Variability of water supply affected shoot biomass and root depth distribution of four temperate grassland species in monocultures and mixtures

2020 ◽  
Vol 13 (5) ◽  
pp. 554-562
Author(s):  
Eamon Haughey ◽  
Jennifer C McElwain ◽  
John A Finn
Keyword(s):  
Water Supply ◽  
White Clover ◽  
Root Biomass ◽  
Rainfall Variability ◽  
Red Clover ◽  
Extreme Rainfall ◽  
Shoot Biomass ◽  
Distribution Models ◽  
Extreme Rainfall Events ◽  
Shoot And Root Biomass

Abstract Aims Research on the effects of extreme rainfall events on ecosystem function has primarily focussed on drought or flooding events, which usually include changes to mean or total rainfall, annually or over a season. However, less is known about the effects of increased rainfall variability without change to mean or total amounts. We investigated the effects of increased variation of water supply on shoot and root biomass as well as the distribution of root biomass of four grassland plant species, grown in monoculture and mixture communities. Methods Perennial ryegrass (Lolium perenne L., shallow-rooting grass), chicory (Cichorium intybus L., deep-rooting forb), white clover (Trifolium repens L., shallow-rooting legume) and red clover (Trifolium pratense L., deep-rooting legume) were established in mesocosms. Four plants of the same species were grown in monoculture communities and one of each species grown in four-species communities. Water supply was manipulated such that; compared with a baseline level with low variation in water supply, there was a treatment with medium variation (±40%) and another with high variation (±80%). Shoot and root biomass were measured, and vertical root distribution models fitted. Important Findings Compared with the low variation treatment, shoot biomass was significantly reduced under high variation for white clover, red clover and four-species communities. Under all conditions, four-species communities produced more shoot and root biomass than predicted by species performance in monoculture (overyielding). Under increased water variation, chicory monocultures allocated a higher proportion of root biomass to deeper soil layers while the total root biomass of white clover monocultures was significantly reduced. These results indicate that increased variability of water supply can negatively affect the shoot and root biomass production of single and multi-species grasslands. There is a need for further investigation of water variation effects on the functioning of multi-species grassland systems at field scale.

scholarly journals Growth Responses of Boreal Scots Pine, Norway Spruce and Silver Birch Seedlings to Simulated Climate Warming over Three Growing Seasons in a Controlled Field Experiment

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 943
Author(s):  
Katri Nissinen ◽  
Virpi Virjamo ◽  
Antti Kilpeläinen ◽  
Veli-Pekka Ikonen ◽  
Laura Pikkarainen ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Root Biomass ◽  
Growing Season ◽  
Silver Birch ◽  
Shoot Biomass ◽  
Growth Responses ◽  
Growing Seasons ◽  
Simulated Climate ◽  
Shoot And Root Biomass

We studied the growth responses of boreal Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. Karst.) and silver birch (Betula pendula Roth) seedlings to simulated climate warming of an average of 1.3 °C over the growing season in a controlled field experiment in central Finland. We had six replicate plots for elevated and ambient temperature for each tree species. The warming treatment lasted for the conifers for three growing seasons and for the birch two growing seasons. We measured the height and diameter growth of all the seedlings weekly during the growing season. The shoot and root biomass and their ratios were measured annually in one-third of seedlings harvested from each plot in autumn. After two growing seasons, the height, diameter and shoot biomass were 45%, 19% and 41% larger in silver birch seedlings under the warming treatment, but the root biomass was clearly less affected. After three growing seasons, the height, diameter, shoot and root biomass were under a warming treatment 39, 47, 189 and 113% greater in Scots pine, but the root:shoot ratio 29% lower, respectively. The corresponding responses of Norway spruce to warming were clearly smaller (e.g., shoot biomass 46% higher under a warming treatment). As a comparison, the relative response of height growth in silver birch was after two growing seasons equal to that measured in Scots pine after three growing seasons. Based on our findings, especially silver birch seedlings, but also Scots pine seedlings benefitted from warming, which should be taken into account in forest regeneration in the future.

