1,721,072 research outputs found
Biomass and Carbon Allocation in Chronosequence of White Pine (Pinus strobus L.) plantations in Southern Ontario, Canada
No full text This study assessed biomass and carbon (C) allocation in a chronosequence of four White pine (Pinus strobus L.) plantation forests planted in 2002 (WPP02), 1989
(WPP89), 1974 (WPP74), and in 1939 (WPP39), in southern Ontario, Canada. A plotbased inventory and destructive tree sampling were conducted in 2004 to assess
allocation of oiomass and C in ecosystem components, as well as allometry of tree
biomass. Seasonal and annual patterns of litter and branch fall were also determined. Individual tree biomass components as well as sapwood area have strong site specific allometric relationships with tree diameter. Except for foliage biomass, strong single allometric equations could also be obtained across all sites and stand ages. Whereas allometry of individual tree components may be affected by site conditions and stand age, total tree biomass solely depended on tree diameter. This suggests that total biomass of White pine may be predicted from single allometric equations with DBH as input variable across sites and even across regions. Relative partitioning of tree biomass components was strongly related to tree age. Stem biomass gains major importance with increasing tree age at the cost of all other components comprising 69% of total tree biomass after 65 years. Whereas site conditions influenced the absolute amount of biomass and allometry of individual tree components, they did not affect their relative partitioning Only biomass of trees, woody debris, and small roots (2-5mm) showed agerelated patterns by increasing with greater stand age. Increase in tree biomass was
highest during the early decades after establishment and after thinning practices. C storage in forest floor was 0.8, 7.5, 5.4, and 12.1 t C ha⁻¹ and C content in mineral soil was 37.2, 33.9, 39.1, and 36.7 t C ha⁻¹ at WPP02, WPP89, WPP74, and WPP39, respectively. Biomass of roots Thus, estimations of C storage in forest ecosystems should include all above and belowground C pools, and its accuracy may be improved by predicting total treebiomass with allometric equations related to stand age and tree diameter.ThesisMaster of Science (MSc
Analysis of nitrogen controls on carbon and water exchanges in a conifer forest using CLASS-CTEMᴺ⁺ model
Full text linkNitrogen (N) controls on carbon and water exchanges were analyzed in a 70-year old eastern temperate conifer forest in Ontario, Canada from 2003 to 2007 using a newly developed nitrogen (N) cycle coupled model -- CLASS-CTEMᴺ⁺. This process-based model incorporates sunlit and shaded big-leaves for C3 and C4 photosynthesis and semi-mechanistic canopy conductance formulation for dynamic plant-functional-types. Recently, key soil and plant N cycling algorithms have also been included (e.g., biological fixation, atmospheric N deposition, fertilization, mineralization, nitrification, denitrification, leaching, soil nitrous dioxide (N₂0) emissions, root N uptake, plant N allocation and N controls on plant photosynthesis capacity). The simulated values of soil-plant N contents and processes rates including N₂0 fluxes were generally in agreement with observations. Comparison of default non-N and C&N-coupled model simulations clearly revealed N controls on photosynthetic uptake and water loss. Predictions of daily gross ecosystem productivity (GEP), ecosystem respiration (Re), net ecosystem productivity (NEP) and evapotranspiration (ET) showed better agreement with eddy covariance (EC) flux measurements when using the N-coupled model (RMSE of 1.97, 0.73, 1.44, 0.92; and MAE of 1.48, 0.55, 1.01, 0.60 for GEP, Re, NEP, and ET, respectively; n=1825) as compared to the non-N model simulations (RMSE of2.95, 1.35, 1.93, 1.03; MAE of2.38, 1.15, 1.55,0.71 for GEP, Re, NEP, and ET, respectively; n=1825) over 5 years (2003-2007). Annual values of N-coupled model simulated NEP were 134, 195, 183, 225 and 255 g C m⁻² yr⁻¹ for 2003-2007, as compared to non-N model simulated annual NEP values, which were 535, 562, 507, 540, and 535 g C m⁻² yr⁻¹ for respective years. These values were compared to measured NEP values of 220±67, 126±67, 33±67, 142±67 and 102±67 g C m⁻² yr⁻¹ for the years 2003-2007, respectively. The difference between N-coupled model simulated and EC measured annual variations of carbon exchanges was largely due to specific extreme weather events (e.g. drought, spring warming) during certain years. Overall, the impacts of N limitations on carbon fluxes were more pronounced during early spring, late autumn and winter seasons. This newly developed model will help to evaluate the response of terrestrial vegetation ecosystems to N variations under different scenarios for future climate change.Master of Science (MS
