Determinants of Polylepis (Rosaceae) Forest Distribution and Treeline Formation in the High Andes

High elevation treelines are formed under common temperature conditions worldwide, but the functional mechanisms that ultimately constrain tree growth are poorly known. In addition to environmental constraints, the distribution of high elevation forests is largely affected by human influence. Andean Polylepis (Rosaceae) forests are an example of such a case, forests commonly growing in isolated stands disconnected from the lower elevation montane forests. There has been ample discussion as to the role of environmental versus anthropogenic causes of this fragmented distribution of Polylepis forests, but the importance of different factors is still unclear. In this thesis, I studied functional, environmental and anthropogenic aspects determining Polylepis forest distribution. Specifically, I assessed the degree of genetic determinism in the functional traits that enable Polylepis species to grow in cold and dry conditions. I also studied the role of environment and human influence constraining Polylepis forest distribution. I found evidence of genetically determined climatic adaptations in the functional traits of Polylepis. High elevation species had reduced leaf size and increased root tip abundance compared to low elevation species. Thus these traits have potentially played an important role in species evolution and adaptation to high elevation habitats, especially to low temperatures. I also found reduced photosynthesis rate among high elevation tree species compared to low elevation species, supporting carbon source limitation at treelines. At low elevations, Polylepis forest distribution appeared to be largely defined by human influence. This suggests that the absence of Polylepis forests in large areas in the Andes is the result of several environmental and anthropogenic constraints, the role of environment becoming stronger towards high elevations. I also show that Polylepis trees grow at remarkably low air and soil temperatures near treelines, and present new evidence of the role of air temperatures in constraining tree growth at high elevations. I further show that easily measurable indices of accessibility are related to the degree of degradation of Polylepis forest, and can therefore be used in the rapid identification of potentially degraded Polylepis forests. This is of great importance for the conservation and restoration planning of Polylepis forests in the Andes. In a global context, the results of this thesis add to our scientific knowledge concerning high elevation adaptations in trees, and increase our understanding of the factors constraining tree growth and forest distribution at high-­elevation treelines worldwide.El límite altitudinal arbóreo está formado bajo condiciones similares de temperatura a nivel mundial, pero los mecanismos funcionales que finalmente constriñen el crecimiento de los árboles son poco conocidos. Además de los factores ambientales, la distribución de los bosques de alturas está afectada por las acciones humanas. Los bosques andinos de Polylepis (Rosaceae) son un ejemplo de este caso: estos bosques crecen en rodales aislados y desconectados de los bosques montanos a menor altitud. Ha habido una amplia discusión sobre el rol de los factores ambientales y antropogénicos que causan esta distribución fragmentada de los bosques de Polylepis, pero la importancia de diferentes factores no está todavía clara. En esta tesis estudié los aspectos ecofisiológicos, ambientales y antropogénicos que pueden determinar la distribución de los bosques de Polylepis. Específicamente, evalué el grado del determinismo genético sobre las características ecofisiológicas que permiten a las especies de Polylepis crecer en condiciones frías y secas. Además, estudié el rol de los factores medio ambientales y antropogénicos que restringen la distribución de los bosques de Polylepis. Mis resultados dan evidencias de adaptaciones climáticos genéticamente determinadas en las características ecofisiológicas de las especies de Polylepis. Las especies de las zonas altas presentan hojas de tamaño reducido e incremento en la abundancia de ápices radiculares en comparación con las especies de las zonas más bajas. Estas características parecen haber desempeñado un rol importante en la evolución de las especies y en la adaptación a los hábitats de mayor altitud, especialmente a temperaturas