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PEET-L archives -- September 1996 (#13)

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Award#0544474 - Collaborative Research: Comparative Hydraulic Architecture; An Analysis of Transport Efficiency and Mechanical Constraints

The need for plants to acquire CO2 for photosynthesis results in the passive loss of large amounts of water vapor from their leaves, which must be continuously replaced by the xylem, a transport tissue consisting of thousands of dead, hollow conduits running from the roots to the leaves. Hydraulic architecture determines the capacity and efficiency with which the xylem is able to supply water to the leaves, and thus limits the rate at which plants can gain carbon and grow. In many woody plants, the xylem conduits serve dual functions of water transport and mechanical support, leading to a partial sacrifice of hydraulic efficiency for mechanical stability. The goals of this research are to classify and understand the diversity of hydraulic architecture across major plant groups and growth forms by evaluating the extent of trade-offs of hydraulic against mechanical functions of xylem. This will be accomplished by determining how several key vascular network traits such as hydraulic conductivity, conduit number and area, and water transport velocity change from near the base of the plant to its uppermost branches. These results will be plotted on graphs to generate hydraulic landscapes. The positions of different plant types on these landscapes will indicate the extent to which the mechanical support function of xylem constrains its hydraulic function. Palms and vines are expected to be more hydraulically efficient than trees because, unlike trees, their xylem only transports water and does not provide structural support. Within temperate trees, a negative relationship between hydraulic efficiency and the proportion of wood devoted to xylem conduits relative to other cell types is expected. Finally, restrictions on xylem structure imposed by freezing should make temperate trees less hydraulically efficient than tropical trees. This research will enhance understanding of intrinsic constraints on the growth and productivity of forests and other natural and managed ecosystems. Broader impacts of this work include training and mentoring opportunities for a postdoctoral scientist, undergraduate and graduate students, was well as for Latin American students who will participate in the work to be carried out in Panama at the Smithsonian Tropical Research Institute.

Award#0614813 - Synergistic Effects of Light and Water on Physiological Diversification in the Hawaiian Llobeliads

Irwin N
Irwin N. Forseth, Jr.

Biophysic101: Lecture Notes
harvad

comparative canopy research questions

Dr. Barbara Bond

Vegetation water use and stream flow at the H.J. Andrews Experimental Forest

GOAL: The long-term of this project is to better understand how vegetation age, structure, and species composition affects hydrological patterns in small watersheds at the H.J. Andrews Experimental Forest.

BACKGROUND: The vegetation cover within watersheds has an important influence on stream flow, but the specific details of this influence are not well understood. In the Oregon Cascade Range, up to 25% of national forest land has been altered by logging activities since the 1930's, resulting in patches of 20 to 40 ha with vegetation of varying ages and species composition (Jones and Grant 1996). It is important to understand how these changes in vegetation affect the hydrologic cycle in order to manage watersheds for multiple uses that include water supply and slope stability.

Following a vegetation-removing disturbance to a watershed, such as fire or harvesting, peak flows as well as total flows of water generally increase for a period of a few to several years (Amthor 1998, Watson et al. in press). Jones and Grant (1996) determined that forest harvesting increased peak discharges in experimental basins in the H.J. Andrews by as much as 50% in small basins and 100% in large basins. After this initial increases in flow, water discharge decreases over a period of time in many watersheds. In at least three long-term datasets (Hubbard Brook, Coweeta, and Eucalyptus regnans forests of southeast Australia), total discharge from watersheds with the vigorous, recovering forests 10-30 years after a major disturbance was actually less than the initial condition with old-growth vegetation.

Some of these changes have good explanations. The initial increase in flow following disturbance is generally attributed to reduced transpiration due to the low leaf area after the disturbance, resulting in a greater amount of surface flow. In a few cases where flow decreased after harvest, it appears that the finely articulated conifer needles of the original forest intercepted significant fog and cloud water, so water input was reduced when trees were removed (Harr 1982, 1986). In most systems, as vegetation recovers following disturbance, the use of water by vegetation for transpiration reduces outflow. However, some of the interactions between vegetation and watershed hydrology are more elusive. Why is there less discharge from watersheds with recovering vegetation than in the original condition? Amthor (1998) proposed that change in atmospheric CO2 levels are affecting forest water use at Hubbard Brook; in Coweeta, it is possible that a shift in species composition in the recovering vegetation has resulted in increased transpiration. In the E. regnans forests of Australia, the overstory trees of the young, recovering forests had a higher leaf area compared with the original old forest, resulting in higher total transpiration (Watson et al. in press). Also in the old forest there was a better-developed understory which used less water per unit leaf area than the overstory (Watson et al. in press). Still, the transpiration per unit leaf area was much higher for young E. regnans trees compared with older trees. This could result from changes in the hydraulic resistance in the trees themselves as they age (Ryan and Yoder 1997). The changes in water discharge in all of these systems apparently result from combination of changes to vegetation structure, composition and age and possibly climate interactions.

