Growth and Water Relations of Pinus Ponderosa Seedlings in Competitive Regimes with Arctostaphylos patula Seedlings

1986 ◽  
Vol 23 (3) ◽  
pp. 957 ◽  
Author(s):  
L. J. Shainsky ◽  
S. R. Radosevich
1999 ◽  
Vol 14 (4) ◽  
pp. 194-199 ◽  
Author(s):  
Philip M. McDonald ◽  
Celeste S. Abbott ◽  
Gary O. Fiddler

Abstract Vegetation management can direct trends in early plant development and species succession and through various treatments achieve specific combinations of species desired by the ecosystem manager. Density and development of several plant species were studied in an area in northern California that was planted with 1-yr-oldponderosa pine (Pinus ponderosa var. ponderosa) seedlings in 1986 and treated with three herbicides (Velpar L, Garlon 4, Escort) in fall 1986 and spring 1987. Abundant species in the new plantation were bush chinquapin (Chrysolepis sempervirens) that regenerated from root crowns, greenleaf manzanita (Arctostaphylos patula)from seed, and bracken fern (Pteridium aquilinum var. pubescens )from rhizomes. After 11 growing seasons, chinquapin sprouts in the control averaged more than 15,900/ac, manzanita seedlings over 16,400/ac, and bracken fronds 11,400/ac. Mean ponderosa pine diameter (5.1 in.), height (12.9 ft), and crown diameter (7.6 ft) were significantly greater in the Velpar treatment than in the control. Additional information is presented on plant diversity, the onset of statistically significant differences among treatments for pine, and the makeup of the plant community in the near future. West. J. Appl. For. 14(4):194-199.


2001 ◽  
Vol 31 (11) ◽  
pp. 1947-1957 ◽  
Author(s):  
K R Hubbert ◽  
J L Beyers ◽  
R C Graham

In the southern Sierra Nevada, California, relatively thin soils overlie granitic bedrock that is weathered to depths of several metres. The weathered granitic bedrock is porous and has a plant-available water capacity of 0.124 m3·m–3, compared with 0.196 m3·m–3 for the overlying soil. Roots confined within bedrock joint fractures access this rock-held water, especially during late summer when overlying soils are dry. We sought to determine seasonal soil and bedrock water changes in a Jeffrey pine (Pinus jeffreyi Grev & Balf.) plantation and to examine concurrent effects on the water relations of Jeffrey pine and greenleaf manzanita (Arctostaphylos patula Greene). In 1996, plant-available water in the 75 cm thick soil was depleted by late June, with soil water potential (ψsoil) <–2.2 MPa, but below 75 cm, bedrock water potential (ψbedrock) was still > –2.2 MPa. Thus, the bedrock, not the soil, supplied water to plants for the remainder of the dry season. Higher values of, and smaller fluctuations in, seasonal predawn pressure potential (ψpredawn) for Jeffrey pine indicated that it is deeply rooted, whereas active roots of greenleaf manzanita were interpreted to be mostly within the upper 100 cm. The extra rooting volume supplied by weathered bedrock is especially important to pine relative to manzanita.


2020 ◽  
Author(s):  
Gerard Sapes ◽  
Patrick Demaree ◽  
Ylva Lekberg ◽  
Anna Sala

