Sources of spatial and temporal heterogeneity in the colonization of an alpine krummholz environment by the weedy subalpine plant Chamerion angustifolium (fireweed)

2006 ◽  
Vol 84 (6) ◽  
pp. 933-939 ◽  
Author(s):  
Amy J. Dona ◽  
Candace Galen
Keyword(s):  
Soil Moisture ◽  
Seed Germination ◽  
Rocky Mountains ◽  
Seedling Survival ◽  
Water Status ◽  
Adult Life ◽  
Life History Stage ◽  
Chamerion Angustifolium ◽  
Moisture Variation ◽  
The Impact

Plant–plant interactions may increase or reduce the impact of abiotic stress on species' distributions, depending on the balance between competition and facilitation. We report on the role of a willow ( Salix ) shrub canopy in mediating the importance of drought stress for performance at seedling and adult life stages of the herbaceous wildflower, Chamerion angustifolium L. (fireweed). Willows form the vegetative boundary (krummholz) between subalpine and alpine life zones in the Rocky Mountains. Chamerion angustifolium is a weedy pioneer species common in subalpine vegetation and advancing upward into the krummholz in the central Rocky Mountains. A mosaic of soil moisture variation dictated spatial patterns of seed germination and seedling survival in C. angustifolium in the absence of willows. However, willows restricted the capacity of C. angustifolium to exploit natural patches of soil moisture during establishment. Seed germination, seedling survival, and net establishment success increased markedly with soil water supply in the open, but not under the willow canopy. For mature plants, willows restricted photosynthesis at the peak of the growing season when rainfall was frequent, but ameliorated the daily decline in leaf water status under drought late in the season. Results suggest that the impact of willows on desiccation stress in alpine populations of fireweed varies with life history stage and phenology.

scholarly journals Contribution of soil moisture feedback to hydroclimatic variability

2010 ◽  
Vol 14 (3) ◽  
pp. 505-520 ◽  
Author(s):  
N. Y. Krakauer ◽  
B. I. Cook ◽  
M. J. Puma
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Cloud Cover ◽  
Temperature Fluctuations ◽  
Substantial Impact ◽  
Empirical Measures ◽  
Spatial And Temporal Scales ◽  
Moisture Variation ◽  
The Impact ◽  
Soil Moisture Feedback

Abstract. While a variety of model experiments and analyses of observations have explored the impact of soil moisture variation on climate, it is not yet clear how large or detectable soil moisture feedback is across spatial and temporal scales. Here, we study the impact of dynamic versus climatological soil moisture in the GISS GCM ModelE (with prescribed sea-surface temperatures) on the variance and on the spatial and temporal correlation scale of hydrologically relevant climate variables (evaporation, precipitation, temperature, cloud cover) over the land surface. We also confirm that synoptic variations in soil moisture have a substantial impact on the mean climate state, because of the nonlinearity of the dependence of evapotranspiration on soil moisture. We find that including dynamic soil moisture increases the interannual variability of seasonal (summer and fall) and annual temperature, precipitation, and cloudiness. Dynamic soil moisture tends to decrease the correlation length scale of seasonal (warm-season) to annual land temperature fluctuations and increase that of precipitation. Dynamic soil moisture increases the persistence of temperature anomalies from spring to summer and from summer to fall, and makes the correlation between land precipitation and temperature fluctuations substantially more negative. Global observation sets that allow determination of the spacetime correlation of variables such as temperature, precipitation, and cloud cover could provide empirical measures of the strength of soil moisture feedback, given that the feedback strength varies widely among models.

The Effect of Microsite Variation on Seed-Germination and Seedling Survival of Eucalyptus delegatensis

1993 ◽  
Vol 41 (2) ◽  
pp. 169 ◽  
Author(s):  
M Battaglia ◽  
JB Reid
Keyword(s):  
Seed Germination ◽  
Seedling Survival ◽  
Soil Conditions ◽  
Small Scale ◽  
Root Penetration ◽  
Mean Survival Time ◽  
The Mean ◽  
Developmental Characteristics ◽  
The Impact ◽  
Eucalyptus Delegatensis

The correlation between microsite and seedling numbers was determined in field sowings, and the impact of microsites on germination and seedling survival tested in artificial seedbeds in the glasshouse. Small scale variation in soil conditions, at the scale of tens of centimetres, markedly affected the germination and establishment of Eucalyptus delegatensis R.T.Baker seeds and seedlings. Under conditions of limiting soil moisture, microsites that afforded protection, and probably resulted in increased humidity, caused a marked increase in germination number and rate. The mean survival time was significantly higher on these protected microsites than on less protected microsites, or on microsites that restricted root penetration. The importance of this variability in microtopography was strongly influenced by season and the level of environmental stress, and was diminished as seedlings aged. Due to the different requirements for seed germination and seedling growth, a favourable microsite for germination was not necessarily a favourable site for seedling survival. A comparison of seed and seedling responses to water stress indicated that for E. delegatensis, at least, selection due to microsite differences at the time of germination may not have an impact on the developmental characteristics of the seedlings.

