Dense Grass Research Articles

Establishment gaps in species‐poor grasslands: artificial biodiversity hotspots to support the colonization of target species

Sowing of grass seed mixtures is a feasible and cost‐effective method for landscape‐scale grassland restoration. However, sowing only grasses usually leads to species‐poor and dense swards, where the establishment of target forbs is hampered by microsite and propagule limitation. To overcome these limitations and increase the diversity of species‐poor sown grasslands, we developed a novel method by creating “establishment gaps.”. We used tillage to open gaps of 1‐, 4‐, and 16‐m2 size in the dense grass sward of six species‐poor restored grasslands in the Great Hungarian Plain. We sowed high‐diversity seed mixtures of 35 native species into all gaps. We analyzed vegetation development during the first 5 years after setting up the trial. We also studied the colonization dynamics of the sown species along four 20‐m transects around each gap, resulting in a total of 1440 plots of 1‐m2 size that were studied. Our results indicated that most of the sown species were able to establish permanently in the gaps. The total cover and the cover of perennial sown species increased and the cover of short‐lived sown species decreased independent of gap size. There was only a moderate level of weed abundance in the gaps, and weed cover decreased over the years. The sown target species started to colonize the species‐poor grasslands surrounding the gaps within 5 years. The highest number of species and individuals dispersed from the 4‐m2 gaps, as they had a more stable development than smaller gaps and were exposed to lower grazing pressure than large ones.

Long‐term monitoring of a highly invaded annual grassland community through drought, before and after an unintentional fire

AbstractQuestions(a) How did seedling numbers and species composition change in the first year after a wildfire during drought, relative to pre‐fire variation? (b) Has the community returned to pre‐fire composition after five years? (c) Has the degree of dominance by exotic annual grasses changed? (d) Is there any evidence that drought conditions affected community cover, before or after fire?LocationExotic‐dominated annual grassland in southern California, USA.MethodsWe monitored community cover and native annual forb densities for four years before and four (cover) to five (densities) years after an unintentional fire (fall 2013) coinciding with the spring 2012–2019 California drought. We also measured seedling emergence both before and during the first year post‐fire. We assessed post‐fire changes in cover and density relative to pre‐fire variation, and tested correlations between community cover and annual rainfall measures.ResultsSeedling emergence declined strongly after fire for exotic grasses, but remained stable for exotic forbs. Seedling densities of the most common native forbs declined, but several previously‐rare natives increased. Community cover initially shifted towards the exotic forbs Erodium spp., then returned to higher exotic grass densities. Yet the previously dominant Bromus diandrus declined steeply, even as other exotic grasses and some native forbs increased. Up to five years after fire, relative cover and abundance of the most common exotic and native species still differed from pre‐fire composition. Common species were uncorrelated with annual precipitation, but several may have responded to shorter growing seasons.ConclusionsImmediate post‐fire conditions favoured exotic and native forbs over grasses, as predicted. Yet in contrast to many previous studies, the community did not return quickly to pre‐fire composition but showed persistent changes that favoured neither natives nor exotics. Our results suggest post‐fire recovery in this habitat may be contingent on abiotic conditions, with drought one potential explanation for changes.

Intensive Cultural Resources Survey of the Proposed Dripping Springs Wastewater System Improvements Project (EID 1), Dripping Springs, Hays County, Texas

Intensive Cultural Resources Survey of the Proposed Dripping Springs Wastewater System Improvements Project (EID 1), Dripping Springs, Hays County, Texas

Clover nodule bacteria as bioindicators of soils contaminated with heavy metals

The article presents the results of a study of vital activity of nodule bacteria of Trifolium praténse, Trifolium hibridum, Trifolium alexandrinum and Trifolium incarnatum as environmentally friendly bioindicators in soil toxicity assessment. The study focused on the number of nodules and their stain with leghemoglobin. The materials were taken from the plots artificially contaminated with heavy metals (lead (Pb), arsenic (As), mercury (Hg), fluorine (F), zinc (Zn) and cobalt (Co)). The results of the experiments showed that environmental distress occurs when the nitrogen-fixing nodules are stained pink or red in the range of 8-15%, which indicates that the lead content in the soil exceeds the threshold limit value (TLV) by 1.2-1.5 times. A significant decrease in nodule activity and weak or no stain were observed with an increase in mercury concentration by 1.1 times. It was found that the mass of rhizobium or the supply of organic nitrogen obtained by plants from fixation from the air is directly dependent on the grass density. At high concentrations of heavy metals in the soil, the nodule bacteria lose the amount of leghemoglobin, therefore the stain of bacteria is disrupted, so this indicator can be used as a bioindicator in soil toxicity assessment.

