Long-Term Steady-State Dry Boreal Forest in the Face of Disturbance

Abstract

We used bioproxies from paleosoils buried within two aeolian dunes to test hypotheses concerning the origin of dry sandy boreal forests in Canada. These forests are dominated today by Pinus banksiana Lamb. One hypothesis is that too frequent Holocene stand-replacing fires would have transformed the original vegetation through extirpation of susceptible species to fire in water stress habitat. Alternatively, the ecosystem would have not changed since the dunes stabilized enough to support forest establishment. The vegetation composition and richness were determined by identification of charcoal and macroremains and radiocarbon dating for the chronology. Both sites revealed a similar history covering 6400 years. Half of the charcoal layers were less than 2500 years old in both sites, indicating that they had been subjected to the same fire history. Data indicated a stable plant composition and richness, although the percentage of Pinus decreased slightly over 4000 years (decreasing rate 1% per century). The fungus Cenococcum geophilum was consistently present, with a stochastic abundance. The vegetation grew under natural fire conditions and soil dryness since 6000 years. The ecosystem was probably not stressed by late-Holocene fires or climate changes, as the multi-millennial steady state reveals a resistant and resilient ecosystem.

Study of the distribution of Glycyrrhiza uralensis production areas as well as the factors affecting yield and quality

“…The third factor is a change in soil conditions. Soil conditions have an important effect on changes in the distribution of plants 32 , 33 , such as changes in soil quality, soil moisture conditions, and nutrient elements. During this study, coal mines were excavated near the wild licorice fields in some areas, and this has resulted in a decline in the groundwater level.…”

Study of the Distribution of Glycyrrhiza uralensis Production Areas as well as the Factors Affecting Yield and Quality

“…The third factor is change in soil conditions. Soil conditions have an important effect on changes in the distribution of plants 32,33 , such as changes in soil quality, soil moisture conditions, and nutrient elements. During this study, coal mines were excavated near the wild licorice fields in some areas, and this has resulted in a decline in the groundwater level.…”

Interactions between xylem traits linked to hydraulics during xylem development optimize growth performance in conifer seedlings

“…We argue that this Da-Dt coordination could be a possible mechanism underlying the safety-efficiency hydraulic co-optimization predicted for conifers species (Liu et al ., 2020). Indeed, jack pine trees typically occur in sandy soils with low water retention (Desponts & Payette, 1992; Carcaillet et al ., 2020; Pacé et al ., 2020), and a constant embolism resistance (e.g., via O ) may be beneficial in such environments where soil water is strongly variable.…”