H.J. Andrews (HJA) Experimental Forest has maintained records of water discharge from small basins (60-101 ha) for over 35 years. These are part of a paired-basin experiment. Experimental harvests were conducted in the 1960s in half of the basins, with clear pre-treatment and post-treatment measurement periods. The HJA is also fortunate to have an outstanding team of hydrology researchers who are on the forefront of new concepts and analysis techniques. For example, Jones and Grant (1996) introduced a new level of statistical rigor to watershed research and revealed surprisingly strong influences of vegetation succession and roads on peak discharges. Tracer studies by Wondzell (unpublished) have revealed strong diurnal trends in the flow from Watershed 1; flow increases over night and decreases during the day. Newer, high-precision weirs are now able to measure this change in flow directly; these instruments indicate that some of the small watersheds in the H.J. Andrews show strong diurnal variation and others do not (Post and Jones 2001). It is likely that the diurnal variation is influenced by water use by streamside vegetation, but there are no data to support this hypothesis. Missing from the current research effort at the H.J. Andrews are studies that relate vegetation processes to change in hydrological cycle.

RESEARCH OBJECTIVES:

Objective I. Evaluate and quantify the impact of three components of vegetation structure and composition and structure on vegetation water use. These are:

1. Species composition (especially hardwoods vs. softwoods, and Douglas-fir vs. hemlock). Within a decade after harvesting, hardwoods and young Douglas-fir dominate young stands. As forests age, hardwoods become less prevalent and in very old forests, hemlock replaces Douglas-fir.
2. Sapwood basal area. Although total basal area increases with stand age after harvesting, preliminary evidence indicates that sapwood basal area is lower in very old forests than in young, mature forests.
3. Tree size/age. Preliminary evidence from Wind River and other locations indicates that tree water use per unit sapwood area is significantly lower in old growth Douglas-fir than in

Objective II. Compare and contrast measurements of vegetation water use with stream flow measurements on time scales ranging from hours to decades.

EXPERIMENTAL APPROACH:

The study focuses on two small watersheds in the Experimental Forest. WS1 was cut in the mid 1960's and is used to evaluate vegetation structure and function of "young/mature" forests. WS2 is an uncut control watershed that is immediately adjacent to WS1. The last major disturbance in WS2 was about 450 ybp. The study includes these key measurements:
1. continuous measurements of transpiration in "young hardwoods" (we are using red alder as a surrogate for all hardwoods), "young Douglas-fir", "old Douglas-fir" and "old western hemlock" (additional species and age classes may be added over time).
2. estimates of vegetation composition in the two watersheds, accomplished with vegetation surveys.
3. continuous measurements of streamflow (part of the core LTER measurements).

Transpiration is measured at 20 minute intervals with "Granier-type" sapflow sensors (Granier 1996) installed in 5 to 7 trees of each species/age-class, with at least two sensors per tree (more details on sensor positions is provided below). These trees were cored with an increment borer to determine sapwood depth. It is critical to note that the power requirements for sapflow measurements preclude a good random sample of trees throughout the watersheds. Instead, the sample trees lie in a cluster near the base of the watersheds and thus the data to date are unavoidably biased due to the sampling design. In WS1 trees lie along two "transects", one each of alder and Doug-fir, just above the weir. These run normal to the stream through a pocket of each vegetation type up the southern (north facing) slope. The transects are 50m long, and 7 trees were selected along the transect at roughly equal intervals. Due to limitations of power and equipment, we measured red alder only in 1999; in subsequent years we estimated sap flux in red alder based on relationships between red alder and Douglas-fir in 1999. We began measurements in WS2 in 2000. In WS 2 we selected 5 Douglas-fir and 4 western hemlock (all overstory trees) in a transect on the N side of the stream about 50m below the weir.

Vegetation surveys were conducted in 1999 in WS1 and 2000 in WS2 to quantify the species composition and basal sapwood area of all woody vegetation >1 cm diameter in the riparian zones (arbitrarily defined as 100m swath centered on the stream bed) of the two watersheds. In each WS, we established transects normal to the stream every 200m upstream from the weir. The transects alternated from one side of the stream to the other. Along each transect we established contiguous square plots - in WS1 there were five 10m-square plots and in WS2 there were three 20m-square plots on each transect (plot dimensions were determined for the horizontal plane - i.e., they were slope-corrected). Within each plot we measured the diameter and species of every tree greater than 1 cm diameter as well as height and sapwood depth of 5 trees of each species in the plot, systematically selected to represent the size distribution in that plot. From the sample of trees used for measurements of height and sapwood depth, we developed species-specific regression equations to predict sapwood area from DBH outside the bark. Cover (by percent area) estimates of shrubs and herbaceous species were made using the line intercept technique from a diagonal transect running from the SW to the NE corners of the plots, with species identified when possible.

