Influence of initial chemistry on decomposition of foliar litter in contrasting forest types in British Columbia

2004 ◽  
Vol 34 (8) ◽  
pp. 1714-1729 ◽  
Author(s):  
C E Prescott ◽  
L Vesterdal ◽  
C M Preston ◽  
S W Simard
Keyword(s):  
British Columbia ◽  
Mass Loss ◽  
Tree Species ◽  
Field Studies ◽  
Decay Rates ◽  
Nutrient Concentrations ◽  
First Year ◽  
Resonance Spectroscopy ◽  
Litter Chemistry ◽  
Initial Litter Chemistry

We compare rates of decay of foliar litters of British Columbia tree species in two field studies, and assess which initial litter chemistry parameters best predict the decay rates. Nutrient concentrations, tannins, and carbon fractions (based on proximate analysis and nuclear magnetic resonance spectroscopy) were measured in fresh litter of 14 tree species in one experiment and seven species in a second experiment. Each study was replicated in a different site in order to assess the transferability of results. Broadleaf litters decayed faster than needle litters only during the first year; thereafter, they decayed slower. Lignin concentration was a good predictor of mass loss only during the first year and only in one of the two experiments, which may have resulted from all foliar litters having high lignin concentrations (>170 mg·kg–1). Litter chemistry effects on first-year decay were consistent and transferable among sites. None of the initial litter chemistry parameters were good predictors of mass remaining after 4 or 5 years, because mass loss of most litters was similar by this time. The convergence in mass losses of litters after 4–5 years despite initial differences indicates that decomposition estimates extrapolated from early rates or initial chemistry may not accurately predict long-term decay.

scholarly journals In situ decomposition of northern hardwood tree boles: decay rates and nutrient dynamics in wood and bark

2014 ◽  
Vol 44 (12) ◽  
pp. 1515-1524 ◽  
Author(s):  
Chris E. Johnson ◽  
Thomas G. Siccama ◽  
Ellen G. Denny ◽  
Mary Margaret Koppers ◽  
Daniel J. Vogt
Keyword(s):  
Mass Loss ◽  
Sugar Maple ◽  
Nutrient Dynamics ◽  
Exponential Model ◽  
Fagus Grandifolia ◽  
Decay Rates ◽  
Nutrient Concentrations ◽  
Betula Alleghaniensis ◽  
Northern Hardwood ◽  
Clear Cutting

The decomposition of coarse woody debris contributes to forest nutrient sustainability and carbon (C) balances, yet few field studies have been undertaken to investigate these relationships in northern hardwood forests. We used a paired-sample approach to study the decomposition of sugar maple (Acer saccharum Marsh.), American beech (Fagus grandifolia Erhr.), and yellow birch (Betula alleghaniensis Britt.) boles at the Hubbard Brook Experimental Forest in New Hampshire. Mass loss over 16 years followed a first-order exponential decay pattern with half-lives ranging from 4.9 to 9.4 years in bark and from 7.3 to 10.9 years in wood. Nitrogen (N) and phosphorus (P) concentrations increased significantly during decomposition, resulting in sharp decreases in C:N and C:P ratios. We did not, however, observe significant net increases in the amount of N or P stored in decomposing boles, as reported in some other studies. Calcium (Ca) concentration decreased by up to 50% in bark but more than doubled in wood of all species. The retention of Ca in decomposing wood helps maintain Ca pools in this base-poor ecosystem. Together, the exponential model for mass loss and a combined power-exponential model for changes in nutrient concentrations were able to simulate nutrient dynamics in decomposing boles after clear-cutting in an adjacent watershed.