Soil water dynamics and yield in maize and Brachiaria ruziziensis intercropping

ABSTRACT In intercropping systems, a high plant density can delay the biomass accumulation and affect the water availability to plants. This study aimed to evaluate the soil water dynamics and the crop yield performance in maize and Brachiaria ruziziensis intercropping under different sowing densities of the forage grass. The experiment was conducted in a randomized block design, with treatments associated to the sowing densities (2 kg ha-1, 4 kg ha-1, 6 kg ha-1 and 8 kg ha-1) and the single cropping for both species as controls. The maize plants were evaluated for grain yield and B. ruziziensis for number of plants per hectare and shoot fresh and dry matter. The intercropping performance was evaluated using the land-use efficiency index. The soil water dynamics was monitored in two soil depths (0-0.3 m and 0.3-0.6 m) by using the time domain reflectometry method. The evaluation of soil water storage was carried out from plots with four of the crop systems (single maize or B. ruziziensis, and intercropping with the extreme sowing densities), at four different times. The increase in the sowing density of B. ruziziensis decreased the grain yield of the intercropped maize by 30.8 %. The intercropping system using 2 kg ha-1 of the grass seeds resulted in the best land-use efficiency (23 %). In addition, the intercropping treatments promoted a higher extraction of water from the soil, mainly at the maize growth stages with higher hydric demand (e.g., flowering and grain filling). These systems stimulate the extraction of water from deeper soil layers, when compared to maize in single cropping.

Population density and tillering of andropogon grass submitted to different cutting heights

ABTRACT The objective of this study was to evaluate the tillering dynamics and population density of Andropogon gayanus cv. Planaltina, submitted to different cutting heights during the dry and rainy season. A randomized block design was adopted in a split plot scheme. In the main plot, the three cutting heights (10, 20, and 30 cm) were allocated, while the subplots included the following periods: dry (October, November, and December) and rainy (April, May, and June). During the dry period at the height of 10 cm, there was a higher population density of tillers, with 1298.44 tillers m-2. The appearance rate was higher in October for heights of 10 and 30 cm and in December for 20 cm. The 10-cm height provided a higher mortality rate. The survival rate and the stability index were higher in October, with 88.47% and 1.38, respectively. In the rainy season, specifically June, the pasture had a higher height (130.06 cm). The rate of appearance and the stability index were higher in April and during June there was greater mortality, while at the 20-cm height, there was less mortality and greater survival (85.71%) of the tillers. The 20-cm cut height provides a higher survival rate and lower mortality rate of andropogon grass in the dry and rainy season.

Seedling growth and competition of a late-seral, native perennial grass and 2 early-seral, native forbs in the presence of 2 densities of the invasive annual grass Bromus tectorum L. (Poaceae)

Seedling growth and competition of a late-seral, native perennial grass and 2 early-seral, native forbs in the presence of 2 densities of the invasive annual grass <i>Bromus tectorum</i> L. (Poaceae)

Potential menace posed by invasive grass and water quality deterioration on macroinvertebrates structural distribution in a dam in North-Western Nigeria

