Life Form Types Research Articles

In and out: Effects of shoot- vs. rooted-presence sampling methods on plant diversity measures in mountain grasslands

Plant diversity measures (e.g., alpha- and beta-diversity) provide the basis for a number of ecological indication and monitoring methods. These measures are based on species counts in sampling units (plots or quadrats). However, there are two alternative conventions for defining a vascular plant species as “present” in a plot, i.e. “shoot presence” (a species is recorded if the vertical projection of any above-ground part falls within the plot) and “rooted presence” (a species is recorded only when an individual is rooted inside the plot). Very few studies addressed the effects of the two sampling conventions on species richness and diversity indices. We sampled mountain dry grasslands in Italy across different plot sizes and vegetation types to assess how large is the difference in alpha- and beta-diversity values and in sample-based rarefaction curves between the two methods. We found that the difference is greatly dependent on plot size, being more relevant, both in absolute and percentage values, at smaller grain; it is also dependent on habitat type, being larger in shallow-soil communities, as they have a sparser vegetation structure and host life-form types with a larger lateral spread. At fine spatial scales (<1m2) the difference is large enough to bias statistical inference, and we conclude that at such scales one should not attempt to compare plant diversity indices if they were not obtained with the same sampling convention.

Detecting the environmental impact of off-road vehicles on Rawdat Al Shams in central Saudi Arabia by remote sensing.

Off-road vehicles can have a devastating impact on vegetation and soil. Here, we sought to quantify, through a combination of field vegetation, bulk soil, and image analyses, the impact of off-road vehicles on the vegetation and soils of Rawdat Al Shams, which is located in central Saudi Arabia. Soil compaction density was measured in the field, and 27 soil samples were collected for bulk density analysis in the lab to quantify the impacts of off-road vehicles. High spatial resolution images, such as those obtained by the satellites GeoEye-1 and IKONOS-2, were used for surveying the damage to vegetation cover and soil compaction caused by these vehicles. Vegetation cover was mapped using the Normalized Difference Vegetation Index (NDVI) technique based on high-resolution images taken at different times of the year. Vehicle trails were derived from satellite data via visual analysis. All damaged areas were determined from high-resolution image data. In this study, we conducted quantitative analyses of vegetation cover change, the impacts of vehicle trails (hereafter "trail impacts"), and a bulk soil analysis. Image data showed that both vegetation cover and trail impacts increased from 2008 to 2015, with the average percentage of trail impacts nearly equal to that of the percentage of vegetation cover during this period. Forty-six species of plants were found to be present in the study area, consisting of all types of life forms, yet trees were represented by a single species, Acacia gerrardii. Herbs composed the largest share of plant life, with 29 species, followed by perennial herbs (12 species), grasses (5 species), and shrubs (3 species). Analysis of soil bulk density for Rawdat Al Shams showed that off-road driving greatly impacts soil density. Twenty-two plant species were observed on the trails, the majority of which were ephemerals. Notoceras bicorne was the most common, with a frequency rate of 93.33%, an abundance value of 78.47%, and a density of 0.1 in transect 1, followed by Plantago ovata.

Variation in leaf and soil δ15N in diverse tree species in a lowland dipterocarp rainforest, Malaysia