scholarly journals Plant Salinity Tolerance Conferred by Arbuscular Mycorrhizal Fungi and Associated Mechanisms: A Meta-Analysis

2020 ◽  
Vol 11 ◽  
Author(s):  
Khondoker M. G. Dastogeer ◽  
Mst Ishrat Zahan ◽  
Md. Tahjib-Ul-Arif ◽  
Mst Arjina Akter ◽  
Shin Okazaki
Keyword(s):  
Superoxide Dismutase ◽  
Arbuscular Mycorrhizal Fungi ◽  
Salinity Stress ◽  
Mycorrhizal Fungi ◽  
Root Biomass ◽  
Meta Analysis ◽  
Biomass Accumulation ◽  
Arbuscular Mycorrhizal ◽  
Shoot Biomass ◽  
Shoot And Root Biomass

Soil salinity often hinders plant productivity in both natural and agricultural settings. Arbuscular mycorrhizal fungal (AMF) symbionts can mediate plant stress responses by enhancing salinity tolerance, but less attention has been devoted to measuring these effects across plant-AMF studies. We performed a meta-analysis of published studies to determine how AMF symbionts influence plant responses under non-stressed vs. salt-stressed conditions. Compared to non-AMF plants, AMF plants had significantly higher shoot and root biomass (p < 0.0001) both under non-stressed conditions and in the presence of varying levels of NaCl salinity in soil, and the differences became more prominent as the salinity stress increased. Categorical analyses revealed that the accumulation of plant shoot and root biomass was influenced by various factors, such as the host life cycle and lifestyle, the fungal group, and the duration of the AMF and salinity treatments. More specifically, the effect of Funneliformis on plant shoot biomass was more prominent as the salinity level increased. Additionally, under stress, AMF increased shoot biomass more on plants that are dicots, plants that have nodulation capacity and plants that use the C3 plant photosynthetic pathway. When plants experienced short-term stress (<2 weeks), the effect of AMF was not apparent, but under longer-term stress (>4 weeks), AMF had a distinct effect on the plant response. For the first time, we observed significant phylogenetic signals in plants and mycorrhizal species in terms of their shoot biomass response to moderate levels of salinity stress, i.e., closely related plants had more similar responses, and closely related mycorrhizal species had similar effects than distantly related species. In contrast, the root biomass accumulation trait was related to fungal phylogeny only under non-stressed conditions and not under stressed conditions. Additionally, the influence of AMF on plant biomass was found to be unrelated to plant phylogeny. In line with the greater biomass accumulation in AMF plants, AMF improved the water status, photosynthetic efficiency and uptake of Ca and K in plants irrespective of salinity stress. The uptake of N and P was higher in AMF plants, and as the salinity increased, the trend showed a decline but had a clear upturn as the salinity stress increased to a high level. The activities of malondialdehyde (MDA), peroxidase (POD), and superoxide dismutase (SOD) as well as the proline content changed due to AMF treatment under salinity stress. The accumulation of proline and catalase (CAT) was observed only when plants experienced moderate salinity stress, but peroxidase (POD) and superoxide dismutase (SOD) were significantly increased in AMF plants irrespective of salinity stress. Taken together, arbuscular mycorrhizal fungi influenced plant growth and physiology, and their effects were more notable when their host plants experienced salinity stress and were influenced by plant and fungal traits.

Including climatic variability in stochastic rainfall for flood catastrophe modelling – The effect of ENSO and SOI in China

2020 ◽  
Author(s):  
Jose Luis Salinas ◽  
Rebecca Smith ◽  
Shuangcai Li ◽  
Ludovico Nicotina ◽  
Arno Hilberts
Keyword(s):  
Tropical Cyclone ◽  
Large Scale ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Climatic Variability ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
Natural Catastrophes ◽  
Socio Economic Impact ◽  
Catastrophe Modelling

