Productivity Increase Through Atmospheric Co of Boreal Forests - Research Paper Example

Productivity increase through atmospheric CO₂ of Boreal forests The models of global vegetation predict the sensitivity of boreal forests to biome shift in the 21st century. The shift would be manifested at biome’s margins as expansion of evergreen forest into tundra with grassland replacement or southern edge of biome’s temperate forest. The productivity of the forest was evaluated from 1982 by linking estimates of satellite in primary productivity within Alaska and precisely boreal (Landsberg and Sands 98). The tree-ring data were also set and both trends recorded which indicated growth increase that was consistent. The increase was at the ecotones of boreal-tundra in contrast with productivity that was drought-induced resulting to decline in the entire region. The hypothesis effects are supported by the patterns on the initiating shift of biome. The dispersal rate of the tree, future climate rate of change and habitat availability undergo geographic range shift that is gradual with a rapid decline. Introduction The model of global vegetation that id dynamic over 21st century predicts the forest conversion experience likeliness to loss in biome’s northward shift especially under greatest warming scenarios. High altitudes in the north part of the forest ecosystems contain 30% of terrestrial carbon. This change modifies future climate substantially. There is increased shrub abundance at high latitudes and in forest environments that have alpines communities; there is a recent migration to elevations higher environmental warming. There is some evidence on directional change at regional scales in terrestrial biomes distribution that is attributed to climate change that is ongoing. The high latitude simulation model ecosystems were noticed to have changed within the last three decades. This duration experienced rise in atmospheric concentration of CO₂ and warming and increased trend of vegetation productivity. Satellite imagery analysis has supported the idea with indications of increased primary gross productivity on remote sensing estimates (Gutman and Reissell 101). Tundra shrub growths increased in the recent field measurements over the period and are in agreement with output models. Cold environment margins at the far north of the tree populations have resulted to positive sustained growth responses on temperature and have grown rapidly at the greatest rate ever recorded. In contrast, field observations that are spatially restricted have anomalously low documentation on productive stands growth trend in Alaska. Moreover, an elevation tree line observation indicates that when the climate warming goes beyond a threshold that is physiological, air temperature and tree growth divergence occurs. Few studies from satellite-base research report provide initial reversal on productivity gains across boreal forest in areas of high latitude. However, the observations have not been linked to measurements of the filed directly. Measurements done through tree-ring provide records that are consistent on productivity of the past but are collected traditionally at transitions of ecosystem zones in testing climate sensitivity than growth trend capturing in the forest stands. In-situ tree measurements in terms of growth are compared to synoptic observation across domains of large scale like satellite data. The establishment of this link gives a potential way to extend observation fields that are relatively limited to the covered partial domain by observations of remote sensing. This provides a biome-wide view that is comprehensive to trends and productivity patterns. The biome boreal forest in the Northern America was dominated by spruce species. A set of data of extensive tree-ring width were collected from the forest stands of the black spruce. These species have been reported in rare cases in the literatures of dendrochronology despite being dominant in the North American boreal. The black spruce (BS) and the white spruce (WS) stands spread to the gradient of east-west from drier are in the continent to a climate that is more maritime mesic. The strands were sampled capturing variations in the productivity of the forest (Beeby and Brennan 149). The set data was compared to sensing observations from remote satellite of vegetation index that has different normalization and gross productivity that is reflected on spectral metric system. The temporal covariance and spatial coherence of the two observational records that were different was assessed in-line with inter-annual variability. This was done for graphical pattern evaluation in connection to vegetation productivity changes over the coincidence period. The patterns are investigated to test the hypothesis undergone by the boreal biome as a range shift. The process has got two characteristics that relate to is the tests. The first characteristic is the increase of productivity at ecotones at boreal-tundra. The second characteristic