ABSTRACT Water bodies in the world have been studied for varied reasons based on their biota composition, diversity, and influence of environmental variables. A study was carried out to ascertain the probable menace posed by Typha grass and some selected environmental variables on the composition and diversity of benthic macroinvertebrates of Kalgwai Dam, Jigawa State, Nigeria. Three (3) distinct sites were selected for the study. Water and macroinvertebrates samples were collected once in a month on each sampling expedition for a period of four (4) months between January and April, 2018, using standard techniques. Among the sampled months, physico-chemical variables were significantly different (p < .05), while no significant difference existed for all the physico-chemical variables (p > .05) except for electrical conductivity, salinity, total dissolved solids, and BOD5. A total of 260 benthic macroinvertebrate specimens comprising of 20 taxa belonging to 9 orders and 20 families were recorded during the study period. Site 2 harbors more macroinvertebrates than other sites and Gastropoda was the most occurring taxa in the study area with Site 2 having the highest abundance among the taxa sampled during the study period. Significant difference (p < .05) was noticed in abundance (number of individuals) among the sites. Species number (taxa) and abundance (number of individuals) were significantly highest in Site 2. Shannon diversity of macroinvertebrates taxa was lowest in Site 1 (0.98 ± 0.28). Analysis of variance (ANOVA) performed showed no significant differences in the indices calculated (p > .05) except for Evenness. Canonical correspondence analysis (CCA) showed a weak relationship between macroinvertebrates composition/abundance and the selected physico-chemical variables. Species such as Corbucilidae, Chironomus sp., Potadoma sp., Unio sp. portray the characteristics of potential bioindicators due to their association to prevailing environmental condition of the sampled sites. Cluster analysis (Bray-Curtis) similarity showed no marked pattern of clustering in the dam. The study revealed that incessant anthropogenic activities and high density of Typha grass in Kalgwai Dam have a deteriorating effect on the structural composition, abundance and diversity of macroinvertebrates in the dam.

Accurate Empirical Path-Loss Model Based on Particle Swarm Optimization for Wireless Sensor Networks in Smart Agriculture

Wireless sensor networks (WSNs) have received significant attention in the last few years in the agriculture field. Among the major challenges for sensor nodes’ deployment in agriculture is the path loss in the presence of dense grass or the height of trees. This results in degradation of communication link quality due to absorption, scattering, and attenuation through the crop’s foliage or trees. In this study, two new path-loss models were formulated based on the MATLAB curve-fitting tool for ZigBee WSN in a farm field. The path loss between the router node (mounted on a drone) and the coordinator node was modeled and derived based on the received signal strength indicator (RSSI) measurements with the particle swarm optimization (PSO) algorithm in the farm field. Two path-loss models were formulated based on exponential (EXP) and polynomial (POLY) functions. Both functions were combined with PSO, namely, the hybrid EXP-PSO and POLY-PSO algorithms, to find the optimal coefficients of functions that would result in accurate path-loss models. The results show that the hybrid EXP-PSO and POLY-PSO models noticeably improved the coefficient of determination (R2) of the regression line, with the mean absolute error (MAE) found to be 1.6 and 2.7 dBm for EXP-PSO and POLY-PSO algorithms. The achieved R2 in this study outperformed the previous state-of-the-art models. An accurate path-loss model is essential for smart agriculture application to determine the behavior of the propagated signals and to deploy the nodes in the WSN in a position that ensures data communication without unnecessary packets’ loss between nodes.

Quantification of carbon stock under different land use regimes of Chitwan district, Nepal

Carbon sequestration in terrestrial ecosystems is gaining a global attention, including Nepal, to address the issues of climate change. Since, the quantification of carbon stock under different land use systems with focus on both biomass and soil profile is lacking, objective of this paper is to quantify carbon stock in biomass and in soil profile under different land use regimes, namely community forest, leasehold forest and agricultural land of Chitwan district. The carbon stock in biomass was calculated using the standard allometric equations, and Dry Combustion Method was used to determine the Soil Organic Carbon (SOC). The carbon content in above ground tree biomass (AGTB) was found to be higher (81.25 t/ha) in community forest than in leasehold forest (80.09 t/ha). The carbon stock in above ground sapling biomass (AGSB) was calculated only for the community forest, and was found to be 3. 67 t/ha. Similarly, the density of leaf litter, herbs and grasses (LHG) was also found to be higher (9. 25 t/ha) in the community forest in comparison to leasehold forest (6.45 t/ha). Further, the root carbon stock density was also higher (16.25 t/ha) in the community forest than in the leasehold forest (16.02 t/ha). However, the SOC density was highest in the agricultural land (73.42t/ha) followed by the community forest (66.38 t/ha)and the leasehold forest (52. 62 t/ha). Overall, the carbon stock was highest in the community forest (176.8 t/ha) then in leasehold forest (155.18 t/ha) followed by the agricultural land (73.42 t/ha). Hence, this study shows that well managed community forest can contribute significantly in offsetting global carbon emission.