Scaling procedures: Sap flux density for each individual sensor over each 20 minute period was determined from temperature differentials using equations in Granier (1987). These measurements were scaled to the whole-tree and species level generally using the procedures described in Phillips et al. 2002. In red alder we installed sensors at three depths (0-20 cm, 20-40 cm and 40-60 cm) in five trees and we determined the average gradient in sapflow from the outer to inner sapwood. Using this gradient we "scaled" outer flux measurements in the other trees to a whole tree basis, and then divided by the total sapwood area of that tree to come up with the average sap flux density. In Douglas-fir and western hemlock we installed most sensors at a depth of 0-20 cm, but we also installed sensors at 20-40 cm in 4 of the old-growth trees. We combined information from these four trees with sap flux measurements from Douglas-fir at Wind River to analyze how radial gradients in sap flow are affected by site, tree age and seasonal variation. From this analysis we developed a predictive relationship to estimate radial variation based on measurements in the outer 2 cm of the sapwood, and we then used these relationships to estimate whole-tree sap flow over 20 min intervals for each measurement tree. For hemlock we took advantage of radial measurements of sapflow by F.R. Meinzer at Wind River. Meinzer's data show that sapflow declines linearly from the outer edge of sapwood to the sapwood/heartwood boundary. We used this relationship to estimate whole tree sapflow from measurements in the outer 2 cm in hemlock. We found no difference in whole-tree sap flux density for any species or size/age class as a function of distance from the stream, so we averaged the data (for each time increment) over the total number of sample trees to develop the mean sapflux density for measurement period for each species/size class. We multiplied this value for red alder by the sapwood basal area of hardwoods in WS1 to estimate hardwood transpiration. We multiplied this value by the sapwood basal area of all conifers (which is >95% Douglas-fir) to estimate conifer transpiration in WS1. We multiplied the valued for old hemlock and Douglas-fir, respectively, by the sapwood basal areas of these species in WS2 (which account for >95% of the sapwood basal area of all trees in this watershed) to estimate transpiration in WS2. The sap fluxes over 20 min intervals were summed to obtain daily sap fluxes.

In many cases, individual sensors were not functional over periods of several days. Because of the small sample sizes, dropping these individuals from the overall mean could result in large artifacts in the time-series data. Therefore, we interpolated to fill "missing" data based on relationships among the sensors when all functioned properly.

Streamflow is monitored continuously as part of the core LTER program. During the summer months, 90-degree v-notch weirs are used to precisely measure stream flow variations at 15 min intervals.

References:

Amthor, J.S. 1998. Searching for a relationship between forest water use and increasing atmospheric CO2 concentration with long-term hydrologic data from the Hubbard Brook Experimental Forest. Environ. Sci. Div. Publ. 4833, Oak Ridge Nat. Lab., Oak Ridge, TN.

Bond, B.J. and K.L. Kavanagh. 1999. Stomatal conductance of four woody species in relation to leaf-specific hydraulic conductance and threshold water potential. Tree Physiology 19:503-510.

Granier, A. 1987. Evaluation of transpiration in a Douglas-fir stand by means of sap flow measurements. Tree Physiology. 3:309-320.

Harr, R.D. 1982. Fog drip in the Bull Run municipal watershed, Oregon. Water Resour. Bull. 18(5):785-789.

Harr, R.D. 1986. Effects of clearcutting on rain-on-snow runoff in western Oregon: A new look at old studies. Water Resour. Res. 22:1095-1100.

Jones, J.J. and G.E. Grant. 1996. Peak flow responses to clear-cutting and roads in small and large basins, western Cascades, Oregon. Water Res. Res. 32:959-974.

Phillips, N., B.J. Bond, N.G. McDowell and M.G. Ryan. 2002. Canopy and hydraulic conductance in young, mature, and old Douglas-fir trees. Tree Physiology 22(2/3):205-212.

Ryan, M.G. and B.J. Yoder. 1997. Hydraulic limits to tree height and tree growth. BioScience 47(4):235-242.

Watson, F.G.R., Vertessy, R.A., Grayson, R.G. In press. Large scale modeling of forest hydrological processes and their long term effect on water yield. Hydrological Processes, Special Issue on Process Interactions in the Natural Environment.

