A strategy for concurrently monitoring the plant water potentials of spatially separated forest ecosystems

1986 ◽  
Vol 16 (2) ◽  
pp. 346-351 ◽  
Author(s):  
W. L Strong ◽  
G. H. La Roi

A technique for estimating plant water potentials in plant communities was used in six forest stands representing a jack pine (Pinusbanksiana Lamb.) and a black spruce (Piceamariana (Mill.) B.S.P.) successional sequence. A set of 31 plants composed of 16 species were measured at 4-day intervals from early May to late August 1982. The six stands had similar patterns of summer plant water potentials with greatest differentiation among species occurring during periods of maximum water stress. Plant water potentials varied more in jack pine stands on sand than in black spruce stands on organic soil. Shallow-rooted ericaceous and (or) evergreen species (e.g., Vacciniummyrtilloides Michx., Vacciniumvitis-idaea L., and Pyrolaasarifolia Michx.) had the widest range of water potentials during summer, whereas deep-rooted Alnuscrispa (Ait.) Pursh had the narrowest range. Maximum morning (0700) water potentials reached−3.1 MPa. All species had fine roots (<2 mm) within the upper 20 cm of the soil, but some species of the Jack Pine Series had roots to 230 cm depth. Soil moisture was usually more available in the upper 20 cm and below 60 cm in mineral soils; the lower amount of soil moisture at middle depths resulted from depletion by plants and lack of downward percolation of precipitation in 1982.

1996 ◽  
Vol 26 (11) ◽  
pp. 1899-1904 ◽  
Author(s):  
Inderjit Inderjit ◽  
A.U. Mallik

The nature of interference potential of Kalmiaangustifolia L., a boreal forest understorey shrub, was investigated in laboratory experiments. Organic and mineral soils, not previously associated with Kalmia, were amended with different quantities of its leaf litter and leaf litter leachates. The objectives of the study were (i) to determine changes in soil chemistry after amending with Kalmia and (ii) to determine the effect of amendment on growth of black spruce (Piceamariana (Mill.) BSP) seedlings. All soils were analyzed for pH, organic matter, PO4−, N, Ba, Cu, Zn, Fe, Mn, Ca, Na, K, Mg, Al, and total phenolics. Chemical characteristics of both organic and mineral soils were significantly changed. Water-soluble phenolics in one of the amended organic soils were significantly higher than in unamended organic soil. However, all of the amended mineral soils had significantly higher total phenolic contents than unamended control soils. A linear decrease in N content was observed in amended organic and mineral soils with increasing quantities of Kalmia leaf litter. Amended mineral soils had higher concentrations of Fe, Mn, Al, and PO4− than the control. We relate higher accumulations of PO4−, Fe, Mn, and Al in amended mineral soils to higher soil phenolic contents. Amendment of organic and mineral soils significantly reduced the root and shoot growth of black spruce. This study demonstrates that Kalmia has potential for nutrient interference and does not rule out allelopathic effects of Kalmia to black spruce seedling growth.


1998 ◽  
Vol 74 (3) ◽  
pp. 428-443 ◽  
Author(s):  
Jean-Claude Ruel ◽  
François Ouellet ◽  
Roch Plusquellec ◽  
Chhun-Huor Ung

This paper presents results from a 30 year monitoring of 15 clearcut areas. Study areas were located before cutting in stands having an abundant advance regeneration. Four study areas were initially dominated by black spruce, four by balsam fir, three by jack pine and the last four comprised a mix of species. Stand inventories and regeneration surveys were conducted before harvesting. Harvesting was done in regular logging operations, without any special care to protect the advance growth. Regeneration surveys were taken again after harvesting, 5 years, 10 years, 20 years and 30 years after harvesting. Black spruce stands regenerated to black spruce dominated stands. Balsam fir, which was sometimes abundant in the advance regeneration, did not invade the stands and the abundance of hardwoods was temporary. In some cases a reduction in yield is to be expected. In balsam fir stands, harwoods were more aggressive. A reduction in softwood yield is predicted for three of the four cutovers. The presence of a tall regeneration seems to lead to higher yields in black spruce and balsam fir stands. The evolution of jack pine and mixed stands is quite variable. In some jack pine stands, hardwoods will constitute a significant component of the new stand. In some mixed stands, softwoods are not very abundant whereas in others they form an important part of the stand at 30 years. This study has shown an urgent need for a better understanding of stand dynamics in young stands. Such an understanding is necessary for an adequate forecast of the yield of second growth stands.