Large variations in leaf δ 15 N in Bornean tropical rainforest trees may indicate that various tropical species have species-specific strategy for nitrogen uptake under low soil nutrient conditions, including root symbiotic microorganisms such as ectomycorrhiza. Lowland tropical rainforests in Southeast Asia are characterized by high species diversity despite limited soil nutrient conditions. The plant nitrogen isotope ratio (δ15N) reflects plant uptake of soil nitrogen. We analyzed δ15N values and nitrogen content (N %) in leaves and roots of 108 woody species with different types of symbiotic microorganisms, of different life forms (emergent, canopy, sub-canopy, understory, and canopy gap species), and from different families in a Bornean lowland dipterocarp forest to gain more insight into the diversity of nitrogen uptake strategy in the rhizosphere. Leaf δ15N values in the species studied varied largely from −7.2 to 5.0 ‰, which is comparable to the values of known Asian trees including temperate, sub-tropical, and tropical mountain forests. Leaf δ15N also varied significantly among both life forms and families, though the phylogenetically independent contrast (PIC) relationships were not statistically significant among life form, family, and symbiotic types. Some families showed specific leaf δ15N values; Dipterocarpaceae, the dominant family in the canopy layer with symbiotic ectomycorrhiza in Southeast Asia, had small intraspecific variation and higher leaf δ15N values (0.03 ‰) compared with species exhibiting arbuscular mycorrhiza, whereas several families such as Burseraceae, Euphorbiaceae, and Myrtaceae showed large interspecific variation in leaf δ15N (e.g., from −7.2 to 5.0 ‰ in Euphorbiaceae). These variations suggest that tropical species may have family- or species-specific strategy, such as root symbiotic microorganisms, for nitrogen uptake under low-nutrient conditions in tropical rainforests in Southeast Asia.

A global assessment of a large monocot family highlights the need for group-specific analyses of invasiveness.

Significant progress has been made in understanding biological invasions recently, and one of the key findings is that the determinants of naturalization and invasion success vary from group to group. Here, we explore this variation for one of the largest plant families in the world, the Araceae. This group provides an excellent opportunity for identifying determinants of invasiveness in herbaceous plants, since it is one of the families most popular with horticulturalists, with species occupying various habitats and comprising many different life forms. We first developed a checklist of 3494 species of Araceae using online databases and literature sources. We aimed to determine whether invasiveness across the introduction-naturalization-invasion continuum is associated to particular traits within the family, and whether analyses focussed on specific life forms can reveal any mechanistic correlates. Boosted regression tree models were based on species invasion statuses as the response variables, and traits associated with human use, biological characteristics and distribution as the explanatory variables. The models indicate that biological traits such as plant life form and pollinator type are consistently strong correlates of invasiveness. Additionally, large-scale correlates such as the number of native floristic regions and number of introduced regions are also influential at particular stages in the invasion continuum. We used these traits to build a phenogram showing groups defined by the similarity of characters. We identified nine groups that have a greater tendency to invasiveness (includingAlocasia, the Lemnoideae andEpipremnum). From this, we propose a list of species that are not currently invasive for which we would recommend a precautionary approach to be taken. The successful management of plant invasions will depend on understanding such context-dependent effects across taxonomic groups, and across the different stages of the invasion process.

Avencas (Adiantum L. - Pteridaceae) do Município de Acará, Pará, Brasil

The Pteridaceae family includes about 50 genera and over 950 species the family consists of five monophyletic groups that one of these groups is formed by genus Adiantum plus vittarioid ferns. In Brazil are several studies about the family but just one study exclusively for the genus that was realized in Rio de Janeiro State. Therefore, this work aim conduct study of genus Adiantum occurring in the municipality of Acara where was observed eight species: Adiantum dolosum, A. glaucescens, A. humile, A. latifolium, A.multisorum, A. paraense, A. terminatum and A.tomentosum. To this purpose, identification key, descriptions, illustrations, pattern of geographical distribution, types of life forms and environments of occurrence were elaborated. Keywords: ferns; taxonomy; Brazilian amazon.

Assessment of liverwort and hornwort flora of Nilgiri Hills, Western Ghats (India)

Abstract Bryophytes are an important part of the flora of the Nilgiri Hills of Western Ghats, a biodiversity hotspot. This paper gives an updated catalogue of the Hepaticae of the Nilgiri Hills. The list includes all available records, based on the authors’ collections and those in LWU and other renowned herbaria. The catalogue of liverworts indicates their substrate and occurrence, and includes several records new for the Nilgiri bryoflora as well as for Western Ghats. The list of Hepaticae contains 29 families, 55 genera and 164 taxa. The list of Anthocerotae comprises 2 families, 3 genera and 5 taxa belonging to almost all life form types.

