Honey Mesquite Transpiration along a Vertical Site Gradient

2003

In the arid Southwest United States, monsoon precipitation plays a key role in ecosystem water balance and productivity. The sensitivity of deeply rooted plants to pulses of summer precipitation is, in part, controlled by the interaction between soil texture, precipitation intensity, and plant rooting depth and activity. In this study we evaluated the water relations of a leguminous tree species Prosopis velutina Woot. (velvet mesquite) occurring across three different aged soils varying in soil texture during two consecutive summers that substantially differed in the amount of monsoonal precipitation (1999 and 2000). We predicted that mesquite trees occurring on different textured geomorphic surfaces would be exposed to different levels of premonsoon water deficit and would not respond equally to summer precipitation. During both years, predawn and midday leaf water potentials were more negative on coarse textured soils than on medium and fine textured soils before the onset of the...

Journal of Hydrology, 1997

The effect of applied water on water use in Tamarix ramosissima (saltcedar) was investigated along the Virgin River (SE Nevada) during a hot, dry summer period. Water was applied to 4 m 2 (2 m x 2 m) basins surrounding Tamar/x thickets once per week for 6 weeks. Irrigations were applied at 0, 50 or 100% of the previous weeks potential evapotranspiration estimate using a modified Penman equation. Transpiration was monitored with stem flow gauges, soil moisture with time domain reflectometry and plant water relations with a steady state porometer and pressure chamber. Results indicated that at least 4 weeks of irrigation were required before a significant increase in water use by Tamar/x would occur. Sap flow measurements indicated that Tamar/x growing in closed stands (canopy over-lapping on three or more sides) transpired higher amounts of water than Tamarix growing in open stands (canopy not over-lapping on any sides). Ratios of post-to predepth weighted salinity in the 0-60 cm depth indicated that water uptake was occurring in this soil region by Tamar/x growing in closed stands to a greater extent than in open stands. A multiple regression equation accounted for 87% of the variability (P = 0.001) in Tamar/x transpiration normalized on a stand volume basis when irrigation volume, leaf area density and average ratio of height to distance of nearest neighboring trees were included in the equation. We conclude that any attempt to characterize evapotranspiration of mature stands of Tamarix will require a detailed spatial assessment of stand density and an evaluation of water availability relative to atmospheric water demand over time and that it is doubtful under typical hot, dry summer conditions that Tamar/x would effectively utilize water from most summer rainfall events. However, if alterations occurred along the river that increased the availability of water to Tamarix, increased transpiration rates would occur with time.

Journal of Range Management, 1983

Honey mequite [Prosopisllrliitro (Swutz) DC. vu.ghmdu~a (Torr.) Cockcreii] response to spnys of 2,4&T [(2,4,5-tricbio-Wb-xY)8=ti-W8ndpiflorun(-*rcid) + 2,4,5-T ~8s ev8iu8ted urd correlated with nuximum driiy photosynthetic rate, upwud movement of methyiene dye, xylem pressure potentW, 8nd percent soii w8ter. Piciorun + 2,4,5-T ~8s superior to 2,4,5-T 8lone for kiiling honey mesquite from M8y 15 through Augusl4. Time of d8y the herbicide ~8s rppiied h8d no dgnifiant effect on control. M8ximum d8iiy photosynthetic rrte varied from 32.9 to 10.1 mg Co1 dm-' ie8fue8 hr-' 8nd ~88 highly correi8ted (r = 0.89 to 0.92) with honey menquite control with herbicides. R8te of upwud movement of methykne blue dye in the xylem vuied from 295 to 44 cm hr-'. (MP8) while soil w8ter content v8ried from 11.5 to 18.6%. UpwUa movement of methyiene blue dye, xylem pressure potenti 8nd percent soii w8ter were not signifkantiy correi8ted with honey mesquite control. Honey mesquite [Rosopis julr&'ora (Swartx) DC. var. glandu-Zosa (Torr.) Cockerell], a woody perennial of the Leguminosae, is adapted to a broad range of environmental conditions. It is distributed throughout much of the southwestern United States and occupies about 25 million ha of Texas rangeland (Smith and Rechenthin 1964). Honey mesquite is generally controlled by foliar sprays of 2,4,5-T [(2,4,Qrichlorophenoxy)acetic acid], picloram (4-amine-3,5,6-trichloropicolinic acid) + 2,4,5-T, or dicamba (36 dichloro-o-anisic acid) + 2,4,5-T, by basal treatment with diesel oil; or by mechanical treatments including bulldozing or chaining. Also, karbutilate [tert-butylcarbamic acid ester with 3(m-hydro-xyphenyl>l,l-dimethylurea[ and tebuthiuron {