Carbon dynamics and greenhouse gas exchanges in an age-sequence of temperate pine forests
No full text Forest ecosystems play an important role in the global carbon (C) cycle by exchanging large amounts of carbon dioxide (CO₂) with the atmosphere. Their potential to act as significant sink for atmospheric CO₂ has been recognized and is relevant to current efforts in reducing atmospheric CO₂ concentrations. Besides the most important greenhouse gas CO₂, forests also emit and consume methane (CH₄) and nitrous oxide (N₂O) as the two other important atmospheric greenhouse gases (GHGs). To date, few attempts have been made to quantify the net effect of forest GHG exchange on the global warming potential. Furthermore, a better understanding of successional and environmental effects on forest processes is required to improve large scale estimates of forest C and GHG exchange. This thesis examines C dynamics and the exchange of the three major greenhouse gases (CO₂, CH₄, and N₂O) in an age-sequence (7-, 20-, 35-, and 70-years-old as of 2009) of afforested pine forests, in southern Ontario, Canada. The impacts of environmental controls on these GHG exchanges were also evaluated. Forest C exchange was determined for 2003 to 2008 using the eddy-covariance (EC) technique and inventory-based biometric measurements. Soil CH₄ and N₂O measurements were conducted from 2006 to 2007 using the static closed-chamber method. In addition, concentrations and fluxes of dissolved organic carbon (DOC) throughout the vertical profile in forest canopy and soil were determined from 2004 to 2005 using throughfall buckets and lysimeters. During periods without climatic constraints, monthly gross ecosystem productivity (GEP) and ecosystem respiration (RE) corrected for differences in site index increased with stand age, whereas monthly net ecosystem productivity (NEP) peaked at the 35-year-old site. In contrast, during constrained periods (e.g. seasonal drought events), monthly GEP and NEP at the 20-year-old site were higher compared to the 35-year-old site because trees may have benefited from sustained availability of soil water in deeper layers. This study further demonstrates that differences in site quality may affect the interpretation of age-related C flux dynamics in chronosequence and synthesis studies (Chapter 2). The temperature-RE relationship was an important control on daily NEP anomalies under optimum growing conditions, whereas constrains on GEP primarily determined NEP during environmentally constrained periods. Furthermore, effects from single environmental variable constrains on NEP anomalies were enhanced as well as outbalanced under multiple environmental variable constrains. The results further indicate that future changes in temperature and precipitation patterns towards drier and warmer conditions as well as greater cloud cover may result in reduced C sequestration potentials in these temperate pine forests (Chapter 3). Early summer drought and heat events in 2005 caused NEP to decrease by approximately 100 g C m⁻² y⁻¹ at each site compared to the other years. This decrease was primarily driven by a decrease in photosynthesis, while the effect of these events on ecosystem respiration was small. Overall, for the years 2003-2007, annual NEP was 219, 155, 36, 148, and 120 g C m⁻² y⁻¹ at the 68-year-old site, 666, 318, 346, 511 and 366 g C m⁻² y⁻¹ at the 33-year-old site, 768, 885, 684, 708 and 826 g C m⁻² y⁻¹ at the 18-year-old site, and-18, 145, 125, 34 and 164 g C m⁻² y⁻¹ at the 5-year-old seedling site, respectively (negative numbers indicating net C source (Chapter 4). Four-year mean values of biometric NEP_(B) and EC-based NEP_(EC) were similar at the 7-year-old seedling (77 and 66 g C m⁻² y⁻¹) and the 70-year-old mature site (135 and 124 g C m⁻² y⁻¹), but differed considerably at the 20-year-old (439 and 736 g C m⁻² y⁻¹) and the 35-year-old sites (170 and 392 g C m⁻² y⁻¹). Integrating NEP across the age-sequence resulted in a total net C sequestration of 137 and 229 t C ha⁻¹ over the initial 70 years as estimated by