Diversity and distribution of the bryophyte flora in montane forests in the Chapada Diamantina region of Brazil

Bryophytes constitute an important component of tropical rain forests, which provide microhabitats favorable for their establishment. Bryophytes are also quite responsive to changes in microclimate, which makes them good bioindicators. This study aimed to determine the diversity and distribution of bryophytes in upper and lower montane forests of the Chapada Diamantina region of the state of Bahia, Brazil. To that end, we studied community aspects such as richness, diversity, substrates colonized, life forms and floristic similarity between areas and regions. In 2007 and 2008, we collected specimens from six forest sites, located from the north to the south of the Chapada Diamantina region. We identified a total of 205 infrageneric taxa. In comparison with the lower montane forests, the upper montane forests presented higher diversity and species richness, as well as greater numbers of substrates colonized, life form types, species of restricted geographic distribution and species typical of shaded areas. We also found low similarity in the species composition, the populations of the upper and lower montane forests forming two large and distinct groups. Although presenting relatively high floristic homogeneity among themselves, the Chapada Diamantina areas presented little similarity with those of the Atlantic Forest. This can be explained by the differences between the two regions in terms of environmental conditions, precipitation, seasonality, elevation and continentality.

Identifying indicator species for bryophyte conservation in fragmented forests

It is important to conserve bryophyte diversity in fragmented forests, due to the vulnerability of this group to environmental change. In this study, the utility of bryophyte functional groups (taxonomic classes, substrate classes, and life-forms) was examined as indicators for planning urban area conservation of bryophyte diversity. The study sites comprised 27 fragmented forests in Kyoto City, Japan. Using linear regression models, it was found that the species richness of almost all functional groups was positively correlated with patch size. Furthermore, two types of bryophyte life-form (fans and thalloid mats) were significantly correlated with environmental factors considered important for conservation planning. The species richness of fan bryophytes was positively correlated with the presence of natural forest patches and was negatively correlated with distance from mountainous areas. Similarly, the species richness of thalloid mat bryophytes was negatively correlated with maintenance practices. These results may be explained by the vulnerability of these two bryophyte groups to environmentally caused drought stress, accompanied by decreasing patch size, maintenance practices, disturbance, and/or loss of natural vegetation. Considering that drought stress represents a major threat to bryophyte diversity in fragmented forests, the species richness of hygrophilous life-forms (e.g., fans and thalloid mats) may be used as an indicator of fragmented forests that are less affected by drought stress, and these species should be preferentially conserved to maintain high levels of bryophyte diversity.

The potential for detecting ‘life as we don't know it’ by fractal complexity analysis

AbstractFinding life in the Universe entirely different to the one evolved on Earth is probable. This is a significant constraint for life-detecting instruments that were sent and may be sent elsewhere in the solar system, as how could we detect life as ‘we don't know it’? How could we detect something when we have no prior knowledge of its composition or how it looks like? Here we argue that disregarding the type of lifeform that could be envisioned, all must share in common the attribute of being entities that decrease their internal entropy at the expense of free energy obtained from its surroundings. As entropy quantifies the degree of disorder in a system, any envisioned lifeform must have a higher degree of order than its supporting environment. Here, we show that by using fractal mathematics analysis alone, one can readily quantify the degree of entropy difference (and thus, their structural complexity) of living processes (lichen growths and plant growing patterns in this case) as distinct entities separate from its similar abiotic surroundings. This approach may allow possible detection of unknown forms of life based on nothing more than entropy differentials of complementary datasets. Future explorations in the solar system, like Mars or Titan, may incorporate this concept in their mission planning in order to detect potential endemic lifeforms.

Interactions between Callitris above-ground biomass, species density and plant form in north-eastern New South Wales

