Journal of Rangeland Science
Volume:13 Issue: 1, Winter 2023

The most important environmental driver is the elevation in mountain ecosystems. It strongly influences the distribution of species richness. Species richness is an indicator of the biological diversity and ecological condition of the area. To understand the status of phytomass, species diversity, and physico-chemical properties of soil along the altitudinal gradient and its influence on the interrelation between phytomass, species diversity, and physicochemical properties of soil. To know the correlation between plant species and environmental factors.We used a transect line method to enumerate the plant community in each sampling plot. Phytomass was estimated by the total harvesting method. Soil properties were determined with standard methods, viz., Blake and Hartge (1986), Chromic Acid Wet Oxidation Method, and Kjeldahl method. SPSS and R programming were used for data analysis.Plant diversity indices, viz., Shannon-Wiener diversity index, Simpson's dominant index, Pielou’s index, and Margalef index were highest at the low altitude and the lowest value at high altitude. AGB, BGB, SOC and STN were highest in high altitude (Jaljale). Phytosociological indices and environmental factors, except moisture and SBD, were high at high elevation. The first axis of ordination was positively correlated with SBD, moisture, ABG, and BGB and negatively with STN.The low-altitude rangelands have high anthropogenic activities; grazing, trampling, and burning disturbed the natural storage of organic carbon, nitrogen, phytomass, and diversity. The study showed a linear negative relationship between phytomass and altitude.

In order to compare the effect of sowing date on plant growth, development stages and forage yield of three Astragalus cyclophyllon G. Beek ecotypes, a study was conducted in 2010-2011 cropping years in Hanna station, Semirom county, Iran. Three Astragalus ecotypes were originated from Hanna, Golpayegan and Chadegan in Isfahan province, Iran. Seeds were sown in spring and autumn sowing dates using split plot design based on completely randomized blocks in three replications. The results showed that the effect of year was not significant, but the ecotype by sowing date interaction effect was significant on yield and yield components (P<0.01). The required temperature units such as Growth Degree Days (GDD) for spring and autumn sowing dates were 2848°C and 2793°C, respectively. The effect of sowing date on emergence percent and forage yield was significant (p<0.05). Regardless of the ecotype type, the percentage of seed germination and forage yield in autumn sowing were 51 and 60% higher than spring sowing date, respectively. The dry weight of Hanna ecotype in autumn cultivation was 1280 kg ha-1, which was 55.8% and 58% higher than Golpayegan and Chadegan ecotypes, respectively. The reason for the increased yield in Hanna ecotype was of a higher ratio of its leaves. It was concluded that cultivation of Hanna ecotypes due to its higher forage production was recommended for cultivation in dryland farming and also to prevent its extinction in the study region.

Salinity stress and drought stress are the major environmental constraint for promoting medicinal plants in the arid lands of Morocco. To extendthe cultivation of Thymus satureioides in Tafilalet zone, Morocco, we investigate (in 2020) the effects of salinity and drought stresses on seed germination traits of T. satureioides. Salinity treatments included six concentrations of NaCl (0, 1, 2.5, 5, 7 and 10 g/l) and drought stress; five osmotic potentials of PolyEtylenGlycol 4000 (0, -0.1, -0.3, -0.6 and -0.9 MPa). Results showed that T. Satureioides tolerated salinity till the concentration of 2.5g/l of NaCl, which was statistically not different from control. Then, a highly significant reduction in germination percentage was recorded with the increasing salt concentration, only 38% seed germination was recorded for 5 g/l and a complete inhibition was started from 7 g/l and 10 g/l of NaCl. Decreasing osmotic potentials inhibited progressively and significantly seed germination, the germination percentage for -0.1 MPa, -0.3 MPa, and -0.6 MPa were 85.3%, 65.3%, 6.6% respectively. The two stresses (Drought and salinity) had negative impacts on seed germination, but the drought effect was accentuated than salinity in reducing germination.