POL: Books page

蒲慕明所长在神经所2006年会上的讲话

973项目长江流域生物多样性变化、可持续利用与区域生态安全
国家重点基础研究发展计划(973) 课题年限：2000.02.01-2005.10.01

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Joshua B. Fisher: PROGRESS REPORT

Quantifying Evapotranspiration in California Forest Ecosystems:

Remote Sensing vs. Flux Measurement

Proposal Recap

Evapotranspiration, a major component in terrestrial water balance and net primary productivity models that control larger general circulation and global climate change models, is difficult to measure and predict, especially on a landscape spatial scale. The objectives of my study are to estimate evapotranspiration from remotely sensed data by scaling ground-based measurements and ecosystem models to FLUXNET data and satellite remote sensing. Both NASA’s Earth Observing System and a global network of ecosystem flux measurement sites (FLUXNET) have produced water vapor estimates that will be validated and analyzed in this project at two study sites in California: Tonzi Ranch (P.I. Dennis Baldocchi) and Blodgett Forest (P.I. Allen Goldstein). I will examine uncertainties in remotely sensed data for evapotranspiration modeling, and offer methodological recommendations by documenting problems and solutions from working with such data and scaling models. It is critical that the observational and modeling activities be linked together, as observations that do not exist in the context of a model-based hypothesis can provide data but little insight, while models unconstrained by observations are frequently of little use in explaining the past or present, let alone for predicting the future. This project, as an integral part of water and energy cycle research, is part of an ultimate objective to close the water budget worldwide; the overall goal is to deliver reliable estimates of precipitation minus evapotranspiration over the whole surface of the earth, and success will depend on a combination of measurements and model estimates of evapotranspiration.

Current Work and Results

Plant Ecophysiology

As my project scales from plant to ecosystem to landscape, I shall commence at the plant ecophysiological level. No biophysical variable is directly measurable at a global scale; consequently, none can be comprehensively validated (Running et al. 2000). A coherent Earth science research strategy must combine findings from global observations with insight gained from specialized studies; in situ measurements made at the Earth surface or in the atmosphere provide “ground truth” against which space-based measurements are compared, thus increasing our knowledge of processes through comprehensive characterization of specific regions, which is not usually possible with remote sensing techniques. To gain understanding of plant-water relations, I studied plant ecophysiology under Professor Todd Dawson. Relevant topics included: the principle of limiting factors, plants and microclimates, radiation balance and leaf energy budgets, stomatal and biochemical control of leaf gas exchange, stable isotopes, water-use efficiency, variation in photosynthetic pathways and carbon allocation, photosynthetic adaptation to light and temperature, canopy architecture and productivity, water in plants and in soils and the atmosphere, root systems and water capture, water use and tissue water relations, plant architecture and hydraulic conductivity, and adaptation to water stress and nutrient availability. These plant-level characteristics will guide ecosystem and landscape responses, which will influence larger-scale modeling.

I have begun my field site and measurement preparation by logistically planning collaborations with the research groups and principal investigators at Blodgett Forest and Tonzi Ranch. Furthermore, I have been reading extensively on measurement methods and theory for sap flow and soil evaporation. Blodgett Forest Research Station (38°53´N, 120°37´W, 1315 m) is a research forest of the University of California, Berkeley (Goldstein et al., 2000). The forest was planted in 1990 and was dominated by ponderosa pine trees (Pinus ponderosa Doug. E. Laws), the most common conifer species in North America. The canopy also included individuals of Douglas fir (Pseudotsuga menziesii), white fir (Abies concolor), giant sequoia (Sequoiadendron giganteum), incense-cedar (Calocedrus decurrens) and California black oak (Quercus kelloggii). The major understory shrubs were manzanita (Arctostaphylos spp.) and Ceonothus spp. (Xu et al., 2001a). In 1997, about 25% of the ground area was covered by shrubs, 30% by conifer trees, 2% by deciduous trees, 7% by forbs, 3% by grass and 3% by stumps. The forest area was in a stage of rapid growth, as exhibited by the 10% increase in leaf area index (LAI) between the 1997 (2.9-4.2) and 1998 (3.2-4.5) growing seasons. The site is characterized by a Mediterranean climate with an average annual precipitation of 163 cm (180 cm in 1997 and 117 cm in 1998), the majority of which falls between September and May, and almost no rain in the summer. The soil is a fine-loamy, mixed, mesic, ultic haploxeralf in the Cohasset series whose parent material was andesitic lahar. Tonzi Ranch (38° 25.896' N, 120° 57.959' W, 177 m) is a savanna site dominated by Blue oak (Quercus doublasii) and grazed grassland (bromus, frescue, oat, medusa head, rose clover) with scattered gray pine (Pinus sabinianai). The climate is also Mediterranean, although the site receives far less precipitation (56 cm annual mean) than does Blodgett Forest. The soil is of the Auburn series and is loamy, mixed, superactive, rocky, silt. I plan to set up sap flow measurements this summer on 6 ponderosa pine trees, 3 manzanita and 3 Ceonothus shrubs, and set up mini-lysimeter measurements of soil evaporation at Blodgett Forest. The selected trees will be coupled with respiration measurements managed by a colleague within my research group. Sap flow of shrubs is unique to understanding the partition of sub-canopy water use; my measurements will also be used to validate and partition a newly installed sub-canopy flux tower. Analogously, I will set up parallel sap flow measurements on 6 Blue oak trees, and set up mini-lysimeter measurements of bare soil evaporation and soil + grass evaporation. Similarly, the selected trees will be coupled with respiration measurements and will be used to partition a sub-canopy flux tower.

