Nutrient-rich Soils Research Articles

Throughfall and stemflow nutrient flux in deodar and oak forests, Garhwal Himalaya, India

Abstract A study to understand the throughfall and stemflow chemistry under deodar and oak forests of Garhwal Himalaya was conducted during 2014–2015. Total rainfall during experimental period was 1473.8 mm and estimated interception loss was 34.018% for deodar forest, 24.85% for oak forest. Stemflow represented the minimum proportion of gross rainfall, i.e. 0.321% in deodar forest and 0.463% in oak forest. pH of throughfall and stemflow in both deodar (6.087 and 6.47 respectively) and oak forests (6.75 and 7.03 respectively) was significantly more acidic than the gross rainfall (7.15). Electrical conductivity was recorded higher in deodar stemflow (231.89 μs/cm) and throughfall (102.75 μs/cm) compared to oak forest (172.92 μs/cm and 83.83 μs/cm respectively). Net nutrient leaching and stemflow were considerably higher from oak forest than deodar forest. Oak forest has better water yield capacity than deodar forest as the interception loss was higher in deodar forest. The idea of sustainable agriculture may be possible surrounding such forests as the need for chemical fertilizer and water can be met by the nutrient-rich soil, available soil moisture and surface water.

Celtic fields en marke- en malebossen

Abstract Iron Age Celtic fields and medieval common woodlands: some considerations on their topological relationship and chronological transition Until recently, Celtic fields could only be distinguished on aerial photographs, especially in open landscapes like arable fields and heathlands. With the emergence of lidar data, however, a new set of these late prehistoric fields have been discovered in afforested areas. A closer examination of the about two hundred known Celtic fields in The Netherlands revealed that about 50-60 percent of them are situated in former common woodlands dating from the later Middle Ages. Apparently, there is a causal connection between the two. After the abandonment of the Celtic fields in the Early Roman period woodland regeneration on these nutrient rich soils was probably more prominent than on the surrounding podzolised soils. Archeological excavations and modern-day field research reveal that there could have been possible interphase of early and high medieval coppice woods on former Celtic fields, which were used for large-scale charcoal production supplying local and regional iron industries. This would diachronically and topographically connect three main narratives of Dutch sandy landscapes i.e. late prehistoric working landscapes, early and high medieval iron production and late medieval and early modern common woodlands.

Assessment of flood recession farming for livelihood provision, food security and environmental sustainability in the Ganga River Basin

Poverty, food insecurity and environmental degradation are the recurrent problems in the Ganga River Basin (GRB). The Ganga River enriches the fertility of floodplain through flooding every year. Farmers have been utilizing this fertility for growing crops by flood recession farming (FRF) since antiquity. In this practice, farmers use moisture and nutrient rich soil of the floodplains for growing crops after water levels recede and harvest them before flooding in the river. This ancient method of food production plays a pivotal role in human well-being and environmental conservation in the GRB. Using the data collected from the farmers living along the Ganga River in Varanasi, this study explores the potentials of FRF through the dimensions of livelihood provision, food security and environmental sustainability. Field visits, household surveys, and focus group discussions (FGDs) were used to collect data. Results indicated that various practices and methods of FRF system underpin not only the livelihood and food security of small and marginal farmers but also enrich the sustainability of the environment. Environmental sustainability was assessed in the context of agro-biodiversity conservation, water resource management, soil health maintenance, and climate change mitigation and adaptation. The study concludes that the full potentials of flood recession farming can be assessed through a comprehensive research about the different aspects of FRF and mainstreaming this practice in policy-making for sustainable food production.