Diatom- and Chironomid-Inferred Eutrophication of Bouchie Lake, British Columbia

2005 ◽  
Vol 40 (4) ◽  
pp. 418-430 ◽  
Author(s):  
Markus L. Heinrichs ◽  
Brian F. Cumming ◽  
Kathleen R. Laird ◽  
J. Sanford Hart
Keyword(s):  
British Columbia ◽  
Land Use Changes ◽  
Head Capsule ◽  
Relative Increase ◽  
Nutrient Concentrations ◽  
The Past ◽  
Nutrient Levels ◽  
Lower Head ◽  
Lower Oxygen ◽  
Historical Land Use

Abstract Diatom and chironomid analysis of sediments encompassing the past 400 years from Bouchie Lake, British Columbia, suggests two distinct periods of limnological conditions. Prior to 1950 AD, Fragilaria construens and F. pinnata are the most common diatom species, and Chironomus, Procladius and Tanytarsini dominate the chironomid record. Moderately low nutrient concentrations consistent with oligo-mesotrophic lakes are inferred. From 1950, the diatom assemblage is dominated by Stephanodiscus parvus, a eutrophic indicator, whereas the chironomid communities show a relative increase in littoral taxa coincident with lower head capsule abundance. Higher nutrient levels, specifically total phosphorus, which increased from 8 µg L-1 prior to 1950 to 20 µg L-1 currently, are coincident with midge communities indicative of lower oxygen concentrations. Observed biotic changes and nutrient levels inferred from the sediment core correspond to historical land-use changes.

Range extensions of grassland species in southern interior British Columbia

1985 ◽  
Vol 63 (12) ◽  
pp. 2240-2242
Author(s):  
Brian M. Wikeem ◽  
Reg F. Newman
Keyword(s):  
British Columbia ◽  
Plant Species ◽  
Field Studies ◽  
Grassland Species

Field studies and herbarium searches during 1983 and 1984 have revealed range extensions of three grassland plant species in the southern interior of British Columbia. These species include Allium geyeri Wats. var. tenerum Jones, Gaura coccinea (Nutt.) Pursh, and Sidalcea oregana (Nutt.) Gray ssp. oregana var. procera C. L. Hitchc. All three taxa were previously unknown to the Kamloops area and Sidalcea oregana is new to the province and Canada.

scholarly journals British Columbia SHIFT: Early Lessons Learned from a Provincial Program for Countering Radicalization to Violent Extremism

Proceedings ◽  
2021 ◽  
Vol 77 (1) ◽  
pp. 8
Author(s):  
Garth Davies ◽  
Madison Reid
Keyword(s):  
British Columbia ◽  
Lessons Learned ◽  
First Year ◽  
Stakeholder Relationships ◽  
Violent Extremism ◽  
Excellent Work ◽  
Services And Supports ◽  
The Right ◽  
Government Initiative ◽  
And Training

Many existing programs for countering violent extremism focus on either end of the radicalization spectrum. On one hand are prevention programs aimed at deterring individuals from starting down the path to violent extremism. On the other hand are disengagement/de-radicalization programs designed for assisting individuals who have been fully radicalized. Conspicuously absent are programs for those who fall in-between, into what might be referred to as the pre-criminal space: individuals who have begun to exhibit signs of radicalization, but for whom radicalization is not yet complete. The British Columbia Shift (BC Shift) initiative was created to assist individuals determined to be in this pre-criminal space; that is, those deemed to be in danger of radicalizing. The goal of BC Shift is to stop individuals from traveling further down the path of radicalization, and, ideally, to turn individuals away from the path. BC Shift operates as a navigational model, connecting at-risk individuals with services and supports in the community. BC Shift is a government initiative supported by the Canada Centre for Community Engagement and Prevention of Violence. It is a civilian organization that partners very closely with, but is separate from, law enforcement. In addition to its primary CRVE mandate, BC Shift has rapidly evolved and expanded into several other responsibilities, including coordination on national CVE standards; liaising with other CVE programs across Canada; maintaining stakeholder relationships; and helping create capacity through dialog and training. Although the program only began accepting referrals in 2019, its operation has already revealed many important lessons for CRVE programs. First, it is critically important to have the right people in the room. There has to be buy-in from the highest levels of partner agencies and stakeholders, particularly early on. Second, programs of this sort should leverage existing resources wherever possible. BC Shift has been lucky enough to coordinate with situation tables, such as the CHART program in Surrey. There are already many organizations doing excellent work in their respective communities; it is very helpful to plug into those resources. Third, even though BC Shift operates as a navigational hub, it has benefitted greatly from having a social worker as part of the team. This skill set is important in helping referred individuals feel comfortable with the process of accessing services and supports. Finally, marketing matters! CRVE programs such as BC Shift have to navigate a complex reality. The very concept of violent extremism is disconcerting to a lot of people in the community; these fears have to be addressed, and difficulties related to differences in perspective and language have to be overcome. BC Shift’s first year-and-a-half of operation has also highlighted several issues that have not yet been satisfactorily resolved. There is, for example, the “low hanging fruit” problem; agencies are typically referring less severe cases. Trying to get agencies to refer more serious cases has proved challenging. We hope that, by outlining these lessons and issues, this presentation proves to be useful to other CRVE initiatives.

