Effect of grazing abandonment on the function and plant diversity of atlantic mountain grasslands

166 p.(eng);120 p.(eus)Doktore-tesi honek, larratze misto estentsiboaren uzteak dituen ondorioak aztertu ditu Aralar NaturParkeko mendiko larre emankorretan, Euskal Herrian. Herbiboroen larratzea esperimentalki ekiditeko 50× 50 m2-ko lau itxitura eraiki ziren. Larratze-gune bana ezarri zen esklusio-gune bakoitzaren ondoan, nonherbiboroek libreki bazkatzen duten landare-hazkuntza sasoian zehar. Hasteko larratzeari uzteareneragina aztertu zen lurzoruko elikagaien zikloan eta mineralizazioan. Larratzeak larreko elikagaienzikloari eragin zion bazkaren kalitatea hobetuz, eta lurzoruko tenperatura-erregimena zein lurzoruko uredukiaaldaraziz. Ondoren, larratzearen eragina aztertu zen landare-komunitatearen egituran eta landaredibertsitatean.10 urteko larratze-esklusioaren ondoren, hau da, aurrez zegoen mekanismo ekualizatzailesendoa epe luzez kendu ondoren, espezie lehiakorrek multzokapen espazial handiak sortu zituzten etalehiaz espezie ahulagoak kanporatu zituzten, horrela landare-dibertsitatea jaitsiz.Lehiazko esklusionabarmena gertatzen da larre emankorretan, nitxo-egonkortzea ahula izaten delako (baliagaietanaberatsak baitira). Nitxo-egonkortze kontrajarriak dituzten bi gune esperimental erabiliz, nitxoegonkortzeaklehiazko esklusioari egiten dion kontrako indarra aztertu zen. Nitxo-egonkortze ahularekin,lehiatze-gaitasun altuko gramineoen nagusitasunak galera handia eragin zuen dibertsitate filogenetikoan.Aldiz, nitxo-egonkortze ertain-sendoak lehiazko esklusioa ahuldu egin zuen eta, ondorioz, galeratxikiagoa izan zen dibertsitate filogenetikoan. Tesiaren ondorio nagusia da ganadu mistoak eginikolarratze tradizionala funtsezko faktore ekologikoa dela larre atlantikoen funtzionamendua eta landaredibertsitateamantentzeko

Floristic Composition Mediates Change in Forage Nutritive Quality of Atlantic Mountain Grasslands after Experimental Grazing Exclusion

Simultaneous reduction of biodiversity and forage nutritive value after grazing abandonment represents a critical agroecological problem observed in temperate mountain grasslands. However, how both processes affect each other after the exclusion of large grazers is not well understood. To address this knowledge gap, we used four Atlantic grassland sites in the Aralar masif (northern Iberian Peninsula) to ask whether floristic composition mediates change in forage nutritive quality after grazing exclusion, and, if so, how much of the effect on forage quality is mediated. To examine the effects of grazing exclusion on forage quality and floristic composition a repeated-measures (2005–10) randomized complete block experiment was used. Then, the direct effects of grazing exclusion on forage quality were disentangled from the indirect effects mediated by concurrent change in floristic composition. Grazing exclusion deteriorated forage mineral content, phosphorus content, neutral detergent fiber and, especially, crude protein and enzymatic digestibility. Concurrent floristic change mediated change in crude protein (80%), enzymatic digestibility (55%) and forage content in calcium (31%). Our study shows that plant diversity and forage quality are intimately linked features of Atlantic mountain grasslands and highlights the importance of preserving leguminous and dicotyledonous species to maintain the nutritive value of these grasslands.This research was funded by the Basque Government—Eusko Jaurlaritza—(grant numbers: ETORTEK10/34, IT1022-16), by the UNESCO Cathedra of the University of the Basque Country—UPV/EHU—(grant number: UNESCO07/07), and by the Ministry of Economy and Competitiveness of the Spanish Government (grant number: AGL2013-48361-C2-1-R)

Photosynthesis is not the unique useful trait for discriminating salt tolerance capacity between sensitive and tolerant quinoa varieties

Main conclusion Growth was not strictly linked to photosynthesis performance under salinity conditions in quinoa. Other key traits, which were varieties-specific, rather than photosynthesis explained better growth performance. Phenotyping for salinity stress tolerance in quinoa is of great interest to select traits contributing to overall salinity tolerance and to understand the response mechanisms to salinity at a whole plant level. The objective of this work was to dissect the responses of specific traits and analyse relations between these traits to better understand growth response under salinity conditions in quinoa. Growth response to salinity was mostly related to differences in basal values of biomass, being reduced the most in plants with higher basal biomass. Regarding the relationship between growth and specific traits, in Puno variety, better photosynthetic performance was related to a better maintenance of growth. Nevertheless, in the rest of the varieties other traits rather than photosynthesis could better explain growth response. In this way, the development of succulence in F-16 and Collana varieties, also the osmotic adjustment but in smaller dimensions in Pasankalla, Marisma and S-15-15 helped to maintain better growth. Besides, smaller increases of Cl- could have caused a limited nitrate uptake reducing more growth in Vikinga. Ascorbate was considered a key trait as a noticeable fall of it was also related to higher reductions in growth in Titicaca. These results suggest that, due to the genetic variability of quinoa and the complexity of salinity tolerance, no unique and specific traits should be taken into consideration when using phenotyping for analysing salinity tolerance in quinoa.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature

Variation in the Climate Sensitivity Dependent on Neighbourhood Composition in a Secondary Mixed Forest

Understanding the vulnerability of individual trees to climate requires moving from population to individual level. This study evaluates individual tree response in a mixed forest by assessing how size and neighbourhood density modulated growth responses to climate among coexisting tree species. To understand the complete variation in growth responses to climate, it is necessary to consider intrapopulation variability. Trees respond as individual entities, and their response is modulated by their characteristics and neighbourhood context. To assess the individual climate sensitivity, all living Iberian birches, European beeches, and pedunculate oaks trees located in a temperate mixed forest were cored in four 40 m × 40 m plots. Standard ring-width chronologies were built at tree and species level for the 1977–2007 period. Chronologies were related to climatic variables (monthly precipitation, hailstorm and mean temperature, and summer (June–August) precipitation). Growth response to climate varied among species and individual trees. Differences in climate–growth relationship among species could be partially attributed to the different xylem anatomy, since secondary growth of ring-porous pedunculate oak (Quercus robur L.) was mainly dependent on the previous-winter climatic conditions (January temperature), while for the diffuse-porous Iberian birch (Betula celtiberica Rothm. and Vasc.) and European beech (Fagus sylvatica L.), spring temperature and summer precipitation were the major constraining factors of growth. Tree features and identity of neighbourhood modulated climatic response, especially for Iberian birch and pedunculate oak. Dominant trees in less crowded neighbourhoods responded more intensely to climate factors. Understanding the individual variability of growth responses to climate will provide more realistic predictions of forests response to climate change.Special thanks to Silvia Martinez de Olcoz for assistance with the fieldwork and the measurements of the tree-rings. Urkiola Natural Park provided the facilities for field work. Urkiola Natural Park provided the facilities for field work and financial support. Additional financial support was provided by a Basque Government (Grupo de Investigacion Consolidado: Grupo Estudio en Flora, Vegetacion y Ecosistemas Terrestres). Furthermore, this work has been supported by the projects CGL2012-34209 and CGL2015-69186-C2-1-R (Spanish Ministry of Economy and Competitivity) and by the Excellence Network "Ecometas" (CGL2014-53840-REDT)

Termites host specific fungal communities that differ from those in their ambient environments

Termites are important plant biomass decomposers. Their digestive activity typically relies on prokaryotes and protozoa present in their guts. In some cases, such as in fungus-growing termites, digestion also relies on ectosymbiosis with specific fungal taxa. To date, the mycobiome of termites has yet to be investigated in detail. We evaluated the specificity of whole-termite associated fungal communities in three wood-feeding termite species. We showed that the whole-termite fungal community spectra are stable over diverse environments, regardless of the host species, and differ markedly from the wood in which they nest. The core mycobiome is similar to that found in other ecologically related insects and consists of a narrow spectrum of common filamentous fungi and yeasts, known for their stress tolerance and their ability to decompose plant biomass. The observed patterns suggest that a number of fungal strains may have a symbiotic relationship with termites, and our results set the stage for future investigations into the interactions between fungi, termites, and their other gut microbiota

Effect of grazing abandonment on the function and plant diversity of atlantic mountain grasslands

166 p.(eng);120 p.(eus)Doktore-tesi honek, larratze misto estentsiboaren uzteak dituen ondorioak aztertu ditu Aralar NaturParkeko mendiko larre emankorretan, Euskal Herrian. Herbiboroen larratzea esperimentalki ekiditeko 50× 50 m2-ko lau itxitura eraiki ziren. Larratze-gune bana ezarri zen esklusio-gune bakoitzaren ondoan, nonherbiboroek libreki bazkatzen duten landare-hazkuntza sasoian zehar. Hasteko larratzeari uzteareneragina aztertu zen lurzoruko elikagaien zikloan eta mineralizazioan. Larratzeak larreko elikagaienzikloari eragin zion bazkaren kalitatea hobetuz, eta lurzoruko tenperatura-erregimena zein lurzoruko uredukiaaldaraziz. Ondoren, larratzearen eragina aztertu zen landare-komunitatearen egituran eta landaredibertsitatean.10 urteko larratze-esklusioaren ondoren, hau da, aurrez zegoen mekanismo ekualizatzailesendoa epe luzez kendu ondoren, espezie lehiakorrek multzokapen espazial handiak sortu zituzten etalehiaz espezie ahulagoak kanporatu zituzten, horrela landare-dibertsitatea jaitsiz.Lehiazko esklusionabarmena gertatzen da larre emankorretan, nitxo-egonkortzea ahula izaten delako (baliagaietanaberatsak baitira). Nitxo-egonkortze kontrajarriak dituzten bi gune esperimental erabiliz, nitxoegonkortzeaklehiazko esklusioari egiten dion kontrako indarra aztertu zen. Nitxo-egonkortze ahularekin,lehiatze-gaitasun altuko gramineoen nagusitasunak galera handia eragin zuen dibertsitate filogenetikoan.Aldiz, nitxo-egonkortze ertain-sendoak lehiazko esklusioa ahuldu egin zuen eta, ondorioz, galeratxikiagoa izan zen dibertsitate filogenetikoan. Tesiaren ondorio nagusia da ganadu mistoak eginikolarratze tradizionala funtsezko faktore ekologikoa dela larre atlantikoen funtzionamendua eta landaredibertsitateamantentzeko