Carbon flux and growth in mature deciduous forest trees exposed to elevated CO2

Whether rising atmospheric carbon dioxide (CO2) concentrations will cause forests to grow faster and store more carbon is an open question. Using free air CO2 release in combination with a canopy crane, we found an immediate and sustained enhancement of carbon flux through 35-meter-tall temperate forest trees when exposed to elevated CO2. However, there was no overall stimulation in stem growth and leaf litter production after 4 years. Photosynthetic capacity was not reduced, leaf chemistry changes were minor, and tree species differed in their responses. Although growing vigorously, these trees did not accrete more biomass carbon in stems in response to elevated CO2, thus challenging projections of growth responses derived from tests with smaller trees.     

Enrofloxacin-induced retinopathy in a guanaco (Lama guanicoe).

A 4-yr-old male guanaco (Lama guanicoe) in a multispecies exhibit presented with a laceration in the axillary region. The laceration was surgically repaired. Medical treatment was initiated with penicillin G procaine and benzathine (1920 IU/kg, i.m., s.i.d. for 14 days), and enrofloxacin (2.4 mg/kg, i.m., s.i.d. for 14 days). The animal was later treated with trimethoprim-sulfadiazine (24 mg/kg, p.o., s.i.d. for 10 days). Twenty-six days after initial presentation, the guanaco was suspected to be blind. An ophthalmic examination confirmed retinal damage. On postmortem histological evaluation, there was outer retinal atrophy that was most severe in the central retina with localized foci of complete retinal atrophy; lesions were similar to those observed in enrofloxacin retinal toxicity in cats.     

Effects of soil bulk density on seminal and lateral roots of young maize plants (Zea mays L.)

It is well established that increasing soil bulk density (SBD) above some threshold value reduces plant root growth and thus may reduce water and nutrient acquisition. However, formation and elongation of maize seminal roots and first order lateral (FOL) roots in various soil layers under the influence of SBD has not been documented. Two studies were conducted on a loamy sand soil at SBD ranging from 1.25 g cm^–3 to 1.66 g cm^–3. Rhizotrons with a soil layer 7 mm thick were used and pre‐germinated plants were grown for 15 days. Over the range of SBD tested, the shoot growth was not influenced whereas total root length was reduced by 30 % with increasing SBD. Absolute growth rate of seminal roots was highest in the top soil layer and decreased with increasing distance from the surface. Increasing SBD amplified this effect by 20 % and 50 % for the top soil layer and lower soil layers, respectively. At the end of the experiment, total seminal roots attributed to approximately 15 % of the total plant root length. Increasing SBD reduced seminal root growth in the lowest soil layer only, whereas FOL root length decreased with SBD in all but the uppermost soil layer. For FOL, there was a positive interaction of SBD with distance from the soil surface. Both, increasing SBD and soil depth reduced root length by a reduction of number of FOL roots formed while the length of individual FOL roots was not influenced. Hence, increasing SBD may reduce spatial access to nutrients and water by (i) reducing seminal root development in deeper soil layers, aggravated by (ii) the reduction of the number of FOL roots that originate from these seminal roots.     

Die Prophylaxe in der Dasselbekämpfung

Zusammenfassung a) Geselich vorgeschrieben ist bisher nur die Stallabdasslung vor Weide- und Alpauftrieb. Sie kann im Rahmen eines Gesamt-Bekämptungsplanes jedoch nur als Teil einer Gesamtanfgabe gewertet werden.b) Die Ausrottung der Rinderdasselfliegen kann nur durch zusäliche und planmäßige Sommerabdasslung auf Weide und Alpe erreicht werden.c) Die prophylaktische Anwendung von Sprühemulsionen auf kontaktinsektizider Basis gestattet, den zukü nftigen Befall stark herabzuseen oder schlagartig zu verhüten.d) Neben dem individuellen Schaden kann somit der Herden- und Häuteschaden merklich herabgeset oder gänzlich vermieden werden.e) Der methodische Wert der Einzelbeulenbehandlung gewinnt durch Prophylaxis weiter an Wert. Dadurch steigt der Erfolg planmäßiger Abdasslungen mit dieser Methode. Im Verein mit der Prophylaxis erscheint es möglich, die Gesamtbekämpfungszeit der Rinderdasselfliegen innerhalb eines Gebietes bis zur gänzlichen Ausrottung stark abzukürzen.f) Die Weidebeständigkeit der Rinderdasselffiegein bedarf nah neuen bioklimatologischen Beobachtungen einer Nachprüfung.g) Günstig beurteilte Folgen der prophylaktischen Besprühungen geälpter Tiere auf deren Fleisch- und Entwicklungszustand durch gleichzeitige Fernhaltung bzw. Bekämpfung der Weidefliegen nnd Bremsen (8) bedarf weiterer Untersnchungen.h) p. o.-Versuche können noch nicht als abgeschlossen gelten.     