2012 ◽  
Vol 9 (1) ◽  
pp. 1021-1053 ◽  
Author(s):  
M. P. Girardin ◽  
X. J. Guo ◽  
P. Y. Bernier ◽  
F. Raulier ◽  
S. Gauthier

Abstract. In spite of the many factors that are occurring and known for positively affecting the growth of forests, some boreal forests across North America have recently felt the adverse impacts of environmental changes. Knowledge of causes for productivity declines in North American boreal forests remains limited and this is owed to the large spatial and temporal scales involved, and the many plant processes affected. Here, the response of pristine eastern boreal North American (PEBNA) forests to ongoing climatic changes is examined using in situ data, community ecology statistics, and species-specific model simulations of carbon exchanges forced by contemporary climatic data. To examine trends in forest growth, we used a recently acquired collection of tree-ring width data from 252 sample plots distributed in PEBNA forests dominated by black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). Results of linear trend analysis on the tree growth data highlight a dominating forest growth decline in overmature forests (age > 120 yr) from 1950 to 2005. In contrast, improving growth conditions are seen in jack pine and mature (70–120 yr) black spruce stands. Multivariate analysis of climate and growth relationships suggests that responses of PEBNA forests to climate are dependent on demographic and species traits via their mediation of temperature and water stress constraints. In support of this hypothesis, the simulation experiment suggests that in old-growth black spruce stands the benefit to growth brought on by a longer growing season may have been low in comparison with the increasing moisture stress and respiration losses caused by warmer summer temperatures. Predicted increases in wildfire frequency in PEBNA forests will likely enhance the positive response of landscape-level forest growth to climate change by shifting the forest distribution to younger age classes while also enhancing the jack pine component.


2006 ◽  
Vol 36 (8) ◽  
pp. 1943-1950 ◽  
Author(s):  
Kevin J Kemball ◽  
G. Geoff Wang ◽  
A Richard Westwood

We examined jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) BSP), and white spruce (Picea glauca (Moench) Voss) seed germination and seedling recruitment in aspen (Populus tremuloides Michx.) and conifer mixedwood stands following the 1999 Black River fire in southeastern Manitoba, Canada. Three postfire seedbed types were tested: scorched (surface litter only partially consumed), lightly burned (surface litter consumed with little or no duff consumption), and severely burned (complete consumption of litter and duff exposing mineral soil). Seeds were sown in 1999, 2000, and 2001, and each cohort was monitored for 3 years. In 1999, severely burned seedbeds had poor germination, while scorched seedbeds had the highest germination. The reverse was true in 2001. After the first growing season, continued survival of seedlings was greater on severely burned seedbeds for all three cohorts. However, better survival on severely burned seedbeds was not sufficient to overcome poor germination in 1999 and 2000. When using artificial seeding to promote conifer regeneration, we recommend a delay of one full year after a severe spring fire for jack pine and two full years for black spruce and white spruce on boreal aspen and conifer mixedwood sites.


2000 ◽  
Vol 9 (4) ◽  
pp. 319-331 ◽  
Author(s):  
L. PIETOLA ◽  
T. SALO

Soils ploughed in autumn were loosened by different tillage tools, or compacted to a depth of 25-30 cm by a tractor weighing 3 Mg (once or three times) before seed bed preparation for carrot under moist soil condition. Sprinkler irrigation was also applied to mineral soils when the soil moisture in top soil was 50% of plant-available water capacity, and the response of additional N application of 30 kg ha-1 was studied in an organic soil. Higher soil moisture tended to promote nutrient uptake, as the P content of carrot tap roots was increased by irrigation in loam. Compaction of organic soil low in P increased P and K contents and uptake by carrot roots and shoots. In severely compacted clay soil, the nutrient use decreased by increasing soil compactness. NO3-N contents were the highest in early season (25-30 mg kg-1 fresh matter) and decreased with advancing season. In loam, NO3-N content was increased by irrigation or loosening. Increasing the N fertilisation of organic soil from 30 kg ha-1 to 60 kg ha-1 increased the NO3-N content 30%. Soil type and its nutrient status, weather conditions, and growth stage had much more significant influence on the P, K, and Mg contents of carrots than soil treatments.