Dense Callitris endlicheri (Parl.) F.M.Bailey (black cypress pine) and C. glaucophylla Joy Thomps. &amp; L.A.S.Johnson (white cypress pine) stands are often viewed as problematic and thinning is often encouraged from a biodiversity perspective. In the present investigation, canonical correspondence analyses (CCAs) of 997 survey sites were undertaken within the public and private reserve network that contains a variety of above-ground biomass (AGB) of C. endlicheri and C. glaucophylla (as measured by diameter at breast height (DBH) and dispersion) and the evenness of the species distribution was undertaken. This was done to further dissect the effect of Callitris AGB on species density (richness per quadrat) of native and introduced species and on broad life-form groupings. Other landscape features such as altitude, physiography, drainage and soil depth were also included in analyses. C. endlicheri and C. glaucophylla grow in different biophysical locations in most instances and this was reflected in the results of the study. No level of AGB or clumping of C. endlicheri was found to affect species density of native or introduced taxa or the distribution of life-forms. Increasing AGB of C. glaucophylla had a positive effect on native species density. The species density of introduced taxa was also increased with an increase in C. glaucophylla AGB. The distribution of life-forms was significantly affected by an increase in Callitris AGB with a decrease in trees, shrubby taxa and hemi-parasites, although herbaceous species had a concomitant increase in number. There is no reason to thin dense Callitris stands to increase local species richness. However, because the distribution of life-form types is significantly affected by C. glaucophylla, there is a need to understand what is occurring in species replacements and what landscape mosaic of structural types is required for this species. It is likely that dense stands of Callitris are important, along with a variety of stand densities so as to maintain the highest regional diversity.

The Cyperaceae in Madagascar show increased species richness in upland forest and wetland habitats

Background and aims – Madagascar is a biodiversity hotspot with a high level of plant endemism. However, not all lineages of plants are equally represented and the highest diversity occurs in forest lineages. Cyperaceae frequently occur in grasslands and wetlands in Africa, and the tribe Hypolytreae and Carex subgenus Vigneastra are among the few predominantly forest lineages. We study the Cyperaceae of Madagascar to discover what lineages are represented (genera/tribes), to determine their unique habitats and key functional traits and to investigate patterns of species richness. Methods – The World Checklist of Monocotyledons was queried for Cyperaceae occurring in Madagascar. The global distribution of these species was investigated to identify endemic taxa and to evaluate other botanical countries where widespread species occur. Data on life form, habitat and photosynthetic type were scored from literature and personal observations. Key results – Madagascar has 321 species of Cyperaceae in 33 genera, representing all major clades of the family. The predominantly tropical Cypereae clade composes about half of the sedge flora, of which Cyperus represents about a third of the species in Madagascar. The Cariceae, a predominantly northern hemisphere temperate clade, is unusually highly represented and composes 10% of the sedge flora, occurring mostly in the highlands. In Madagascar, 55 species (17% of flora, mainly Carex and Cyperus) occur in forests and all are C3 perennials. Bulbostylis and Pycreus, exclusively C4 taxa with high proportion of annuals compared to C3 genera in Madagascar, occur outside forests in seasonal or permanent wetlands. Endemism among the sedge flora is 37% (121 species), a third of which (42 species) occur in forests, mostly in the Central and Eastern highlands. Conclusion – Cyperaceae are among top ten species richest angiosperm families in Madagascar. When compared with other botanical countries, Madagascar has the second highest endemism level, second to the Cape Provinces. The sedge flora assembly has involved long distance dispersal(s) coupled with Neogene radiation in upland humid forests and open wetland habitats.

Comparison and assessment of coarse resolution land cover maps for Northern Eurasia