Ecosystem Ecology

As I scale up from plant-level to ecosystem scales, the functioning of plants begin to act as interacting systems in a different functional context. To understand ecosystem function and responses to water, I studied ecosystem ecology under Professors John Battles and Whendee Silver. Relevant topics included: water balance and budgets in global patterns of ecosystem distribution, energy and carbon balance, soil development and biology, nutrient cycling and decomposition, net primary productivity, population dynamics, equilibrium and non-equilibrium models of ecosystem dynamics, ecosystem development during primary and secondary succession, resource gradients on landscape patterns in ecosystem structure and function, biodiversity, and climate change. Ecosystem characteristics will guide the scaling of plant level measurements via sap flow to stand level responses via leaf area index (LAI) and percent cover. These same characteristics will guide scaling to remote sensing based on biophysical variables that can be made from various band spectrums like the normalized difference vegetation index (NDVI) and LAI relationship, temperature and thermal bands connection, and soil moisture and microwave spectrum link.

In my original proposal, I had planned on comparing a suite of process based and empirical evapotranspiration models (e.g. Monteith, 1965; Priestley and Taylor, 1972) to the ground-truthed measurements from the tower and tree scale measurements because remote sensing cannot detect evapotranspiration directly and thus evapotranspiration must be derived from models driven by various vegetation and meteorological variables. Evapotranspiration models vary widely in complexity from simple temperature driven methods to multi-layer process-based methods. Very few studies have compared evapotranspiration at forest ecosystems or FLUXNET sites not only because of a general focus on agriculture, but also because of the difficulty of obtaining evapotranspiration measurements for such an ecosystem. I have completed two papers on this objective, one of which I am primary author on and has been submitted to Environmental Modeling and Software, and the other of which I am secondary author on and has been submitted to Journal of Hydrology. The first paper scrutinizes the models in-depth, examines the mathematics and environmental variables, and includes uncertainty analyses; data used are from two growing seasons at the Blodgett Forest FLUXNET site. The second paper extends the analysis to multiple FLUXNET sites and focuses on site differences and similarities governing the model outcomes.

Remote Sensing of Natural Resources

Scaling from ecosystem measurements and evapotranspiration models to remote sensing relies on a combination of image processing, analysis and modeling. To understand remote sensing data acquisition, analysis, information extraction, and integration into geographic information systems (GIS), I studied Advanced Remote Sensing of Natural Resources under Professor Peng Gong. Relevant topics included: image calibration (radiometric, geometric, topographic), image enhancement (filtering, data reduction and transformation, texture measures), interpretation, classification, accuracy assessment, linear feature extraction, change detection, and multiple data source integration. In line with my NASA Earth System Science Fellowship, I focused on how spectral values translate into biophysical variables such as evapotranspiration; and, if effective models are developed, how we can validate those estimates since we cannot measure evapotranspiration directly on such large scales. Although many models exist that estimate evapotranspiration using remote sensing, the majority of those require ground measurements or weather station inputs. These inputs are infeasible in relatively inaccessible areas of the globe.

I reviewed two models that estimate evapotranspiration solely from remote sensing digital numbers: the “Simplified Method” (Jackson et al., 1977) and the NDVI-DSTV Triangle Method (Chen et al., 2002). To validate these models, I applied them to the Blodgett Forest FLUXNET study site using EO-1 imagery (Figure 1). The “Simplified Method” is used to obtain the integrated daily evapotranspiration from surface radiant temperature over variable vegetation (Carlson and Buffum, 1989; Carlson et al., 1995; Lagouarde, 1991; Lagouarde and McAneney, 1992; Nieuenhuis et al., 1985; Sandholt and Anderson, 1993; Seguin and Itier, 1983). The “Simplified Method” was designed to estimate evapotranspiration from a very few easily obtainable measurements, these being the surface radiant temperature near the time of local maximum (about 1300 h local time), a corresponding air temperature, and the net radiation integrated over a 24-h period. A common form of the model is as follows: LE = R_N – B(T_s – T_50m)ⁿ (cm/day) where LE is evapotranspiration, R_N is net radiation, T_s is surface temperature, T_50m is the air temperature at 50-m (obtainable from some weather stations and remote sensing), and B and n are functions of NDVI. The NDVI-DSTV (diurnal surface temperature variation) Method is based on the hypothesis that a triangle shape would result from a plot of NDVI and the difference between the surface temperatures obtained at day and night. Presence of green vegetation is a major determinant of evapotranspiration from the land surface due to enhanced surface roughness increasing turbulent exchange of water vapor and plant roots extracting water from the soil more rapidly than the water can diffuse to the soil surface (Smith and Choudhury, 1991). A multiple-regression equation from the values reported by Chen et al. (2002) for seven major land-cover types in south Florida is: ET = 6 + 6.4NDVI – 0.22DSTV. Surface temperature for both models can be estimated from the thermal bands in remote sensing alone, as specified by Kerr et al. (1992): T_s = C x T_v + (1 – C)T_soil; T_v = -2.4 + 3.6(Thermal 11mm) – 2.6(Thermal 12mm); T_soil = 3.1 + 3.1(Thermal 11mm) – 2.1(Thermal 12mm).