is the decline in productivity at margins that are warmer of the current distributions. Method The method used from the year 1982 to the year 2008 was known as gross productivity that is remotely sensed. This method was mapped on annual basis from a time series that is gridded as a mean during the season of growth. At the same time partial variation was accounted for in the length of the growing season. According to National Aeronautics and Space Administration (NASA), the global inventory modeling and mapping studies (GIMMS) data set spreads across the entire period at spatial resolution. The derived measurements were carried by Advanced Very High Resolution Radiometer (AVHRRs) through the satellite series of NOAA afternoon-viewing. The processing of data included effects of atmospherics aerosols correction from eruptions of Pinatubo and El Chichon, sensor degradation and differences and zenith angle effects of solar. This gave 24 global images per years with the first 15 days of the month represented by the first image of each month (Biosvenue 126). The remotely sensed gross productivity (Prs) was mapped for every year between 1982 and 2008. The mapping of growing season length (GLS) was done at 30 arc-second spatial resolution of land cover products’ dynamics from the Moderate Resolution Imaging Spectroradiometer (MODIS). The GSL was estimated to be the period between dates of latest greening start and the start dormancy date recorded in the earliest stage by MOD12Q2 data between the year 2001 and 2004. The season of snow melt events that come early and late in the fall could not overlap with the estimates of growing season was met by shortening the GSL estimates by a third. The GSL resulting map was then averaged to solutions of temporal and spatial data to determine each GIMMS-NDVI grid cell. During the growing season, Prs was mapped and calculated annually as a mean using the GSL map for accounting of spatial variation. The yearly variation was accounted for in the growing season at every start and end and each Prs maximum output value set for an average moving time series having window length. The map trend data were filtered further for non-deterministic series and anthropogenic mask changes. The land cover map of boreal of 2005 and a spatial 15 arc-seconds resolution were reclassified from the classifications of International Geosphere-Biosphere Programme to three platforms (III, Sala and Huber-Sannwald 133). The first platform covers anthropogenic land that involves urban or agricultural land. The second platform involves non-vegetated lands and the third platform involves vegetated lands. The grid cells of GIMMS were excluded from the analysis in case of more than 40% of non-vegetated classification. The exclusion also takes place when vegetated land covers less than three times larger than the cover of anthropogenic land. Prs change patterns were compared to mapped tree cover gradients in MODIS continuous vegetation fields’ product and temperature on monthly basis for the period from 1982 to 2008. They were both gridded in matching the set GIMMS data. Tree-ring Sampling The radial growth were measured in 839mature trees, of which 212 were BS and 627 were WS dominant in the landscape currently with no visible signs of damage by insect of fire. The pooling of trees was then done creating the wood growth (WG) stand –level estimates at 42 BS and 46WS based on the trees location on the GIMMS grid cell. The number of sampled trees in the stand varied with a medium of 6. In the entire sampling time span, the stand-level growth mean was calculated that generated 88 series along the median which equaled to 20 in the pairing of GIMMS data and growth (Parrent 148). The de-trending of the age range in the spruce trees were not done in the tree-ring data in the study because it exhibits the trend in age-related growth by infinite. Moreover, it was revealed that there were negligible effects in de-trending on the relationship of growth and climate. The calculation of mean radial growth was done per stand beginning with tree-rings series that are non-normalized for preservation of large tree contributions to WG stand-level. The estimation of soil wetness in relation to topography was done for tree stands models of 60-m digital elevation and local draining of upslope area calculated through contour lengths per certain unit points. Statistical Methods Prs temporary trends are subjected to Vogel-sang (III, Sala and Huber-Sannwald) test before mapping to determine the presence of deterministic temporal trend in the data. The stationary test of Vogel-sang controls for the possible correlation in strong serial in the spurious trend data generation. The test is valid despite the result having stationary errors or a unit root and serial correlation estimates of nuisance parameters is not required. The test is useful in masking Prs stochastic changes in the landscape like the ones that have disturbance association. The temporal changes in the Prs and series of trees