Analysis of Soil Moisture Characteristics with the Application of Soil in Civil Engineering in 2011 in Gaoyao

2012 ◽  
Vol 568 ◽  
pp. 31-34 ◽  
Author(s):  
Ling Li Fan
Keyword(s):  
Regression Analysis ◽  
Soil Moisture ◽  
Civil Engineering ◽  
Dominant Role ◽  
Soil Humidity ◽  
Moisture Analysis ◽  
Sunshine Hours ◽  
Moisture Variation ◽  
The Impact ◽  
Soil Moisture Variation

The data of soil moisture in layer of 0-50cm, precipitation, temperature, sunshine hours and cloudiness in 2011 in Gaoyao were analyzed. The results showed that the soil moisture was vertical uniformly distributed in Gaoyao. The soil humidity was larger in an overcast day than in the others. It was relatively smaller in a sunny day than in the others, because of the impact of solar radiation and temperature on soil moisture. Three layer soil moisture variations were almost synchronous, but the variation amplitude of soil moisture in 0-10cm layer was biggest, and 30-50cm soil moisture variation was least. Regression analysis showed that, precipitation and cloudiness played a dominant role on soil moisture variation, while temperature and sunshine had little effect on the soil moisture. Analysis of soil moisture characteristics with the application of soil was useful to civil engineering in Gaoyao.

scholarly journals The impact of snow loss and soil moisture on convective precipitation over the Rocky Mountains under climate warming

2021 ◽  
Author(s):  
Brendan Wallace ◽  
Justin R. Minder
Keyword(s):  
Soil Moisture ◽  
Snow Cover ◽  
Rocky Mountains ◽  
Land Surface ◽  
Regional Climate ◽  
Warm Season ◽  
Surface Fluxes ◽  
Convective Precipitation ◽  
Precipitation Frequency ◽  
The Impact

AbstractWarm season moist diurnal convection can be particularly sensitive to changes in land surface characteristics such as snow cover and soil moisture. Over regions of mountainous terrain, climate change is expected to reduce snow cover along the low-elevation seasonal snowpack margin. These snow reductions alter surface albedo and soil moisture content, leading to changes in surface fluxes and alterations in mesoscale orographic circulations that act to transport moisture and provide ascent. A set of convection-permitting regional climate simulations centered on the Rocky Mountains of Colorado are conducted from April through July across a period of 12 years (2002–2013). These include a reanalysis forced control run (CTR), a pseudo global warming run (PGW), and an additional altered land surface run (DSURF) used to isolate the effects of the snow albedo and soil moisture changes on orographic convection. Over the mountains, daytime hourly precipitation accumulation (0900–1800 MST) decreased in PGW by an average of 4.2% while precipitation in DSURF increased by 12.5%. On days with weak synoptic forcing, the PGW response more closely follow the DSURF response with daytime hourly increases averaging 29.7% for PGW and 28.7% for DSURF. For PGW, hourly daytime precipitation intensity increases of up to 82% overcome reductions in precipitation frequency to produce higher accumulations. DSURF shows smaller increases in intensity of up to 23% and broad increases in daytime frequency indicating that surface changes act to moderate reductions in the frequency of convective precipitation. Reduced snow cover contributes to this convective response by increasing convective instability and boundary layer moisture and decreasing lifting condensation level over the high terrain. Alterations in orographic thermal circulations contribute to this response by converging moisture over the high terrain and enhancing mesoscale ascent.

Soil moisture continues declining in North China over the regional warming slowdown of the past 20 years

2021 ◽  
Author(s):  
Xin Li ◽  
Guoyu Ren ◽  
Qinglong You ◽  
Suyan Wang ◽  
Wen Zhang
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
North China ◽  
Potential Evapotranspiration ◽  
Regional Warming ◽  
Continuous Increase ◽  
The Past ◽  
Moisture Variation ◽  
Percent Contribution ◽  
The Impact