bajas. Asimismo, encontré una tasa reducida de fotosíntesis en las especies de las zonas altas en comparación con las especies de las zonas más bajas. Esto apoya la hipótesis de limitación de adquisición de carbono en el límite altitudinal arbóreo. A menor altitud, la distribución de los bosques de Polylepis parece estar fuertemente afectada por las acciones antropogénicas. Esto sugiere que la ausencia de los bosques de Polylepis en la mayor parte de los Andes es el resultado de una serie de limitaciones ambientales y antropogénicas, donde el rol de los factores ambientales se incrementa hacia las zonas altas. También encontré que los árboles de Polylepis cerca del límite altitudinal arbóreo crecen a considerablemente bajas temperaturas del aire y del suelo. Además presento nuevas evidencias del rol de la temperatura del aire en la limitación del crecimiento de los árboles en las zonas altas. Adicionalmente, demuestro que los índices de accesibilidad que son fácilmente medibles están relacionados con el grado de degradación de los bosques de Polylepis y pueden ser aplicados para una identificación rápida de los bosques degradados. Esto es de gran importancia para la conservación y planificación de restauración de los bosques de Polylepis en los Andes. En el contexto mundial, los resultados de esta tesis contribuyen a incrementar el conocimiento científico relacionado a las adaptaciones de especies arbóreas en hábitats montañosos y el entendimiento de los factores que limitan el crecimiento de los árboles y la distribución de los bosques en el límite a altitudinal arbóreo a nivel mundial.Vuoristopuurajat esiintyvät maailmanlaajuisesti samanlaisissa lämpötilaolosuhteissa, mutta puiden kasvua rajoittavat ekofysiologiset mekanismit tunnetaan kuitenkin huonosti. Ympäristöolosuhteiden lisäksi ihmisvaikutuksella on myös suuri merkitys vuoristometsien levinneisyyteen. Andien Polylepis-metsät ovat yksi esimerkki tällaisesta tapauksesta. Metsät kasvavat eristyneinä laikkuina alemman yhtenäisen vuoristometsävyöhykkeen yläpuolella. Ympäristöolosuhteiden ja ihmisvaikutuksen merkitystä Polylepis-metsien levinneisyydelle on tutkittu paljon, mutta eri tekijöiden merkitys metsien levinneisyydelle on edelleen epäselvä. Tutkin väitöskirjassani puiden ekofysiologiaan, ympäristöolosuhteisiin ja ihmisvaikutukseen liittyviä tekijöitä, jotka voivat selittää Polylepis­metsien levinneisyyttä. Tulokseni osoittivat, että osa tutkimistani Polylepis-­puiden ekofysiologisista piirteistä ilmensi geneettisesti määräytyneitä ilmastollisia sopeumia: korkean paikan lajeilla oli pienemmät lehdet ja enemmän juurenkärkiä kuin matalampien paikkojen lajeilla. Näillä piirteillä on todennäköisesti ollut tärkeä merkitys lajien evoluutiossa ja sopeutumisessa ylävuoriston elinympäristöihin, erityisesti mataliin lämpötiloihin. Tuloksieni mukaan korkean paikan lajeilla oli myös alentunut fotosynteesikapasiteetti matalampien paikkojen lajeihin verrattuna. Tämä tukee hypoteesia hiilen sitomiseen liittyvistä rajoitteista vuoristopuurajalla. Alemmilla korkeuksilla ihmistoiminnalla näytti olevan erityisen suuri merkitys Polylepis-metsien levinneisyyteen. Tuloksieni perusteella voidaan todeta, että Polylepis-metsien nykylevinneisyys on seurausta useasta eri ympäristöön ja ihmistoimintaan liittyvästä tekijästä, joista ympäristön merkitys levinneisyyden selittäjänä kasvaa siirryttäessä kohti ylävuoristoa. Tutkimustulokseni myös osoittivat, että Polylepis-­puut kasvavat huomattavan alhaisissa lämpötilaolosuhteissa lähellä puurajaa, sekä ilman että maaperän lämpötilan suhteen. Lisäksi tulokseni osoittivat, että erityisesti ilman lämpötilalla on merkitystä puiden kasvulle vuoristossa. Havaitsin myös, että helposti mitattavat, metsien saavutettavuuteen perustuvat indeksit selittävät Polylepis-­metsien rakennetta, ja näin ollen myös metsien kunnon heikkenemistä. Näitä indeksejä voidaan käyttää tunnistamaan nopeasti ja helposti alueita, joilla Polylepis-­metsät ovat huonokuntoisimpia. Tällä tiedolla on merkitystä Polylepis-­metsien suojelu-­ ja kunnostussuunnitelmille Andeilla. Väitöskirjatyöni tulokset lisäävät myös tietoa puiden sopeutumisesta vuoristo-­olosuhteisiin ja auttavat ymmärtämään eri tekijöiden merkitystä puiden kasvulle ja metsien levinneisyydelle vuoristopuurajoilla maailmanlaajuisesti.Siirretty Doriast

Elevational patterns of Polylepis tree height (Rosaceae) in the high Andes of Peru: role of human impact and climatic conditions

