Chaparral growth-ring analysis as an indicator of stand biomass development

2016 ◽  
Vol 25 (10) ◽  
pp. 1086 ◽  
Author(s):  
Kellie A. Uyeda ◽  
Douglas A. Stow ◽  
John F. O'Leary ◽  
Christina Tague ◽  
Philip J. Riggan

Chaparral wildfires typically create even-aged stands of vegetation that grow quickly in the first 2 decades following a fire. Patterns of this growth are important for understanding ecosystem productivity and re-establishment success, but are logistically challenging to measure over long time periods. We tested the utility of a novel method of using shrub growth rings to estimate stand-level biomass accumulation at an annual time scale in southern California chaparral. We examined how temporal variation in precipitation and spatial variation in solar irradiation influence that accumulation. Using field measurements and a relationship between stem basal area and aboveground biomass, we estimated current biomass levels in an 11-year-old chaparral stand, and used growth-ring diameters to estimate growth in each year from age 4 to 11 years. We found that annual growth as measured by shrub growth rings tracked closely with patterns of annual precipitation, but not with time since fire. Solar irradiation was not found to be a significant covariate with total biomass by plot, possibly due to sampling area limitations. The close relationship of annual biomass accumulation with annual precipitation indicates that shrub growth-ring measurements can provide a useful metric of stand-level recovery.


Author(s):  
Muhammad Zeeshan Mehmood ◽  
Ghulam Qadir ◽  
Obaid Afzal ◽  
Atta Mohi Ud Din ◽  
Muhammad Ali Raza ◽  
...  

AbstractSeveral biotic and abiotic stresses significantly decrease the biomass accumulation and seed yield of sesame crops under rainfed areas. However, plant growth regulators (such as Paclobutrazol) can improve the total dry matter and seed production of the sesame crop. The effects of the paclobutrazol application on dry matter accumulation and seed yield had not been studied before in sesame under rainfed conditions. Therefore, a two-year field study during 2018 and 2019 was conducted with key objectives to assess the impacts of paclobutrazol on leaf greenness, leaf area, total dry matter production and partitioning, seed shattering, and seed yield of sesame. Two sesame cultivars (TS-5 and TS-3) were treated with four paclobutrazol concentrations (P0 = Control, P1 = 100 mg L−1, P2 = 200 mg L−1, P3 = 300 mg L−1). The experiment was executed in RCBD-factorial design with three replications. Compared with P0, treatment P3 improved the leaf greenness of sesame by 17%, 38%, and 60% at 45, 85, and 125 days after sowing, respectively. However, P3 treatment decreased the leaf area of sesame by 14% and 20% at 45 and 85 days after sowing than P0, respectively. Compared with P0, treatment P3 increased the leaf area by 46% at 125 days after sowing. On average, treatment P3 also improved the total biomass production by 21% and partitioning in roots, stems, leaves, capsules, and seeds by 23%, 19%, 23%, 22%, and 40%, respectively, in the whole growing seasons as compared to P0. Moreover, under P3 treatment, sesame attained the highest seed yield and lowest seed shattering by 27% and 30%, respectively, compared to P0. This study indicated that by applying the paclobutrazol concentration at the rate of 300 mg L−1 in sesame, the leaf greenness, leaf areas, biomass accumulation, partitioning, seed yield, and shatter resistance could be improved. Thus, the optimum paclobutrazol level could enhance the dry matter accumulation and seed production capacity of sesame by decreasing shattering losses under rainfed conditions.



1986 ◽  
Vol 16 (5) ◽  
pp. 1041-1049 ◽  
Author(s):  
K. C. Yang ◽  
C. A. Benson ◽  
J. K. Wong

The distribution and vertical variation of juvenile wood was studied in an 81-year-old dominant tree and an 83-year-old suppressed tree of Larixlaricina (Du Roi) K. Koch. Two criteria, growth ring width and tracheid length, were used to demarcate the boundary of juvenile wood. The width of juvenile wood, expressed in centimetres and the number of growth rings, decreased noticeably from the base to the top of the tree. The volume of juvenile wood decreased in a similar pattern. These decreasing trends had a strong negative correlation with the year of formation of cambial initials at a given tree level. The length of these cambial initials decreased with increasing age of formation of the cambial initials. In the juvenile wood zone, there was a positive linear regression between the growth ring number (age) and the tracheid length. The slopes of these regression lines at various tree levels increased as the age of the year of formation of the cambial initials increased. At a given tree level, the length of tracheids increased from the pith to a more uniform length near the bark. However, the number of years needed to attain a more uniform tracheid length decreased from the base to the top of the tree. These relationships suggest that the formation of juvenile wood is related to the year of formation of the cambial initials. Consequently, the juvenile wood is conical in shape, tapering towards the tree top.





