Fragmentation and recreational use affect tree regeneration in urban forests     

Susanna Lehvävirta  Ferenc Vilisics  Leena Hamberg  Minna Malmivaara-Lämsä  D. Johan Kotze 《Urban Forestry & Urban Greening》2014,13(4):869-877

The aim of this study was to test whether fragmentation or recreational use affect tree regeneration in urban forests, and to quantify these effects. We sampled tree saplings at different distances from edges in spruce (Picea abies) dominated forests, and at different distances from paths that represented different levels of wear. Generalized linear mixed models were used to test our hypotheses. We found that fragmentation favours the regeneration of deciduous trees in urban spruce dominated forests: distance from the edge had a pronounced effect on regeneration, at least up to 80 m into the forests. Saplings of Betula pendula, Populus tremula, other deciduous species and Pinus sylvestris benefited from edge conditions. Betula pubescens saplings, however, were most abundant in the interior and small Sorbus aucuparia saplings at 25–30 m from the edge. All species suffered from the direct effects of trampling, while varying responses of species to distance from the paths were observed up to 6 m, and possibly further. As trees essentially define the living conditions for other forest species, we suggest that the spatial extent of edge and trampling effects should be studied for different types of forests. This knowledge should then be used in urban forestry and planning to define the threshold value that will allow for at least some “intact” interior. We suggest a diameter larger than 160 m to support indigenous species in boreal spruce dominated forests.  相似文献   

Automated analysis of fine‐root dynamics using a series of digital images     

Aiko Nakano  Hidetoshi Ikeno  Toshifumi Kimura  Hiromichi Sakamoto  Masako Dannoura  Yasuhiro Hirano  Naoki Makita  Leena Finér  Mizue Ohashi 《植物养料与土壤学杂志》2012,175(5):775-783

Information related to the growth of fine roots is important for understanding C allocation in trees and the mechanisms of C cycling in ecosystems. Observations using a camera or scanner embedded in the soil enabled us to obtain continuous images of fine‐root‐growth dynamics. However, these methods are still labor‐intensive because the image analysis has to be conducted manually. We developed an automated method for tracking movement or elongation of fine roots using a sequence of scanner images. We also show how data obtained with these methods can be used for calculating fine‐root behavior. Two A4‐size scanners were buried in a mixed forest in Japan and images were taken continuously from within the soil. We preprocessed these images by extracting the fine‐root area from the images and developed an automated calculation plug‐in we named A‐root for tracking growth movement of the tips of fine roots. A‐root and manual‐tracking results were compared using the same images. The results show the A‐root and manual‐tracking methods yielded similar levels of accuracy. The average growth rate of 17 fine roots tracked using the program was 0.16 mm h^–1. The observation of the direction of growth in fine roots showed the direction may be influenced by the original root's growth where the fine roots branched, distribution of soil particles, other roots, and the force of gravity. The A‐root analysis also suggested there may be an interaction between speed of growth and changes in direction of growing fine roots.  相似文献   

Fine-tuning banana Xanthomonas wilt control options over the past decade in East and Central Africa     

Guy Blomme  Kim Jacobsen  Walter Ocimati  Fen Beed  Jules Ntamwira  Charles Sivirihauma  Fred Ssekiwoko  Valentine Nakato  Jerome Kubiriba  Leena Tripathi  William Tinzaara  Flory Mbolela  Lambert Lutete  Eldad Karamura 《European journal of plant pathology / European Foundation for Plant Pathology》2014,139(2):265-281

Xanthomonas wilt, caused by Xanthomonas campestris pv. musacearum has, since 2001, become the most important and widespread disease of Musa in East and Central Africa. Over the past decade, new research findings and especially feedback from small-scale farmers have helped in fine-tuning Xanthomonas wilt control options. During the initial years of the Xanthomonas wilt epidemic in East Africa, the complete uprooting of diseased mats and the burning or burying of plant debris was advocated as part of a control package which included the use of clean garden tools and early removal of male buds to prevent insect vector transmission. Uprooting a complete mat (i.e. the mother plant and a varying number of lateral shoots) is understandably time-consuming and labour intensive and becomes very cumbersome when a large number of diseased mats have to be removed. Recent research findings suggest that Xcm bacteria do not colonize all lateral shoots (i.e. incomplete systemicity occurs) and even when present that this does not necessarily lead to symptom expression and disease. This led to a new control method whereby only the visibly diseased plants within a mat are cut at soil level. The underlying idea is that the continued removal of only the diseased plants in a field will reduce the inoculum level and will bring down disease incidence to an acceptable level. This method is less labour intensive and takes a short time compared to the removal of a complete mat. However, single diseased stem removal needs to go hand in hand with prevention of new infections that can occur through the use of contaminated garden tools or through insect vector transmission. Novel transgenic approaches are also discussed. This paper presents an overview of past and ongoing research towards the development of a more practical and less demanding control strategy for Xanthomonas wilt.  相似文献   

Trait‐related variation in the reproductive characteristics of female pikeperch (Sander lucioperca)          下载免费PDF全文

