in vivo and caused a doubling in steady-state acetylation levels by 4-6 h after addition. However, hyperacetylation was transient due to loss of TSA inhibition. TSA-induced overexpression of cellular deacetylase activity produced hypoacetylation by 18 h treatment with enhanced acetate turnover labeling of alfalfa histones. Thus, application of TSA to change gene expression in vivo in plants may have unexpected consequences.

Who Dies? International Trade, Market Structure and Industrial Restructuring

This paper examines the role of changing factor endowments in the growth and decline of industries and regions. The implications of an endowment-based Heckscher-Ohlin trade model for plant entry and exit are tested on 20 years of data for the entire US manufacturing sector. The trade model provides predictions for which industries will see growth through the positive net entry of plants. A multi-region version of the same model has predictions for which regions will see high turnover and net entry of plants. In a country such as the U.S. that is augmenting both its physical and human capital, the least capital-intensive, least skill-intensive industries are correctly predicted to have the lowest rate of net entry. In addition, increases in regional capital and skill intensity are associated with higher probabilities of shutdown, especially for plants in industries with low initial capital and skill intensities.