<p>Damages from flooding in China account on average for 60-70% of the total Annual Losses derived from natural catastrophes. The extreme rainfall events responsible for these inundations can be broadly categorised in two well differentiated mechanisms: Tropical Cyclone (TC) induced, and non Tropical Cyclone induced (nonTC) precipitation. Between 2001 and 2015, inland nonTC rainfall flood events occurred roughly with double the frequency as TC events. While TC events can be highly destructive for coastal locations, over the entire China territory nonTC flooding accounted for more than half of the total economic flood loss for events with significant socio-economic impact, highlighting the importance of the nonTC flooding mechanism on the regional and national scale.</p><p>Large-scale modes of climate variability modulate in different ways TC and nonTC induced precipitation, both in the frequency and the magnitude of the events. In a stochastic rainfall generation framework, it becomes therefore useful to model these two mechanisms separately and include their differentiated long-term climatic influences in order to fully reproduce the overall observed rainfall variability. This work presents results on the effect of ENSO and Southern Oscillation Index (SOI) values on seasonal rainfall in China, and how to include this climatic variability in stochastic rainfall for flood catastrophe modelling.</p>

scholarly journals Characterizing past and future trend and frequency of extreme rainfall in urban catchments: a case study

2020 ◽  
Vol 3 (1) ◽  
pp. 288-305
Author(s):  
Philip Mzava ◽  
Patrick Valimba ◽  
Joel Nobert
Keyword(s):  
Trend Analysis ◽  
Rainfall Variability ◽  
Extreme Rainfall ◽  
Dar Es Salaam ◽  
Extreme Rainfall Events ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
The Past ◽  
The Future ◽  
Urban Catchments

Abstract Urban communities in developing countries are one of the most vulnerable areas to extreme rainfall events. The availability of local information on extreme rainfall is therefore critical for proper planning and management of urban flooding impacts. This study examined the past and future characteristics of extreme rainfall in the urban catchments of Dar es Salaam, Tanzania. Investigation of trends and frequency of annual, seasonal and extreme rainfall was conducted, with the period 1967–2017 taken as the past scenario and 2018–2050 as the future scenario; using data from four key ground-based weather stations and RCM data respectively. Mann–Kendall trend analysis and Sen's slope estimator were used in studying changes in rainfall variability. Frequencies of extreme rainfall events were modeled using the Generalized Pareto model. Overall, the results of trend analysis provided evidence of a significant increase in annual and seasonal maximum rainfall and intensification of extreme rainfall in the future under the RCP4.5 CO2 concentration scenario. It was determined that extreme rainfall will become more frequent in the future, and their intensities were observed to increase approximately between 20 and 25% relative to the past. The findings of this study may help to develop adaptation strategies for urban flood control in Dar es Salaam.

On the spatial validity of heavy point rainfall measurements

1998 ◽  
Vol 37 (11) ◽  
pp. 21-28 ◽  
Author(s):  
Th. Einfalt ◽  
G. Johann ◽  
A. Pfister
Keyword(s):  
Catchment Area ◽  
Rainfall Variability ◽  
Extreme Rainfall ◽  
West Germany ◽  
Statistical Parameters ◽  
Extreme Rainfall Events ◽  
North West ◽  
Areal Rainfall ◽  
Rain Events ◽  
Using Data

Model simulations rely on rainfall measurements, mostly recorded by point measurement devices, i.e. raingauges. When using data from extreme rainfall events, the model user has to take into account the validity of point measurements in space. The presented study outlines investigations in the field of rainfall variability due to the actual situation of general weather types during several events. The Boye catchment is part of the Emscher system (850 km2), located in north west Germany. Data from seven continuous raingauges (1990 to 1996) were analysed, together with data from synoptic classifications of the general weather type. Various statistical parameters were computed for the 200 most important rain events, both stationwise and for the whole event over the complete catchment area. The investigation results show that for particular synoptic rainfall situations, the raingauge in the centre of the catchment overestimated the areal rainfall calculated by the Thiessen procedure from all seven raingauges. The results also demonstrate the spatial variation of rainfall as well as observed event duration and event volume variation for different synoptic situations. It is pointed out that reduction factors should be applied to the data of the single raingauge in the centre of the 80 km2 catchment area used in longterm simulation.

