Microclimatic and soil moisture responses to gap formation in coastal Douglas-fir forests

2002 ◽  
Vol 32 (2) ◽  
pp. 332-343 ◽  
Author(s):  
Andrew N Gray ◽  
Thomas A Spies ◽  
Mark J Easter
Keyword(s):  
Soil Moisture ◽  
Solar Radiation ◽  
Pacific Northwest ◽  
Air Temperature ◽  
Douglas Fir ◽  
Organic Substrates ◽  
Gap Formation ◽  
The North ◽  
Soil Temperatures ◽  
Closed Canopy

The effects of gap formation on solar radiation, soil and air temperature, and soil moisture were studied in mature coniferous forests of the Pacific Northwest, U.S.A. Measurements were taken over a 6-year period in closed-canopy areas and recently created gaps in four stands of mature (90–140 years) and old-growth (>400 years) Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forest in the western Cascade Range of central Oregon and southern Washington. Gap sizes ranged from 40 to 2000 m2. Summer solar radiation levels and soil temperatures differed significantly among gap sizes and positions within gaps and were driven primarily by patterns of direct radiation. Nevertheless, effects on air temperature were slight. Soil moisture was more abundant in gaps than in controls, was most abundant in intermediate gap sizes, and tended to decline during the growing season in single-tree gaps and on the north edges of large gaps. However, there was substantial variation in moisture availability within individual gaps, primarily related to the variety of organic substrates present. Moisture in gaps declined over multiple years, likely caused by encroachment of vegetation within and around gaps. Low light levels probably limit filling of natural gaps in these forests, but the variety of microenvironments in large gaps may facilitate diverse plant communities.

scholarly journals Seasonal Changes in Soil and Air Temperature at Three Locations in Puerto Rico, 1963-67

1969 ◽  
Vol 56 (3) ◽  
pp. 307-317 ◽  
Author(s):  
M. A. Lugo-López ◽  
Modesto Capiel
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Air Temperature ◽  
Soil Cover ◽  
Bare Soil ◽  
Soil Conditions ◽  
Adequate Explanation ◽  
The North ◽  
Air Temperatures ◽  
Soil Temperatures

Soil temperature data at Río Piedras in the north, Lajas in the southwest, and Fortuna in the south, are given in this paper for the 5-year period 1963- 67. Seasonal variations in soil and air temperatures follow distinct patterns somewhat, depending on the nature of the soil cover and rainfall. Mean maximum and minimum temperatures at the 2-inch depth, respectively, are: Río Piedras, 96.2° F. and 79.6° F.; Lajas, 102.1° F. and 69.0° F.; and Fortuna, 93.2° F. and 79.1° F. The corresponding soil temperatures at the 8-inch depth, respectively, are: Río Piedras, 80.5° F. and 77.4° F.; Lajas, 83.4° F. and 77.8° F.; and Fortuna, 85.7° F. and 82.7° F. The differences and trends of soil temperature at 2-inch and 8-inch depths can find adequate explanation when soil moisture and soil cover are considered. However, the differences between maximum and minimum soil temperatures at 8 inches of depth are roughly one fifth of the corresponding ones at the 2-inch depth. The maximum and minimum air temperature at Lajas, Fortuna and Río Piedras are much more similar to each other than the corresponding soil temperature, especially at the 2-inch depth. This is mainly because air temperature is rather measured on a macro and integrating scale while soil temperature measurements exhibit localized effects of soil cover and soil moisture. It was found that highly significant 2-inch soil-air temperature relationships are evident under bare soil conditions. The same relationships were not significant under sod cover at Fortuna.

Prediction of Flash Droughts over the United States

2020 ◽  
Vol 21 (8) ◽  
pp. 1793-1810
Author(s):  
Kingtse C. Mo ◽  
Dennis P Lettenmaier
Keyword(s):  
United States ◽  
Soil Moisture ◽  
High Temperature ◽  
Pacific Northwest ◽  
Heat Wave ◽  
Late Summer ◽  
The United States ◽  
Late Spring ◽  
The North ◽  
June July

AbstractWe examine reforecasts of flash droughts over the United States for the late spring (April–May), midsummer (June–July), and late summer/early autumn (August–September) with lead times up to 3 pentads based on the NOAA second-generation Global Ensemble Forecast System reforecasts version 2 (GEFSv2). We consider forecasts of both heat wave and precipitation deficit (P deficit) flash droughts, where heat wave flash droughts are characterized by high temperature and depletion of soil moisture and P deficit flash droughts are caused by lack of precipitation that leads to (rather than being the cause of) high temperature. We find that the GEFSv2 reforecasts generally capture the frequency of occurrence (FOC) patterns. The equitable threat score (ETS) of heat wave flash drought forecasts for late spring in the regions where heat wave flash droughts are most likely to occur over the north-central and Pacific Northwest regions is statistically significant up to 2 pentads. The GEFSv2 reforecasts capture the basic pattern of the FOC of P-deficit flash droughts and also are skillful up to lead about 2 pentads. However, the reforecasts overestimate the P-deficit flash drought FOC over parts of the Southwest in late spring, leading to large false alarm rates. For autumn, the reforecasts underestimate P-deficit flash drought occurrence over California and Nevada. The GEFSv2 reforecasts are able to capture the approximately linear relationship between evaporation and soil moisture, but the lack of skill in precipitation forecasts limits the skill of P-deficit flash drought forecasts.