scholarly journals PRODUCTIVITY OF PERENNIAL GRASSES AND MIXTURES WITH DIFFERENT SOWING DATES IN WESTERN SIBERIA

2020 ◽  
pp. 24-32
Author(s):  
V. A. Petruk
Keyword(s):  
Dry Matter ◽  
Crop Yields ◽  
Growing Season ◽  
Single Species ◽  
Field Studies ◽  
Perennial Grasses ◽  
First Year ◽  
Sowing Dates ◽  
Second Year ◽  
Sowing Period

The results of field studies for 2017 - 2019 are presented. yields of perennial grasses sown at different times of the growing season. Spring, summer, and winter sowing periods were compared. Alfalfa, clover, rump, and also their mixtures were sown in 2017 under the cover of barley. The value of the cover crop yield of spring and summer sowing periods did not differ significantly and amounted to 4-5 t / ha of absolutely dry matter. Winter barley crops have not formed. On average, over 2 years of use, the highest yields were observed in alfalfa-crust grass mixtures - 3.4 t / ha of absolutely dry matter. The lowest yield was obtained in the single-species seeding of the rump. Correspondingly, in the spring, summer and winter periods of sowing, the yield of rump was 1.6; 1.1 and 1.3 t / ha. With a late sowing period, the yield of perennial grasses is significantly lower compared to spring and summer. With winter sowing periods, the yield was the highest for grass stands of alfalfa and alfalfacrust grass mixture - 2.3 and 2.4 t / ha. It should be noted that in the second year of use, the yield by the sowing dates in single-species crops and grass mixtures is leveled. The winter crops of perennial grasses in the first year of use formed a low yield. Only in the second year (third year of life) the productivity of perennial grasses of winter sowing began to increase. Consequently, in the area under perennial grasses of the winter sowing period, during one growing season (the next year after sowing), the crop was not actually formed. Based on the data obtained, production can be recommended for spring and summer planting of perennial grasses under the cover of barley. The winter sowing period provides economically valuable crop yields only by the third year of life.

scholarly journals Repeated Negative Teaching Evaluations: A Form of Habitual Behaviour?

2015 ◽  
Vol 45 (4) ◽  
pp. 298-321
Author(s):  
J Paul Grayson
Keyword(s):  
British Columbia ◽  
Generational Status ◽  
First Year ◽  
Not Given ◽  
Campus Engagement ◽  
Teaching Evaluations ◽  
University Of British Columbia ◽  
Mcgill University ◽  
The University ◽  
Do So

Teaching evaluations have become part of life on Canadian campuses; however, there is no agreement among researchers as to their validity. In this article, comparisons were made between first- and third-year collective evaluations of professors’ performance at the University of British Columbia, York University, and McGill University. Overall, it was found that students who provided low evaluations in their first year were also likely to do so in their third year. This effect held independent of degree of campus engagement, sex, student status (domestic or international), and generational status (students who were the first in their families to attend university, compared to those who were not). Given that over the course of their studies, students likely would have been exposed to a range of different behaviours on the part of their professors, it is argued that the propensity of a large number of students to give consistently low evaluations was a form of “habitual behaviour.”  

