Quantifying the effects of harvesting on carbon fluxes and stocks in northern temperate forests

Harvest disturbance has substantial impacts on forest carbon (C) fluxes and stocks. The quantification of these effects is essential for the better understanding of forest C dynamics and informing forest management in the context of global change. We used a process-based forest ecosystem model, PnET-CN, to evaluate how, and by what mechanisms, clear-cuts alter ecosystem C fluxes, aboveground C stocks (AGC), and leaf area index (LAI) in northern temperate forests. We compared C fluxes and stocks predicted by the model and observed at two chronosequences of eddy covariance flux sites for deciduous broadleaf forests (DBF) and evergreen needleleaf forests (ENF) in the Upper Midwest region of northern Wisconsin and Michigan, USA. The average normalized root mean square error (NRMSE) and the Willmott index of agreement (d) for carbon fluxes, LAI, and AGC in the two chronosequences were 20% and 0.90, respectively. Simulated gross primary productivity (GPP) increased with stand age, reaching a maximum (1200–1500 g C m−2 yr−1) at 11–30 years of age, and leveled off thereafter (900–1000 g C m−2 yr−1). Simulated ecosystem respiration (ER) for both plant functional types (PFTs) was initially as high as 700–1000 g C m−2 yr−1 in the first or second year after harvesting, decreased with age (400–800 g C m−2 yr−1) before canopy closure at 10–25 years of age, and increased to 800–900 g C m−2 yr−1 with stand development after canopy recovery. Simulated net ecosystem productivity (NEP) for both PFTs was initially negative, with net C losses of 400–700 g C m−2 yr−1 for 6–17 years after clear-cuts, reaching peak values of 400–600 g C m−2 yr−1 at 14–29 years of age, and eventually stabilizing in mature forests (\u3e 60 years old), with a weak C sink (100–200 g C m−2 yr−1). The decline of NEP with age was caused by the relative flattening of GPP and gradual increase of ER. ENF recovered more slowly from a net C source to a net sink, and lost more C than DBF. This suggests that in general ENF may be slower to recover to full C assimilation capacity after stand-replacing harvests, arising from the slower development of photosynthesis with stand age. Our model results indicated that increased harvesting intensity would delay the recovery of NEP after clear-cuts, but this had little effect on C dynamics during late succession. Future modeling studies of disturbance effects will benefit from the incorporation of forest population dynamics (e.g., regeneration and mortality) and relationships between age-related model parameters and state variables (e.g., LAI) into the model

Observations on the gynoecial pathway for pollen tube growth in sweet lowbush blueberry (Vaccinium angustifolium Ait.)

Gynoecial structure in sweet lowbush blueberry, Vaccinium angustifolium Ait., was investigated in order to characterize the pollen tube pathway in order to provide a framework for further studies on pollination and fungal infection. Closed flower buds and pollinated open flowers were collected from managed lowbush blueberry fields in Colchester County, Nova Scotia, Canada. Following chemical fixation, the tissue samples were examined histologically using light and scanning electron microscopy. The continuous pathway was characterized by a fluted, exudate-filled stylar canal that connects the wet stigmatic surface with the exudate covered surface of the ovarian placentae. Following pollen deposition and germination, tubes growing along the pathway eventually arrive at the micropyles of the anatropous ovules; ovule penetration by pollen tubes and fertilization of the female gametophytes ensue. The pollen tube pathway of this taxon conforms to the general pattern reported from other ericalean taxa

Submarine slides from the walls of Smeerenburgfjorden, NW Svalbard

The steep slopes of glacially eroded fjord walls are potential sites for slope failure and mass wasting (Syvitski et al. 1987). Slides of sedimentary material are relatively common, but require that sediment is present on fjord sides, often deposited from glaciers before and during their retreat through fjord systems. This debris then fails to produce slides that run out onto fjord floors and leave scars on fjord sidewalls.This is the author accepted manuscript. The final version is available from the Geological Society of London via https://doi.org//10.1144/M46.2

Identification of Atlantic water inflow on the north Svalbard shelf during the Holocene