Soil development in weathering pits of a granitic dome (Enchanted Rock) in central Texas

Weathering pits form on various rock types worldwide and often contain unique ecosystems in periodically flooded or desiccated depressions. However, little is known about soil formation in such pits. Here, we investigated two weathering pits (WP1 and WP2) on the summit of Enchanted Rock, a granitic exfoliation dome in central Texas. We aimed at unravelling the origin of the parent material, evaluating evidence for dating the soil development, and identifying the major soil forming processes. We sampled five soil profile cores in each pit and analyzed diverse soil properties, such as C and N contents, pH, exchangeable cations, texture, and iron oxides. In addition, we performed energy dispersive X-ray spectroscopy and applied optically stimulated luminescence (OSL) and 14C dating analyses. Both pits were affected by redoximorphic features and organic matter accumulation (2.5 ± 1.4% C in the topsoil). WP1 revealed Na accumulation in the subsoil and pronounced translocation of clay minerals, which accumulated at the bottom (up to 50% clay in the subsoil, 13–34% in topsoil). Such processes were absent in WP2, in which clay contents and their variations were comparatively small (16–25%). Here, acidic and nutrient poor soil horizons (pH 4.0–4.4, 0.5–1.5% C, 4.1–4.6 mg kg−1P) alternated several times with nutrient rich and neutral soil horizons (pH 5.1–5.6, 2.0–2.5% C, 23–33 mg kg−1P). This phenomenon was observed down to the bottom of the pit. We conclude that the parent material for soil development consists of three sources: autochthonous material from in-situ weathering of the solid rock, granitic grus particles from upslope positions, and eolian sediments from the area surrounding Enchanted Rock. Phases of sedimentation may have alternated with phases of stability and topsoil formation, resulting in buried former topsoils. OSL dating revealed that sedimentation began not later than 5110 years ago in 42 cm depth of WP1 and 2290 years ago in 26 cm depth of WP2. Due to contamination by younger carbon, 14C dates underestimate the beginning of soil development. The intensity of post sedimentary soil forming processes (clay mineral translocation, sodium enrichment, ferrolysis, organic matter accumulation) depends on the age of the pit and on its morphology, i.e. on the possibility of water and dissolved substances running off.

Root uptake under mismatched distributions of water and nutrients in the root zone

Abstract. Most plants derive their water and nutrient needs from soils where the resources are often scarce, patchy, and ephemeral. It is not uncommon for plant roots to encounter mismatched patches of water-rich and nutrient-rich regions in natural environments. Such an uneven distribution of resources necessitates plant reliance on strategies for exploring and acquiring nutrients from relatively dry patches. We conducted a laboratory study that elucidates the biophysical mechanisms that enable this adaptation. The roots of tomato (Solanum lycopersicum) seedlings were laterally split and grown in two adjacent, hydraulically disconnected pots, which permitted precise control of water and nutrient applications to each compartment. We observed that the physical separation of water-rich and nutrient-rich compartments (one received 90 % water and 0 % nutrients and the other received 10 % water and 100 % nutrients) does not significantly stunt plant growth and productivity compared to two control treatments (control 1: 90 % water and 100 % nutrients versus 10 % water and 0 % nutrients; control 2: 50 % water and 50 % nutrients in each compartment). Specifically, we showed that soil dryness does not reduce nutrient uptake, vegetative growth, flowering, and fruiting compared to control treatments. We identified localized root proliferation in nutrient-rich dry soil patches as a critical strategy that enabled nutrient capture. We observed nocturnal rewetting of the nutrient-rich but dry soil zone (10 % water and 100 % nutrients) but not in the nutrient-free and dry zone of the control experiment (90 % water and 100 % nutrients). We interpreted the rewetting as the transfer of water from the wet to dry zones through roots, a process commonly known as hydraulic redistribution (HR). The occurrence of HR likely prevents the nutrient-rich soil from drying due to permanent wilting and the subsequent decline of root functions. Sustaining rhizosphere wetness is also likely to increase nutrient mobility and uptake. Lack of HR in the absence of nutrients suggests that HR is not entirely a passive, water-potential-gradient driven flow. The density and size of root hairs appeared to be higher (qualitative observation) in the nutrient-rich and dry compartments than in the nutrient-free and dry compartments. We also observed organic coating on sand grains in the rhizosphere of the nutrient-rich and dry compartments. The observations are consistent with prior observations that root hairs and rhizodeposition aid rhizosphere wetting. These findings were synthesized in a conceptual model that explains how plants of dry regions may be adapted to mismatched resources. This study also suggests that separating the bulk of applied nutrients from the frequently irrigated soil region can increase nutrient use efficiency and curtail water pollution from intensive agricultural systems.