Native forest pathogens facilitate persistence of Douglas-fir in old-growth forests of northwestern California

2011 ◽  
Vol 41 (6) ◽  
pp. 1256-1266 ◽  
Author(s):  
Ashley E. Hawkins ◽  
Terry W. Henkel
Keyword(s):  
Bark Beetles ◽  
Tree Mortality ◽  
Douglas Fir ◽  
Native Forest ◽  
Gap Formation ◽  
Old Growth ◽  
Forest Pathogens ◽  
Canopy Trees ◽  
White Fir ◽  
Closed Canopy

Forest pathogens and insects can accelerate tree mortality, increase stand structural heterogeneity, and alter tree community composition. In northern California, the canopy trees Abies concolor var. lowiana (Gord. & Glend.) Lemmon (white fir) and Pseudotsuga menziesii var. menziesii (Mirbel) Franco (Douglas-fir) co-occur but vary in shade tolerance and regenerative abilities following disturbance. Field observations suggested that mortality and turnover of white fir exceeded that of Douglas-fir and that native pathogens may be important drivers in the absence of fire. Pathogens and bark beetles were sampled in old-growth white fir – Douglas-fir stands in northwestern California to assess their contribution to tree mortality, gap formation, and regeneration. We determined abundances and size class distributions of canopy trees, presence of pathogens and bark beetles, and causes of tree mortality. We sampled canopy gaps and closed-canopy forests for overstory species composition, cause of mortality of gap-maker trees, and regeneration of white fir and Douglas-fir. Root-rot fungi accounted for significantly higher mortality and gap formation in white fir than in Douglas-fir. Relative seedling–sapling density of Douglas-fir was higher in pathogen-induced canopy gaps than in closed-canopy forest. In the absence of fire, native forest pathogens enable regeneration and persistence of Douglas-fir by enhancing mortality of white fir, resulting in canopy gap formation.

scholarly journals Specifics of soil temperature under winter wheat canopy

2013 ◽  
Vol 43 (3) ◽  
pp. 209-223 ◽  
Author(s):  
Jana Krčmáŕová ◽  
Hana Stredová ◽  
Radovan Pokorný ◽  
Tomáš Stdŕeda
Keyword(s):  
Soil Moisture ◽  
Winter Wheat ◽  
Soil Temperature ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Soil Surface ◽  
Regression Equations ◽  
Experimental Plot ◽  
Near Surface ◽  
Soil Temperatures

Abstract The aim of this study was to evaluate the course of soil temperature under the winter wheat canopy and to determine relationships between soil temperature, air temperature and partly soil moisture. In addition, the aim was to describe the dependence by means of regression equations usable for phytopathological prediction models, crop development, and yield models. The measurement of soil temperatures was performed at the experimental field station ˇZabˇcice (Europe, the Czech Republic, South Moravia). The soil in the first experimental plot is Gleyic Fluvisol with 49-58% of the content particles measuring < 0.01 mm, in the second experimental plot, the soil is Haplic Chernozem with 31-32% of the content particles measuring < 0.01 mm. The course of soil temperature and its specifics were determined under winter wheat canopy during the main growth season in the course of three years. Automatic soil temperature sensors were positioned at three depths (0.05, 0.10 and 0.20 m under soil surface), air temperature sensor in 0.05 m above soil surface. Results of the correlation analysis showed that the best interrelationships between these two variables were achieved after a 3-hour delay for the soil temperature at 0.05 m, 5-hour delay for 0.10 m, and 8-hour delay for 0.20 m. After the time correction, the determination coefficient reached values from 0.75 to 0.89 for the depth of 0.05 m, 0.61 to 0.82 for the depth of 0.10 m, and 0.33 to 0.70 for the depth of 0.20 m. When using multiple regression with quadratic spacing (modeling hourly soil temperature based on the hourly near surface air temperature and hourly soil moisture in the 0.10-0.40 m profile), the difference between the measured and the model soil temperatures at 0.05 m was −2.16 to 2.37 ◦ C. The regression equation paired with alternative agrometeorological instruments enables relatively accurate modeling of soil temperatures (R2 = 0.93).

scholarly journals Specifics of soil temperature under winter oilseed rape canopy