MP thanks the ERASMUS + programme for the financial support during her secondment at the University of St Andrews.Nordaustlandet is located in the northeastern part of the Svalbard archipelago, within the northernmost reach of the West Spitsbergen Current. This current transports Atlantic water to the Arctic Ocean along the western and northern Svalbard margins. This region is well-suited for reconstructing the history of changing Atlantic water inflow to the Arctic Ocean. We studied the marine sediment core HH12-04-GC from Rijpfjorden. Benthic foraminiferal assemblages and sedimentological data are combined to reconstruct the paleoenvironment of the fjord from the end of the last local deglaciation to the late Holocene. The local deglaciation, between 11.3 and 10.6 cal. ka BP, was dominated by active glacier calving processes, associated with a strong inflow of Atlantic water. This led to the establishment of glaciomarine conditions. The Holocene was initially characterized by a relatively stable and warm environment associated with a strong contribution of Atlantic water. Glaciomarine influence progressively decreases after 9.7 cal. ka BP and Atlantic water contribution increases. The late Holocene display similar environment to today, with the influence of glaciomarine conditions and limited Atlantic water inflow. These results confirm that Atlantic water inflows made a continuous contribution to northern Nordaustlandet throughout the postglacial period.PostprintPeer reviewe

Telesaadete loomine Eestis ETV päevakajasaadete ja Kanal 2 telemängude näitel

The aim of the bachelor thesis “Creating TV formats in Estonia on the basis on public affairs programmes on ETV and gameshows on Kanal 2“ was to find out how TV shows are created in Estonia. As the field of TV production is case-based the thesis focused on four shows that had high profile premieres last autumn in Estonia. The shows in question were “Revidendid” and “Vabariigi kodanikud”, two public affairs programmes on public broadcaster ETV, and “Braavo!” and “Eesti vs. Jõekalda”, two gameshows on commercial channel Kanal 2. To examine these shows the method of qualitative semi structured expert interview was used. The most interesting case of this thesis is that of “Revidendid” which showed that too many opinions, too many people, lack of real staff and major structural change of the channel can do no good for a project of such massive scale. Therefore, in a way the faults that were made in the development point quite clearly out why the programme was cancelled only three months after its first broadcast. The study found out that usually TV shows in Estonia are developed as follows: first somebody must have an idea that can be developed. Then the idea is brought to either the broadcaster who greenlights it or to the producer who has the assignment of producing it. Either way the next step is to turn the idea into something that is fit for screen. If the format is thoroughly thought out then decisions about technical aspects must be made. If all that has been done then there might be a pilot or test shooting that shows some of the mistakes that were not seen previously. This is followed by actual shooting and broadcasting of the programme. Still, it is nearly impossible to draw conclusions on the basis of only four shows but it is interesting to point out that the real purposes of creating these shows were of pragmatic kind: channels needed to strengthen the time slot or simply to show something in an available slot or the host needed some work. While examining this thesis a series of additional themes and topics surfaced. This proves that this branch of study should be further investigated as there is a lot to examine.http://tartu.ester.ee/record=b2450980~S1*es

Tuleb muinasjutt

http://www.ester.ee/record=b4096073~S1*es

Tantsukompositsioon II

BeSt programmi toetusel loodud e-kursusel käsitletakse põhjalikumalt tantsu loomiseks vajalikke teadmisi ruumilises, vormilises ja muusikalises perspektiivis ning koreograafilise materjali analüüsi võtteid

Diabeedi kujunemine, fertiilsuse ja energia ainevahetuse häired Wfs1 puudulikkusega hiirel kui Wolframi sündroomi loommudelil