the biometric and EC method, respectively. The total ecosystem C pool at the 70-year-old site suggested an accumulation of 160 t C ha⁻¹. These three estimates resulted in a mean C sequestration of 175 ± 48 t C ha⁻¹ (Chapter 5). For both CH₄ and N₂O, we observed uptake and emission ranging from -160 to 245 μg CH₄ m⁻² hour⁻¹ and -52 to 21 μg N₂O m⁻² hour⁻¹, respectively (negative values indicate net uptake). Mean N₂O fluxes from mid-April to mid-December across the 7-, 20-, 35-, 70-years old stands were -3.7, 1.5, -2.2, and-7.6 μg N₂O m⁻² hour⁻¹, without age-related pattern, whereas the uptake rates of CH₄ increased with stand age from 6.4 to -7.9, -10.8, and-23.3 μg CH₄ m⁻² hour⁻¹, respectively. For the same period, the combined contribution of CH₄ and N₂O exchanges to the global warming potential (GWP) calculated from net ecosystem exchange of CO₂ and aggregated forest floor exchanges of CH₄ and N₂O was on average DOC concentration in forest floor leachates was positively correlated to stand age, aboveground biomass and forest floor carbon pools. From the period of Mid-April to December, DOC fluxes via precipitation, throughfall, and leaching through forest floor and Ah-horizon were in the range of ~1 to 2, 2 to 4, 0.5 to 3.5, and 0.1 to 2 g DOC m⁻², respectively. DOC export from the forest ecosystem during that period through infiltration and groundwater discharge decreased with increasing stand age from ~7 to 4, 3, and 2 g DOC m⁻² (Chapter 7). This thesis improved our understanding of C and GHG exchange dynamics and their environmental, physical, and physiological controls in forest ecosystems. This study will also contribute to efforts being made to better predict future forest C and GHG dynamics and their feedbacks on climate under changing environmental conditions. ThesisDoctor of Philosophy (PhD
CARBON EXCHANGE IN A TEMPERATE DECIDUOUS FOREST IN SOUTHERN ONTARIO
Full text linkContinuous measurements of carbon fluxes and meteorological variables were made at a newly initiated flux tower site at an oak-dominant temperate deciduous forest in Southern Ontario, Canada from January to December 2012. Results indicate this forest was a moderate carbon sink in 2012. Annual values of net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (R) were 263 ± 30, 1192 and 922 g C m-2, respectively. An unusual warm period in March caused a strong increase in R. Erratic peaks of daily air temperature in April also increased R. A drought in July and early August reduced NEP rates when soil moisture values reached the lowest point of the year in late July and early August (minimum 0.023 m3 m-3). This decrease in NEP was mostly caused by a decrease in GEP, rather than increased R. Water use efficiency at this deciduous forest was 2.86 g C kg-1 H2O, indicating conservative water use by the forest. Downwelling photosynthetic active radiation (PAR) was a dominant environmental control on photosynthesis, followed by air temperature and vapour pressure deficit, except in extreme dry periods when soil water stress affected carbon uptake. Extremely cloudy days in the growing season resulted in net carbon release due to low photosynthetic uptake values. Results indicate that large climatic fluctuations in this region may cause high instability in photosynthetic carbon uptake and release from soil carbon pools. This study helps to evaluate and quantify the responses of deciduous forests in the Great Lakes region to future climate change and extreme weather events.Master of Science (MSc
Investigating Carbon Dynamics of a Young Temperate Coniferous Forest Using Long-Term Eddy Covariance Flux Observations
Full text linkoai:macsphere.mcmaster.ca:11375/28983Plantation and managed forests are major sink of atmospheric CO2 in North America and
across the world. If properly managed, these forests may help to offset anthropogenic
greenhouse gas emissions to mitigate climate change. This study investigated the impacts
of climate variability, extreme weather events, and disturbance (thinning) on the growth
and carbon (C) exchanges of a young temperate coniferous plantation forest (48-year-old
white pine (Pinus strobus)) in the Great Lakes region in Canada using long-term eddy
covariance flux observations. CO2 fluxes, as well as meteorological and soil variables
were continuously measured from 2008 to 2021 (14 years) to estimate net ecosystem
productivity (NEP), ecosystem respiration (RE), and gross ecosystem productivity (GEP).