2014 ◽  
Vol 44 (3) ◽  
pp. 205-218
Author(s):  
Jana Krčmářová ◽  
Tomáš Středa ◽  
Radovan Pokorný
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Oilseed Rape ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Regression Equations ◽  
Winter Oilseed Rape ◽  
Determination Coefficient ◽  
Soil Temperatures ◽  
Dwarf Variety

Abstract The aim of this study was to evaluate the course of soil temperature under the winter oilseed rape canopy and to determine relationships between soil temperature, air temperature and partly soil moisture. In addition, the aim was to describe the dependence by means of regression equations usable for pests and pathogens prediction, crop development, and yields models. The measurement of soil and near the ground air temperatures was performed at the experimental field Žabiče (South Moravia, the Czech Republic). The course of temperature was determined under or in the winter oilseed rape canopy during spring growth season in the course of four years (2010 - 2012 and 2014). In all years, the standard varieties (Petrol, Sherpa) were grown, in 2014 the semi-dwarf variety PX104 was added. Automatic soil sensors were positioned at three depths (0.05, 0.10 and 0.20 m) under soil surface, air temperature sensors in 0.05 m above soil surfaces. The course of soil temperature differs significantly between standard (Sherpa and Petrol) and semi-dwarf (PX104) varieties. Results of the cross correlation analysis showed, that the best interrelationships between air and soil temperature were achieved in 2 hours delay for the soil temperature in 0.05 m, 4 hour delay for 0.10 m and 7 hour delay for 0.20 m for standard varieties. For semi-dwarf variety, this delay reached 6 hour for the soil temperature in 0.05 m, 7 hour delay for 0.10 m and 11 hour for 0.20 m. After the time correction, the determination coefficient (R2) reached values from 0.67 to 0.95 for 0.05 m, 0.50 to 0.84 for 0.10 m in variety Sherpa during all experimental years. For variety PX104 this coefficient reached values from 0.51 to 0.72 in 0.05 m depth and from 0.39 to 0.67 in 0.10 m depth in the year 2014. The determination coefficient in the 0.20 m depth was lower for both varieties; its values were from 0.15 to 0.65 in variety Sherpa. In variety PX104 the values of R2 from 0.23 to 0.57 were determined. When using multiple regressions with quadratic spacing (modelling of hourly soil temperature based on the hourly near surface air temperature and hourly soil moisture in the 0.10-0.40 m profile), the difference between the measured and modelled soil temperatures in the depth of 0.05 m was -3.92 to 3.99°C. The regression equation paired with alternative agrometeorological instruments enables relatively accurate modelling of soil temperatures (R2 = 0.95).

An index of photosynthesis for comparing forest sites in western Oregon

1977 ◽  
Vol 7 (1) ◽  
pp. 165-174 ◽  
Author(s):  
William H. Emmingham ◽  
Richard H. Waring
Keyword(s):  
Soil Moisture ◽  
Carbon Fixation ◽  
Unit Area ◽  
Carbon Assimilation ◽  
Forest Productivity ◽  
Douglas Fir ◽  
Soil Drought ◽  
Forest Sites ◽  
Annual Carbon ◽  
Soil Temperatures

An index was developed that takes into account the combined influence of air and soil temperatures, light, and the availability of soil moisture upon photosynthesis by a unit area of fully exposed foliage of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco). The index is derived from a summation of daily estimates of carbon assimilation (milligrams CO2 assimilation per decimeter per day) for an entire year. In a comparison of forest environments in western Oregon the index was correlated to a measure of forest productivity (r2 = 0.99). Furthermore, it suggests that much of the annual carbon fixation occurs during the mild winters characteristic of the region. The ability to assess the effects of frost, soil drought, and other variables separately was valuable in explaining differences between coastal, valley, and mountainous sites.

scholarly journals An individual-based forest model links canopy dynamics and shade tolerances along a soil moisture gradient

2016 ◽  
Vol 3 (2) ◽  
pp. 150589 ◽  
Author(s):  
Jean Liénard ◽  
Nikolay Strigul
Keyword(s):  
Soil Moisture ◽  
Multiple Scales ◽  
Environmental Gradients ◽  
Spatial Competition ◽  
Climatic Changes ◽  
Moisture Gradient ◽  
The North ◽  
Trade Offs ◽  
Shade Tolerant Species ◽  
Closed Canopy

Understanding how forested ecosystems respond to climatic changes is a challenging problem as forest self-organization occurs simultaneously across multiple scales. Here, we explore the hypothesis that soil water availability shapes above-ground competition and gap dynamics, and ultimately alters the dominance of shade tolerant and intolerant species along the moisture gradient. We adapt a spatially explicit individual-based model with simultaneous crown and root competitions. Simulations show that the transition from xeric to mesic soils is accompanied by an increase in shade-tolerant species similar to the patterns documented in the North American forests. This transition is accompanied by a change from water to sunlight competitions, and happens at three successive stages: (i) mostly water-limited parkland, (ii) simultaneously water- and sunlight-limited closed canopy forests featuring a very sparse understory, and (iii) mostly sunlight-limited forests with a populated understory. This pattern is caused by contrasting successional dynamics that favour either shade-tolerant or shade-intolerant species, depending on soil moisture and understory density. This work demonstrates that forest patterns along environmental gradients can emerge from spatial competition without physiological trade-offs between shade and growth tolerance. Mechanistic understanding of population processes involved in the forest–parkland–desert transition will improve our ability to explain species distributions and predict forest responses to climatic changes.