Global climate change has been linked to the increase in greenhouse gas (GHG) emissions. Wooded grasslands refer to an understudied landscape contributing an unknown quantity of GHGs to global climate change. The objective of this study was to determine the effects of topography and vegetation cover on carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes. The study was carried out in Ilmotiok community ranch, Laikipia County. An in situ experiment was done during the January, February, March and April of 2017. Randomized complete block design (RCBD) with split plot arrangement was used main plots topographical zones (TZ) (mid-slope (MS), foot slope (FS), and toe slope (TS)) and subplots vegetation cover (VC) (tree (T), grass (G) and bare (B)). Static chamber frames were installed for the three VC (T, G and B) in three TZ (MS, FS, and TS). GHGs were measured every 7-10 days from January, February, March and April between 8 and 12 hr local time. Sampling was done after fitting the lid at time zero (T0), 10 minutes (T1), 20 minutes (T2) and 30 minutes (T3). During the rainy season, CH4N2O and CO2 fluxes were significantly higher than the dry season. Methane fluxes ranged from -0.32 to 0.24 mg.m-2.h-1 with the lowest (-0.32 mg.m-2.h-1) recorded under TS*T whereas CO2 was highest under TS*G (47 mg.m-2.h-1) as compared to MS*G (19 mg.m-2.h-1). TZ*VC significantly influence N2O with MS*B recording the lowest (0.008) as compared to TS*B (2.228 mg.m-2.h-1). CO2, N2O and CH4 emissions were low in January and February and it increased in March and April in all the TZ*VC. From the study results, soil greenhouse gas emissions were significantly increased by topography and vegetation cover. Topography and vegetation cover primarily control the patterns of soil N2O, CO2 and CH4 fluxes, therefore, topography and vegetation features must be explicitly included in the predictions of the responses of soil GHGs emissions.

Coronilla varia L., crown vetch, has wide adaptation, and desirable morphological characteristics for a grazing plant, tolerates short periods of overgrazing, and accordingly has potential as a forage crop. In this study, 15 traits were investigated to assess the morphological diversity of 52 populations using univariate and multivariate analyses. Crown vetch seeds provided by the Natural Resources Gene Bank of Iran were sown in an experiment field of Research Institute of Forests and Rangelands, Alborz province, over two years (2019–2020). Based on the flowering date, two taxa C. varia var. varia (as perennial that go to flowering in the first year) and C. varia (as perennial that go to flowering in the second year) were identified. However, a close relationship was found between local and exotic crown vetch populations. The populations were significantly variable in all traits. The high variability was found among populations for plant height, plant canopy, internode length, stem number, and biomass yield. Biomass yield was statistically significant (p < 0.05) and positively correlated withlant height (r=0.63) and plant canopy diameter (r=0.48), internode length (r = 0.57), stem number (r=0.66), and pod length (r=0.52). The principal component analysis showed that the variations observed in the populations were mainly caused by traits such as plant height, stem number, the number of days to 50% flowering and seed ripening indicating that their contribution was important in discriminating the populations. Direct selection can also be made for the populations with high biomass yield based on the recorded performance of these populations during the field experiments. In C. varia, 12 populations classified in cluster 1 with the highest values for 12 out of 15 traits could be useful for including in future breeding programs. Besides, in C. varia var. varia, population Bojnurd (for plant height and canopy diameter), population Rezvanshahr (for internode length and stem number), and populations Karaj1 and 2 (for biomass yield) had higher mean values and were recommended for breeding programs.

This study investigated the effect of grazing on plant community structure. Two adjacent areas: one grazed for five years and non-grazed were sampled in March-April 2020. On each area, three sampling sites were selected. Quadrats of 1×1m were placed at 5m intervals along 50m transects (198~ 40 transects in total). Plants were identified and percentage cover was estimated following Braun-Blanquet method. Indicator values were calculated for each species. T-test compared the means between sites. Multi-response permutation procedures compared plant species composition between sites. Species richness (t=3.44, p<0.01) and evenness (t=-8.06, p<0.01) were significantly higher in non-grazed sites than grazed ones. Diversity showed the opposite trend (p<0.01). Mean cover differed (p<0.05) at species level. Density was significantly higher (t=6.93, p<0.01) in non-grazed sites than in grazed ones. Mean grass species richness was significantly higher (t= 2.97, p<0.01) in grazed sites than non-grazed ones while for herbs it was opposite (t=-5.94, p<0.01). 18 grass species were perennial while 1 was annual. Sporobolus pyramidalis (Low palatability, Increaser II) was found exclusively in the non-grazed areas, 7 others including Paspalum scrobiculatum (Moderate palatability, Increaser II) and Eragrostis curvula (Moderate palatability, Increaser II) were found in the grazed sites only and 11 were common to both sites. These include Themeda triandra (high palatability, Decreaser), Panicum natalense (low palatability, Decreaser), Eustachys paspaloides (high palatability, Decreaser) and Melinis repens. (Low palatability, Increaser II), Eragrostis racemosa (moderate palatability, Increaser II) and mean cover of P. natalense (t=-2.07, p<0.05), M. repens (t=-5.68, p<0.01) and E. racemosa (t=-7.54, p<0.01) was significantly higher in grazed areas than in non-grazed ones. Themeda triandra (t=13.0, p<0.01) and E. paspaloides (t=2.12, p<0.05) had significantly higher mean cover in non-grazed sites than in grazed ones. Our results indicate that grazing has negative impact on highly palatable species. We suggest long term monitoring of vegetation change.