AbstractCarbon and water relations are fundamental to plant life and strongly interact. Under drought, the ability of plants to assimilate carbon is reduced, which increases their consumption of stored labile carbon in the form of non-structural carbohydrates (NSC). This process may impair plant water relations, but mechanisms are not clear, and we do not know if their effects are independent of water deficit. If so, carbon costs of fungal symbionts could also indirectly influence drought tolerance of plants through stored NSC depletion. We connected well-watered Pinus ponderosa seedling pairs via ectomycorrhizal (EM) networks where one seedling was shaded and the other experienced full light and compared responses to seedling pairs in the light. We measured plant water relations and traced carbon movements using 13CO2 to explore the mechanisms linking stored NSC to water relations, and to identify potential tradeoffs between drought tolerance and maintaining EM fungi under carbon-limiting conditions. We found that even in the absence of drought, mild NSC depletion decreased plant drought tolerance by indirectly impairing osmoregulation capacity and turgor maintenance. This demonstrates that NSC storage influences plant drought tolerance independently of plant water status. We also found that EM networks propagated NSC depletion and its negative effects on drought tolerance from carbon stressed hosts to non-stressed hosts. These results highlight carbon allocation tradeoffs between supporting fungal symbionts and retaining water via stored NSC and have implications for biotic interactions and forest drought responses.Significance StatementThe potential effects of future drought on global carbon cycles, vegetation-climate feedbacks, species distributions and their ecological impacts, urgently call for a clear understanding of factors influencing vegetation tolerance to drought. Key to this is the understanding of mechanisms and processes by which plants tolerate drought and how prevalent plant-fungal interactions may influence these processes.We demonstrate that even mild depletion of plant non-structural carbohydrate (NSC) storage readily decreases plant water retention capacity, therefore decreasing tolerance to drought. Because plant-fungal interactions depend on NSC exchange, plants face carbon-allocation tradeoffs between maintaining drought tolerance and feeding fungal symbionts. The impacts of these tradeoffs extend across plants connected via ectomycorrhizal networks as fungi propagate NSC depletion from NSC-limited plants to non-stressed individuals.


1994 ◽  
Vol 9 (1) ◽  
pp. 24-28
Author(s):  
Philip M. McDonald ◽  
Celeste S. Abbott ◽  
Gary O. Fiddler

Abstract One-year-old Sierra chinkapin (Castanopsis sempervirens) sprouts, greenleaf manzanita (Arctostaphylos patula var. platyphylla) seedlings, and new fronds of bracken fern (Pteridium aquilinum var. pubescens), present in a 1-yr-old ponderosa pine (Pinus ponderosa var. ponderosa) plantation in northern California, were treated once with one of three herbicides (Velpar L, Escort, and Garlon 4) in fall 1986 and spring 1987 and their density and development compared among treatments and to a control. After 6 growing seasons, chinkapin sprouts in the control averaged more than 16,000 per acre, manzanita seedlings over 19,000, and bracken ferns more than 13,000 per acre. After 6 growing seasons, mean ponderosa pine diameter ranged from 2.03 in. in the Velpar treatment to 1.28 in. in the control. Cover of combined shrubs, also after six seasons, was about 3% with Velpar, 7% with Garlon, 20% with Escort, and 51% in the control. Bracken fern cover was greatest (13%) where foliage-active Garlon reduced competing shrubs, and least in the soil-active Velpar treatment (2%) and the control (3%), where heavy competition from shrubs precluded establishment. West. J. Appl. For. 9(1):24-28.


Weed Science ◽  
1984 ◽  
Vol 32 (3) ◽  
pp. 395-402 ◽  
Author(s):  
Sandra M. Paley ◽  
Steven R. Radosevich

Correlations between herbicide damage and several physiological factors were examined in the field for ponderosa pine (Pinus ponderosaDougl. ex P&C Lawson) and greenleaf manzanita (Arctostaphylos patulaGreene). Pine injury caused by 2,4-D [(2,4-dichlorophenoxy) acetic acid], glyphosate [N-(phosphonomethyl) glycine], or triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid]} was compared to leader growth rate, needle growth rate, predawn xylem potential, daytime xylem potential, and photo synthetic rate occurring on the dates of herbicide application. Shrub injury for each of the three herbicides was compared to predawn xylem potential, daytime xylem potential, and photo synthetic rates. Both species exhibited less injury from herbicide applications made at the end of September than from any applications made from April through October. Comparison of factors highly correlated to herbicide damage indicates that highest herbicide selectivity occurs when pine has ceased growing, the xylem potential of the pine is relatively low (high water stress), and the xylem potential of the manzanita is relatively high.


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