ФЛОРА ГАЗОНОВ ГОРОДА УФЫ

The paper presents a study in the flora of lawns in Ufa. The lawn flora is represented by 192 species belonging to 31 families. Based on coenotic and ecological characteristics, four ecological coenotic groups of species were singled out that were described in the lawn designated areas. The ecological coenotic groups were analysed for life form spectra, hemeroby, species activity. Among the plant communities of typical low-trampled and well-maintained urban lawns (the ecological coenotic group of Festuca pratensis) Poaceae, Asteraceae, Fabaceae, Rosaceae, Apiaceae families were the leading ones, where hemicryptophytes and oligo-meso-αeuhemerobes dominated. The lawns subjected to significant anthropogenic impact (trampling, salinization) (the ecological coenotic group of Taraxacum officinale) had a large number of species that belonged to the «ruderal» Polygonaceae, Asteraceae, Fabaceae, Brassicaceae, Lamiaceae families, where hemicryptophytes and meso-euhemerobes dominated. Ruderal species of Asteraceae, Poaceae, Amaranthaceae, Lamiaceae, Malvaceae, Polygonaceae families prevailed, with a large share of ruderal and semi-ruderal annual and biennial plants, β-eupolyhemerobes, in the lawn designated areas where gramineous plant community did not develop after soil disturbance (the ecological coenotic group of Chenopodium album). Ruderal species of Poaceae, Chenopodiaceae, Polygonaceae families with a large portion of ruderal annual and biennial β-eupolyhemerobes also dominated in humid and waterlogged lawn areas. The ecological ecoenotic groups of Taraxacum officinale, Chenopodium album and Bidens tripartita had a large number of neophyte species. The lawn areas with the ecological coenotic groups of Taraxacum officinale, Chenopodium album and Bidens tripartite were found as most colonized with ruderal plants. A number of measures are required to build dense grass covering: reconstruction and heavy maintenance of lawns combined with sowing quality lawn grass mixtures, regular mowing practices to reduce the number of ruderal hemytherophytes and therophytes, timely plant nutrition and watering.

Legacy effects of precipitation amount and frequency on the aboveground plant biomass of a semi-arid grassland

Precipitation is known to have legacy effects on plant diversity and production of many terrestrial ecosystems. Precipitation regimes are expected to become more variable with increasing extreme precipitation events. However, how previous-year precipitation regimes affect the current-year aboveground biomass (AGB) remains largely unknown. Here we measured long-term (2004–2017) AGB in a semi-arid grassland of the Chinese Loess Plateau to evaluate the impact of previous-year precipitation amount on current-year AGB. Furthermore, to assess the response of current-year AGB to previous-year precipitation regimes, we conducted a field manipulation experiment that included three precipitation regimes during 2014–2017: (i) ambient precipitation, (ii) monthly added four 5 mm rain events, and (iii) monthly added one 20 mm event. Both the long-term (2004–2017) observations under ambient precipitation and short-term (2014–2017) measurements under manipulative treatments showed significant positive effects of previous-year precipitation on current-year AGB. Our path analysis suggested that previous-year precipitation frequency had negative effects on the current-year density and mean height of grass (Leymus secalinus) while had positive effects on forb (Artemisia capillaris). The forb had much smaller height and AGB (65% and 53% less, respectively) than the grass. Consequently, the AGB reduced in the weekly small events treatment, causing the sensitivity of AGB to precipitation to decrease. Therefore, our findings indicated that the impacts of precipitation regimes on plant community dynamics should be taken into consideration while assessing the precipitation legacy effect on ecosystem production.

Cover crops are not affected by tobacco soil residual herbicides but also do not provide consistent weed management benefits