Rangelands ecosystems play a critical role in regulating the emission and uptake of the most important Greenhouse Gases (GHGs) such as CO2, CH4, and N2O. However, the effects of grazing management on GHG fluxes in the semi-arid lands of East Africa remain unclear. The present study compared the effects of three grazing systems on cumulative CO2, CH4, and N2O fluxes in the semi-arid grazing land ecosystem in Yohani ranch Makueni County, Kenya. The study followed a pseudo-replication design in which there were three treatments: 1) Continual grazed, 2) rotational grazed and 3) and ungrazed. Greenhouse gas samples were collected using the static chamber method for a period of three months covering the dry and wet season as well as a transition period. Cumulative soil CO2 fluxes were highest in continual grazing system (2357±123.9 kg ha-1 3 months), followed by rotational grazing (1285±123.9 kg ha-1 3 months) and lowest in the ungrazed (1241±143 CO2 kg ha-1 3 months), respectively. The three month cumulative N2O and CH4 fluxes were also highest in continual grazing and lowest in ungrazed site 677.9±130.1, 208.6±127.3 and 162.2±150.3 (g ha-1 3 months) and CH4, 232.7±126.6, 173.1±126.6 and 80±46.2 (g ha-1 3 months) respectively. The results suggest that the continual livestock grazing system increases emissions of GHGs compared to rotational grazing.

This research was conducted in Mustang district to see the effect of plant diversity and soil properties on aboveground biomass in altitudinal gradient. Above ground biomass estimation was done using various mathematical equations. Soil properties determination was done using calorimetric, Kjeldahl Dry-block method, feel method and core sampling methods. Simpson's Diversity Index and Shannon-Wiener’s diversity index were used to study species diversity. Result shows that above ground biomass decreased with increase in altitude (R2 = 0.148). Above ground biomass increased with increase in species richness (R2= 0.1676). Lete-Kunjo site has high dominance of species than that of Kowang site accounting 23 and 12 respectively. Kobresia spp. has high IVI (91.134) followed by Carex spp. (52.178) in Kowang. Above ground biomass was found significantly higher on lower zone. Above ground biomass increased with increase in soil organic matter percentage (R2= 0.145). Above ground biomass increased with increase in soil nitrogen percentage (R2= 0.1607). Above ground biomass decreased with increase in soil pH (R2= 0.1393). There is positive linear relationship between above ground biomass and species richness. Soil Nitrogen and organic matter have positive linear relationship with above ground biomass but not with the soil pH. So to increase the aboveground biomass of grasslands and to protect the diversity of Mustang district, it necessary to conserve mountain grassland, especially in higher altitude zones, by protecting soil from erosion and landslides, and rotational grazing of livestock’s for increasing soil organic matter.

Growth season rain pulses affect biological and physiological activities of wild plants in arid and semi-arid regions. Despite of numerous reports on the effects of rain pulses on plant physiological indices, there is little information on how rain pulses may affect secondary metabolites of medicinal plants. Caper (Capparis spinosa L.) plays a critical role on soil conservation and economy of arid and sub-tropical inhabitants. Accordingly, present research was conducted to investigate the physiological and phytochemical responses of caper to a growth season rainfall in its natural habitat in Mazdavand, Sarakhs, Iran. Leaf samples (4 replicates) were taken 2, 4, 7 and 10 days after a natural rain event (10 mm) in 17 May 2018. Results showed increase of antioxidant enzymes (catalase and ascorbate peroxidase activity by 77 and 34 %, respectively) and decrease (23%) in proline content by the day after the rain pulse, whereas, photosynthetic pigments were not affected by soil moisture changes. Total alkaloid content was higher (16%) in vegetative than reproductive phase. From the secondary metabolites and 14 major phytochemical compounds detected in leaf extract, phenol content was reduced whereas alkaloid content increased by decreasing soil moisture during the days after rainfall. In conclusions, the phytochemical compounds showed contrasting (increase or decrease) responses to the soil moisture pulse and inter-pulse conditions. These results indicate the best time of leaf harvest to achieve highest concentrations of specific secondary metabolites after the growth season rain pulses.