Although the “Simplified Method” significantly overestimated evapotranspiration relative to the slight overestimation by the NDVI-DSTV Triangle Method, the “Simplified Method” is more physically based than is the NDVI-DSTV Triangle Method because the former is bounded by net radiation. The upper bound to potential evapotranspiration should be the net radiation (under relatively stable conditions). According to energy balance models, incoming net radiation is partitioned into latent heat, sensible heat, and heat absorbed by the ground—therefore, latent heat, as a fraction of net radiation, should not exceed net radiation. A major problem with both models is the lack of soil moisture information—this absence is notably evident in areas or times of drought-stress such as in California. In the “Simplified Method,” only the surface temperature might increase if there was no soil moisture, but the estimated evapotranspiration would still be heavily weighted towards the net radiation. If there is no soil moisture to evaporate or transpire, then the net radiation becomes completely unimportant no matter how high or low it is. The NDVI-DSTV Triangle Method begins with an initial evapotranspiration of 174 W/m² to add to a value from the NDVI that would theoretically range from 0 to 185 W/m² (maximum of 359 W/m²). To account for lower bound from the soil moisture-surface temperature relationship, the DSTV would have to be 56ºC to estimate a zero evapotranspiration flux. These values are unrealistic, but not impossible, and the relationship between surface temperature and soil moisture must be examined closer to assess the lower bound of these models. Soil moisture, which varies widely throughout a landscape, affects land evaporation and plant transpiration, two processes that link the fluxes of energy (sensible and latent heat), water and carbon between land and atmosphere. New research has shown that wavelengths in the microwave portion of the spectrum respond to the amount of water present in the soil. Recent developments in both science and associated technologies now make the exploitation of the microwave region for soil moisture mapping feasible.

Sociology of Natural Resources

As an interdisciplinary scientist, I address the social dimension to biophysical research, and my focus in this project is ownership and intellectual property rights over shared data (e.g., FLUXNET or remote sensing) and models. I plan to submit a paper this summer on the relationship between data producers and data users over shared data whereby common property and intellectual property rights theory frame questions about ownership and usufruct rights, rewards, costs, and patents and copyrights. Based on semi-structured interviews, I documented and analyzed specific cases of successful and unsuccessful data sharing relationships. Ostrom’s seven design principles—clearly defined boundaries, appropriation rules related to local conditions, collective-choice arrangements, monitoring, graduated sanctions, conflict-resolution mechanisms, minimal recognition of rights to organize—provide a theoretical framework of rules that, if followed, will result in peaceful, long-lived self-governance of common property (Ostrom, 1991). In the cases analyzed, success (defined as lack of conflict or irresolvable disagreement) was marked by clearly defined boundaries, collective-choice arrangements, and conflict-resolution mechanisms. Data sharing is often confined to academia where the currency is frequently in the form of publication—when due payment (co-authorship) is not made, there tends to be conflict.

In addition, I have worked on furthering the exposure and application of GIS and spatial statistics into the social sciences. I have submitted an abstract to the conference of American Public Health Association on using GIS and spatial statistics for Environmental Justice and Air Toxics. I have a manuscript in preparation that I plan to submit following the conference.