growth were consistently compared and quantified using Kendall’s τ and calculated at each site from radial growth and cross-time tabulation. The trends of growth and Prs were quantified through the use of regression model that describe linear function of τ Prs in the weighing of the number of ring-width measurements available. The WS and BS were included in the regression but sites were excluded with burning evidence in the earlier years of 1950. The year-to-year variation in growth and Prs was compared in isolation from trends of multi-year. The Prs and yearly radical growth change was calculated at every site with the use of Kendall’s τ in agreement with yearly changes. The agreement was then calculated in yearly increasing growth and decreasing growth separately in the availability of observation of 5 years. Later the agreement was assessed for statistical significance across all sites using a test known as Wilcoxon signed rank. This gave a number of results to the research in relation to the determination of significant atmospheric CO₂ productivity in boreal forest (Lorenz and Lal 211). Results There has been within-stand variation in the trend of tree growth present in the satellite records over the past years from the year 1982. The results showed that 48 of 88 stands of trees that displayed both negative and positive growth trend. The raw rings mean inter-series correlation width during the period of growth reference of 1950 to collection date that was high generally. This indicated that estimations that are based on tree-ring of stand-level WG samples were robust. Across boreal, both satellite-derived Prs and WG had a predominant decline from 1982 except in areas that are more of maritime of the western part. Non-stochastic trend in the entire gross productivity was indicative of the remote sensing data across the tree-ring sites. The yearly values of Prs and WG had a strong positive correlation and temporal trend that was negative being displayed between 1982 and 2008. The decrease in WG that was relative to previous years had a weekly correlation with Prs changes. WG increases in the consecutive years were not associated consistently with Prs equivalent increases by contrast. This indicates that allocation of resources to WG and leaf mass is not regulated necessarily at time scale that is identical. The tree-rings used in the research were collected from trees that are mature in stands that were unburned because the wildfire legacy was reflected in the Prs time series of the satellite. The effects of the fire magnitude depend upon the burning severity and the extent of timing (Parry 176). There may not be an agreement between Prs and WG consequently in some areas that have characteristics of vegetation mortality or rapid vegetation re-growth as a result from fire effects. After the exclusion of stochastic changes that are disturbance-related in Prs through the use of Vogel-sang test and burn history data, the tundra area reveals Prs increase to the near-ubiquitous. The boreal areas that are coldest and are sparsely populated by forestation in the current state like the ones that are boreal-tundra ecotones, revealed deterministic productivity increases in three decades of the past. All the boreal zone forested areas had productivity decline dominance including the densely forested and warmest areas creating a contrast. There was no significant difference in the topographical wetness between sites that had decreased or increased productivity, whether through gross productivity measurements as either satellite-derived or WG with indications of declined productivity in 8 of 10 sites that are the wettest. Discussion There is an increase globally of the CO₂, tropospheric ozone, and temperature and nitrogen deposition concentrations in the past three decades. These concentrations potentially drive vegetation productivity shifts. The concentrations mean ozone in Alaska was very low in comparison to areas that are more populated and are considered generally to have global background levels. This results to needle-leaved trees that have greater tolerance to ozone concentrations that are elevated, projecting ozone increases over 21st century have no expectations that affect vegetation productivity adversely in Alaska. There is unlikely explanation from the recent increase in productivity patterns of the recent increases that are documented (Keller, Bustamante and Gash 241). In the same manner, nitrogen disposition rate that is relatively low in the interior of Alaska are an indication of lower magnitude than experimentally found rates to tree growth boreal limit. This becomes consistent with the recent results from the model of process-based biogeochemistry coupled with nitrogen and carbon cycles. The cycle indicates Nitrogen deposition over the past decades that have effects that are very small on exchange ecosystem of boreal net. Simulations model reveals that increased concentrations of atmospheric CO₂ from the year 1750 have increased net carbon uptake