Information on land cover at global and continental scales is critical for addressing a range of ecological, socioeconomic and policy questions. Global land cover maps have evolved rapidly in the last decade, but efforts to evaluate map uncertainties have been limited, especially in remote areas like Northern Eurasia. Northern Eurasia comprises a particularly diverse region covering a wide range of climate zones and ecosystems: from arctic deserts, tundra, boreal forest, and wetlands, to semi-arid steppes and the deserts of Central Asia. In this study, we assessed four of the most recent global land cover datasets: GLC-2000, GLOBCOVER, and the MODIS Collection 4 and Collection 5 Land Cover Product using cross-comparison analyses and Landsat-based reference maps distributed throughout the region. A consistent comparison of these maps was challenging because of disparities in class definitions, thematic detail, and spatial resolution. We found that the choice of sampling unit significantly influenced accuracy estimates, which indicates that comparisons of reported global map accuracies might be misleading. To minimize classification ambiguities, we devised a generalized legend based on dominant life form types (LFT) (tree, shrub, and herbaceous vegetation, barren land and water). LFT served as a necessary common denominator in the analyzed map legends, but significantly decreased the thematic detail. We found significant differences in the spatial representation of LFT's between global maps with high spatial agreement (above 0.8) concentrated in the forest belt of Northern Eurasia and low agreement (below 0.5) concentrated in the northern taiga-tundra zone, and the southern dry lands. Total pixel-level agreement between global maps and six test sites was moderate to fair (overall agreement: 0.67–0.74, Kappa: 0.41–0.52) and increased by 0.09–0.45 when only homogenous land cover types were analyzed. Low map accuracies at our tundra test site confirmed regional disagreements and difficulties of current global maps in accurately mapping shrub and herbaceous vegetation types at the biome borders of Northern Eurasia. In comparison, tree dominated vegetation classes in the forest belt of the region were accurately mapped, but were slightly overestimated (10%–20%), in all maps. Low agreement of global maps in the northern and southern vegetation transition zones of Northern Eurasia is likely to have important implications for global change research, as those areas are vulnerable to both climate and socio-economic changes.

Pattern and process in MAEUL, a traditional Korean rural landscape

Land-use changes due to the socio-economic environment influence landscape patterns and processes, which affect habitats and biodiversity. This study considers the effects of such land-use changes, particularly on the traditional rural "Maeul" forested landscape, by analyzing landscape structure and vegetation changes. Three study areas were examined that have seen their populations decrease and age over the last few decades. Five types of plant life-forms (Raunkier life-forms) were distinguished to investigate ecosystem function. Principle component analysis was used to understand vegetation dynamics and community characteristics based on a vegetation similarity index. Ordination analysis transformed species-coverage data was introduced to clarify vegetation dynamics. Landscape indices, such as area metrics, edge metrics, and shape metrics, showed that spatial heterogeneity has increased over time in all areas. Pinus densiflora was the main land-use plant type in all study areas but decreased over time, whereas Quercus spp. increased. Over a decade, P. densiflora communities shifted to deciduous oak and plantation. These findings indicate that the impact of human activities on the Maeul landscape is twofold. While forestry activities caused heavy disturbances, the abandonment of traditional human activities has led to natural succession. Furthermore, it can be concluded that the type and intensity of these human impacts on landscape heterogeneity relate differently to vegetation succession. This reflects the cause and consequence of patch dynamics. We discuss an approach for sustainable landscape planning and management of the Maeul landscape based on traditional management.

The influence of gap creation on the regeneration of Pinus tabuliformis planted forest and its role in the near-natural cultivation strategy for planted forest management

It remains unclear whether or not creating gaps in planted forests can increase the plant species composition, structure, and biodiversity, and also whether it can be helpful for restoring planted forests (to a more natural state). Based on a comparison of species composition and structure among forest patches, small gaps (4–25 m 2), medium gaps (25–150 m 2) and large gaps (150–450 m 2), we found that (1) creating gaps enhanced vascular plant diversity. Both the species richness and Shannon diversity indices of small, medium and large gaps were significantly higher than in the understory. The pattern of increasing diversity of vascular plants with gap creation could be partly attributed to the emergence of novel shade intolerant species in gaps. (2) Creating gaps favored the colonization and regeneration of native species. Gap size influenced not only the emergence and density of individuals of different species, but also the emergence of different life form types. Small gaps promoted the regeneration of some shrub species, such as Ostryopsis davidiana, Rosa hugonis, and Forsythia suspense, leading to these species becoming canopy dominants early on in succession. The medium and large gaps favored the growth of tree species, such as Populus davidiana and Betula platyphylla (early successional stage), and Quercus liaotungensis and Pinus tabulaeformis (later successional phase). (3) The canonical correspondence analysis showed that plant species composition and distribution were mainly influenced by gap size and slope aspect, and that the recorded plant species could be divided into three life forms (trees, shrubs and herbs) on the biplot diagram. (4) Finally, creating gaps provided opportunities not only for native pioneer species in the early successional stage, but also for climatic climax species to grow to canopy dominants in later successional phases, suggesting that a more natural forest will develop with plant succession. Gap size plays an important role in plant regeneration, and it could be used to produce desired successional communities in near natural management for planted forests.