2020 ◽  
Vol 12 (6) ◽  
pp. 23
Author(s):  
Yuxin He ◽  
Chao Liu ◽  
Heping Xie ◽  
Jingchen Wang ◽  
Yang Wang ◽  
...  

Agriculture is a crucial area to be considered when exploring and exploiting the use of deep-underground space. We investigated the feasibility of deep-underground seed storage by keeping canola seed in either envelopes or sealed packages at four depths below the Earth’s surface (0, 240, 690, and 1410 m) at a gold mine in northeastern China. We studied the effects of storage depth and duration by conducting germination tests with the stored seed. The results showed that the rate of germination was reduced in seed stored at deeper levels and was also lower at all depths after a more prolonged period of storage. Seeds from sealed packages exhibited better resistance to the deep-underground environment than seeds kept in envelopes. However, measurements of hypocotyl lengths and biomass accumulation revealed that the germination of seeds stored in deep-underground was initially inhibited but recovered well compared with the control as the storage depth increased. The total biomass of the hypocotyl increased as the depth of seed storage deepened, indicating the existence of a compensatory effect on seed germination. The findings suggest that short-term deep-underground storage of seeds in sealed packages would improve the germination performance of cultivated canola in terms of the hypocotyl length and biomass accumulation and might be considered as a pre-sowing strategy.



2005 ◽  
Vol 17 (41) ◽  
pp. 251-264
Author(s):  
Gilbert Cestre

The present study is one of the unpublished research projects which are known to have been conducted in New England and in Eastern Canada under the guidance of the late Richard J. LOUGEE, long-time professor of Geomorphology at Clark University. Over a number of years, this writer has worked in close relationship with Lougee and much evidence in the field was studied together. It is believed that here has been recorded a most detailed work of surveying, and this undoubtedly accounts for the somewhat exceptional results that will be presented. The area selected for this study (about 80% of it is woodland) is located in the highlands of Central Massachusetts in Worcester County, about twenty miles (32 kilo-meters) northwest of the city of Worcester. It consists of the valley of the Otter River draining north, and of a small portion of the East Branch of the Ware River draining south. Since completion of this study, parts of the low area which held the ancient glacial lakes have been flooded to become water reservoirs. That proglacial lakes, though temporary they may have been, once submerged much of the area under study, is shown by an abundance of deltas, kames, eskers and deltaic kames terraces. It is believed that all of these were built under water in such lakes. Other features, such as kettle-holes and glacial outlets, especially ice-marginal channels cut diagonally down the slope, have also been studied. By plotting on a profile of the most characteristic elevations (often carefully surveyed), it is possible to find the water planes of ancient proglacial lakes. To this must be added experiments conducted in a sedimentation tank as also measurements of both the imbrication of cobbles in eskers and the « smoothness indexes » of such stones and pebbles, using A. Cailleux' methods. Thus were obtained results which tend to show that : 1- the area under study probably was in a deep interlobate space created between the Connecticut Valley lobe to the west and the Boston Basin lobe to the east ; 2— ice-marginal channels are an indication of the existence of a thick, fast-retreating ice border ; 3- an isostatic balance restored itself by sometimes quick and strong adjustments of the crust of the earth ; 4— an early upwarping, made up of various zones of tilting articulated on hinge lines, has been referred to as Hubbard Uplift and is the earliest known in the post-Glacial history of New England.



2004 ◽  
Vol 155 (6) ◽  
pp. 208-212 ◽  
Author(s):  
Peter Bebi ◽  
Alejandro Casteller ◽  
Andrea Corinna Mayer ◽  
Veronika Stöckli

Snow, avalanches, and permafrost are extreme site conditions for plants. Reactions and adaptations to such extreme conditions can be reconstructed with growth ring analysis and linked with corresponding climate and disturbance data. On the basis of five case studies in and around the long-term research site Stillberg, near Davos, we discuss both the potential and the limits of dendroecology to understand the effect of such extreme site conditions. Despite some uncertainties in reliably assigning plant reactions, growth ring analysis is a valuable addition to better understand the effects of extreme site conditions on the survival and growth of plants. This can lead to improved management strategies associated with natural hazards, especially in the case of avalanches.



Author(s):  
Huan Pablo de Souza ◽  
Mauro Valdir Schumacher ◽  
Aline Aparecida Ludvichak ◽  
Dione Richer Momolli ◽  
Claudiney Do Couto Guimarães ◽  
...  