Significance of reservoir operation during extreme rainfall event in flood mitigation and water demand management in a metropolitan city of India: a case study

2020 ◽  
Author(s):  
Anandharuban Panchanthan ◽  
Michele La Rocca ◽  
Elango Lakshmanan
Keyword(s):  
Water Supply ◽  
Water Demand ◽  
Reservoir Operation ◽  
Extreme Rainfall ◽  
Flood Mitigation ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Reservoir Storage ◽  
Time To Peak ◽  
Initial Storage

<p>Increasing water demand and climate change poses a great challenge in managing water resources availability. Reservoir operation during heavy rainfall events in an urbanized region is crucial in terms of decision making. The objective of this study is to assess the significance of reservoir operation during extreme rainfall events on flood mitigation and future domestic water supply. One of the major water supply reservoirs in Chennai city was chosen for this study. Rainfall record of recent four decades were analyzed and a major flood event occurred in 2015 was chosen. A combined model of hydrologic-hydraulic processes was carried out using Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS) and a box model based on input-output parameters. These models were calibrated and validated with historical flood events with good performance indications. Four different scenarios were framed for the analysis by targeting reduction in outflow and higher storage in the end of the event. Reducing the reservoir storage in advance and releasing with its maximum capacity at the beginning of the event will reduce the outflow from 5 to 27% and increase the time to peak by 11 to 16 hours. Available hydraulic facilities for higher storage at the end of the event were analyzed. It reveals that with the available facilities, reducing the initial storage from 75 to 50% will help to store 27 to 40% of inflow at the end of the event. Whereas the available hydraulic facilities will not allow to have a 75% of the reservoir storage at the end of this event. New gates can be provided for the safe operation during extreme rainfall events associated with the higher initial storage in the reservoir. Increased storage capacity combined with additional provisions of gates will reduce the outflow by 30% and increase the time to peak by 20 hours with the actual condition. By adapting these reservoir operation strategies, flood mitigation and fresh water augmentation during extreme events can be achieved to a significant extent. The developed combined modelling approach can be used to simulate various combinations of reservoir operations to assess the significance of timely decision on release during extreme rainfall events.</p><p>Keywords: flood mitigation, reservoir operation strategies, urban water supply, modelling</p>

scholarly journals Watershed-Based Rainfall variability and trends of extreme rainfall events in South East Awash Basin, Ethiopia

2019 ◽  
Vol 6 (6) ◽  
pp. 5524-5530
Author(s):  
Yonas Tadesse Alemu
Keyword(s):  
Coefficient Of Variation ◽  
Rainy Season ◽  
Rainfall Variability ◽  
Extreme Rainfall ◽  
Annual Rainfall ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Precipitation Distribution ◽  
Precipitation Concentration ◽  
Dire Dawa

This study presents analysis of Rainfall variability and trends of extreme rainfall events in the Oda Gunufeta -Cherecha -Dechatu watershed, Awash Drainage Basin, Eastern Ethiopia. The study employed the coefficient of variation and the Precipitation Concentration Index (PCI) as statistical descriptors of rainfall variability. The indices at the five stations were subjected to non-parametric Mann-Kendall test to detect the trend over the period between 1985 to 2014. The results of the study revealed that, the watershed experiences moderate inter-annual rainfall variability. The Belg rainfall shows high variability than Kiremt rainfall. Highest Belg & Kiremt rainfall variability is observed in Dire Dawa with coefficient of variation of 46% and 40% respectively. The annual PCI for the watershed in all the stations under investigation during the record periods showed that 100% of the years for which the annual PCI was estimated fell within the irregular precipitation distribution range or high precipitation concentration. The irregular precipitation distribution also extended to all the stations in short rainy season (Belg rainfall) and in two stations in the main rainy season (Kiremt season). With regard to the rainfall trend, the annual rainfall has showed a negative trend in most of the stations for the period 1985-2014. The Mann–Kendall trend test during the Kiremt season shows a positive trend in Dengego, Dire Dawa, Combolcha and Haramaya and the increasing tendency is significant at p<0.1 in Degego, p<0.05 in Dire Dawa, p <0.05 in Combolcha and p <0.01 in Haramaya. The heavy rainfall events, the 90th & 95th percentiles, in all the five stations showed an increasing pattern but except in Combolcha the trends are not statistically significant. This implies that the watershed has been under increased rainfall intensity and this in turn has the potential cause for high risk of flood occurrences.