Functional Divergence between Várzea and Igapó Forests: A Study of Functional Trait Diversity in the Colombian Orinoco Basin

Research Highlights: Functional diversity studies help to better understand how organisms respond to different environmental conditions. Conditions in tropical flooded forests are highly variable, including levels of nutrient availability, pH, and flood depth, but few studies have explored the impact of variation in these factors on plant functional diversity. Background and Objectives: In the Orinoco basin, as in the Amazon, floodplain forests have been classified into várzea (white-water rivers, with nutrient-rich soils) and igapó (black-water rivers, associated with nutrient-poor soils). We evaluated the functional diversity of plant species in várzea and igapó, as well as the influence of external and internal filters on the plant community assembly of each forest type, and compared our results with studies in the Amazon basin. Materials and Methods: Six functional traits were recorded in the várzea and igapó forests of the Colombian Orinoco basin (one-hectare plot for each forest type, with no replicates). We evaluated plant species diversity (richness, Fisher’s α, Shannon and Simpson indices), as well as functional diversity (functional richness, functional evenness, functional divergence, and functional dispersion) and the influence of external and internal filters, based on a comparison of variance at different organizational levels. Results: A high functional differentiation between várzea and igapó was found, as well as a high functional divergence within each forest type. We also observed a greater influence of internal filters on the community assembly of both forest types, compared to external filters. Functional traits such as wood density and leaf dry matter content, showed the same patterns as the várzea and igapó forests in the Amazon. Conclusions: Despite the low taxonomic and functional richness, there is high functional divergence within flooded forests. We also show that in forests under stress (e.g., from flooding), internal filters can be key in assembling communities and promote high functional divergence. Given that the functional diversity of the várzea and igapó in the Orinoco is largely unexplored, we highlight the need for more research for the effective conservation of these flooded forests.

Fencing enclosure alters nitrogen distribution patterns and tradeoff strategies in an alpine meadow on the Qinghai-Tibetan Plateau

The grasslands of Qinghai-Tibetan Plateau have become extremely degraded, resulting in widespread deficiency of soil N. In efforts to restore degraded lands, fencing enclosure has been used extensively. However, the effect of fencing on N allocation patterns and nutritional strategy of alpine plants are equivocal. In this study, we used 15N tracer (CO (15NH2)2, 10 g N m−2) to examine the allocation and distribution of N in plants and soil in grasslands either grazed heavily by livestock or fenced for three years in an alpine meadow of Northern Tibet. The 15N recovery (15Nrec) in shoots of the fenced enclosure increased by 207% in grasses, decreased by 103% in forbs, and did not change in sedges when compared to the grazed meadow. The 15Nrec in shoots accounted for only 1.97% and 4.65% of the total N in the grazed and fenced meadows, respectively. Fencing increased soil 15N content at 0–5 cm depth by 6.9%, but decreased the content at 5–10 cm depth by 11.7%. The results demonstrated that fencing altered the soil N distribution by increasing 15Nrec in top soil and by decreasing 15Nrec in subsurface soil. In addition, fencing had no impact on root 15N storage (33%–39%), 15N losses (9.6%–12.5%) and soil available 15Nrec (NH4+-N, NO3–-N and light fraction organic N), but decreased root:shoot 15Nrec ratio by 49.8% (16.9:1 in grazed and 8.4:1 in fenced grassland). Fencing increased soil organic carbon, total N and NO3–-N concentrations, which indicated that the strategy of the plants was to allocate relatively more N to roots in nutrient-poor soil (grazed) but relatively more N to shoots in nutrient-rich soil (fenced).