by boreal ecosystems and arctic like the fertilization effects of CO₂. However, the effect is seen as overweighed by carbon losses of strong increase to the atmosphere from the biosphere at the pan-arctic scale because of climate and fire disturbance shifts. This takes place through combustion and moisture, temperature and controls of succession on photosynthesis to the extent that Co₂ fertilization is not detestable over the investigated period of 30 years. Generally, the pattern of productivity that is documented in unburned mature forests is climate driven more than the effects of CO₂ fertilization, nitrogen nor ozone. The observed productivity pattern of spatiotemporal productivity reveals that temperature of colder areas had limitations on growth of spruce that are released in the decades of warming. This takes place while there is a shift in climate beyond the optimum for growth in the zones that are warmer in the interior of Alaska. Earlier carbon isotopes analysis in the WS attributes to induced drought stress temperature decline in growth in the interior Alaska. Moreover, additional analysis reveals drought-induced shift that is equally strong of BS tissues in isotopic composition in early 1980s. This indicates an increase in water availability that limits dominant tree species productivity in Alaska boreal forests (Kabat, Claussen and Dirmeyer 125). Boreal forest drought can originate from inefficient soil moisture or evaporation demands that are excessive. The summer precipitations have been shown as experimentally limiting spruce trees productivity. However, the precipitation does not indicate directional changes of boreal on the span of investigations. The finding reveals that recent productivity decreases are non-restricted to sites in the upland but are prominent equally in floodplains having buffered ground water against water deficits that are precipitation-driven. Moreover, the findings indicate that the widespread productivity decline is not driven by soil moisture. Contrary to stress on soil moisture, demands of evaporation have increased in the last decades including the periods of relatively stable temperature. The finding support the contention on productivity’s observed decrease that are as a result of stemming drought stress from imposed hydraulic limitations through pressure deficit of high vapor during warm summer photosynthesis periods. Moreover, the responds on plant growth are non-linear to both temperature and vapor pressure deficits (VPDs) that are coupled in a consistent observation with relationship reports of temperature-growth. The productivity trends that are negative in the boreal forest are pronounced from mid 1990s to be in contrast to increased widespread productivity in tundra and forest areas in the decades that proceeded. From the mid-1990s, climate warming divergent response is observed in forests and tundra arctic areas which are consistent with earlier NDVI Alaska and North America trends. Tundra productivity increases are as a result of warmer climates thereby constraining boreal forests’ photosynthetic activity. The global models of ecosystem simulations indicate increased primary productivity in tundra and forests areas in Alaska from the year 2000 to the year 2009. This has failed apparently to capture observed declines through satellite imagery. Plant respiration increases generally with temperature making the net productivity to be at odds with observed gross productivity boreal forests that experience undisturbed maturity. There is a consistent increase in net productivity with metabolic response that is assumed to temperature rise in cold climates resulting to recent simulation that show no vegetation productivity moisture limits (Newman 171). The observation reveals that limited Alaskan forests productivity is as a result of higher temperatures in the recent decades resulting to coincidental evaporation demand increases in consistence with measurements of in-situ and experiments in connection to simulation models. The observed changes in productivity of forests in the satellite periods that are recorded and temperature relationship indicates that drought stress are a result of warming,. This has exerted limiting role that is increasing on tree growth and Prs across ecosystem of boreal forest in the interior part of Alaska. The observance of increasing Prs and growth is only noticed in the low tree marginal zone in the western part of Alaska that constitutes to boreal-tundra ecotones and current trees beyond limit with sub-optimal tree growth temperature in the 20th century. The projection of identical shift pattern in forest productivity of boreal through the model of global vegetation has occurred over the 21st century course resulting to changes in biome-wide such as regional recession of drought-induced forests and forest expansion northwards. The records of current observational confluence with longer projection terms latter provide hypothesis support for already underway biome shift on a scale