Sap-Feeding Behavior and Tree Selection in the Endangered Akiapolaau (Hemignathus Munroi) in Hawaii

Abstract The Akiapolaau (Hemignathus munroi), an endangered Hawaiian honeycreeper, drills 3–5 mm deep holes in particular ohia trees (Metrosideros polymorpha) and drinks the sap that emerges, a remarkable example of convergent evolution in sap-feeding behavior with mainland woodpeckers and Australian sugar-gliders. There has been little research on how this species selects sap trees (“Aki trees”) and what advantages they confer. We marked the locations of and collected sap samples and microhabitat data from 101 Aki trees and 73 randomly selected control trees in Hakalau Forest National Wildlife Refuge, Hawaii. Aki trees were rare (2 ha−1), spatially clustered, and defended by Akiapolaau. Sap flow volume and speed were substantially greater in Aki trees than in controls. Aki trees also were larger, had thinner bark, and were more likely to be located on convex east-facing slopes where more light is available. Those results support the hypothesis that Aki trees are selected on the basis of high sap flow and a suite of unique microhabitat and tree characteristics. Sap may be an important energy source in times of low insect availability and a potent alternative to nectar for the Akiapolaau. Aki trees are both a fascinating example of niche specialization and a factor that should be considered when conserving or restoring habitat for this endangered species.

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Dynamics of xylem and phloem sap flow in an outdoor zelkova tree visualized by magnetic resonance imaging

Tree Physiology ◽

10.1093/treephys/tpz120 ◽

2019 ◽

Vol 40 (3) ◽

pp. 290-304

Author(s):

Yasuhiko Terada ◽

Yusuke Horikawa ◽

Akiyoshi Nagata ◽

Katsumi Kose ◽

Kenji Fukuda

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Cross Section ◽

Sap Flow ◽

Diurnal Changes ◽

Flow Volume ◽

Resonance Imaging ◽

Flow Measurements ◽

Phloem Sap ◽

Xylem Flow

Abstract Xylem and phloem sap flows in an intact, young Japanese zelkova tree (Zelkova serrata (Thunb.) Makino) growing outdoors were measured using magnetic resonance imaging (MRI). Two propagator-based sequences were developed for q-space imaging: pulse field gradient (PFG) with spin echo (PFG-SE) and stimulated echo (PFG-STE), which were used for xylem and phloem flow measurements, respectively. The data evaluation methods were improved to image fast xylem flow and slow phloem flow. Measurements were taken every 2–3 h for several consecutive days in August 2016, and diurnal changes in xylem and phloem sap flows in a cross-section of the trunk were quantified at a resolution of 1 mm2. During the day, apparent xylem flow volume exhibited a typical diurnal pattern following a vapor pressure deficit. The velocity mapping of xylem sap flow across the trunk cross section revealed that the greatest flow volume was found in current-year earlywood that had differentiated in April–May. The combined xylem flow in the 1- and 2-year-old annual rings also contributed to one-third of total sap flow. In the phloem, downward sap flow did not exhibit diurnal changes. This novel application of MRI in visualization of xylem and phloem sap flow by MRI is a promising tool for in vivo study of water transport in mature trees.

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Sap-Feeding Behavior and Tree Selection in the Endangered Akiapolaau (Hemignathus munroi) in Hawaii

The Auk ◽

10.2307/4090418 ◽

2004 ◽

Vol 121 (2) ◽

pp. 548-556

Keyword(s):

Feeding Behavior ◽

Sap Feeding

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“Late Winter/Early Spring” Xylem Sap Characteristics Influence Pecan Crop Load

HortScience ◽

10.21273/hortsci.49.7.886 ◽

2014 ◽

Vol 49 (7) ◽

pp. 886-890 ◽

Cited By ~ 1

Author(s):

Bruce W. Wood

Keyword(s):