Plans for the coming year

This summer I plan on working extensively in the field to gather data, processing satellite imagery for both field sites, and coding and testing some terrestrial ecosystem models such as BIOME-BGC, which is designed to simulate hydrologic processes across multiple scales (Running and Hunt, 1993). Remote sensing data integrated within an ecological process model framework provides an efficient mechanism to evaluate scaling behavior, interpret patterns in coarse resolution data, and identify appropriate scales of operation for various processes (Kimball et al., 1999). BIOME-BGC has been used to compare estimates of hydrologic processes to observed data for different boreal forest stands (Kimball et al., 1997), used to simulate water balance and evapotranspiration over a historical 88-year record for a broadleaf forest (White et al., 1999), and coupled with remote sensing information to evaluate the sensitivity of boreal forest regional evapotranspiration (Kimball et al., 1999). In addition to BIOME-BGC, I will investigate the Boreal Ecosystems Productivity Simulator (BEPS), which is based on the same principles as BIOME-BGC, but BEPS is modified to better represent canopy radiation processes (Chen et al., 1996; Liu et al., 1997). BEPS outputs spatial fields of evapotranspiration, and it has been used to upscale tower measurements of NPP to the Boreal Ecosystem-Atmosphere Study (BOREAS) study region by means of remote sensing and modeling (Liu et al., 1999). Further, I will consider a simple model of energy exchange between the land surface and the atmospheric boundary layer, driven primarily by remote sensing data, that partitions surface flux into latent and sensible heat (Mecikalski et al., 1999). I plan on taking my Ph.D. qualifying exam in the Fall, and will continue to expand my knowledge breadth with classes in soils and statistics.

Support

I will work closely with my UC Berkeley graduate advisor, Dr. Greg Biging, whose research is focused on remote sensing of natural resources. I will be working in conjunction with the Center for the Assessment and Monitoring of Forest and Environmental Resources (CAMFER) at the University of California, Berkeley, led by Drs. Greg Biging and Peng Gong, who both specialize in remote sensing of natural resources; CAMFER is a NASA-supported Center for Excellence in Remote Sensing Applications. At the Blodgett Forest field site, I will work with Dr. Allen Goldstein and his research group; at the Tonzi Ranch field site, I will work with Dr. Dennis Baldocchi and his research group. Furthermore, I will be collaborating with the Numerical Terradynamic Simulation Group (NTSG) at the University of Montana, led by Dr. Steven Running.

References

Carlson, T.N. and Buffum, M.J., 1989. On estimating total daily evapotranspiration from remote surface temperature measurements. Remote Sensing of Environment, 29: 197-207.

Carlson, T.N., Capehart, W.J. and Gillies, R.R., 1995. A new look at the Simplified Method for remote sensing of daily evapotranspiration. Remote Sensing of Environment, 54: 161-167.

Chen, J.H., Kan, C.E., Tan, C.H. and Shih, S.F., 2002. Use of spectral information for wetland evapotranspiration assessment. Agricultural Water Management, 55: 239-248.

Chen, J.M., Liu, J. and Cihlar, J., 1996. Boreal ecosystems productivity simulator (BEPS) using remote sensing, meteorological and soil data, 1996 Annual Combined Meeting of the Ecological Society of America on Ecologists/Biologists as Problem Solvers. Bulletin of the Ecological Society of America, Providence, Rhode Island, USA.

Goldstein, A.H., Hultman, N.E., Fracheboud, J.M., Bauer, M.R., Panek, J.A., Xu, M., Qi, Y., Guenther, A.B. and Baugh, W., 2000. Effects of climate variability on the carbon dioxide, water, and sensible heat fluxes above a ponderosa pine plantation in the Sierra Nevada (CA). Agricultural and Forest Meteorology, 101: 113-129.

Jackson, R.D., Reginato, R.J. and Idso, S.B., 1977. Wheat canopy temperature: a practical tool for evaluating water requirements. Water Resources Research, 13: 651-656.

Kerr, Y.H., Lagouarde, J.P. and Imbernon, J., 1992. Accurate land surface temperature retrieval from AVHRR data with use of an improved split window. Remote Sensing of Environment, 41: 197-209.

Kimball, J.S., Running, S.W. and Saatchi, S.S., 1999. Sensitivity of boreal forest regional water flux and net primary production simulations to sub-grid-scale land cover complexity. Journal of Geophysical Research-Atmospheres, 104(D22): 27789-27801.

Kimball, J.S., White, M.A. and Running, S.W., 1997. BIOME-BGC simulations of stand hydrologic processes for BOREAS. Journal of Geophysical Research-Atmospheres, 102(D24): 29043-29051.

Lagouarde, J.P., 1991. Use of NOAA-AVHRR data combined with an agrometeorological model for evaporation mapping. International Journal of Remote Sensing: 1853-1864.

Lagouarde, J.P. and McAneney, K.J., 1992. Daily sensible heat flux estimation from a single measurement of surface temperature and maximum air temperature. Boundary-Layer Meteorology, 59: 341-362.

Liu, J., Chen, J.M., Cihlar, J. and Chen, W., 1999. Net primary productivity distribution in the BOREAS region from a process model using satellite and surface data. Journal of Geophysical Research-Atmospheres, 104(D22): 27735-27754.

Liu, J., Chen, J.M., Cihlar, J. and Park, W.M., 1997. A process-based boreal ecosystem productivity simulator using remote sensing inputs. Remote Sensing of Environment, 62(2): 158-175.