that is quasi-continental. In the existence of increase in temperature, composition changes, mortality and intensified stress will be experienced in the current forest areas. Moreover, the ecotones transition of northern and western Alaska will be more stable climatically enhancing growth associated to forest migration and tree recruitment (Stantuff and Madsen 117). Finally, boreal forest resilience to forest migration possibility and climate change by rates of habitat availability and tree dispersal will shape the spread the biome shift in speed and extent. Both the satellite data and in-situ tree-ring presented reveals that the climate has shifted beyond physiological optimum in the last few decades for spruce growth throughout the boreal ecosystem. There is need for intensified monitoring to document observed pattern in relation to result in boreal biome rapid decline instead of geographical shift of gradual range. This is because direct climatic warming effects on growth of trees can amplify direct effects through increased insect disturbance susceptibility. Moreover, expansion of forests into tundra areas will vary geographically because it is impacted by effects of climate that are indirect like fire and thermokrast and are limited physiologically by drought (Kabat, Claussen and Dirmeyer 94). Finally, in case of the rate of tree migration being outpaced by continued climate optimum forest growth continued shift, there is more likeliness of boreal biome contraction in the 21st century at the northward. This can also result to distributional elevation shift. Conclusion In the case on rise in CO₂ content in the air, almost all the earth plants with the inclusion of forest ecosystems do respond through increased rate of photosynthesis and more biomass production. The phenomena will allow perennial species that are long-lived with forest ecosystem characteristics to sequester large carbon amounts within the wood for an extended time span. This will result to CO₂ counterbalance in the ultimate emissions of mankind fossil fuel produce usage. This provides atmospheric CO₂ response enrichment and carbon sequestration. The increase in growth and photosynthesis is a result of elevation of atmospheric CO₂ in both coniferous and broad-level species. Elevated Co₂ increases the biomass production and rate of photosynthetic rates in boreal forest by leading a greater amount of sequestration carbon. The rise in temperature spurs loss of carbon from the trees and soils exacerbating global warming. In case of temperature rise by 10 to 29 degrees results to increased forests seedlings with increased biomass production and rate of photosynthesis. The increases in CO₂ content in the air results to increase sequester carbon of forests earth’s ability. The atmosphere that has more of CO₂ will provide photosynthetic rates exhibited in a greater rate and reduced respiratory rate. These observations with the inclusion of atmospheric CO₂ enrichment findings have minimal effects on the decomposition rate of plant tissues. Therefore, biologically-fixed carbon depicts residency time that is greater within plant tissues. In the direction of carbon into products of wood, there will be increased atmospheric CO₂ enrichments substantially. Some of the atmospheric CO₂ enrichments can be kept from circulation for a longer period of time such as a decade or beyond. Works Cited Beeby, Alan and Anne-Maria Brennan. First Ecology: Ecological Principles and Environmental Issues. New York: Oxford University Press, 2008. Biosvenue, Celine. Assessing Forest Responce to Climate and Resolving Productivity Measurements Across Spatial Scales. United States: Proquest Information and Learning Company, 2006. Gutman, Garik and Anni Reissell. Eurasian Arctic Land Cover and Land Use in a Changing Climate. New York: Springer, 2010. III, F. Straut Chapin, Osvaldo E. Sala and Elisabeth Huber-Sannwald. Global Biodiversity in a Changing Environment: Scenarios for the 21st Century. New York: Springer, 2013. Kabat, Pavel, et al. Vegetation, Water, Humans and the Climate. Berlin: Springer-Verlag, 2004. Keller, Michael, et al. Amazonia and Global Change. Carlifonia: John Wiley & Sons Publishers, 2013. Landsberg, Joe J. and Peter Sands. Physiological Ecology of Forest Production: Principles, Processes and Models. London: Academic Press, 2010. Lorenz, Klaus and Rattan Lal. Carbon Sequestration in Forest Ecosystems. New York: Springer, 2009. Newman, Jonathan A. Climate Change Biology. Canada: CABI, 2011. Parrent, Jeri Lynn. Global Climate Change and The Ectomycorrhizal Symboisis: Consequences of Fungal Communities and Nutrient Transport Regulation. United States: ProQuest Information and Learning Company, 2007. Parry, Martin L. Climate Change 2007: Impacts, Adaptation and Vulnerability:Contribution of working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. London: Cambidge University Press, 2007. Stantuff, John A. and Palle Madsen. Restoration of Boreal and Temperate Forest. Florida: CRC Press, 2010. Read More