Soil respiration (Rs) was also measured using automatic soil chambers from 2017 to
2019. Selective thinning was conducted first time in this stand in January 2021 to remove
approximately 1/3 of the basal area. Study results showed that climate conditions in the
early growing season, from late May to mid-July, determined the overall strength of C
uptake in any given year. However, above-average temperature and precipitation in the
late growing season significantly reduced NEP and even in some cases, transformed the
forest into a net C source for short periods due to large pulses of RE. Mean annual GEP,
RE and NEP values were 1660 ±199, 1087 ±96 and 592 ±169 g C m-2 yr-1, respectively,
from 2008 to 2021. Thinning did not significantly impact the C uptake of the forest as the
stand remained a net C sink with an annual NEP of 648 g C m-2 yr-1 in 2021. Changes in
annual GEP, RE and NEP in 2021 remained within the range of interannual variability
over the study period. Overall, Rs accounted for roughly 89% of the annual RE in this
stand. A complete understanding of the response of forest C dynamics to climate
variability and thinning in young plantation forests is critical to guiding future forest
management efforts for enhancing the growth and C uptake of these forest plantations to
maximize their potential in support of providing nature-based climate solutions.ThesisMaster of Science (MSc
The Water Use Dynamics of Temperate Pine Forest Plantations and their Response to Thinning and Climate Variability
Full text linkForest plantations have been long-employed to reverse land degradation and support biodiversity, and are now recognized to both take in atmospheric carbon dioxide, reducing the intensity of the greenhouse effect, and moderate local weather. It is important to consider the impact forest aging and management will have on provisioning of these services under climate change and extreme weather events, such as drought. This study encompasses a chronosequence of three Eastern White Pine stands planted in 1939, 1974 and 2002, situated in Turkey Point, Ontario, Canada. The oldest forest received two selective thinning treatments, removing 30% of trees, in 1983 and 2012.
Forest water use efficiency (WUE), which represents the amount of gross ecosystem productivity (GEP) per unit of water released through evapotranspiration (E), was compared among the three sites over 2008-2013. The youngest forest’s annual WUE increased over the study period, surpassing that of the older sites by 2013. When bulk surface conductance (Gs), representing gas exchange, was compared across the sites for the same years, the youngest site had the lowest Gs, particularly during drought. Gs at the oldest forest was highest and the most variable. Statistical analysis showed that across all the sites, E was more responsive to air temperature than atmospheric demand, soil moisture, and incident radiation. This study indicated that younger plantations may be more water-conservative during drought, and that air temperature is important to consider in projections of temperate coniferous forests’ carbon and water exchange.
To assess the impact of the 2012 selective thinning on tree-level and ecosystem-level water use at the oldest forest, sapflow velocity (Js), transpiration (Et) and E were compared between the two stands planted in 1939 and 1974, from 2011 to 2013. A relatively severe drought over the 2012 growing season led to a decline in Et at the unthinned site for that year, however the Et decline was more pronounced at the older, thinned site. From 2011 to 2012, Js increased at the thinned site, converse to the unthinned site – wherein Js was low as expected during drought. Hydraulic redistribution and lag time from sapflow at 1.3 m height to canopy evapotranspiration were seemingly unaffected by the thinning, indicating that low-level selective harvesting was not detrimental to the hydrological functionality of the stand, and may have been beneficial in allowing more soil moisture access per tree. As such, the stand may be better positioned to withstand recurrent dry spells resulting from precipitation variability, as predicted with climate change.ThesisMaster of Science (MSc
Carbon Dynamics in Temperate Forests
Full text linkForests ecosystems cover about 30% of the Earth’s land surface, corresponding to an area of roughly 42 million km2 globally. Forests play an important role in the global carbon cycle by exchanging carbon dioxide (CO2) with the atmosphere. Annually, forests act to effectively sequester large amounts of anthropogenically-emitted CO2 from the atmosphere through photosynthetic processes. Through the unparalleled increase of CO2 emissions over the past century and the subsequent climatic inconsistencies due to global climate change, the carbon sink-capacity of the world’s forests remains uncertain. Furthermore, since increasing temperatures have been shown to extend the vegetative growing season in forests, phenological responses to this change are of particular interest. In an effort to effectively assess the future carbon sequestration potential of forests, a better understanding of the climatic controls on phenology, and its influence on carbon processes, is needed.
The eddy covariance (EC) technique is a stand-level, in-situ, method used widely to assess the net CO2 exchange across the canopy-atmosphere interface. Together with meteorological data, the sequestration of CO2 and the subsequent ecosystem productivity can be quantified over various time scales (half-hours to decades). This dissertation reports results from field observations of EC measured fluxes that were used to study the climatic impacts on forest phenology and the resulting carbon dynamics in southern Ontario, Canada. The study sites, part of the Turkey Point Observatory, consisted of two similarly-aged, temperate, North American forests growing under similar climatic and edaphic conditions: the 80-year old (in 2019) white pine plantation (coniferous evergreen) and 90+ year-old, naturally-regenerated, white oak (deciduous broadleaf) forest. These forests were studied from 2012 to 2017, using the EC technique, digital phenological cameras, and remote-sensing measurements.