Co-occurrence of papillomas related to Equus caballus papillomavirus type 2 and cutaneous habronemiasis

The present report describes a case of cutaneous papillomatosis related to equine papillomavirus type 2 (EcPV2) with concomitant cutaneous habronemiasis. A 2-year-old female Pura Raza Española horse was referred for a dermatological evaluation because of the onset of cutaneous multifocal, nodular lesions on the face characterised by a warty and partially ulcerated overlying epidermis. Multiple biopsies were taken from these lesions, and cutaneous viral papillomas with a concomitant severe focal eosinophilic dermatitis with intralesional Habronematidae nematode larvae were diagnosed. Immunohistochemistry revealed papillomaviral capsid protein L1 in the epidermal proliferative lesion, confirming the presence of a productive infection. Rt-qPCR confirmed the presence of EcPV type 2. To the authors’ knowledge, this is the first report of EcPV2-related papillomas with concurrent habronemiasis.     

Atmospheric deposition and leaching of nitrogen in Chinese forest ecosystems

Data have been compiled from published sources on nitrogen (N) fluxes in precipitation, throughfall, and leaching from 69 forest ecosystems at 50 sites throughout China, to examine at a national level: (1) N input in precipitation and throughfall, (2) how precipitation N changes after the interaction with canopy, and (3) whether N leaching increases with increasing N deposition and, if so, to what extent. The deposition of dissolved inorganic N (DIN) in precipitation ranged from 2.6 to 48.2 kg N ha⁻¹ year⁻¹, with an average of 16.6 kg N ha⁻¹ year⁻¹. Ammonium was the dominant form of N at most sites, accounting for, on average, 63% of total inorganic N deposition. Nitrate accounted for the remaining 37%. On average, DIN fluxes increased through forest canopies, by 40% and 34% in broad-leaved and coniferous forests, respectively. No significant difference in throughfall DIN inputs was found between the two forest types. Overall, 22% of the throughfall DIN input was leached from forest ecosystems in China, which is lower than the 50–59% observed for European forests. Simple calculations indicate that Chinese forests have great potential to absorb carbon dioxide from the atmosphere, because of the large forest area and high N deposition.     

Climate signal age effects—Evidence from young and old trees in the Swiss Engadin

A potential limitation of tree-ring based climate reconstructions is related to climate signal age effects (CSAE). CSAE may arise if the climatic response of young tree-rings differs from that of old tree-rings. This could mean that climatic signals become stronger (or weaker) with tree aging, or that the seasonality of signals or the sensitivity to a specific element (e.g., temperature, precipitation) changes over time. Such changes would affect the interpretation of dendroclimatic reconstructions, as the tree-rings included in these records are generally oldest at the end of a record (e.g., 21st century)—which is the time period generally used for calibration with instrumental data.We here addressed this concern by analyzing young and old Pinus cembra trees from three high elevation sites in the central European Alps. Core and disc samples were collected in pre-defined plots to allow for a representative analysis of tree ages with tree-ring width (TRW) measurement series categorized into age classes (i) >1880, (ii) 1880–1939, and (iii) 1940–2002. Notably we report on the signal of the very young category (iii) not yet described in literature, and thus allow estimation of climate response and signal strength characteristics during the first years of the trees’ lifespans.Comparison of age classes (i)–(iii) revealed differences in TRW coherence and size, but little change in climatic signal. CSAE are in the order of the differences recorded among high elevation sites—a conclusion that holds for inter-annual to decadal scale TRW variations at near-treeline Swiss stone pine. Such data are typically included in regional and larger-scale temperature reconstructions; thus, our results add confidence to long-term climate estimates integrating a range of tree-ring age classes. Other findings, such as the reaction wood in juvenile tree-rings, and sensitivity of the climate signal to sample replication, suggest that comparisons of young and old age classes, and separate calibration of these categories against instrumental climate data might further the estimation of long-term uncertainty changes in tree-ring based climate reconstructions.     

Pronounced fluctuations of spruce bark beetle (Scolytinae: Ips typographus) populations do not invoke genetic differentiation

The dynamics of a recent outbreak of the spruce bark beetle (Ips typographus) in Switzerland was ruled by a devastating winter storm in 1999 and the drought and heat of the summer 2003. Starting from a similar level of population sizes, estimated as the rate of infested growing stock, beetle populations increased differently in magnitude and time among different regions in Switzerland. Accordingly, we expected local or regional genetic differentiation as a result of such repeated population expansion/breakdown dynamics. We analyzed 5 nuclear microsatellites of spruce bark beetles sampled from pheromone traps at 30 locations distributed over Switzerland. Our genetic results did not indicate any sign of population differentiation, structure, isolation by distance, or recent bottlenecks. This complete lack of genetic structure suggests that spruce bark beetles are highly mobile, precluding the formation of a spatial structure at neutral molecular markers. Thus, this molecular–genetic approach does not allow us to discriminate among regional gene pools and to identify the origin of expanding beetle populations.