Photosynthetic responses to phosphorus nutrition in two-year-old maritime pine seedlings

Nitrate and ammonium are the main forms of inorganic nitrogen available to plants. The present study aimed to investigate the metabolic changes caused by ammonium and nitrate nutrition in maritime pine (Pinus pinaster Ait.). Seedlings were grown with five solutions containing different proportions of nitrate and ammonium. Their nitrogen status was characterized through analyses of their biomass, different biochemical and molecular markers as well as a metabolite profile using 1H-NMR. Ammonium-fed seedlings exhibited higher biomass than nitrate-fed-seedlings. Nitrate mainly accumulated in the stem and ammonium in the roots. Needles of ammonium-fed seedlings had higher nitrogen and amino acid contents but lower levels of enzyme activities related to nitrogen metabolism. Higher amounts of soluble sugars and L-arginine were found in the roots of ammonium-fed seedlings. In contrast, L-asparagine accumulated in the roots of nitrate-fed seedlings. The differences in the allocation of nitrate and ammonium may function as metabolic buffers to prevent interference with the metabolism of photosynthetic organs. The metabolite profiles observed in the roots suggest problems with carbon and nitrogen assimilation in nitrate-supplied seedlings. Taken together, this new knowledge contributes not only to a better understanding of nitrogen metabolism but also to improving aspects of applied mineral nutrition for conifers.

Download Full-text

Regeneration of Riparian and Maritime Pine Forests after a Large Wildfire on the Largest Public Forest of Portugal

Forests ◽

10.3390/f12040477 ◽

2021 ◽

Vol 12 (4) ◽

pp. 477

Author(s):

Francisca C. Aguiar ◽

Carolina Rodrigues ◽

João P. Pina ◽

Paula Soares

Keyword(s):

Natural Regeneration ◽

Fire Severity ◽

Floristic Composition ◽

Maritime Pine ◽

Ecosystem Structure ◽

Native Plant ◽

Stream Channels ◽

Pine Seedlings ◽

Pine Stands ◽

The One

Eighty-six percent of the largest Portuguese public forest, Leiria National Forest (Mata Nacional de Leiria—MNL), central west, was burned in a wildfire in October 2017. Most of the area was covered by maritime pine stands (Pinus pinaster Aiton) crossed by riparian forests along small-sized streams. This work aims to characterize the post-fire vegetation and evaluate its natural regeneration. Sampling was carried out c. 6 months after the fire in 28 plots distributed at pine stands (3.5 × 3.5 m2) and in 24 plots (5 × 20 m2) at stream channels and riverbanks. These latter surveys were repeated in 2019. Data include the floristic composition and cover data of pine stands and streams, and the number of pine seedlings. Six months after the fire, 60% and 93% of the pre-fire species were observed at streams and pine stands, respectively. Fire severity was not related to differences in flora composition, nor with species richness. Pine seedlings were significantly more abundant in pine stands >60 years old compared to younger (<25 y) stands, but no significant differences were observed in the regeneration of understory. On riparian landscapes, the germination and resprouting of invasive exotic species, such as Acacia sp., created dense vegetation formations with decreased native plant diversity and altered the ecosystem structure. Following large wildfires, such as the one in MNL, managers should prioritize preserving the natural regeneration potential in the soil and aerial seed banks.

Download Full-text

Effects of potassium deficiency on cell water relations and elongation of tap and lateral roots of maritime pine seedlings

New Phytologist ◽

10.1046/j.1469-8137.1997.00647.x ◽

1997 ◽

Vol 135 (2) ◽

pp. 183-190 ◽

Cited By ~ 15

Author(s):

MARIE-BEATRICE TRIBOULOT ◽

JEREMY PRITCHARD ◽

GERARD LEVY

Keyword(s):

Water Relations ◽

Lateral Roots ◽

Potassium Deficiency ◽

Maritime Pine ◽

Cell Water ◽

Pine Seedlings

Download Full-text

Effects of soil burn severity on germination and initial establishment of maritime pine seedlings, under greenhouse conditions, in two contrasting experimentally burned soils

International Journal of Wildland Fire ◽

10.1071/wf08116 ◽

2011 ◽

Vol 20 (2) ◽

pp. 209 ◽

Cited By ~ 12

Author(s):

M. T. Fontúrbel ◽

J. A. Vega ◽

P. Pérez-Gorostiaga ◽

C. Fernández ◽

M. Alonso ◽

...

Keyword(s):

Organic Matter ◽

Organic Matter Content ◽

Matter Content ◽

Maritime Pine ◽

Burn Severity ◽

First Year ◽

Soil C ◽

Burned Areas ◽

Pine Seedlings ◽

Soil Burn Severity

The effects of soil burn severity on initial establishment of maritime pine in burned areas are not well known. Many factors may interact in the field, thus making it difficult to determine the exact role played by soil burn severity in the post-fire regeneration process. Monoliths of two contrasting soils – an acid, coarse-textured soil, with high organic matter content, and a neutral heavy-textured soil with low organic matter content – were experimentally burned to provide two markedly different levels of soil burn severity. The burned monoliths were sown with Pinus pinaster seeds and then placed in a greenhouse under a preselected water regime to determine the effect of burn severity on emergence and initial establishment of pine seedlings. High soil burn severity in the coarse-textured soils delayed germination, increased mortality and temporarily decreased the height of pine seedlings in the first year after sowing. This response was affected by: soil heating level, soil C consumption, post-fire soil C, depth of burn and post-fire duff-depth. Ash had no influence on the above processes. These factors did not explain the variability in the response of regeneration variables in the heavy-textured soils. The applicability of the results to field conditions is discussed.

Download Full-text