At the deciduous broadleaf forest, mid-summer (July and August) meteorological conditions were the key period in determining the annual carbon sink-strength of the site, acting to regulate the interannual variability in carbon uptake. The forest experienced higher net ecosystem productivity (+NEP; carbon sink) when soil temperatures ranged from 15 to 20°C and vapor pressure deficit was 0.7 and 1.2 kPa. From 2012 to 2016, the forest remained a net annual sink, with mean NEP of 206 ± 92 g C m-2 yr-1, similar to that of other North American deciduous forests.
Spring and autumn phenological transition dates were calculated for each year (2012 to 2017) from measured EC data and digital camera greenness indices. The timing of spring and autumn transition dates were impacted by seasonal changes in air temperature and other meteorological variables. Contrary to past studies, an earlier growing season start did not equate to increased annual carbon uptake. In autumn, a later end to the deciduous forest growing season negatively impacted the net carbon uptake of the forest, as ecosystem respiration (RE) outweighed the gains of photosynthesis. The digital camera indices failed to capture the peak dates of photosynthesis, but accurately measured the spring and autumn transition dates, which may be useful in future remote sensing applications.
A comparison of the two forests from 2012 to 2017 found the coniferous forest to have higher but more variable annual NEP (218 ± 109 g C m-2 yr-1) compared to that of the deciduous broadleaf forest (200 ± 83 g C m-2 yr-1). Similarly, the mean annual evapotranspiration (ET) was higher (442 ± 33 mm yr-1) at the coniferous forest compared to that of the broadleaf forest (388 ± 34 mm yr-1). The greatest difference between years resulted from the response to heat and drought. During drought years, deciduous carbon and water fluxes were less sensitive to changes in temperature or water availability compared to the evergreen forest.
Carotenoid sensitive vegetative indices and the red-edge chlorophyll index were shown to effectively capture seasonal changes in photosynthesis phenology within both forests via proximal remote sensing measurements during the 2016 growing season. Satellite vegetative indices were highly correlated to EC photosynthesis, but significant interannual variability resulted from either meteorological inputs or the heterogeneous landscapes of the agriculturally-dominated study area.
This dissertation improved our understanding of the dynamics of carbon exchange within the northeastern North American deciduous forest ecozone, through the examination of climatic variability and its impact on carbon and phenology. This dissertation also contributed to efforts being made to better evaluate the impact of species composition on carbon dynamics in geographically similar forests. Moreover, the use of the digital phenological camera observations and remote sensing techniques to complement and better understand the fluxes observed with the EC method was innovative and may help other researchers in future studies.DissertationDoctor of Philosophy (PhD
Data-driven approaches for sustainable operation and defensible results in a long-term, multi-site ecosystem flux measurement program
Full text linkModern advances in biometeorological monitoring technology have improved the capacity for measuring ecosystem exchanges of mass, energy and scalars (such as CO2). Translating these measurements into robust and accurate scientific information (and ultimately, understanding) requires careful assessment of operations throughout the biometeorological data life cycle. In response, this research analyzed and optimized aspects of data collection, management and filtering for an ecosystem exchange measurement program over an age-sequence of temperate white pine forests. A comprehensive data workflow and management system (DWMS) was developed and implemented to support the entire data life cycle for all past, present and future measurement operations in our research group, and meet the needs of a collaborative, student-led data management environment. Best practices for biometeorological data management were introduced and used as standards to assess system performance. Roving eddy covariance (rEC) systems were examined as a means of producing reliable time-integrated carbon exchange estimates at multiple sites, by rotating an EC system in a resource-mindful approach. When used with an optimal gap-filling model and rEC rotation schedule (2 sites with 15-day rotations), the results suggested its viability, as annual NEE estimate uncertainties ranged between 35 and 63% of the annual NEE flux magnitude at our study sites – even though approximately 70% of half-hours were filled. Lastly, a data-driven approach was used to investigate the effects of different friction velocity and footprint filtering methods on time-integrated carbon exchange estimates at our fetch-limited forests. Though predicted flux source areas varied considerably between footprint models, our objective analyses identified the model (Kljun et al., 2004) and within-fetch requirement (80%) that optimized reliability and representativeness of carbon exchange estimates. Applying this footprint model decreased annual NEE by 31 to 129% (59 to 207 g C m-2 y-1) relative to no footprint application, and highlighted the importance of objective analyses of EC flux filtering methods.Doctor of Philosophy (PhD