scholarly journals Seedling Performance Associated with Live or Herbicide Treated Tall Fescue

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jonathan J. Halvorson ◽  
David P. Belesky ◽  
Harry W. Godwin
Keyword(s):  
White Clover ◽  
Tall Fescue ◽  
Nutritive Value ◽  
Plant Competition ◽  
Fungal Endophytes ◽  
Red Clover ◽  
Shoot Biomass ◽  
Soil Conditions ◽  
Seedling Performance ◽  
Systemic Fungal Endophytes

Tall fescue is an important forage grass which can host systemic fungal endophytes. The association of host grass and endophyte is known to influence herbivore behavior and host plant competition for resources. Establishing legumes into existing tall fescue sods is a desirable means to acquire nitrogen and enhance the nutritive value of forage for livestock production. Competition from existing tall fescue typically must be controlled to ensure interseeding success. We used a soil-on-agar method to determine if soil from intact, living (L), or an herbicide killed (K) tall fescue sward influenced germination and seedling growth of three cultivars of tall fescue (E+, MaxQ, and E−) or legumes (alfalfa, red clover, and white clover). After 30 days, seedlings were larger and present in greater numbers when grown in L soil rather than K soil. Root growth of legumes (especially white clover) and tall fescue (especially MaxQ) were not as vigorous in K soil as L soil. While shoot biomass was similar for all cultivars of tall fescue in L soil, MaxQ produced less herbage when grown in K soil. Our data suggest establishing legumes or fescue cultivars may not be improved by first killing the existing fescue sod and seedling performance can exhibit significant interseasonal variation, related only to soil conditions.

Phosphorus efficiency in pasture species. VI. A comparison of Italian ryegrass, phalaris, red clover and white clover over time

1991 ◽  
Vol 42 (3) ◽  
pp. 541 ◽  
Author(s):  
PD Kemp ◽  
GJ Blair
Keyword(s):  
White Clover ◽  
Red Clover ◽  
P Uptake ◽  
Italian Ryegrass ◽  
Phosphorus Efficiency ◽  
Shoot Biomass ◽  
Root Weight ◽  
P Efficiency ◽  
Over Time ◽  
Broad Scale

Two problems in comparative studies of the P efficiency of pasture species are the choice of measurement to define P efficiency and the basis of comparison to use. Therefore, the degree to which the level of P supply and plant age, or time of harvest, influence a variety of measures of P efficiency was examined in four temperate pasture species grown in a soil at a range of P levels in a glass house. The four species were Italian ryegrass, phalaris, red clover, and white clover. Italian ryegrass was the most P efficient and red clover the least P efficient species in terms of the broad scale measures of P effiency, shoot yield per unit of P applied and total P uptake over the first 40 days after sowing (DAS), and shoot P concentration at 68 DAS. Nevertheless, by 68 DAS the shoot fresh weight yield of the four species was similar at both the low (5 kgP ha-1) and the high (80 kg P ha-1) P rate. The superior shoot biomass production at lower P rates over 40 DAS of Italian ryegrass and phalaris compared with red and white clovers was largely the result of a greater root weight and P uptake per plant. Early root weight was determined by the relationship between seed weight and root relative growth rate (PGR), whereas P uptake per plant was influenced by root weight and plant P demand as measured by relative P uptake rate (RPR). The understanding of such relationships was shown to be essential to the effective interpretation of broad scale measures of P efficiency. The comparative broad scale P efficiences of the four species changed over time. When Italian ryegrass and phalaris were compared on an ontogenetic basis, number of leaves per plant, shoot yield and P uptake per plant were similar. The comparison of the P efficiency of species on both an ontogenetic and temporal basis is proposed.

Sign in / Sign up

Export Citation Format

Share Document