Fruit provision from Berberis microphylla shrubs as ecosystem service in Nothofagus forest of Tierra del Fuego

Berry production is a non-wood product worldwide recognized by its nutritional value and taste, but the most studied species are non-native commercial plants in productive areas, leaving aside native berries. We propose that native berries (Berberis microphylla G.Forst) naturally growing in degradation forests areas could diversify livestock establishment production and complement traditional uses (e.g., livestock). The aims of this work were to 1) environmentally characterize (e.g., soil nutrient content and physical conditions, air conditions and photosynthetically active radiation) in three degraded Nothofagus antarctica Oerst. forest (due to past fires and livestock use) of Tierra del Fuego; and 2) evaluate berries production of B. microphylla in terms of quality production (e.g., fruit number and weigh per shrub) and in terms of quality (individual fruit weight, fruit pulp percentage, and soluble solids content) to assess provisioning ecosystem service of this native shrub in different degraded areas. Studied sites were defined as: 1) Severe soil degradation condition (SEV) (high frequency of horses, bulls and some native guanacos year round, severe soil erosion, and shorter herbaceous layer), 2) Moderate soil degradation condition (MOD) (cattle and guanaco year round, intermediate level of soil erosion and intermediate height of herbaceous layer), and 3) Slight soil degradation condition (SLI) (livestock only during winter, but high frequency of native guanacos, lower soil erosion and taller herbaceous layer). (SEV) had the highest air and soil temperature, least soils nutrients content, highest bulk density, the least soil water content and the poorest fruit production. (MOD) had the highest soil water content and nutrient-rich soils, while (SLI) had the highest relative air humidity and PAR. B. microphylla shrubs grow with similar morphology on the different soil degraded condition. The highest fruit production were at (SLI), however the (SEV) had the highest soluble solids. We conclude that calafate shrubs in degraded Nothofagus forests offer a provisioning ecosystem service through their excellent fruits quality. Livestock farms could diversify their production through native fruits taking advantage of the altered areas occupied by B. microphylla. However, we recommend avoiding intensive livestock use in burned forests since it could lead to an irreversible soil erosion. Proper livestock management in Nothofagus burned forest could keep over the time not only the recognized ecosystem provision services (fruits, meat, wood), but also those of regulation and support that calafate shrubs offer and that make the functionality of the ecosystem.

Organic Nutrients Induced Coupled C- and P-Cycling Enzyme Activities During Microbial Growth in Forest Soils

Besides environmental and soil physical drivers, the functional properties of microbial populations, i.e. growth rate, enzyme production and maintenance requirements are dependent on the microbes’ environment. The soil nutrition status and the quantity and quality of the substrate input, both infer different growth strategies of microorganisms. It is uncertain, how enzyme systems respond during the different phases of microbial growth and retardation in soil. The objective of this study was to uncover the changes of microbial functioning and their related enzyme systems in nutrient-poor and nutrient-rich beech forest soil during the phases of microbial growth. We determined microbial growth via kinetic approach by substrate-induced respiratory response of microorganisms, enabling the estimation of total and growing biomass of the microbial community. To induce microbial growth we used glucose, while yeast extract simulated additional input of nutrients and factors indicating microbial residues (i.e. necromass compounds). Microbial growth on glucose showed a 12–18 h delay in associated enzyme activity increase or the absence of distinct activity responses (Vmax). β-glucosidase and chitinase (NAG) demonstrated clear differences of Vmax in time and between P-rich and P-poor soils. However, during microbial growth on glucose + yeast extract, the exponential increase in enzymatic activity was clearly stimulated accompanied by a delay of 8–12 h, smoothing the differences in nutrient-acquisition dynamics between the two soils. Furthermore, cross-correlation of β-glucosidase and acid phosphatase between the two sites demonstrated harmonized time constraints, which reflected the establishment of comparable and balanced enzymatic systems within the decomposition network. The network accelerated nutrient acquisition to maintain microbial growth, irrespective of the contrasting soil properties and initial nutrient stocks, indicating similar tradeoffs of C- and P- cycling enzymes in both soils. This reflects comparable temporal dynamics of activities in nutrient-poor and nutrient-rich soil when the glucose + yeast extract was added. During lag phase and phase of exponential microbial growth, substrate turnover time of all enzymes was shortened in nutrient-poor forest soil exclusively, reflecting that the quality of the added substrate strongly matters during all stages of microbial growth in soil.