Woody vegetation of protected areas in northern Togo. Cases of Barkoissi, Galangashi and Oti-Keran: ecological and structure analyses of plant communities

The 170 samples obtained from ligneous investigation in Barkoissi, Galangashi and Oti-Keran protected areas (northern Togo) were subjected to floristic processing and several multivariate analyses in order to study plant diversity, life form and chorological type distribution and to classify and identify the main plant communities with their demographic structure. First, the overall life form and phytogeographical type frequencies were calculated to analyze and show the distribution of the 68 plants species in this area. Then plant communities were determined by using the hierarchical clustering with wards method. The plant communities found were identified by the technique of indicator value (IndVal). For each grouping diversity index such as specific richness, Shannon index and Pielou’s evenness was set out. The canonical correspondence analysis (CCA) was also used to relate the impact of environment factors and the distribution of samples. Finally the variance analysis (ANOVA) associated to post-hoc test was used to compare the similarity between the groupings. From these 170 samples, 12 plant communities were discriminated, three for the reserve of Barkoissi, three for the reserve of Galangashi and six for the reserve of Oti-Keran. The samples were well distributed in the factorial plan form by axe 1 and 3 of CCA. The plant communities were distributed along the moisture gradient in the ordination. The Sudano-Zambesian species followed by Sudanian species were the phytogeographical types most found in these areas. The microphanerophytes were the most represented life form. The structural parameters such as diameter and height means, the basal area and the densities determined and submitted to post-hoc test show some important similarity between some groups found. In overall, the vegetation condition of the three protected areas is somehow disturbed while most of the plant communities are stable. These preliminary ecological data obtained are essential and fundamental for the management and protection for these ecosystems.

Analysis of the biological spectrum of vascular flora of Ravni Srem flood forests

One of the essential analyses performed during the floristic study of a region is the analysis of the biological spectrum. The analysis of the biological spectrum of the flora includes the determination of the type of life form for each taxon described in the flora of the study region. If it is considered that life form is a specific structural-functional response to the environmental effects and the result of the adaptation during the species evolution, it is clear that the basic characteristics of the site are more or less reflected in any life form. This fact is confirmed by the analysis of the biological spectrum of the flora of Ravni Srem. The analysis of the Ravni Srem flora shows the domination of the hemicryptophytes and the subdomination of the phanerophytes with a considerable participation of the therophytes.

Size-dependent leaf area ratio in plant twigs: implication for leaf size optimization

Although many hypotheses have been proposed to explain variation in leaf size, the mechanism underlying the variation remains not fully understood. To help understand leaf size variation, the cost/benefit of twig size was analysed, since, according to Corner's rule, twig size is positively correlated with the size of appendages the twig bears. An extensive survey of twig functional traits, including twig (current-year shoots including one stem and few leaves) and leaf size (individual leaf area and mass), was conducted for 234 species from four broadleaved forests. The scaling relationship between twig mass and leaf area was determined using standardized major axis regression and phylogenetic independent comparative analyses. Leaf area was found to scale positively and allometrically with both stem and twig mass (stem mass plus leaf mass) with slopes significantly smaller than 1.0, independent of life form and habitat type. Thus, the leaf area ratio (the ratio of total leaf area to stem or twig mass) decreases with increasing twig size. Moreover, the leaf area ratio correlated negatively with individual leaf mass. The results of phylogenetic independent comparativeanalyses were consistent with the correlations. Based on the above results, a simple model for twig size optimization was constructed, from which it is postulated that large leaf size-twig size may be favoured when leaf photosynthetic capacity is high and/or when leaf life span and/or stem longevity are long. The model's predictions are consistent with leaf size variation among habitats, in which leaf size tends to be small in poor habitats with a low primary productivity. The model also explains large variations in leaf size within habitats for which leaf longevity and stem longevity serve as important determinants. The diminishing returns in the scaling of total leaf area with twig size can be explained in terms of a very simple model on twig siz