AbstractSoil moisture is an important variable of the climate system and is used to measure dry–wet change in hydro-climate. The warming trend has slowed in China over the past 20 years since 1998, and how the soil moisture changes in this period deserves our attention. With North China as a research region, this study uses the Global Land Data Assimilation System and ground observations to investigate the causes of changes in soil moisture during 1998–2017 versus 1961–1997. The results show that: (1) annual mean soil moisture experienced an almost continued decrease from to 1960s to 2010s, and no pause in the decrease of soil moisture over the regional warming slowdown of the past 20 years could be detected; (2) with the stabilization or even increase in solar radiation and wind speed as well as the continuous increase land surface air temperature, the impact of potential evapotranspiration on soil moisture gradually became prominent, and the impact of precipitation decreased, since 1998; (3) the percent contribution of annual potential evapotranspiration to soil moisture variation increased by 26% during 1998–2017 relative to that in 1961–1997, and the percent contribution of summer potential evapotranspiration even increased by 45%. Our results will provide insight into the land surface water budget and mechanism involved in drought development in North China.

scholarly journals A new agricultural drought index considering the irrigation water demand and water supply availability

2020 ◽  
Vol 104 (3) ◽  
pp. 2409-2429
Author(s):  
Zikang Xing ◽  
Miaomiao Ma ◽  
Yongqiang Wei ◽  
Xuejun Zhang ◽  
Zhongbo Yu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Irrigation Water ◽  
Water Demand ◽  
Drought Index ◽  
Agricultural Drought ◽  
Drought Event ◽  
Moisture Condition ◽  
Irrigation Water Demand ◽  
Moisture Variation ◽  
The Impact

Abstract Agricultural drought has a tremendous impact on crop yields and economic development under the context of global climate change. As an essential component of water balance in irrigated areas, artificial irrigation, which is not widely incorporated into agricultural drought indices in previous studies. Therefore, an irrigation water deficit index (IWDI) based on the estimation of irrigation water demand and supply is proposed. The performance of the new index was compared with the Soil Moisture Anomaly Percentage Index (SMAPI) over the upstream of the Zi River basin (UZRB). The results indicated the IWDI is highly correlated with precipitation, runoff, and potential evapotranspiration, combined with a more comprehensive moisture condition than the previous agricultural drought index. Due to the consideration of crop growth process and farmland spatial distribution, the proposed index showed a significant advantage in stressing drought conditions of agricultural concentration area and eliminating the impact of invalid soil moisture drought of non-growing seasons. Furthermore, the drought condition identified by the new index presented a good agreement with the historical drought event that occurred in 2013.7–8, which accurately reproduced the soil moisture variation and vegetation growth dynamics.

scholarly journals Influence of Illumination Time and Soil Moisture on Seed Germination and Seedling Establishment of Magnolia sprengeri Pamp.

HortScience ◽  
2021 ◽  
pp. 1-6
Author(s):  
Tong Zhang ◽  
Yingjie Yan ◽  
Chuantong Li ◽  
Junmei Liu ◽  
Dongxue Yin ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Seed Germination ◽  
Seedling Establishment ◽  
Seedling Survival ◽  
Lateral Roots ◽  
Germination Percentage ◽  
Dominant Factor ◽  
Continuous Illumination ◽  
Illumination Time ◽  
Magnolia Sprengeri

This study investigated the effects of illumination time and soil moisture on seed germination and seedling establishment of Magnolia sprengeri Pamp. to improve the seed germination percentage and seedling survival percentage of M. sprengeri. It is of great significance for rapid propagation, seedling regeneration, field management, and artificial high-efficiency cultivation of M. sprengeri. In this study, the seeds of natural M. sprengeri populations from original habitat were used as test materials. Seed germination and seedling establishment of M. sprengeri were performed under different illumination time and soil moisture treatments in artificial climate incubator. The study found that there were significant differences among various key parameters related to seed germination and seedling establishment under different treatments (P < 0.05). Germination percentage, germination potential, germination index, vigor index, germination rate, plant height, number of leaves, base diameter, taproot length, number of lateral roots, maximum lateral root length, single plant leaf area, fresh weight, and seedling survival rate reached the maximum at continuous illumination and 13% of soil moisture, respectively. By the integrative evaluation for the influence of these two factors on seed germination and seedling establishment, soil moisture is a dominant factor affecting seed germination and seedling establishment, whereas illumination is an important promoting factor for seedling establishment of M. sprengeri. Continuous illumination and 13% of soil moisture content is suitable for seed germination and seedling establishment of M. sprengeri.

scholarly journals THE INFLUENCE OF BIOLOGICAL ADDITIVES ON THE MOISTURE RETENTION OF SOIL

2018 ◽  
Author(s):  
Inga ADAMONYTĖ ◽  
Vilda GRYBAUSKIENĖ ◽  
Gitana VYČIENĖ
Keyword(s):  
Soil Moisture ◽  
Raw Materials ◽  
Moisture Regime ◽  
Moisture Retention ◽  
Critical Temperatures ◽  
Soil Moisture Regime ◽  
Moisture Variation ◽  
Berry Crops ◽  
The Impact ◽  
Soil Moisture Retention