Agricultural Water Management, 2002

Analysis of ®eld water balance components provides information necessary to minimize the risk of offsite movement of contaminants from crop production practices or animal manure applications. The objective of this study was to determine the timing and amount of surface runoff and drainage from the root zone for a hillslope in the Ozark Highlands of US. A 0.4 ha watershed with slopes of 8± 20% having tall fescue (Festuca arundinacea Schreb.) cover was established in northwestern Arkansas (35856 H W, 93851 H N). Continuous measurements of water balance parameters were made from June 1997 to August 1998. Soil water drainage was estimated as the residual of weekly water balance calculations. Runoff occurred in response to three precipitation events in the winter of 1998 and totaled 30.6 mm of water or 2.6% of the 1185 mm of precipitation that fell at the site during the study period. Storms of comparable or greater intensity during other seasons failed to produce runoff, a result that was likely due to dry soil conditions and taller grass canopy. Drainage through the root zone totaled 117 mm and occurred primarily during an 83-day interval in the winter of 1998. The water balance was dominated by evaporation, which accounted for 91% (1080 mm) of the precipitation. Tall fescue was capable of sustaining relatively high evaporation rates between infrequent summer rains thereby dewatering the soil pro®le, which was not replenished until winter. Delaying spring animal manure applications in the Ozarks until evaporation has increased and the soil pro®le has begun to dry would decrease the risk of offsite transport of potential contaminants contained in the manure. Published by Elsevier Science B.V. (T.J. Sauer).

Hydrological Processes, 2021

Quantifying the spatial variability of species-specific tree transpiration across hillslopes is important for estimating watershed-scale evapotranspiration (ET) and predicting spatial drought effects on vegetation. The objectives of this study are to (1) assess sap flux density (J s) and tree-level transpiration (T s) across three contrasting zones a (riparian buffer, mid-hillslope and upland-hillslope, (2) determine how species-specific J s responds to vapour pressure deficit (VPD) and (3) estimate watershed-level transpiration (T w) using T s derived from each zone. During 2015 and 2016, we measured J s in eight tree species in the three topographic zones in a small 12-ha forested watershed in the Piedmont region of central North Carolina. In the dry year of 2015, loblolly pine (Pinus taeda), Virginia pine (Pinus virginiana) and sweetgum (Liquidambar styraciflua) J s rates were significantly higher in the riparian buffer when compared to the other two zones. In contrast, J s rates in tulip poplar (Liriodendron tulipifera) and red maple (Acer rubrum) were significantly lower in the buffer than in the mid-hillslope. Daily T s varied by zone and ranged from 10 to 93 L/day in the dry year and from 9 to 122 L/day in the wet year (2016). J s responded nonlinearly to VPD in all species and zones. Annual T w was 447, 377 and 340 mm based on scaled-J s data for the buffer, mid-hillslope and uplandhillslope, respectively. We conclude that large spatial variability in J s and scaled T w was driven by differences in soil moisture at each zone and forest composition. Consequently, spatial heterogeneity of vegetation and soil moisture must be considered when accurately quantifying watershed level ET.

Journal of Hydrology, 2008

To improve basin-scale modeling of ground water discharge by evapotranspiration (ET) in relation to water table depth, daily ET was measured using the Bowen ratio energy balance method during 1999-2005 in five herbaceous plant dominated wetlands in an arid intermountain basin in Colorado, USA. Three wetlands were wet meadows supplied primarily by regional ground water flow and two were playas supplied primarily by local stream flow. In wet meadows, mean daily water table depth (WTD) ranged from 0.00 m (ground surface) to 1.2 m, with low inter-annual variability. In wet meadows, annual actual ET (ET a) was 751-994 mm, and ground water discharge from the shallow aquifer (ET g) was 75-88% of ET a. In playas, mean daily WTD ranged from À0.65 to 1.89 m, with high inter-annual variability. In playas, annual ET a was 352-892 mm, and ET g was 0-77% of ET a. The relationship of annual ET g to WTD was compared to existing ET g-WTD models. For wet meadows, ET g decreased exponentially as WTD increased from 0.13 to 0.95 m (r 2 = 0.83, CV = 5%, p < 0.001). In comparison with our findings, existing models under-and overestimate ET g by À30% to 47% at WTD of 0.13 m, and they underestimate ET g by À12% to À42% at WTD of 0.95 m. This study found that as the water table declined from near the soil surface to 0.95 m, ET g decreased only $26% versus 39-55% estimated by existing models. The magnitude of ET g decrease was 220 mm, whereas existing models predicted decreases up to 700 mm (218% greater). In playas, there was no clear ET g-WTD relationship. Instead, ET g was strongly dependent on the surface water supply. When sufficient surface water inputs occurred to meet ET demand, ET g was %0 mm/yr and independent of WTD. When inputs did not meet ET demand, ET g was positive though highly variable at WTD up to 1.68 m.