M. Olin  A. Vainikka  T. Roikonen  J. Ruuhijärvi  H. Huuskonen  M. Kotakorpi  S. Vesala  P. Ala‐Opas  J. Tiainen  L. Nurminen  H. Lehtonen 《Fisheries Management and Ecology》2018,25(3):220-232

Maternal characteristics typically affect the recruitment of an exploited fish population. The size and age at maturity, as well as the effects of maternal traits on relative fecundity and egg dry weight, were studied in six exploited pikeperch populations in Finnish lakes. The among‐lake variation in the maternal characteristics was substantial. The estimated total length at maturity (L₁₀, L₅₀, L₉₀) varied between 318–444, 403–423 and 444–527 mm, respectively, largely depending on the average growth rate and body condition of pikeperch. The estimated L₅₀ was generally close to the recently imposed national minimum size limit (42 cm). The estimated age at maturity (A₅₀) ranged from 4.2 to 6.9 year. Both relative fecundity and egg dry weight significantly increased with female size and age, indicating size‐ and age‐dependent maternal effects on egg characteristics and quantity, and emphasising the importance of large individuals for reproduction. The observed among‐population differences in the size‐dependent maternal influences highlight the need for stock‐specific management of pikeperch fisheries. The conservation of large females should be promoted to increase recruitment and reduce its variability.  相似文献   

Structural comparison of arabinoxylans from two barley side-stream fractions     

Pitkänen L  Tuomainen P  Virkki L  Aseyev V  Tenkanen M 《Journal of agricultural and food chemistry》2008,56(13):5069-5077

The structures of barley ( Hordeum vulgare) arabinoxylans isolated from two industrial side fractions, barley husks (BH) and barley fiber (BF), were characterized. Arabinoxylans were extracted with saturated barium hydroxide after enzymatic pretreatment. Barium hydroxide was selective toward arabinoxylans, and only a minor amount of glucose-containing material was coextracted. Acid methanolysis followed by gas chromatography, 1H NMR spectroscopy, and specific enzymatic treatments followed by anion exchange chromatography with pulse amperometric detection (HPAEC-PAD) revealed that the chemical structure of barley husk arabinoxylan (BHAX) clearly differed from that of barley fiber arabinoxylan (BFAX). BFAX was more branched, containing more beta-D-xylopyranosyl (beta-D-Xylp) residues carrying alpha-L-arabinofuranosyl (alpha-L-Araf) units at both O-2 and O-3 positions. BHAX, on the other hand, contained more 2-O-beta-D-Xyl p-alpha-L-Ara f substituents than BFAX. BHAX and BFAX also differed with respect to the hydrodynamic properties investigated with multidetector size exclusion chromatography. BFAX had a higher weight-average molar mass and larger hydrodynamic volume, the latter indicating less dense conformation than BHAX. Mn, Mw /Mn, Rh, and the Mark-Houwink a value were also determined for both arabinoxylans.  相似文献   

Genomic prediction of grain yield in commercial Finnish oat (Avena sativa) and barley (Hordeum vulgare) breeding programmes     

Hanna Haikka  Timo Knürr  Outi Manninen  Leena Pietilä  Mika Isolahti  Esa Teperi  Esa A. Mäntysaari  Ismo Strandén 《Plant Breeding》2020,139(3):550-561

Genomic selection has been adopted in many plant breeding programmes. In this paper, we cover some aspects of information necessary before starting genomic selection. Spring oat and barley breeding data sets from commercial breeding programmes were studied using single, multitrait and trait-assisted models for predicting grain yield. Heritabilities were higher when estimated using multitrait models compared to single-trait models. However, no corresponding increase in prediction accuracy was observed in a cross-validation scenario. On the other hand, forward prediction showed a slight, but not significant, increase in accuracy of genomic estimated breeding values for breeding cohorts when a multitrait model was applied. When a correlated trait was used in a trait-assisted model, on average the accuracies increased by 9%–14% for oat and by 11%–28% for barley compared with a single-trait model. Overall, accuracies in forward validation varied between breeding cohorts and years for grain yield. Forward prediction accuracies for multiple cohorts and multiple years’ data are reported for oat for the first time.  相似文献   

Erratum to “Factors causing variation in fine root biomass in forest ecosystems” [Forest Ecol. Manage. 261 (2010) 265-277]     

Leena Finér  Mizue OhashiKyotaro Noguchi  Yasuhiro Hirano 《Forest Ecology and Management》2011,262(4):701

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Feeding under predation risk: potential sex‐specific response of perch (Perca fluviatilis)     

Satu Estlander  Leena Nurminen 《Ecology of Freshwater Fish》2014,23(3):478-480

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Ecology. How did the cuckoo get its polymorphic plumage?     

J Mappes  L Lindström 《Science (New York, N.Y.)》2012,337(6094):532-533

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Transgenic barley by particle bombardment. Inheritance of the transferred gene and characteristics of transgenic barley plants     

Anneli Ritala  Reino Aikasalo  Kristian Aspegren  Marjatta Salmenkallio-Marttila  Satu Akerman  Leena Mannonen  Ulrika Kurtén  Riitta Puupponen-Pimiä  Teemu H. Teeri  Veli Kauppinen 《Euphytica》1995,85(1-3):81-88

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