Nitrous oxide emissions of undrained, forestry-drained, and rewetted boreal peatlands

Drained peatlands, especially nitrogen (N) -rich ones, are sources of nitrous oxide (N2O) to the atmosphere. As this emission is largely caused by N mineralization in oxic peat soil, rewetting the peat soil is likely to decrease the N2O emissions to similar levels with natural, undrained peatlands. Emissions from these water-saturated peat soils have often been assumed negligible, for example in the Intergovernmental Panel on Climate Change (IPCC) guidelines for national greenhouse gas inventories. However, the number of published data of annual N2O emissions from undrained peatlands is small and even smaller for rewetted peatlands. Thus, we still have limited understanding of the effects of land-use change such as drainage and rewetting. We analyzed N2O flux data, mostly previously unpublished, from 28 undrained, 65 forestry-drained, and 24 rewetted boreal peatland study sites in Finland and calculated annual N2O emissions for each site, including emissions from ditches at 51 sites. We classified the sites into nutrient-rich and nutrient-poor ones, similar to the IPCC guidelines. Annual N2O emissions from the undrained peatlands were consistently small, but not negligible, averaging 0.11 and 0.10 g m−2 a–1 in the nutrient-rich and nutrient-poor sites, respectively. Emissions from the drained peatlands were significantly higher than from the undrained peatlands in the nutrient-rich (mean 0.23 g m−2 a–1) but not in the nutrient-poor (mean 0.08 g m−2 a–1) sites. Emissions from the rewetted peatlands (means 0.05 and 0.08 g m−2 a–1 for nutrient-rich and nutrient-poor sites, respectively) were similar or lower than from the undrained ones. Emissions from ditches were similar to those from strips and correlated positively with strip emissions at the drained sites. Nutrient-rich soil (low CN ratio) and a low water table increased emissions significantly at the drained sites, whereas the continuously higher water tables kept emissions low at all undrained and rewetted sites. In conclusion, rewetting is an effective means to decrease the N2O emissions of nutrient-rich drained peatlands back to natural levels, although this natural level is not zero, as has been suggested earlier.

Light and nutrient limitations for tree growth on young versus old soils in a Bornean tropical montane forest

We examined forest and tree responses to decreasing nutrient availability with soil aging in a species-rich tropical montane rain forest on Mount Kinabalu, Borneo. Community composition and structure and tree growth rates were compared between two 1 ha plots on nutrient-rich young soil versus nutrient-deficient old soil. Myrtaceae and Fagaceae dominated both plots. With soil aging, the dominance of Lauraceae, stem density, basal area and aboveground biomass decreased, and the forest understory became brighter. Some dominant taxa on the old soil (Podocarpaceae and the genus Tristaniopsis in Myrtaceae) were virtually absent on the young soil; this was attributed to light limitation in the understory. Growth rates of understory trees were lower on the young soil, whereas those of canopy trees were lower on the old soil. This suggested that the growth of understory trees was limited by light on the young soil, whereas that of canopy trees was limited by nutrients on the old soil. Of the eight species that were abundant in both plots, the dominance of five species was considerably lower on the old soil, four of which also exhibited decreased maximum sizes and lower growth rates. The remaining three species showed similar dominance across plots without a decline in growth rates, although they exhibited decreased maximum sizes on the old soil. These analyses demonstrated divergent responses of species to the soil-age gradient. We suggest that the differential responses of species to decreasing nutrient availability with a concomitant increase in understory light levels explain floristic turnover with soil aging.

Constructability Criteria for Farmland Reclamation and Vegetable Cultivation Using Micro-Dam Sediments in Tigray, Ethiopia

The Ethiopian agriculture sector is characterized by rain-fed smallholder systems. The Ethiopian Government has promoted micro-dam construction in micro-watershed in Tigray for the past two decades. The lack of proper conservation measures to control severe soil erosion at the micro-watershed level, however, has often filled downstream micro-dams in with sediments. Sedimentation has affected the irrigation performance of micro-dams due to their bottom pipes becoming clogged with nutrient-rich soils eroded from upstream farmlands. While there is a growing need for adequate resource management to mitigate severe soil erosion at the watershed-level, it is urgent that methods to make use of the sediments deposited in micro-dam reservoirs to facilitate rural agricultural development are discovered. One practical solution is to use sediments to rehabilitate the bare land excavated for micro-dam embankment construction and turn it into reclaimed farmland. The purpose of this paper is to relate the constructability criteria to the farmland reclamation to solve sedimentation problems. This case study reports the yield of vegetable cultivation on farmland reclaimed using sediments from a micro-dam reservoir in Tigray. This case study highlights the practical potential of such a method to contribute to the livelihoods of farmers through the production of vegetable cash crops. The future research needs cost reduction factors on durability, safety or other related aspects to improve our “Constructability Criteria” approach.

