Pre-emergence herbicides affect seedling emergence of tropical forest tree species

Published Date
Original Paper

First Online: 

28 November 2016

DOI: 10.1007/s11676-016-0348-5

Cite this article as: 

de Souza, D.C. & Engel, V.L. J. For. Res. (2016). doi:10.1007/s11676-016-0348-5

Author

• Diego Cerveira de SouzaEmail author
• Vera Lex Engel

Abstract

Testing techniques to reduce weed infestation is a crucial step in developing direct tree seeding systems. The use of pre-emergence herbicides may be an alternative to manual weeding techniques, but so far, information on how they affect the seeds of native tree species is scarce. We established a greenhouse experiment to evaluate the effects of four pre-emergence herbicides (atrazine, diuron, isoxaflutole and oxyfluorfen) on weed suppression and seedling emergence and early growth of seven tropical forest tree species (Annona coriacea Mart., Citharexylum myrianthum Cham., Cordia ecalyculata Vell., Peltophorum dubium (Spreng.) Taub., Psidium guajava L., Pterogyne nitens Tul. and Schinus terebinthifolia Raddi). The experimental design was a randomized complete block design with five treatments and five replicates. The treatments consisted of a single dose of each pre-emergence herbicide and a control. Throughout the 60 days after sowing we evaluated weed cover and seedling emergence and early growth of tree species. Overall, our results suggest that all tested herbicides reduced weed cover; however, they also negatively affected tree species seedling emergence. Of the four herbicides tested, atrazine and diuron showed the greatest effects on tree seedling emergence, oxyfluorfen was least aggressive towards native species and isoxaflutole was most effective in weed control. Native tree species varied in their responses to herbicides, indicating that future experiments should increase the number of species tested as well as investigate how seed traits can affect the species responses to different herbicides.

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Effects of anthropogenic disturbances on natural regeneration and population structure of gum arabic tree (Acacia senegal) in the woodlands of Lake Baringo ecosystem, Kenya

Published Date

Original Paper

First Online: 

30 November 2016

DOI: 10.1007/s11676-016-0349-4

Cite this article as: 

Omondi, S.F., Odee, D.W., Ongamo, G.O. et al. J. For. Res. (2016). doi:10.1007/s11676-016-0349-4

Author

• Stephen F. OmondiEmail author
• David W. Odee
• George O. Ongamo
• James I. Kanya
• Damase P. Khasa

Abstract

Despite the ecological and economic importance of Acacia senegal, little is known about the effects of anthropogenic disturbances on its natural regeneration patterns and population structure. We investigated the effects of these factors within the Lake Baringo woodland ecosystem. Data was collected from 60 plots of 20 m × 20 m systematically distributed in four A. senegal-dominated populations within the Lake Baringo woodland. Sample populations spanned a degradation gradient measured by a population disturbance index (PDI). Trees were measured for diameter at breast height (DBH) and categorized by growth stages: seedling, sapling and adult tree. Higher seedling and sapling densities were recorded in lightly than heavily disturbed populations, but only sapling density was significantly different between the two disturbance levels (P = 0.02). Lightly disturbed populations revealed a reversed J-shape size-class distribution (SCD) indicative of stable structure unlike the heavily disturbed populations. The quotient and permutation indices indicated unstable populations with episodic recruitment and mortality. Our study reveals that natural regeneration and population structure of A. senegal were affected majorly by selective harvesting and heavy browsing. Suitable management strategies to control livestock grazing and illegal tree harvesting within the woodland is required to promote conservation of the species genetic resources

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TECHNICAL NOTE: VELOCITY OF ULTRASONIC WAVES IN LIVE TREES AND IN FRESHLY-FELLED LOGS

Author

Raquel Gonçalves, Cinthya Bertoldo Pedroso, Marcus Vinicius Massak, Fernando Batista, Chiara Barros Secco

ABSTRACT

The objective of this study was to evaluate variations between the velocity of ultrasonic wave propagation in trees and in freshly felled logs as well as to investigate the correlation between those speeds and corrections that would improve this correlation. The study was conducted using 210 exotic trees growing in Brazil, including the species Eucalyptus grandis, Pinus elliottii, Toona ciliata, and Eucalyptus resulting from cloning. Although the velocity of ultrasonic wave propagation in a tree (V_t) is not equal to that in a freshly felled log (V_t), the two values are correlated such that V_t can be obtained from V_st. The regression indicated a nonlinear equation for determining the log velocity from the tree velocity.