Transactions of the ASABE, 2013

Quantifying actual evapotranspiration (ET a) of riparian zones is important for more robust water balance analyses that will enable better planning, managing, and allocating of water resources as well as developing strategies to protect delicate riparian ecosystem functions. The ET a , sensible heat flux (H), net radiation (R n), soil heat flux (G), meteorological variables (air temperature, T a ; incoming shortwave radiation, R s ; wind speed, u 3 ; relative humidity, RH; vapor pressure deficit, VPD; precipitation, etc.), and albedo were measured on an hourly time step, and leaf area index (LAI) and plant height were measured on a weekly basis for a common reed (Phragmites australis) dominated cottonwood (Populus deltoides) and peach-leaf willow (Salix amygdaloides) riparian plant community in 2009 and 2010 through extensive field campaigns conducted in the Platte River basin in central Nebraska. The two growing seasons were contrasted by warmer air temperatures, higher precipitation, and presence of flood water on the surface during the 2010 season. The seasonal variations of daily average ET a were mainly controlled by R n and air temperature. In 2009, total ET a and precipitation were 679 mm and 280 mm, respectively, and the values were substantially greater in 2010 (982 mm and 508 mm, respectively). The seasonal daily ET a for the mixed plant community ranged from 0.5 to 8.5 mm d-1 with a seasonal average of 3.7 mm d-1 in 2009 and from 0.5 to 11 mm d-1 with a seasonal average of 5.5 mm d-1 in 2010. In 2010, ET a varied widely with meteorological conditions and in response to variations in phenology of the vegetation to flooding. In 2009, on a seasonal average basis, a total of 77% and 14% of the available energy was partitioned into ET a and H, respectively. In 2010, over 90% and-12% (negative due to flooding) of the available energy was partitioned into ET a and H, respectively. The research results presented here provide valuable ET a data and information for enhancing the understanding of the interactions between the surface/vegetation conditions and the surrounding microclimate and surface energy balance for mixed riparian vegetation. The results of this research should aid water managers and decision/policy makers in accounting for water use rates of phragmites-dominated cottonwood and peach-leaf willow riparian plant communities in water balance analyses to make better-informed water resources planning and management decisions.

2000

Interest in transport of dissolved nitrogen (N) and carbon (C) in forested ecosystems is growing because of potential effects of these solutes on streamwater quality and implications for C sequestration. Additional research will further the understanding about the dynamics of these soil solutes, particularly in response to harvesting of forests. Also, the purported role of riparian buffers, where logging is restricted along stream channels, in retaining soil solutes is not well studied in the steeply sloping terrain of the southern Appalachian Mountains. I examined solute transport in a first-order watershed in the Nantahala National Forest in North Carolina that was harvested in February 2006 with retention of a 10-m riparian buffer. To quantify the movement of dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), and dissolved organic carbon (DOC), four transects of lysimeters, approximately 30 m apart, were installed perpendicular to the stream on one hillslope. Porous ceramic cup (2-bar) lysimeters were installed in each transect 1, 4, 10, 16, 30, and 50 m from the stream in the A horizon and B horizon, and 4, 16, and 50 m from the stream in the saprolite layer. Samples were removed from the lysimeters 24 hr after 50 centibars of tension were placed on them, and riparian groundwater well and stream samples were collected at the same time as lysimeter samples. Collection of samples from the lysimeters, wells, and stream occurred every four to six weeks for one calendar year beginning March 2007. A 16-wk laboratory N mineralization study was conducted on A horizon soils. Mean nitrate values in the soil solution of the A horizon in the spring were 1.53mg-N/L and decreased through the growing season to 0.030mg-N/L. Mean soil solution nitrate values in the B horizon and saprolite layer were 0.40mg-N/L in the spring and summer and decreased to 0.031mg-N/L in the winter. Mean soil solution ammonium concentrations were higher in the A horizon (0.090mg-N/L) than the B horizon and saprolite layer (0.034mg-N/L) and were lowest during the summer and fall. Dissolved organic C was significantly higher in the A horizon, with values ranging from 2.3mg/L to 599mg/L, than in the relatively stable B horizon and saprolite (1.9mg/L to 36.6mg/L). Dissolved organic C was logarithmically correlated to DON (r 2 = 0.64), and DON values were highest in the A horizon (0.70mg/L). Cumulative N mineralization potential ranged from 48.1mg-N/kg to 75.6mg-N/kg and was not a useful predictor for nitrate soil solution values.

Journal of Range Management, 1991

This study examined water loss by fully grown honey mesquite (Prosopis glan&dosa var. glandidosa Torr.) trees at 2 levels of resolution, the whole plant (canopy) and the individual leaf. Trees were manipulated by severing lateral roots during winter dormancy. Leaf transpiration and photosynthesis were measured in root-severed and unsevered (control) trees for 2 growing seasons following treatment. An empirical model which integrated leaf transpiration, whole plant leaf area, and influence of shading within the canopy on leaf transpiration was used to calculate dally water loss from individual trees. During the flnt growing season leaf abscision occurred on root-severed, but not control trees, in early July, resulting in a 50% reduction in whole plant leaf area. Following abscission, transpiration and photosynthesis of rc malning leaves on root-severed trees were significantly greater than on control trees from July through September. Because of increased transpiration of remaining leaves on root-severed trees, dally water loss per tree was not significantly different between root-severed and similar-size control trees before or after leaf abscission. No differences in leaf or canopy transplratlon were found between root-severed or unsevered honey mesquite during the second growing season. Daily water loss per tree ranged from 30 to 75 liters during the study. These responses illustrate that water loss from mesquite may be regulated by various combinations of stomata1 control and adjustment of transpirational surface area.

1951