Legacy of soil health improvement with carbon increase following one time amendment of biochar in a paddy soil – A rice farm trial

“4 per 1000 Initiative” launched at COP21 has strongly recommended that increasing soil organic carbon (SOC) is a global imperative. However, the strategies to improve agricultural soil functioning and health by an increase in soil C have been poorly addressed. In a rice farm trail, topsoil samples were collected in 2015 respectively in a field amended with biochar (BA) (equivalent to 10 t ha−1) in 2009 and an adjacent field with no biochar (NB). Soil aggregation, biochemical activities and microbial communities of the samples were analyzed with microscopic, micro-biochemical and molecular assays respectively. Compared to NB field, SOC storage increased by 45%, total and available nitrogen pool enhanced by approximately 30% while the bulk density decreased and soil pH unchanged in BA field. A 25% increase in mean weight diameter of water stable aggregates was observed in the BA compared to NB field. Correspondingly, microbial biomass nitrogen and enzyme activities in BA field was enhanced both by approximately 30% compared to NB field. Furthermore, with community structure altered, a moderate (32%) increase in total bacterial abundance and a significant decrease in microbial abundance of amino acid metabolism and fungal pathotrophs were observed in BA field compared to NB field. This could link to the higher (10%) grain yield with lower yield inter-annual variability in BA field compared to NB field, reported previously. All these changes clearly demonstrated a legacy of paddy soil health improvement over years following one time biochar amendment. Overall, addition of biochar to the clayey nutrient rich paddy soil could sustain an increase in SOC, soil aggregation and soil health functioning, with positive changes in microbial community over years. Thus, carbon increase as per required by the “4 per 1000 Initiative” could be a mechanistic driver to enhance soil fertility and improve soil-(plant) health for ensuring food production in world rice agriculture facing land degradation and climate change impacts, which could be assisted by biochar from crop residue in an approach of circular economy.

Does defoliation frequency and severity influence plant productivity? The role of grazing management and soil nutrients

Rangeland management approaches, including rotational grazing, rely on assumptions about plant growth responses to the intensity, or severity (sward height) plus frequency, of defoliation. We tested these assumptions at the farm, patch and plant scale using data from a grazing management trial in an Eastern Cape mesic grassland of South Africa along with field plot and glasshouse pot experiments. The grazing trial tested season-long grazing (SLG), four-camp grazing (FCG) and holistic planned grazing (HPG) at equivalent stocking rates over three years. We found that grass growth responses in both potted plants and field plots were reduced under more frequent and severe defoliation but that this was mitigated under elevated soil nutrients, in line with the Compensatory Continuum Hypothesis which predicts that compensatory growth will increase across an increasing fertility gradient. In the farm trial, SLG, which theoretically causes high frequency, low severity defoliation, reduced bare ground cover and increased vegetation greenness with increasing defoliation intensity on nutrient-rich soils. This effect was not present under FCG or HPG and disappeared under very high defoliation intensities and on relatively water- and nutrient-poor soils. Managers are advised to only increase grazing frequency on relatively high nutrient soils, while maximizing recovery on poorer nutrient soils.

Leaf nutrient dynamics of shrubs in a tropical dry deciduous forest in Rajasthan in North-West India