KEYWORDS

Forest sector;acoustic evaluation;selection of trees

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EFFECT OF GAMMA IRRADIATION ON MICROCRYSTALLINE STRUCTURE OF PHRAGMITES CELLULOSE

Author
Ke-qin Wang, Xing-yao Xiong, Jing-ping Chen, Liang Chen, Yun Liu

ABSTRACT

Effect of ⁶⁰Co-γ irradiation treatment on cellulose structure originating from Phragmites communis trim (PCT) was investigated on the basis of irradiation doses of 0 to 2000 kGy at a dose rate of 2 kGy h^-1. Scanning electron micrograph images showed that surface morphologies of PCT cellulose could become fragmented after being treated with ⁶⁰Co-γ irradiation. Based on X-ray diffraction profiles, crystallinity and amorphous region of microcrystalline cellulose treated by irradiation were obviously changed. Fourier transform IR spectroscopy data indicated that a new characteristic peak corresponding to carbonyl (1734 cm ^-1) appeared after PCT cellulose was treated with ⁶⁰Co-γ irradiation, which suggested that PCT cellulose was degraded after irradiation treatment.

KEYWORDS

<i>Phragmites communis</i> trim (PCT);microcrystalline cellulose;⁶⁰Co-γ irradiation;SEM;XRD;FT-IR

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How Electricity is Generated from Biomass

Biomass is biomaterial from living or recently living organisms such as timber, agriculture wastes and animal manure. There are several ways can get useful renewable energy from biomass other than burning it directly. In this article I’m going to explain how we can how we can generate electricity from biomass. 

If you are simply looking for a general overview of biomass, go to Biomass Energy Pros and Cons.

Author  From poop to power

There are several methods to convert biomass into electricity. The first one is simply to burn biomass directly, heat water to steam, and sending it through a steam turbine, which then generates electricity.

The second way requires gasification of biomass. A biomass gasifier takes dry biomass, such as agriculture waste, and with the absence of oxygen and high temperatures produces synthesis gas (CO + H2), also known as pyrolysis of biomass.

The gasification process turns wet biomass, such as food waste and manure, into methane (CH4) in a digestion tank. Both methane and synthesis gas (syngas) can be used in a gas engine or a gas turbine for electricity production.

Below is a short video of a biomass/biogas power plant in a familiy farm in Ontario, which by using manure that otherwise would go to waste, generate enough electricity to power 800 homes (1.3MW).

A third way to produce electricity from gasified biomass is by using fuel cells. If we have biogas/bio-syngas with high enough purity we can use fuel cells to produce bio-electricity. The fuel cells breaks down quickly if the gas in any way contains impurities. This technology is not yet commercial.

Biofuels, like ethanol, biodiesel and bio-oil can be also be used for power production in most types of power generators built for gasoline or diesel. 

There are several other types of new interesting biofuels coming such as algae biofuel. Read more about this in What is Biodiesel from Algae?

Efficiency of biomass/biogas power plants

The generation of electricity from biomass results not only in electricity, but also a lot of heat. A traditional gas engine will have an efficiency of 30-35 percent. Gas turbines and steam turbines will end up at around 50 percent.

It is common also use the from these processes, thus increasing the overall energy efficiency. In countries with good governmental support for renewable energy, such as Germany and the Netherlands, there are many plants that combine heat and power production from biomass.

The biogas plant cost does indeed go up, but the long term savings that come with better energy efficiency is in most cases worth it.

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