What Causes Spatio-Temporal Variations in Leaf Herbivory Levels within a Canopy of Fagus crenata?

Abstract -This paper investigates spatio-temporal variations in leaf herbivory levels within a single tree canopy. I observed leaf clusters of Fagus crenata under various light conditions without tearing leaves off, and monitored changes in leaf area consumed by insect herbivores. Although there was no clear relationship between relative photosynthetic photon flux density (rPPFD) and consumed leaf area (CLA) in May, immediately after leaf flush, a significant decrease in CLA with increasing rPPFD was observed after June, one or more months after leaf flush. Changes in such leaf characteristics as leaf mass per area (LMA), carbon concentration, nitrogen concentration, C/N ratio, concentration of total phenolics, and condensed tannin concentration, were observed within one month after leaf flush. Although values of these characteristics were generally not influenced by rPPFD for the first month after leaf flush, they subsequently showed a clear increase or decrease in values as rPPFD increased. In late season, significant positive or negative correlations were found between measured leaf characteristics and CLA

What causes spatio-temporal variations in leaf herbivory levels within a canopy of fagus crenata ?

京都大学Proceedings : IUFRO Kanazawa 2003 "Forest Insect Population Dynamics and Host Influences"., Scedule:14－19 September 2003, Vemue: Kanazawa Citymonde Hotel, Kanazawa, Japan, Joint metting of IUFRO working groups : 7.01.02 Tree resistance to Insects | 7.03.06 Integrated management of forset defoloating insects | 7.03.07 Population dynamics of forest insects, Sponsored by: IUFRO-J | Ishikawa Prefecture | Kanazawa City | 21st-COE Program of Kanazawa University, Editors: Kamata, Naoto | Liebhold, Nadrew M. | Quiring, Dan T. | Clancy, Karen M

The Behavioral Role of Males of Platypus Quercivorus Murayama in Their Subsocial Colonies

The behavioral role of male ambrosia beetles, Platypus quercivorus, in subsocial colonies both field and laboratory has been investigated. The entrance tunnels, where the male beetles are staying, are short, with a mean 4 cm long and mostly incline upwards from outside to inside at an angle of around 20º. To examine the role of males, another male or female (as the invader) was placed into a tunnel. When inhabitant males stayed in the tunnel they quickly expelled the invaders, regardless of their sex of the invaders. However, when an inhabitant male was removed an introduced male or female could freely enter the tunnel and was accepted by the inhabitant female. Upon replacing an inhabitant male with an invader male or female and then putting another invader male or female into the tunnel, no rejection occurred, suggesting that invader males and females play no role in guarding the tunnel. Based on the results an inhabitant male seems to have three responsibilities; protection of the gallery from invaders, protection of progeny (larva) from falling down and also keeping the gallery clean from frass. The 20º angle of the entrance tunnel tends to aid both in gallery protection and in frass clearing

eDNA metabarcoding analysis reveals the consequence of creating ecosystem‐scale refugia from deer grazing for the soil microbial communities

シカの森林被害は土壌微生物にも波及する --大規模生態系操作実験と環境DNA分析の融合--. 京都大学プレスリリース. 2023-12-22.Ungulate overbrowsing is a growing problem in forests worldwide due to its prolonged and pervasive impact on plant biodiversity and ecosystem functioning. It has been shown that overbrowsing not only reduces plant species diversity and biomass (i.e., direct effects) but also causes a loss of associated trophic levels that could potentially feedback to influence plant community structure (i.e., indirect effects). One of the primary pathways of such indirect effects that have not been fully examined is the impact of overbrowsing on soil microorganisms. Recent studies have shown that soil microorganisms maintain vegetation diversity and drive succession, so it is of critical importance to understand how soil microbial communities might be affected by or protected from the deer impact. To assess the consequence of creating artificial grazing refugia on the structure and composition of soil microbial communities, we compared the distribution and abundance of soil microbial taxa (bacteria, archaea, fungi) at the fenced versus unfenced control sites in the context of a catchment-scale field experiment in Japan. The eDNA metabarcoding analysis of soil microbial communities showed that the numbers of archaea and basidiomycetes fungal species were greater in the fenced site than in the control, while no such pattern was found for bacteria and ascomycetes fungi. Despite the lack of significant influence of the fence treatment on taxonomic composition in the soil fungal communities, their functional guild composition was influenced by the fenced treatment, with significant changes in the abundance of animal pathogens. Thus, although the effect of fencing on soil microbial communities is characterized by complex responses that vary from taxon to taxon, our work suggests that creating ecosystem-scale refugia from deer overgrazing might help sustain certain, if not all, taxa of soil microbial communities