On the Origin of Cells and Viruses

It is proposed that the precellular stage of biological evolution unraveled within networks of inorganic compartments that harbored a diverse mix of virus‐like genetic elements. This stage of evolution might makes up the Last Universal Cellular Ancestor (LUCA) that more appropriately could be denoted Last Universal Cellular Ancestral State (LUCAS). Such a scenario recapitulates the ideas of J. B. S. Haldane sketched in his classic 1928 essay. However, unlike in Haldane's day, considerable support for this scenario exits today: lack of homology between core DNA replication system components in archaea and bacteria, distinct membrane chemistries and enzymes of lipid biosynthesis in archaea and bacteria, spread of several viral hallmark genes among diverse groups of viruses, and the extant archaeal and bacterial chromosomes appear to be shaped by accretion of diverse, smaller replicons. Under the viral model of precellular evolution, the key components of cells originated as components of virus‐like entities. The two surviving types of cellular life forms, archaea and bacteria, might have emerged from the LUCAS independently, along with, probably, numerous forms now extinct.

How is global warming affecting our daily life in South Africa and what can we do about it?

Global warming is a steadily increasing problem that is affecting the daily lives of people all over the world, including South Africa. It has the potential to cause extensive devastation in the future if action is not taken to mitigate it. By simple definition global warming is the gradual rise in the average temperature of the earth's surface, due to the increase of certain gasses in the atmosphere. In more detail, the earth receives radiation from the sun which passes through the atmosphere as short-wave light energy. It is then absorbed by the earth's surface and re-radiated back into the atmosphere as long-wave heat energy which warms the air. There are several gasses in the atmosphere - such as carbon dioxide, methane and water vapour - that absorb this long-wave heat energy and prevent it from leaving the earth. They form an insulating layer around the earth, causing the ground and air below to be much hotter than they would be without the benefit of this layer. This is known as the natural greenhouse effect. It is essential to all life on earth because, without it, the average temperature of the earth would be too cold to sustain any type of life form. However, with the increase in greenhouse gasses being emitted into the air, the temperature on earth could rise excessively, leading to an enhanced greenhouse effect which, in effect, is global warming.

Atmospheric CO2 enrichment induces life strategy- and species-specific responses of collembolans in the rhizosphere of sugar beet and winter wheat

We studied atmospheric CO2 enrichment effects on life form types, species composition, dominance structure and individual density of collembolans under cultivation of sugar beet and winter wheat. The study was part of a long-term CO2 enrichment field experiment (FACE: Free Air CO2 Enrichment) at the Federal Agricultural Research Centre (FAL) in Braunschweig (Germany), using isotopically labelled CO2. The stable C-isotopic signature (δ13C) of collembolan species, plant material, and soil indicated CO2 impacts on C translocation. The δ13C values of both crops significantly increased from above-ground to below-ground plant parts and significantly decreased under FACE conditions. The δ13C values of collembolan species differed significantly depending on CO2 treatment and crop and showed a distinct tendency depending on plant growth stage. The extent, to which δ13C values of collembolans decreased under FACE conditions, was species- and life strategy-dependent. The stable C-isotopic signatures of euedaphic and hemiedaphic species were similar in the control, but, depending on crop, differently affected by atmospheric CO2 enrichment. Under winter wheat cultivation, hemiedaphic species showed more negative δ13C values than euedaphic ones under FACE conditions. CO2 enrichment effects on occurrence, density and dominance distribution of the collembolan species differed strongly between crops and their developmental stages, which reveal crop-specific below-ground effects due to different food qualities in the rhizosphere. CO2 impacts were stronger under sugar beet compared to winter wheat cultivation. Independent of crop, CO2 enrichment enhanced the diversity of collembolans before harvest and increased the proportion of hemiedaphic in relation to euedaphic species in a community. Our results on collembolan communities imply CO2-induced changes in the root-derived carbon resources used by the soil food web. The present study reveals atmospheric CO2 enrichment impacts to specifically affect collembolan species according to their food preferences.