Sap Flow ◽

Xylem Sap ◽

Sampling Period ◽

Field Studies ◽

Early Spring ◽

Late Winter ◽

Flow Volume ◽

Alternate Bearing ◽

Simple Carbohydrates ◽

Individual Trees

Alternate bearing (AB) by individual trees is a major biological problem faced by pecan [Carya illinoinensis (Wangenh.) K. Koch] nut producers. The linkage between flowering and subsequent cropload with xylem sap characteristics at the time of floral bud swelling and expansion is unknown. Multiyear field studies of mature ‘Cheyenne’ and ‘Moneymaker’ trees, in “on” or “off” phases of AB, were evaluated regarding this linkage. Xylem sap flowing from trunks of ‘Cheyenne’ trees just before, and at the time of, budbreak (i.e., “late winter/early spring”) consisted of a variety of simple sugars. These were hexoses (fructose and glucose), a disaccharide (sucrose), polysaccharides (raffinose and stachyose), and sugar alcohols (xylitol and sorbitol). Sucrose was the overwhelmingly dominant simple carbohydrate at this growth stage, comprising 55% to 75% of the total molar composition, regardless of tree bearing status or sampling time during the seasonal transition from late winter to early spring as buds swell, break, and begin to produce shoots and flowers. Both sap flow volume and concentration of individual carbohydrates were much greater in “on” phase than “off” phase trees. “On” phase xylem sap contained ≈19.9-fold more sucrose than sap from “off” phase trees. The concentration of all sap carbohydrates was much greater at flow inception, declining quickly as buds transition from “bud swell” to “budbreak” and subsequent “shoot growth.” Depending on crop year, individual “on” phase ‘Cheyenne’ trees (≈25 years old) exhibited flow volumes 5.5- to 20.2-fold greater than “off” phase trees. In-shell nut yield by both ‘Cheyenne’ and ‘Moneymaker’ trees (110 years old) increased hyperbolically with increasing “late winter/early spring” sap flow volume. Sap flow from ‘Cheyenne’ and ‘Moneymaker’ resulted in near maximum nut yield when flow volume per xylem tap peaked was at ≈10 L/tree and ≈15 L/tree, respectively, over a 16-day sampling period. These findings are suggestive that sucrose, and possibly other simple carbohydrates, moving acropetally toward axillary bud meristems of shoots during “late winter/early spring” at about the time of “bud swelling” influences the final phase of floral development and therefore subsequent cropload.

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Maple syrup from Manitoba maple (Acer negundo L.) on the Canadian prairies

The Forestry Chronicle ◽

10.5558/tfc73327-3 ◽

1997 ◽

Vol 73 (3) ◽

pp. 327-330 ◽

Cited By ~ 1

Author(s):

John Kort ◽

Patricia Michiels

Keyword(s):

Key Words ◽

Sap Flow ◽

Sugar Maple ◽

Sugar Content ◽

Flow Volume ◽

Canadian Prairies ◽

Maple Syrup ◽

Acer Negundo ◽

Commercial Scale

Manitoba maple (Acer negundo L.), which occurs naturally throughout Saskatchewan and Manitoba and has been planted extensively in prairie shelterbelts, is now beginning to be used to produce maple syrup on a small commercial scale. The product is a light-coloured syrup which has been judged to have a distinctly pleasant flavour. The product is presently sold locally with an emphasis on its distinctiveness of flavour and its origin on the prairies. Studies completed at Indian Head, Saskatchewan show that sap sugar content is slightly less than that of the sugar maple and that its sap flow volume is considerably lower. A three year mean sap yield of 9.8 L per tap resulted in a syrup yield of 0.23 L per tap. This is about one quarter to one half of that in a sugar maple. Key words: Maple syrup, Manitoba maple, prairie shelterbelts

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SAP-FEEDING BEHAVIOR AND TREE SELECTION IN THE ENDANGERED AKIAPOLAAU (HEMIGNATHUS MUNROI) IN HAWAII

The Auk ◽

10.1642/0004-8038(2004)121[0548:sbatsi]2.0.co;2 ◽

2004 ◽

Vol 121 (2) ◽

pp. 548 ◽

Cited By ~ 10

Author(s):

Liba Pejchar ◽

Jack Jeffrey

Keyword(s):

Feeding Behavior ◽

Sap Feeding

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On the Use of Sap Flow Measurements to Assess the Water Requirements of Three Australian Native Tree Species

Agronomy ◽

10.3390/agronomy12010052 ◽

2021 ◽

Vol 12 (1) ◽

pp. 52

Author(s):

Xi Sun ◽

Jie Li ◽

Donald Cameron ◽

Gregory Moore

Keyword(s):

Soil Moisture ◽

Tree Species ◽

Sap Flow ◽

Potential Evapotranspiration ◽

Vapour Pressure Deficit ◽

Weather Conditions ◽

Pulse Velocity ◽

Ratio Method ◽

Flow Volume ◽

Flow Measurements

The measurement of sap movement in xylem sapwood tissue using heat pulse velocity sap flow instruments has been commonly used to estimate plant transpiration. In this study, sap flow sensors (SFM1) based on the heat ratio method (HRM) were used to assess the sap flow performance of three different tree species located in the eastern suburbs of Melbourne, Australia over a 12-month period. A soil moisture budget profile featuring potential evapotranspiration and precipitation was developed to indicate soil moisture balance while the soil-plant-atmosphere continuum was established at the study site using data obtained from different monitoring instruments. The comparison of sap flow volume for the three species clearly showed that the water demand of Corymbia maculata was the highest when compared to Melaleuca styphelioides and Lophostemon confertus and the daily sap flow volume on the north side of the tree on average was 63% greater than that of the south side. By analysing the optimal temperature and vapour pressure deficit (VPD) for transpiration for all sampled trees, it was concluded that the Melaleuca styphelioides could better cope with hotter and drier weather conditions.

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