Discrimination among host tree species by the ambrosia beetle Platypus quercivorus

The ambrosia beetle Platypus quercivorus is a vector for the fungus that causes Japanese oak wilt, and susceptibility to infestation by P. quercivorus varies by tree species. We postulated that P. quercivorus discriminates among host tree species differing in susceptibility to attack. To test this postulate, we counted the number of flying male beetles (NFM), the number of holes bored by male beetles (NH), and the number of flying female beetles (NFF) per unit area of bark surface in three fagaceous tree species: Quercus crispula (with high susceptibility to infestation) and Q. serrata and Castanea crenata (both with low susceptibility). NFM and NH were used to calculate the proportion of male beetles that bored holes out of those that flew to the tree (PBM). We used generalized additive models to predict NFM, NFF, and PBM. The locations of trees, expressed as x and y coordinates, numbers of weeks after the first male beetle’s flying (WEEK), diameters of trees 130 cm above ground (DBH), and tree species (SP) were incorporated into the models as candidate explanatory variables. The best-fit models for NFM and NFF included WEEK and DBH and the effect of location; SP was not included in the models. For PBM, the best-fit model included WEEK, DBH, and SP. The results indicate that male P. quercivorus prefer Q. crispula to Q. serrata and C. crenata and that selection is made before boring holes on trees, but that P. quercivorus do not discriminate among host species when they fly to trees

ブナ樹冠内における被食レベルの時空間的変異とその要因

京都大学0048新制・論文博士博士(農学)乙第11590号論農博第2550号新制||農||903(附属図書館)学位論文||H17||N3994(農学部図書室)UT51-2004-U487(主査)教授 菊澤 喜八郎, 教授 藤崎 憲治, 教授 二井 一禎学位規則第4条第2項該当Doctor of Agricultural ScienceKyoto UniversityDFA

日本に植栽された Quercus laurifolia におけるカシノナガキクイムシの繁殖成功度

Mortality of Quercus laurifolia trees that had been planted in Japan occurred in 2006. This was caused by an attack by the ambrosia beetle Platypus quercivorus, which causes a disease called Japanese oak wilt and results in mass mortality of Fagaceae trees in Japan. In order to study the infestation of Q. laurifolia by P. quercivorus, dead trees were cut into bolts, and the density of holes bored by P. quercivorus was examined for each bolt. Tube traps were attached to each hole in the bolts of the cut trees, and the number of offspring that emerged from the hole during 2007 (the year following the infestation) was counted. Similar to other Japanese Fagaceae species, the density of holes bored by P. quercivorus decreased with increase in the height of Q. laurifolia. The sex ratio of the emerged beetle was biased towards males, and the number of offspring per hole ranged from 0 to 41. The effects of the height and the hole density on the number of offspring were analyzed with zero-altered negative binomial models with a hurdle component and a truncated count component. The results of the hurdle component in the model for zero counts showed that the probability that one or more beetles emerged from holes was negatively affected by the height above the ground. According to the results of the count component of the model for positive counts, the number of offspring showed a unimodal distribution, with a peak at around one in the density of holes per 100cm[2].京都に植栽されていたローレルオーク (Quercus laurifolia)が, 日本各地でブナ科樹木の集団枯死被害 (ナラ枯れ)を引き起こしているカシノナガキクイムシ (Platypus quercivorus)によって2006年に枯死した. 枯死したローレルオークは伐採して玉切りし, 丸太毎に穿孔密度を調査した後, 各穿孔穴に羽化トラップを取り付け, 2007年に脱出してきた次世代のカシノナガキクイムシの頭数を調査した. 日本の他のブナ科樹木の場合と同様に, カシノナガキクイムシの穿孔密度は地上高が高くなるに従い低くなっていた. 脱出虫の性比は雄に偏っており, 1穿孔穴あたりの脱出頭数は0頭から41頭だった. 地上高と穿孔密度が脱出頭数に及ぼす影響を zero-altered negative binomial model を用いて解析した. その結果, 1頭以上の次世代虫が脱出する確率には地上高が負の影響を及ぼしていた. また, 1頭以上の脱出頭数は穿孔密度に対して一山型の分布を示し, 樹幹上の穿孔密度が100cm[2] あたり1個程度の時に最大となっていた