AbstractWinter cover crops (CCs) provide soil conservation benefits for strip-tillage tobacco producers, but soil-residual herbicides may interfere with their establishment and growth. Tobacco is planted later than many agronomic crops, but growers often terminate CCs early to minimize CC residue at planting, and this may reduce weed suppression potential. We examined residual herbicide effects on CCs across two seasons and the potential for CC-based weed suppression within strip-tilled tobacco. Mixtures of wheat plus crimson clover and cereal rye plus crimson clover were examined, with a no-CC control. Herbicides included two rates of PRE sulfentrazone (177 or 354 g ai ha–1) plus carfentrazone (20 or 40 g ai ha–1); the higher rate was also followed by POST clomazone (840 g ai ha–1) or mixed with PRE pendimethalin (1,400 g ai ha–1). Controls with no weed management and hand weeding were also included. CC density and biomass were not reduced by weed management (WM) treatments with residual herbicides. However, CCs did not reduce density of annual grasses, small-seeded broadleaves, or perennials in the tilled in-row or untilled between-row zones. Cereal rye plus crimson clover resulted in lower weed biomass at tobacco harvest in the untilled between-row zone in 2017. WM effects were variable between the years, weed groups, and zones. Adding clomazone or pendimethalin was more consistent for reducing weed density and biomass compared to the low rate of sulfentrazone plus carfentrazone. Tobacco yield was unaffected by CCs in 2017 but lower in some WM treatments in 2018. In this study, tobacco herbicides did not interfere with wheat, cereal rye, or crimson clover establishment, but additional research should determine if these results apply to other environments and soil types. However, when these CC species were terminated 5 to 6 wk before transplanting, they did not consistently contribute to weed control.

Native Vegetation Composition in Crested Wheatgrass in Northwestern Great Basin

Crested wheatgrass, an introduced perennial bunchgrass, has been seeded extensively on the rangelands of western North America. There is a perception that this species is very competitive and that it forms monoculture or low diversity stands where successfully seeded. However, there is limited information on species composition in sites previously seeded to crested wheatgrass. We measured native vegetation and environmental characteristics in areas seeded with crested wheatgrass across the northwestern Great Basin. Plant community composition within these crested wheatgrass stands was variable, from seedings that were near monocultures of crested wheatgrass to those that contained more diverse assemblages of native vegetation, especially shrubs. Environmental factors explained a range of functional group variability from 0% of annual grass density to 56% of large native bunchgrass density. Soil texture appeared to be an important environmental characteristic in explaining vegetation cover and density. Native vegetation was, for all functional groups, positively correlated with soils lower in sand content. Our results suggest environmental differences explain some of the variability of native vegetation in crested wheatgrass stands, and this information will be useful in assessing the potential for native vegetation to co-occupy sites seeded with crested wheatgrass. This research also suggests that crested wheatgrass seedings do not always remain in near monoculture vegetation states as seedings substantially varied in native vegetation composition and abundance with some seeded areas having a more diverse assemblage of native vegetation. In half the sites, there were five or more perennial herbaceous species and 63% of sites contained Wyoming big sagebrush. Although not exclusively true, species most commonly encountered in crested wheatgrass seedings are those that are able to minimize competition with crested wheatgrass via temporal (i.e., Sandberg bluegrass, annual forbs, annual grasses) or spatial (i.e., shrubs) differentiation in resource use.

Habitat and space use of wintering Sprague's Pipits (Anthus spragueii) in northern Mexico

Understanding home range size and habitat preferences is an important component of monitoring species in steep decline. Sprague's Pipit (Anthus spragueii) is a declining grassland specialist with a substantial portion of its population wintering in the highly threatened grasslands of the Chihuahuan Desert. We radio-tagged and tracked 10 wintering pipits between 2014 and 2017 at 3 sites across northern Mexico to generate baseline home range estimates and habitat preferences on their wintering grounds. We found that mean home range and core-use area size with 95% and 50% kernel density estimators were 11.4 ha and 2.4 ha, respectively, almost twice as large as some other grassland specialist passerines. Two birds left the study area and one individual shifted its home range 1.3 km after 20 d of monitoring, indicating that some individuals are flexible in their space use strategies. Within their home ranges, pipits selected grasslands with more bare ground and less “other cover” (litter, duff, animal excrement, and rocks) than what was available on the landscape. We found no relationship at the microhabitat scale between pipits and grass height nor shrub cover and heights, which in previous studies have been shown to influence habitat selection at larger scales. These findings may reflect different habitat use, diet, and predator avoidance strategies than other grassland passerines that select for denser grass cover during winter in the Chihuahuan Desert and highlight the importance of structurally heterogeneous grasslands. For this reason, strategies to manage and conserve Chihuahuan Desert grasslands and its avifauna must consider the diverse habitat and area needs of grassland birds to be effective.