The objective of this study was to quantify the biomass and the macronutrient stock in an experiment of fertilization with Eucalyptus urophylla, planted in arenized soil at 12 months-old, in Rio Grande do Sul, Brazil. The experiment had a completely randomized design with five treatments (T1, T2, T3, T4 and T5) with three replications. The treatments T2, T3, T4 and T5, received increasing doses of triple superphosphate. On the other hand, the T1 treatment was the only one to receive natural phosphate in planting. For the determination of the biomass, fifteen trees were felled and separated in the following components: leaves, branches, stem bark, stem wood and roots. Samples of the components were collected and transported to the laboratory for biomass determination and chemical analysis. The total biomass varied between the treatments, with highest biomass accumulation of 6.83 Mg ha-1 occurring in T5. The T1 presented the highest biomass for roots representing 33.4% of the total biomass. The biomass distribution among the different components in the decreasing order was: roots > stem wood > leaves > branches > stem bark, for all the treatments. The treatment with higher doses of fertilizers (T5) presented the highest amount of nutrient accumulation in the total biomass (131.26 kg ha-1). The concentration and accumulation of nutrients presented the following trend K > N > Ca > Mg > P > S. Analyzing the different components of biomass, the highest amounts of nutrients followed the order: leaves > roots > stem wood > branches > stem bark. Fertilization influenced the biomass production of E. urophylla in arenized soil in the Pampa biome, but without significant differences to date (12 months). The leaves had the highest concentration of macronutrients, with the exception of Ca, which was higher in the bark. The K was the element that presented highest accumulation in whole tree. The plantation of eucalyptus with fertilization management may be an alternative for the economic use of arenized soil.



Author(s):  
E.F. Chernikova ◽  
◽  
I.V. Fedotova ◽  
M.M. Nekrasova

Abstract: Working conditions at metallurgical enterprises are characterized by the impact of a complex of harmful production factors that do not correspond to the normalized levels, which causes the risk of developing professional and professionally conditioned pathology. Trained workers who are exposed for a long time to industrial noise that exceeds the permissible values by 10 dB or more are considered as a risk group for the development of aural (sensorineural hearing loss, SHT) and extraaural (high blood pressure, HBP) pathology. Hearing loss is an important medical and social problem, as it turns into a cognitive dissonance and a violation of verbal communication for the employee. Working conditions at one of the modern metallurgical plants were evaluated according to the data of sanitary and hygienic characteristics of working conditions. The study of the prevalence of SHT and HBP was carried out based on the materials of a medical examination and a questionnaire survey of workers (n=73, male, aged 36-75 years (57.32±0.89), with work experience of 8-58 years (34.29±1.16)). To assess the joint influence of age and seniority, an original scoring system was used, which allowed us to distinguish 3 observation groups. The severity of SHT and HBP was also assessed in points. The study showed a significant increase in the prevalence and severity of hearing loss and HBP with an increase in the duration of exposure and the age of employees. The presence of a close relationship between the analyzed pathology and working conditions is illustrated by the value of the odds ratio in groups 1-3 (ORSHT = 3.75-4.71; ORHBP = 2.0-5.0). Thus, the studied professional group of trained qualified metallurgists needs to develop health-improving measures to preserve labor longevity.



Author(s):  
Joanna D. Haigh ◽  
Peter Cargill

This chapter looks at how the Sun varies in terms of its emissions of radiation and particles and how these changes might be associated with variations in weather and climate on Earth. Investigations of climate variability and climate change depend crucially on the existence, length, and quality of meteorological records. Ideally, records would consist of long time series of measurements made by well-calibrated instruments densely situated across the globe. For longer periods, and in remote regions, records have to be reconstructed from indirect indicators of climate known as proxy data. The chapter introduces one well-established technique for providing proxy climate data: dendrochronology, or the study of the successive annual growth rings of trees.



Author(s):  
J. Paluch ◽  
S. Keren ◽  
Z. Govedar

Abstract In this study, we analysed patterns of spatial variation in the basal area of live and dead trees and structural complexity in close-to-primeval forests in the Dinaric Mts. The results were compared with an analogous study conducted in the Western Carpathians. The research was carried out in the Janj, Lom and Perucića forest reserves (Bosnia and Herzegovina) in mixed-species stands of silver fir Abies alba Mill., European beech Fagus sylvatica L. and Norway spruce Picea abies (L.) H. Karst. In the core zones of the reserves, concentric sample plots (154 and 708 m2) were set in a regular 20 × 20 m grid covering approximately 10 ha. The analyses revealed varying distribution patterns of live canopy trees, suggesting that these characteristics may fluctuate to some extent at the regional level. At the spatial scale of 708 m2, attractive associations between dead canopy trees were found, but this tendency disappeared with increasing area. Although stands in the Dinaric Mts. are characterized by an almost twofold greater biomass accumulation compared to those from the Western Carpathians, the study revealed analogous bell-shaped distributions of stand basal areas of live trees and a very similar trend of decreasing variation in stand basal area and structural heterogeneity with increasing spatial scale. Nonetheless, the higher growing stocks, lower ratios of dead to live tree basal area and lower proportion of homogeneous structure types found in the Dinaric Mts. may suggest a less severe disturbance history over recent decades in this region compared to the Western Carpathians.



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