The leaf nutrient dynamics of shrubs was evaluated in a tropical dry deciduous forest in Rajasthan, North-West India (27°4′ to 28°4′N and 76°7′ to 77°13′E). Samples of immature, mature and senescing leaves of deciduous shrubs, Justicia adhatoda and Grewia flavescens and an evergreen shrub, Capparis sepiaria were collected from three locations from the middle part of the West facing hill slope in the protected Bala-fort forest. The leaves for each species for each developmental stage were analysed to estimate the percentage of 11 elements by X-ray fluorescence method. The immature leaves of Capparis sepiaria showed maximum percentage of K (2.1) and Ca (1.17) in comparison to other elements. Similarly Justicia adhatoda and Grewia flavescens exhibited highest percentage of K and Ca in immature leaves. In mature leaves percentage of K and Ca increased in Justicia adhatoda, percentage of only K increased in Grewia flavescens whereas percentage of K declined and Ca increased in Capparis sepiaria. Out of the 11 elements evaluated, Justicia adhatoda, Grewia flavescens and Capparis sepiaria resorbed 10, 8 and 5 elements, respectively. Different shrubs concentrate and reabsorb varying amounts of different elements in their leaves. The resorption efficiency of elements in deciduous shrubs was higher than the evergreen shrub. The resorption efficiency of elements in shrubs was higher in the nutrient rich soil. Thus, it may be suggested that resorption pattern of shrubs is different from that of tree species. The slow leaf nutrient dynamics of the evergreen shrub may be attributed to its small size and longer life span of leaves as compared to the other two species. Thus, the low nutrient requirement for leaf development appears to be a better adaptation of the evergreen shrub than the deciduous shrubs in this semi-arid climate of this region. It may be suggested that shrubs play important role in the conservation of nutrients in the tropical dry deciduous forests of semi-arid regions in India.

Plasticity of Root Traits under Competition for a Nutrient-Rich Patch Depends on Tree Species and Possesses a Large Congruency between Intra- and Interspecific Situations

Belowground competition is an important structuring force in terrestrial plant communities. Uncertainties remain about the plasticity of functional root traits under competition, especially comparing interspecific vs. intraspecific situations. This study addresses the plasticity of fine root traits of competing Acer pseudoplatanus L. and Fagus sylvatica L. seedlings in nutrient-rich soil patches. Seedlings’ roots were grown in a competition chamber experiment in which root growth (biomass), morphological and architectural fine roots traits, and potential activities of four extracellular enzymes were analyzed. Competition chambers with one, two conspecific, or two allospecific roots were established, and fertilized to create a nutrient ‘hotspot’. Interspecific competition significantly reduced fine root growth in Fagus only, while intraspecific competition had no significant effect on the fine root biomass of either species. Competition reduced root nitrogen concentration and specific root respiration of both species. Potential extracellular enzymatic activities of β-glucosidase (BG) and N-acetyl-glucosaminidase (NAG) were lower in ectomycorrhizal Fagus roots competing with Acer. Acer fine roots had greater diameter and tip densities under intraspecific competition. Fagus root traits were generally more plastic than those of Acer, but no differences in trait plasticity were found between competitive situations. Compared to Acer, Fagus roots possessed a greater plasticity of all studied traits but coarse root biomass. However, this high plasticity did not result in directed trait value changes under interspecific competition, but Fagus roots grew less and realized lower N concentrations in comparison to competing Acer roots. The plasticity of root traits of both species was thus found to be highly species- but not competitor-specific. By showing that both con- and allospecific roots had similar effects on target root growth and most trait values, our data sheds light on the paradigm that the intensity of intraspecific competition is greater than those of interspecific competition belowground.

Rill treatments to enhance nutrient rich soil, a case study

Rill treatments to enhance nutrient rich soil, a case study

Different responses of leaf and root traits to changes in soil nutrient availability do not converge into a community-level plant economics spectrum

Spatial heterogeneity in soil can influence the distribution of plant communities because plants differ in their ability to acquire resources. In nutrient-poor soils, plants should bear traits that prioritize conservation of resources over growth, whereas the opposite is expected in nutrient-rich soils. A coordinated response to soil fertility, in which leaves and roots converge into the same strategy, would lead to a community-level plant economics spectrum (PEScom). Here, we examine how nutrient availability across different soil types shapes the functional structure of desert shrub communities and how much of this variation is explained by species turnover or intraspecific variability (ITV). We measured leaf and root traits of 16 shrub species in four sites with contrasting soil nutrient availability in the southern edge of the Atacama Desert. In leaves, changes in soil nutrient availability were associated with a leaf economics spectrum, shifting from communities with more acquisitive strategies to communities with more conservative strategies with increasing nutrient limitation. No such pattern of co-variation was observed for roots; thus, the relationship between above and below-ground traits did not fit the PEScom. Variation of leaf traits was mainly determined by species turnover, while for root traits it was determined equally by species turnover and ITV. The lack of a PEScom appears to be related to the co-limitation of multiple resources, which promotes different responses in root traits. We highlight the importance of incorporating leaf and root traits to understand how multiple resource limitation shapes plant ecological strategies.