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Wolframi sündroom (WS) on autosoom-retsessiivse pärandumismustriga neurodegeneratiivne haigus, mille peamisteks kliinilisteks avaldusteks on varases lapseeas algav 1. tüüpi diabeet, nägemisnärvi atroofia, magediabeet ja sensorineuraalne kuulmislangus. Lisaks võivad esineda ka urotrakti väärarendid, mitmed erinevad neuroloogilised ning psühhiaatrilised probleemid. Wolframi sündroomi põhjuseks on WFS1 geeni mutatsioon, mis paikneb 4. kromosoomi lühikeses õlas (4p16). Esimeseks kliiniliseks avalduseks WS korral on diabeet. Diabeet tekib WS haigetel keskmiselt 6-aastaselt, poistel pisut varem kui tüdrukutel. Võrreldes 1. tüüpi diabeediga esineb Wolframi sündroomiga patsientidel vähem mikrovaskulaarseid komplikatsioone, ketoatsidoosi ja ka insuliini vajadus on väiksem. Täpne diabeedi tekkemehhanism WS korral ei ole teada. Sageli kaasub WS-ga lühike kasv, mille üheks põhjuseks on leitud kasvuhormooni puudulikkus. Siiani puudub info WS-ga patsientide fertiilsusest. Meile teadaolevalt ei ole siiani uuritud WFS1 geeni rolli fertiilsuse mõjutamisel. Puuduvad ka andmed WS patsientide kilpnäärme funktsiooni ja energia ainevahetuse kohta. Meie eesmärgiks oli uurida diabeedi kujunemist ja selle võimalikke patofüsioloogilisi põhjuseid WS loommudelil – Wfs1 puudulikkusega hiirel. Samuti soovisime anda ülevaate isasloomade viljakusest ning leida võiamaliku viljatuse põhjuseid. Leidsime, et kasvuhäire ja diabeedi kujunemisel esinevad tõsised sugudevahelised erinevused. Kasvuhäire on Wfs1KO isashiirtel väljendunud juba sünnil, kusjuures emashiirtel kujuneb see alles esimeste elukuude jooksul. Mõlemast soost Wfs1KO hiirtel esineb väljendunud glükoosi tolerantsuse häire, kuid väljendunud diabeet koos madala plasma insuliini tasemega kujuneb ainult isashiirtel. Näitasime, et diabeedi tekkepõhjuseks Wfs1KO hiirtel pole mitte niivõrd primaarselt insuliini defitsiit, kuivõrd võimetus konverteerida mitteaktiivset proinsuliini aktiivseks insuliiniks. Näitasime, et mutatsiooniga isashiirte viljakus on langenud ja selle põhjuseks on testistes ja spermas esinevad morfoloogilised muutused. Leidsime histoloogilisi muutuseid ka isashiirte kilpnäärmetes, kuid need ei mõjuta oluliselt kilpnäärme funktsiooni. Samuti ei esine olulisi erinevuseid Wfs1-defitsiitsete hiirte energia ainevahetuses. Küll aga viitavad meie uuringutulemused ka võimalikule leptiini resistentsusele Wfs1KO emasloomadel, mille tõestamine vajab aga täiendavaid uuringuid.Wolfram syndrome (WS) is an autosomal recessive disorder usually diagnosed in childhood when non-autoimmune type I diabetes occurs with optic atrophy, cranial diabetes insipidus and sensorineural deafness. Also dilated renal outflow tracts, multiple neurological abnormalities and various neurological and psychiatric disorders can be present. The reason for WS is the mutation in the WFS1 gene. The exact mechanism of the development of the diabetes related to the WS is yet not known. Some data has shown that the onset of diabetes tends to occur earlier in boys than in girls. As yet there has been no data regarding the fertility of patients with WS. Previous studies have described anterior pituitary dysfunction and, in male patients, the presence of primary gonadal atrophy and hypergonadotropic hypogonadism. As far as we know, the role of the Wfs1 gene in fertility, as well as in thyroid function and in energy metabolism, has not been studied. The aim of the study was to describe the development of the diabetes, fertility and energy metabolism disturbances in an animal model of WS – Wfs1-deficient mouse. We showed that the fertility of male mutant mice is impaired and the reasons for that are the morphological changes in the testes and sperm. Sperm motility is not affected in Wfs1KO mice. There are severe sex-related differences in the development of growth failure and diabetes. Growth failure in male Wfs1KO mice is already present from birth, whereas in females it develops during the first months of life. Severe glucose intolerance developed in both sexes, but overt diabetes with low plasma insulin levels occurs only in male Wfs1KO mice. One of the reasons for developing WS related diabetes is not the insulin deficiency itself, but the impairment in converting proinsulin to active insulin. The energy metabolism did not differ significantly between Wfs1 KO and wt mice. Our data also suggest some degree of leptin resistance in female Wfs1KO mice, which needs to be confirmed in further studies

Regilaulu maailm kaasaegses akadeemilises heliloomingus: vestlused kolme eesti heliloojaga : loomingulise magistrieksami kirjalik osa

http://www.ester.ee/record=b4683075*es