Variations in the Botanical Diversity of Forbs–Bunchgrass Steppes of Eastern Mongolia over an 11-Year Period (2008–2018)

The dynamics of the botanical diversity of plain forbs–bunchgrass steppes is analyzed for the period of 2008–2018 based on materials from the biomonitoring of plant cover at the Tumentsogt experimental station (Eastern Mongolia) as part of the scientific program of an integrated Russian–Mongolian biological expedition. Eight permanent test plots of 100 m2 were laid along the transect on the plain between hills in the northeastern part of the experimental station. We analyzed the correlation between the main parameters of the plant communities (the species composition, richness, and saturation; the height and abundance of species; and the density of grass stands) with the meteorological conditions (the heat supply and the amount and distribution of precipitation during the growing period). A combined analysis of phytocenotic and climatic data was performed with nonparametric multidimensional scaling of indirect ordination. Ecotopic fluctuations caused by changes in the amount and regime of precipitation in different years, as well as by the dynamics of the temperature regime, were studied. The species saturation of communities was maximal in years with low ombrothermic indices and lowest in years with high indices. The floristic composition of communities of three–feather-grass steppes includes a flora-cenotic core composed of 23 permanent perennial steppe and forest–steppe species, which provides a relative stability of ecosystems under changing environmental conditions. The dynamics of steppe ecosystems of the East Mongolian steppes is phytocyclic.

DIURNAL AND NOCTURNAL HABITAT USE IN RETICULATE COLLARED LIZARDS (CROTAPHYTUS RETICULATUS)

Patterns of habitat use in animals can vary over time and space in predictable ways. For ectotherms, behavioral cycles are tightly linked to varying temperatures in the environment such that microhabitat availability can constrain individual performance, fitness, and life history. A long history of research on diurnal microhabitat use in lizards exists; however, comparatively little is known about nocturnal microhabitat use that might also constrain individual lizard performance, fitness, and life history. In this study, we compared diurnal and nocturnal microhabitat sites of the reticulate collared lizard (Crotaphytus reticulatus), a threatened species in Texas, to available microhabitat sites. We found significant differences between diurnal and nocturnal microhabitat characteristics, and both of these were significantly different from random microhabitat sites available. We observed that C. reticulatus used diurnal and nocturnal microhabitats with a gravel substrate and scattered boulders that were covered by a short overstory of woody and succulent plants rather than more heavily vegetated sites with dense grasses and forbs. We also observed that diurnal microhabitats were moderately open, shallow gravel slopes compared with nocturnal microhabitats that contained dense thickets of woody and succulent plants. The open, gravelly characteristics of diurnal microhabitats with occasional vegetative structure were more consistent with microhabitat descriptions of other Crotaphytids, which as a group are visual predators. However, the daily shift to dense, thorny plant cover at night appears unique to C. reticulatus among Crotaphytids in general. This study suggests that private land stewardship across the C. reticulatus distribution in Texas has benefitted the species by maintaining habitat used by the lizard, and it suggests that future conservation actions for the species will be most successful with continued engagement with private landowners.

Grazing exclusion promotes grasses functional group dominance via increasing of bud banks in steppe community

To understand the bud banks response to grazing exclusion, we conducted a demographic experiment in long-term grazing exclusion (20 year and 30 year) typical steppe. Results showed that grass functional group constituted the vast majority of the aboveground vegetation and belowground bud bank in all treatments. Long-term grazing exclusion significantly increased total aboveground biomass (2.5 and 2.6 times in 20y and 30y grazing exclusion grasslands, respectively), and decreased total stem density (31% and 37% in 20y and 30y grazing exclusion grasslands, respectively). Grazing exclusion for 20 and 30 years increased grass aboveground biomass respectively by 6.0 and 8.0 times, and decreased grass stem density by 38% and 33%. Grazing exclusion had different effects on belowground bud density of grass and forb functional group. Long-term grazing exclusion significantly increased plant buds and bud bank size (25% and 37% in 20y and 30y grazing exclusion grasslands, respectively), especially for grass functional group (49% and 95% in 20y and 30y grazing exclusion grasslands, respectively), but had no significant effects on forb bud density. Changes of aboveground community were significantly related to changes of belowground bud bank under both grazing and grazing exclusion grasslands. The bud bank density of grass functional group was significantly positive with total (R2 = 0.33, P < 0.05) and grass aboveground biomass (R2 = 0.36, P < 0.01), while negative related with total (R2 = −0.27, P < 0.05) and grass stem density (R2 = −0.22, P < 0.05). Grazed grasslands, 20y and 30y grazing exclusion grasslands all were not meristem limited and had large reserve bud banks, which would completely replace the aboveground stem population during the growing season. These findings indicate that grazing exclusion could not only improve a large bud bank for grassland restoration but also improve the dominance of grass functional group by increasing grass belowground bud banks in typical steppe community. We propose that the belowground bud bank might be a good approach to indicating potential succession direction of aboveground community.