We studied tree height in stands of high-Andean&nbsp;Polylepis&nbsp;forests in two cordilleras near Cuzco (Peru) with respect to variations in human impact and climatic conditions, and compared air and soil temperatures between qualitatively defined dry and humid slopes. We studied 46 forest plots of 100 m2&nbsp;of five&nbsp;Polylepis&nbsp;species at 3560&ndash;4680 m. We measured diameter at breast height (dbh) and tree height in the stands (1229 trees in total), as well as air and soil temperatures in a subset of plots. The data was analyzed combining plots of given species from different sites at the same elevation (&plusmn;100 m). There was no elevational decrease of mean maximum tree height across the entire data set. On humid slopes, tree height decreased continuously with elevation, whereas on dry slopes it peaked at middle elevations. With mean maximum tree heights of 9 m at 4530 m on the humid slopes and of 13 m at 4650 m on the dry slopes, we here document the tallest high-elevation forests found so far worldwide. These highest stands grow under cold mean growing season air temperatures (3.6 and 3.8&deg;C on humid vs. dry slopes) and mean growing season soil temperatures (5.1 vs. 4.6&deg;C). Mean annual air and soil temperature both decreased with elevation. Dry slopes had higher mean and maximum growing season air temperatures than humid slopes. Mean annual soil temperatures did not significantly differ and mean annual air temperatures only slightly differed between slopes. However, maximum air temperatures differed on average by 6.6 K between dry and humid slopes. This suggests that the differences in tree height between the two slopes are most likely due to differences in solar radiation as reflected by maximum air temperatures. Our study furthermore provides evidence that alpine&nbsp;Polylepis&nbsp;treelines grow under lower temperature conditions than global high-elevation treelines on average, suggesting that&nbsp;Polylepis&nbsp;species may have evolved special physiological adaptations to low temperatures.</p

Elevational Shifts in the Topographic Position of Polylepis Forest Stands in the Andes of Southern Peru

 The patchy distribution of high-Andean treeline forests has provoked discussion aboutthe relative importance of anthropogenic and climatic causes of this pattern, both of whichvary with topography. We aimed to understand the topographic controls on the distribution ofPolylepis subsericans  treeline forests in the Andes of southern Peru, and the changes in these controlsalong an elevational gradient. We mapped Polylepis  forests in the Cordillera Urubamba, Cusco,using high-resolution aerial images and related forest cover to topographic variables extracted from adigital terrain model (30-m resolution). The variables were selected based on their expected biologicalrelevance for tree growth at high elevations. We constructed logistic regression models of forestcover, separately for each of five 100-m elevational belts. To deal with spatial autocorrelation, modelswere based on randomized 10% subsampling of the data with 1000 repetitions. The results suggest aconsistent shift in topographic preference with elevation, with forests at lower elevations showinga preference for topographically protected sites near rivers and forests at higher elevations beingincreasingly restricted to north-facing and well-drained sites. Our study offers the first indication ofthe ability of Andean treeline forests to benefit from the topographic heterogeneity of the high-Andes.Providing that dispersal and establishment are possible, local relocation between microsites could help these forests to persist regionally in spite of changing climatic conditions.</p

Multisite Evaluation and Validation of a Sensitive Diagnostic and Screening System for Spinal Muscular Atrophy that Reports SMN1 and SMN2 Copy Number, along with Disease Modifier and Gene Duplication Variants

Spinal muscular atrophy is a severe autosomal recessive disease caused by disruptions in the SMN1 gene. The nearly identical SMN2 gene copy number is associated with disease severity. SMN1 duplication markers, such as c.*3+80T>G and c.*211_*212del, can assess residual carrier risk. An SMN2 disease modifier (c.859G>C) can help inform prognostic outcomes. The emergence of multiple precision gene therapies for spinal muscular atrophy requires accurate and rapid detection of SMN1 and SMN2 copy numbers to enable early treatment and optimal patient outcomes. We developed and evaluated a singletube PCR/capillary electrophoresis assay system that quantifies SMN1/2 copy numbers and genotypes three additional clinically relevant variants. Analytical validation was performed with human cell lines and whole blood representing varying SMN1/2 copies on four capillary electrophoresis instrument models. In addition, four independent laboratories used the assay to test 468 residual clinical genomic DNA samples. The results were >98.3% concordant with consensus SMN1/2 exon 7 copy numbers, determined using multiplex ligation-dependent probe amplification and droplet digital PCR, and were 100% concordant with Sanger sequencing for the three variants. Furthermore, copy number values were 98.6% (SMN1) and 97.1% (SMN2) concordant to each laboratory's own reference results. (J Mol Diag