THE IMPACT OF INDUCED DROUGHT ON TRANSPIRATION AND GROWTH IN A TEMPERATE PINE PLANTATION FOREST
Full text linkA study evaluating the response of canopy transpiration (Ec) and growth rates to reduced water input, was conducted in a managed 70-year old planted temperate white pine (Pinus strobus L.) forest, in Southern Ontario, Canada from January to December 2009. In order to induce the drought, a 20m x 20m throughfall exclusion setup was established using interlocking aluminum troughs at a 3-inch slope. Throughfall was excluded from April 1st until July 3rd. During this period, 270mm of rainfall occurred (27% of annual precipitation) of which 90% was excluded. Sap flow velocity, soil moisture and soil temperature (at multiple depths) were measured continuously in both reference and drought plots. Dendrometer bands were also installed on all instrumented trees. Prior to enforced drought, adjacent plots showed slight variability in soil moisture while tree diameter and soil temperature did not show significant variability. Daily values of Ec from each plot ranged from 0 to 1.6 mm d-1 over the growing season (March-November) for the drought and reference plot respectively. The impact of the rainfall exclusion did not affect Ec until early June, 60 days after the drought was in place. Normalized values of Ec showed a 20% decrease from the drought trees compared to the reference. Cumulative growth rates between the two plots showed a net decrease in the drought trees of 42% from the reference and earlier termination of growth. However, the growing season Ec values were 174 mm y-l and 171 mm y-l for the drought and reference plot respectively. Currently, the effects of extreme droughtevents on carbon and water balances in conifer forests are poorly understood, dueto their sporadic occurrence in natural ecosystems. The findings of this study helpto establish the impacts drought may have on these ecosystems and evaluate theirpotential responses under predicted future climate regimes.Master of Science (MS
BIOMETRIC-BASED CARBON ESTIMATES AND ENVIRONMENTAL CONTROLS WITHIN AN AGE-SEQUENCE OF TEMPERATE FORESTS
Full text linkUnderstanding the response of forest carbon uptake and growth to interannual climate variability and forest management practices is important, given the large quantity of carbon stored in forests, and their significant role in the global carbon cycle. Since 2004, biometric and micrometeorological measurements were taken in an age-sequence (10-, 38- and 73-years-old as of 2012) of white pine (Pinus strobes L.) plantation forests in southern Ontario, Canada, providing an 8 year record of carbon sequestration, growth and climate. The 73-year old conifer site was thinned in early 2012, where 25% of trees were removed to improve light and water dynamics of this stand, providing an opportunity to study the impacts of thinning on its carbon cycle. Additionally, in 2012, similar biometric and micrometeorological measurements were initiated in a naturally-regenerated, managed 80-year-old deciduous (Carolinian) forest, located in close proximity to the pine stands. Similar to the conifer sites, the deciduous site is also a managed forest. The objectives of this study were to determine differences in carbon pools and carbon sequestration capacity: (a) across an age-sequence of afforested, managed conifer stands; (b) between similarly-aged managed coniferous and deciduous stands; and (c) in a mature conifer plantation before and after a thinning event. Results show that carbon assimilated in the stem of mature white pine trees follows a linear growth trend, while that of young white pines shows an exponential increase in carbon assimilation over the course of this study. Overall, carbon sequestration increased with stand age across the age-sequence, except when disturbed by an event such as thinning. Thinning substantially reduced the live aboveground carbon pool (by 14%), while increasing woody debris (by 122%) due to logging residue left on-site. Comparison between the mature coniferous and deciduous stands, showed that total aboveground carbon storage within the pine stand (144 t C/ha) was generally higher than in the oak-dominated deciduous stand (83 t C/ha), despite both growing in similar soil and climate. While monthly tree growth exhibited a positive correlation with mean monthly temperature across all sites, tree growth negatively correlated with precipitation at the 10-year old white pine and 80-year old deciduous sites and no apparent correlation existed at the 73- and 38-year old sites. At the three coniferous stands, total annual net primary productivity (NPP) exhibited no correlation with mean growing season temperature or precipitation. This suggested that tree growth in young coniferous stands could be as sensitive as that of mature deciduous stands to precipitation. However, overall NPP seemed to be less sensitive to climatic variables across these stands, irrespective of their age and NPP may be driven more by stand physiology. Finally, eddy covariance and biometric estimations of NPP and NEP were compared, and results showed that although some growth trends do compare between the two techniques, magnitude discrepancies do exist and should be studied further. Results from this study will be informative to forest managers, forest conservationists and those interested in forest carbon sequestration.Master of Science (MSc
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