With the onset of climate change, dry periods are more frequent, and therefore the rational use of naturally accumulating soil moisture can be a tool to regulate the unfavourable soil moisture regime. Demand for new biological materials is increasing rapidly with the development of biotechnological science. Superabsorbent or water retaining material is considered promising material that is widely used in the fields of industry and agriculture. These can both absorb large amounts of water, as much as hundreds of times their own mass. The use of biological environmentally friendly additives to the cultivation of agricultural products, particularly germination and rooting periods, can ensure the required moisture content of the soil. The use of additives is more economical growing relatively more expensive raw materials, so in most cases it is related to vegetable and berry crops. The aim is to investigate the extent to which biological additives can absorb and give back moisture, assessing the different incorporation relations, as well as different biological additives. Soil moisture variation for samples with embedded biological additives ended after 24 and 26 days under laboratory conditions at 17 and 19 °C; it ended after 15 days in an environmental chamber at 20 °C. On average, soil moisture retention increases by 14 days more than the control without additives. The results showed that at low temperatures all the biological additives considered help to keep the moisture available to the plants longer in the soil for approximately the same number of days. In assessing these results, it should be emphasized that the conditions in the nature are different from the simulated critical temperatures and without the addition of moisture, in the natural conditions the impact of biological additives will be longer.

Soil moisture strongly limits Douglas-fir seedling establishment near its upper elevational limit in the southern Rocky Mountains

2020 ◽  
Vol 50 (8) ◽  
pp. 837-842 ◽  
Author(s):  
Alison C. Foster ◽  
Patrick H. Martin ◽  
Miranda D. Redmond
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Seedling Establishment ◽  
Rocky Mountains ◽  
Negative Impact ◽  
Seedling Survival ◽  
Douglas Fir ◽  
Southern Rocky Mountains ◽  
Precipitation Regimes ◽  
Maximum Temperatures

Climate change is causing significant shifts in tree species distributions to higher elevations and latitudes. Seed germination and seedling establishment are particularly important steps in tree range expansion under warmer conditions, yet seedling establishment is influenced by a range of factors beyond temperature, including herbivory, microenvironment, and the timing and amount of precipitation. We conducted an experiment to assess how augmented precipitation regimes, wildlife herbivory, and microclimate influence germination and first-season survival of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) near the upper elevational limit of its range in the southern Rocky Mountains. Germination was strongly influenced by moisture, with over three times higher germination in watered treatments. Seedling survival was similar across watered treatments but was negatively associated with microenvironments with higher maximum temperatures. These results indicate that soil moisture effects on germination and the negative impact of hot growing-season temperatures on seedling survival limit initial seedling establishment in Douglas-fir, even at the cooler and wetter end of its range, suggesting that the planting of this species will be most successful in cooler and wetter microsites. Taken together, this study suggests that continued warming and projected increases in droughts may strongly limit Douglas-fir regeneration and thus its ability to shift upwards with climate change.

scholarly journals Contribution of soil moisture feedback to hydroclimatic variability

2009 ◽  
Vol 6 (6) ◽  
pp. 6967-6999
Author(s):  
N. Y. Krakauer ◽  
B. I. Cook ◽  
M. J. Puma
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Cloud Cover ◽  
Temperature Fluctuations ◽  
Substantial Impact ◽  
Empirical Measures ◽  
Spatial And Temporal Scales ◽  
Moisture Variation ◽  
The Impact ◽  
Soil Moisture Feedback

Abstract. While a variety of model experiments and analyses of observations have explored the impact of soil moisture variation on climate, it is not yet clear how large or detectable soil moisture feedback is across spatial and temporal scales. Here, we study the impact of dynamic versus climatological soil moisture in the GISS GCM ModelE (with prescribed sea-surface temperatures) on the variance and on the spatial and temporal correlation scale of hydrologically relevant climate variables (evaporation, precipitation, temperature, cloud cover) over the land surface. We also confirm that synoptic variations in soil moisture have a substantial impact on the mean climate state, because of the nonlinearity of the dependence of evapotranspiration on soil moisture. We find that including dynamic soil moisture increases the interannual variability of seasonal (summer and fall) and annual temperature, precipitation, and cloudiness. Dynamic soil moisture tends to decrease the correlation length scale of seasonal (warm-season) to annual land temperature fluctuations and increase that of precipitation. Dynamic soil moisture increases the persistence of temperature anomalies from spring to summer and from summer to fall, and makes the correlation between land precipitation and temperature fluctuations substantially more negative. Global observation sets that allow determination of the spacetime correlation of variables such as temperature, precipitation, and cloud cover could provide empirical measures of the strength of soil moisture feedback, given that the feedback strength varies widely among models.

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