A global framework for linking alpine-treeline ecotone patterns to underlying processes

Globally, treeline ecotones vary from abrupt lines to extended zones of increasingly small, stunted and/or dispersed trees. These spatial patterns contain information about the processes that control treeline dynamics. Describing these patterns consistently along ecologically meaningful dimensions is needed for generalizing hypotheses and knowledge about controlling processes and expected treeline shifts globally. However, existing spatial categorizations of treelines are very loosely defined, leading to ambiguities in their use and interpretation. To help better understand treeline-forming processes, we present a new framework for describing alpine treeline ecotones, focusing on hillside-scale patterns, using pattern dimensions with distinct indicative values: 1) the spatial pattern in the x-y plane: a) decline in tree cover, and b) change in the level of clustering. Variation along these dimensions results in more or less 'discrete' or 'diffuse' treelines with or without islands. These patterns mainly indicate demographic processes: establishment and mortality. 2) Changes in tree stature: a) decline in tree height, and b) change in tree shape. Variation along these dimensions results in more or less 'abrupt' or 'gradual' treelines with or without the formation of environmental krummholz. These patterns mainly indicate growth and dieback processes.Additionally, tree population structure can help distinguish alternative hypotheses about pattern formation, while analysing the functional composition of the ecotonal vegetation is essential to understand community-level processes, controlled by species-specific demographic processes.Our graphical representation of this framework can be used to place any treeline pattern in the proposed multi-dimensional space to guide hypotheses on underlying processes and associated dynamics. To quantify the dimensions and facilitate comparative research, we advocate a joint effort in gathering and analysing spatial patterns from treelines globally. The improved recognition of treeline patterns should allow more effective comparative research and monitoring and advance our understanding of treeline-forming processes and vegetation dynamics in response to climate warming

Global protected area expansion is compromised by projected land-use and parochialism

Peer reviewe

Uraohjaus osana väitöskirjaohjausta

Ohjauksen laatua on pyritty jatkuvasti parantamaan yliopistossa työn tehokkuuden ja oppimistulosten parantamiseksi. Tässä hankkeessa tarkasteltiin uraohjauksen merkitystä ohjauksen laadun parantamisessa kartoittamalla opiskelijoiden ja ohjaajien kokemuksia uraohjauskeskusteluista. Hanke toteutettiin Turun yliopiston biologian, maantieteen ja geologian tohtoriohjelmassa. Sekä opiskelijat että ohjaajat kokivat uraohjauskeskustelut keskimäärin erittäin hyödyllisiksi, mikä kannustaa uraohjauksen liittämistä osaksi tohtoriopiskelijoiden ohjausta. </p

Rethinking science-policy interface for sustainable future of the Andean environment and society - Learning from the diversit

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Elevational Shifts in the Topographic Position of Polylepis Forest Stands in the Andes of Southern Peru

The patchy distribution of high-Andean treeline forests has provoked discussion about the relative importance of anthropogenic and climatic causes of this pattern, both of which vary with topography. We aimed to understand the topographic controls on the distribution of Polylepis subsericans treeline forests in the Andes of southern Peru, and the changes in these controls along an elevational gradient. We mapped Polylepis forests in the Cordillera Urubamba, Cusco, using high-resolution aerial images and related forest cover to topographic variables extracted from a digital terrain model (30-m resolution). The variables were selected based on their expected biological relevance for tree growth at high elevations. We constructed logistic regression models of forest cover, separately for each of five 100-m elevational belts. To deal with spatial autocorrelation, models were based on randomized 10% subsampling of the data with 1000 repetitions. The results suggest a consistent shift in topographic preference with elevation, with forests at lower elevations showing a preference for topographically protected sites near rivers and forests at higher elevations being increasingly restricted to north-facing and well-drained sites. Our study offers the first indication of the ability of Andean treeline forests to benefit from the topographic heterogeneity of the high-Andes. Providing that dispersal and establishment are possible, local relocation between microsites could help these forests to persist regionally in spite of changing climatic conditions