Growth dynamics of deciduous species during their life period: A case study of urban green space in India

It is evident that grass density (GD) and shoot growth rate (SGR) governs the differential settlement of substructure, groundwater recharge, and stability of green infrastructure. GD and SGR are usually assumed to be constant during the entire life period of vegetation. However, spatial and temporal dynamics of GD and SGR in urban green space were rarely explored previously. The main objective of this study is to explore the spatial and temporal dynamics of GD and SGR in urban space vegetated with deciduous species (mix grass i.e., Poaceae and Bauhinia purpurea). Field monitoring was conducted in the urban green space for one year (i.e., life period of selected species). The monitoring period includes the growth period and gradual wilting period. Substantial spatial variation of GD was found during the first six months. GD away from the tree trunk was found to be 1.02–56.3 times higher than that near the tree trunk during the first six months. Thereafter, any spatial variation of GD was not found in the next six months. Unlike the GD, SGR was found to vary during the entire life period of mix grass. In addition, SGR away from the tree trunk was found to be 1.1–4.6 times higher than that near the tree trunk. Any relationship between GD and rainfall depth was not found. Whereas, SGR mainly depends on rainfall depth. The hypothesis of uniformity in GD and SGR during the life period of deciduous species was not found to be true.

Characteristics of growth and development of perennial grasses on the basis of meadow tetraploid clover

Perennial grasses are less dependent on weather and soil conditions than other crops due to their plasticity, low demand for growing conditions, and a large variety of species. In 2013-2017 in the conditions of the Udmurt Republic the biological properties of meadow tetraploid clover (Trifolium pratense L.), alfalfa changeable (Medicago x varia Martyn), birds-foot trefoil (Lotus corniculatus L.), eastern galega (Galéga orientális Lam.) and timothy grass (Phleum pratense L.) in double and triple agrocenoses were studied according to the age of the grass stand and the term of mowing. Plant density of perennial grasses in agrocenoses depended on the biological characteristics of the species, the age of grass stand and the term of mowing. In the first year of use of agrophytocenoses the density of stalk stand was at the level of 374-542 pcs /m2, in the second year of use it was a little higher (348-688 pcs /m2), in the third year of use – 240-594 pcs /m2. High density of meadow tetraploid clover in the grass stand was noted in the second year of use – 266-520 pcs/m2. The number of timothy grass stems (122-194 pcs/m2) in the grass mixture was high even in the first year of grass stand use, in the following years there was a further increase of this indicator to 196-412 pcs/m2. By the third year of use there was an increase in the number of stems of alfalfa changeable to 86-148 pcs/m2 and birds-foot trefoil – up to 108-200 pcs/m2. The plant density of the eastern galega in agrocenoses was low. The agrometeorological conditions of the year and the term of mowing affected the height and leafiness of perennial grass plants in agrocenoses. The leafiness of meadow tetraploid clover reached 64%, of the eastern galega – 74%. Timothy grass plants were less leafy – 23-38%. The height of meadow clover plants was at the level of 51 cm, of timothy grass – 75-78 cm. Birds-foot trefoil was the shortest component of grass mixtures. High yield of dry mass of single-species sowing of meadow tetraploid clover was obtained in the first two years of use – 7.8 and 6.5 t/ha, respectively. By the third year of use, the productivity of clover decreased to 2.9 t/ha. The highest yields for the years of research were formed by the following agrocenoses: clover + alfalfa, clover + timothy, and clover + alfalfa + timothy – 5.9-6.3 t/ha.