2012 ◽  
Vol 9 (7) ◽  
pp. 2523-2536 ◽  
Author(s):  
M. P. Girardin ◽  
X. J. Guo ◽  
P. Y. Bernier ◽  
F. Raulier ◽  
S. Gauthier

Abstract. In spite of the many factors that are occurring and known for positively affecting the growth of forests, some boreal forests across North America have recently felt the adverse impacts of environmental changes. Knowledge of causes for productivity declines in North American boreal forests remains limited, and this is owed to the large spatial and temporal scales involved, and the many plant processes affected. Here, the response of pristine eastern boreal North American (PEBNA) forests to ongoing climatic changes is examined using in situ data, community ecology statistics, and species-specific model simulations of carbon exchanges forced by contemporary climatic data. To examine trends in forest growth, we used a recently acquired collection of tree-ring width data from 252 sample plots distributed in PEBNA forests dominated by black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). Results of linear trend analysis on the tree growth data highlight a dominating forest growth decline in overmature forests (age > 120 years) from 1950 to 2005. In contrast, improving growth conditions are seen in jack pine and mature (70–120 years) black spruce stands. Multivariate analysis of climate and growth relationships suggests that responses of PEBNA forests to climate are dependent on demographic and species traits via their mediation of temperature and water stress constraints. In support of this hypothesis, the simulation experiment suggests that in old-growth black spruce stands the benefit to growth brought on by a longer growing season may have been low in comparison with the increasing moisture stress and respiration losses caused by warmer summer temperatures. Predicted increases in wildfire frequency in PEBNA forests will likely enhance the positive response of landscape-level forest growth to climate change by shifting the forest distribution to younger age classes while also enhancing the jack pine component.


2006 ◽  
Vol 86 (Special Issue) ◽  
pp. 203-217 ◽  
Author(s):  
Vincent Balland, Jagtar Bhatti ◽  
Ruth Errington, Mark Castonguay ◽  
Paul A. Arp

Impacts of climate change on above- and below-ground heat and moisture conditions were modeled so that other impacts on, e.g., local carbon (C) and C-based pools for nutrients and pollutants such as Hg can be predicted reliably. This paper shows how the 199–-2003 data for the jack pine (jp; Pinus banksiana Lamb.), black spruce (bs; Picea mariana) and aspen (ta; Populus tremuloides) sites of the Southern Study Area of the BOREAS project were used to estimate some of the hydrothermal soil responses at these locations to daily variations in precipitation and air temperature. This was done by initializing and calibrating a forest hydrology model that has the capacity to simulate flow and retention of moisture and heat, as modified by canopy closure, ground cover, forest-floor depth, and soil composition. The calculations and data revealed strong but predictable site-specific differences in soil temperature and frost penetration (jp: 1–2 m > ta: 0.5–1 m > bs: 0–0.5 m), in soil moisture freezing (ta < bs < jp), and in moisture retention (jp < ta < bs). Apart from daily weather, these differences depended on soil texture (loamy/sandy texture impeded/encouraged soil freezing, respectively), and on the thermal insulation and moisture retention of the combined forest floor, moss and lichens layers (ta < jp < bs). Key words: Jack pine, aspen, black spruce, soil moisture, soil temperature, frost penetration, snowpack, boreal conditions


1995 ◽  
Vol 25 (2) ◽  
pp. 307-318 ◽  
Author(s):  
Sonia Duchesne ◽  
Luc Sirois

The objective of this study was to investigate the first stage of post-fire regeneration of black spruce and jack pine in a black spruce woodland and a jack pine forest burned over in 1989 in the Radisson's region, in northern Quebec. Emphasis was given to determine the optimal microsites for black spruce and jack pine regeneration. Our results show that the burned over jack pine forest offers better substrates for seedling germination than the burned over black spruce one. A total of 139 seedlings were observed in the jack pine forest, whereas only 42 were recorded in the black spruce forest. In the jack pine forest, burned over humus was the preferred substrate for germination. Soil moisture content correlated with seed germination of both species. Soil temperatures at −5 cm and the soil surface influenced survival of black spruce seedlings in the jack pine forest


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