Mecikalski, J.R., Diak, G.R., Anderson, M.C. and Norman, J.M., 1999. Estimating fluxes on continental scales using remotely sensed data in an atmospheric-land exchange model. Journal of Applied Meteorology, 38(9): 1352-1369.

Monteith, J.L., 1965. Evaporation and the environment. Symposium of the Society of Exploratory Biology, 19: 205-234.

Nieuenhuis, G.J.A., Schmidt, E.A. and Tunnissen, H.A.M., 1985. Estimation of regional evapotranspiration of arable crops from thermal infrared images. Journal of Remote Sensing, 6(1319-1334).

Ostrom, E., 1991. Governing the Commons: The Evolution of Institutions for Collective Action. Cambridge University Press, Cambridge.

Priestley, C.H.B. and Taylor, R.J., 1972. On the assessment of surface heat flux and evaporation using large scale parameters. Monthly Weather Review, 100: 81-92.

Running, S.W. and Hunt, E.R., Jr., 1993. Generalization of a forest ecosystem process model for other biomes, BIOME-BGC, and an application for global-scale models. In: J.R. Ehrlinger and C. Field (Editors), Scaling Processes between Leaf and Landscape Levels. Academic Press, San Diego, CA, pp. 141-158.

Sandholt, I. and Anderson, H.S., 1993. Derivation of actual evapotranspiration in the Senegalese Sahel, using NOAA-AVHRR data during the 1987 growing season. Remote Sensing of Environment, 46: 164-172.

Seguin, B. and Itier, B., 1983. Using midday surface temperature to estimate daily evaporation from satellite thermal IR data. International Journal of Remote Sensing, 4: 371-383.

Smith, R.C.G. and Choudhury, B.J., 1991. Analysis of normalized difference and surface temperature observations over southeastern Australia. International Journal of Remote Sensing, 12(10): 2021-2044.

White, M.A., Running, S.W. and Thornton, P.E., 1999. The impact of growing-season length variability on carbon assimilation and evapotranspiration over 88 years in the eastern US deciduous forest. International Journal of Biometeorology, 42(3): 139-145.

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Year 2
progress report

glossary of the principal mathematical symbols
with commonly recognized variants

introductory
brush up your arithmetic
some points in algebra
comparisons of magnitudes
shapes and numbers
logarithms
graphical aids to calculation
rates of change
the calculation of small changes
relations involving rates of change
lengths areas and volumes
acceleration greatest and least values
series
directed magnitudes
some useful integrals
physical and chemical magnitudes
methods of solving equations
matrices
change and probability
distributions
simple statistical procedures
colson notation arithmetic made easy

Databases at The Swedish Museum of Natural History

http://www.nrm.se/researchandcollections/databases.4.5fdc727f10d795b1c6e80008884.html
North American Breeding Bird Survey Home http://www.pwrc.usgs.gov/BBS/index.html
Ecological Monitoring and Assessment Network http://www.eman-rese.ca/eman/
environmental information centre(NERC)
"european topic center on catalogue of data sources" european environmental agency
forest inventory and analysis US forest service
global change master directory NASA
global population dynamics database center for population biology, NSF
ISRIC soil information system
LTER
national environmental data index NOAA nedi.gov
national environmental satellite data and information service NESDIS/ NOAA
National geophysical data center NGDC NOAA
National ocean data center NODC NOAA
national soils data access facility NSDAF NRCS
national water information system NWIS USGS
NERC data centres www.nerc.ac.uk
threatened and endangered species US FWS US forest and wildlife service
national climatic data center www.ncdc.noaa.gov
carbon dioxide information analysis center cdiac.esd.ornl.gov
distributed active archive center for biogeochemical dynamics(ORNL DAAC) www-eosdis.ornl.gov

Research Beyond Google: 119 Authoritative, Invisible, and Comprehensive Resources | OEDb

How to Read a Scientific Research Paper-- 发布帖子

Actinidia deliciosa - Plants For A Future database report

Weaver/Molecular Biology

甘草5克 黄连5克 加水武火煮开,文火煮20分钟,滤出药水,呈透明黄色.
两种喂服方法:
1、用小毛笔沾药汁滴入新生宝宝口中，一次滴10-15滴，不限次数。
2、用温白开水稀释药汁，用奶瓶喂给新生宝宝喝，不限次数。
注意：
此方法用于1-5天内新生儿
新生宝宝服用后会多次排便，基本上会在出生3天内排净胎便，一但便便 已经从黑色转变为黄色，就可停药了。

Darwin Foundation, Galapagos Islands, The Charles Darwin Foundation in Galapagos, Charles Darwin Research Station Galapagos, Galapagos National Park, Ecuador

Darwinizing Culture

genebial - sas 资源

Forceps delivery