Design of a Fuzzy Control System for Integrative Irrigation in Field

2011 ◽  
Vol 291-294 ◽  
pp. 2630-2634
Author(s):  
Ying Mei Zhang ◽  
Li Li Yao
Keyword(s):  
Soil Moisture ◽  
Control System ◽  
Fuzzy Control ◽  
Air Temperature ◽  
Fuzzy Controller ◽  
Irrigation System ◽  
Three Dimension ◽  
Fuzzy Control System ◽  
The North ◽  
And Control

A set of integrative irrigation fuzzy control system is designed to the question of the north field crops irrigation in this paper. In this system, the biogas digester, generating system, irrigation system, and control system are combined organically; the power needed is supplied by the biogas generator; the signals of soil moisture and air temperature are collected by the PLC; according to the control scheme that mainly controls soil moisture while air temperature is considered secondarily, a three-dimension fuzzy controller is designed to irrigate precisely; the local and remote communications are realized via the Ethernet and GPRS respectively; four monitoring modes (local operator monitor, SMS, website and C/S client) are designed in this system. The automatic irrigation system can save water, power and fertilizer at the same time.

scholarly journals Numerical procedure for estimating temperature in solarized soils

2006 ◽  
Vol 41 (3) ◽  
pp. 533-537 ◽  
Author(s):  
Chigueru Tiba ◽  
Raquel Ghini
Keyword(s):  
Solar Radiation ◽  
Temperature Variation ◽  
Air Temperature ◽  
Input Data ◽  
Numerical Procedure ◽  
Monthly Means ◽  
Acceptable Accuracy ◽  
Proposed Model ◽  
Soil Temperatures ◽  
Maximum Air Temperature

The objective of this work was to develop a simplified numerical procedure for the estimation of accumulated monthly hours of solarized soil temperatures. The proposed model requires monthly means of daily solar radiation and maximum air temperature as input data, and a daily pattern of temperature variation assumed to be sine-shaped. The procedure was verified using observations made during the years 1992 and 1993 in Jaguariúna, SP. The proposed procedure can predict monthly temperature hours at 10 cm depth in the solarized soil, with acceptable accuracy, in the region for which it was developed.

scholarly journals Contribution of Surface Solar Radiation and Precipitation to Spatiotemporal Patterns of Surface and Air Temperature Warming in China from 1960 to 2003

2016 ◽  
Author(s):  
Jizheng Du ◽  
Kaicun Wang ◽  
Jiankai Wang ◽  
Qian Ma
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Energy Budget ◽  
South China ◽  
North China Plain ◽  
North China ◽  
Spatiotemporal Patterns ◽  
The North ◽  
The North China Plain ◽  
The Impact

Abstract. Although the global warming has been successfully attributed to the elevated atmospheric greenhouses gases, the reasons for spatiotemporal patterns the warming rates are still under debate. In this paper, we report surface and air warming based on observations collected at 1977 stations in China from 1960 to 2003. Our results show that the warming of daily maximum surface (Ts-max) and air (Ta-max) temperatures showed a significant spatial pattern, stronger in the northwest China and weaker in South China and the North China Plain. These warming spatial patterns are attributed to surface shortwave solar radiation (SSR) and precipitation, the key parameters of surface energy budget. During the study period, SSR decreased by −1.50 W m−2 10 yr−1 in China and caused the trends of Ts-max and Ta-max decreased by 0.139 and 0.053 °C 10 yr−1, respectively. More importantly, South China and the North China Plain had an extremely higher dimming rates than other regions. The spatial contrasts of trends of Ts-max and Ta-max in China are significantly reduced after adjusting for the impact of SSR and precipitation. For example, the difference in warming rates between North China Plain and Loess Plateau reduce by 97.8 % and 68.3 % for Ts-max and Ta-max respectively. After adjusting for the impact of SSR and precipitation, the seasonal contrast of Ts-max and Ta-max decreased by 45.0 % and 17.2 %, and the daily contrast of warming rates of surface and air temperature decreased by 33.0 % and 29.1 % over China. This study shows an essential role of land energy budget in determining regional warming.

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