Genetic structure of Doronicum austriacum (Asteraceae) in the Carpathians and adjacent areas: toward a comparative phylogeographical analysis of tall-herb species

Tall-herb communities play an important role in the vegetation of the European mountains. They are developed in humid habitats with nutrient-rich soil, from submontane to subalpine zones. As its contemporary flora consists of different geographical elements, their history, especially in relation to the climatic oscillations throughout the Pleistocene, is not straightforward. We analyze the phylogeography of Doronicum austriacum, one of the main species building Central European tall-herb communities. We additionally discuss these new data in the context of earlier phylogeographical studies of key species of tall-herb communities to compare the major patterns of their lineage distributions. The study was based on AFLP fingerprinting and DNA sequencing of sampled populations from the Carpathians and adjacent lowland, Alps, Sudetes, and Balkan Peninsula. Our results confirm the phylogeographical break between the Western and South-Eastern Carpathians as a major regional biogeographical feature. Close affinity of the Western Carpathian and Sudetes populations was also confirmed as a significant feature in common for studied tall-herb species. In contrast to the phylogeographical structure of other tall-herb species, a divergence of D. austriacum populations from the Balkan Peninsula was observed supporting the presence of divergent and taxonomically distinct lineage in the latter area. The general phylogeographical pattern indicates past survival in several distinct areas but only partly common features for the community level emerge. Finally, the history of low-elevation populations of D. austriacum at the northern margin of the distribution range remains unclear but mainly their close affinity to the forest Western Carpathian populations is suggested.

Nitrogen immobilization may reduce invasibility of nutrient enriched plant community invaded by Phragmites australis

Nutrient enrichment, particularly nitrogen, is an important determinant of plant community productivity, diversity and invasibility in a wetland ecosystem. It may contribute to increasing colonization and dominance of invasive species, such as Phragmites australis, especially during wetland restoration. Providing native species a competitive advantage over invasive species, manipulating soil nutrients (nitrogen) may be an effective strategy to control the invasive species and that management tool is essential to restore the degraded ecosystems. Therefore, we examined competition between Phragmites australis and Melaleuca ericifolia in a greenhouse setting with activated carbon (AC) treatments, followed by cutting of Phragmites shoots in nutrient-rich soils. Additionally, we evaluated the effect of AC on plant-free microcosms in the laboratory, to differentiate direct effects of AC on soil microbial functions from indirect effects. Overall, the objective was to test whether lowering nitrogen might be an effective approach for reducing Phragmites invasion in the wetland. The AC reduced Phragmites total biomass more significantly in repeated cut regime (57%) of Phragmites shoots compared to uncut regime (39%). Conversely, it increased Melaleuca total biomass by 41% and 68% in uncut and repeated cut regimes, respectively. Additionally, AC decreased more total nitrogen in above-ground biomass (41 to 55%) and non-structural carbohydrate in rhizome (21 to 65%) of Phragmites, and less total nitrogen reduction in above-ground biomass (25 to 24%) of Melaleuca in repeated cut compared to uncut regime. The significant negative correlation between Phragmites and Melaleuca total biomass was observed, and noticed that Phragmites acquired less biomass comparatively than Melaleuca in AC-untreated versus AC-treated pots across the cutting frequency. AC also caused significant changes to microbial community functions across Phragmites populations, namely nitrogen mineralization, nitrification, nitrogen microbial biomass and dehydrogenase activity (P ≤ 0.05) that may potentially explain changes in plant growth competition between Phragmites and Melaleuca. The overall effects on plant growth, however, may be partially microbially mediated, which was demonstrated through soil microbial functions. Results support the idea that reducing community vulnerability to invasion through nutrient (nitrogen) manipulations by AC with reducing biomass of invasive species may provide an effective strategy for invasive species management and ecosystem restoration.