Differential Tolerance of Clearfield Rice Cultivars to Imazamox

2011 ◽  
Vol 25 (2) ◽  
pp. 192-197 ◽  
Author(s):  
Jason A. Bond ◽  
Timothy W. Walker
Keyword(s):  
Growth Stage ◽  
Rice Yield ◽  
Field Studies ◽  
First Year ◽  
Growth Stages ◽  
Rice Cultivars ◽  
Rough Rice ◽  
Rice Yields ◽  
Clearfield Rice ◽  
Two Hybrid

Field studies were conducted to compare the response of one inbred (‘CL161’) and two hybrid (‘CLXL729’ and ‘CLXL745’) Clearfield (CL) rice cultivars to imazamox. Imazamox was applied at 44 and 88 g ai ha−1to rice in the panicle initiation (PI) and PI plus 14 d (PI + 14) growth stages and at 44 g ha−1to rice in the midboot growth stage. Maturity of hybrid CL cultivars was delayed following imazamox at 44 g ha−1applied at PI + 14 and midboot. Furthermore, imazamox at 44 g ha−1, applied at midboot, delayed maturity of CLXL745 more than CLXL729. Expressed as a percentage of the weed-free control plots, rough rice yields for CLXL729 were 91% following imazamox at 44 g ha−1applied at PI + 14, 78% following imazamox at 44 g ha−1applied at midboot, and 77% for imazamox at 88 g ha−1applied at PI + 14. Rough rice yield for CLXL745 was 77 to 92% of the control following all imazamox treatments. All imazamox treatments reduced CLXL745 rough rice yield compared with CL161. Rough rice yield, pooled across CL cultivar, varied with imazamox treatment between years, and these differences may have been a consequence of lower temperatures and solar radiation in the first year. Hybrid CL cultivars CLXL729 and CLXL745 were less tolerant than was CL161 when imazamox was applied at nonlabeled rates (88 g ha−1) and/or timings (PI + 14 or midboot). Because of variability in rice growth stages and irregularities in imazamox application in commercial fields, inbred CL cultivars should be planted where an imazamox application will likely be required.

Glacial Isostatic Adjustment Modelling of the Coast Mountains of British Columbia and Southeastern Alaska

2021 ◽  
Author(s):  
Maximilian Lauch ◽  
Thomas James ◽  
Lucinda Leonard ◽  
Yan Jiang ◽  
Joseph Henton ◽  
...  
Keyword(s):  
British Columbia ◽  
Mass Loss ◽  
Thermal Emission ◽  
Tectonic Setting ◽  
Ice Age ◽  
High Mass ◽  
Cascadia Subduction Zone ◽  
Climate Projections ◽  
Coast Mountains ◽  
Crustal Motion

<p>The Coast Mountains in British Columbia and southeastern Alaska contain around 9040 km<sup>2 </sup>of glaciers and ice fields at present. While these glaciers have followed an overall trend of mass loss since the Little Ice Age (or LIA around 300 years before present), the past decade has seen a significant increase in melting rate that is likely to continue due to the effects of climate change. The region is home to a complex tectonic setting, having proximity to the Queen Charlotte-Fairweather transform plate boundary in the northern region and the Cascadia subduction zone (CSZ) in the southern region, which has an associated active volcanic arc underlying the glaciated area. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) glacier melt data collected between 2000 and 2019 represent a melt rate that is averaged between periods of relatively low mass loss (2000-2009) and high mass loss (2010-2019). As a preliminary test, this average melt rate was assumed to be constant back to the LIA. A history of gridded ice thicknesses was calculated to create an ice loading model for input to a series of forward modelling calculations to determine the crustal response. Predictions of vertical crustal motion are compared to available Global Navigation Satellite System (GNSS) measurements of uplift rate to constrain Earth rheology. The results using this simplified loading model favour a thin lithosphere (around 20-40 km thick) and asthenospheric viscosities on the order of 10<sup>19</sup> Pa s. These values are significantly lower than those of rheological profiles used in extant global GIA models, but are in general agreement with previous GIA modelling of the forearc region of the CSZ. To improve the glacial history model, the Open Global Glacier Model (OGGM), driven by historic climate data and statistically downscaled climate projections, is being employed to create a more accurate loading model and refine our estimates of Earth rheology and regional crustal motion. The best-fitting models will be employed to separate GIA and tectonic components of crustal motion and to generate improved regional sea-level projections.</p>

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