Several plant communities in central Panama, each community located near a weather station, contain trees with annual growth rings, i. e. Cordia alliodora, Pseudobombax septenatum, and Annona spraguei. Tree-ring data are particularly valuable when concomitant weather information is readily available. Patterns of growth for the above species of trees were investigated across central Panama in relation to climate. A linear aggregate climate model was fitted to chronologies of each species at three sites along a rainfall gradient. Comparisons were made among sites to help explain how climate influences tree growth within central Panama.
variables (minimumtemperature, daily thermal oscillation, rainfall and atmospheric pressure) and the onset of the spawning period of the common frog (Rana tem- poraria) in the Atlantic region of the Basque Country (Northern Spain) is analyzed. The onset of the spawn- ing period is coincident with a change
contribution to help forecast the potential duration of xylogenesis in silver fir. Figure 1. Location of the three study sites along the Italian Peninsula. BOR indicates the northern site; PES the central site; SER the southern site. Figure S1. Minimumtemperature (on the left) and precipitation (on the right
richardsonii and L. xanthura were significantly correlated with monthly mean daily maximum and minimumtemperatures. The optimum temperature of L. punc- tatovittata was 28.8 °C in daytime retreats. Biomass ranged from 505-900 g/ha in E. richardsonii and from 968-1152 g/ha in L. punctatovittata. All three
This paper reviews and summarizes the results of investigations at the Oxford Forestry Institute on the occurrence of seasonal growth rings in the wood of one of Africa's most widely distributed genera in the arid areas, Acacia. The ring boundaries are marked by fine marginal parenchyma containing small crystals of Ca-oxalate. Rings are usually annual and produced in the rainy season. Ring width is related to precipitation and/or minimum temperature. Rooting characteristics of the various species studied influence the type of relationship found.
During a period of study of floral phenology and pollen production in the cork-oak, Quercus suber L. (199799), an interruption of catkin development was detected in spring 1998. The cause might have been a sharp drop in minimum temperatures during that period, which coincided with the initial stages of microsporogenesis. Results show that environmental temperatures close to 0 ºC halted microsporogenesis and catkinelongation, resulting in their complete death. No fruits were observed in the affected zone, as a possible consequence of the lack of pollen. Phenological, histological, andaerobiological data are analyzed as a whole in order to gain a better understanding of the phenomenon. Cold spells during flowering may be one of the factors influencing the high interannual variability of acorn production in Quercus species.
The seasonal dynamics of cambial activity of Chinese pine (Pinus tabulaeformis Carr.) was studied at the northern limit of its natural distribution in a semi-arid grassland ecosystem in North China. We collected micro-cores from five even-aged trees at weekly intervals from April 15 to September 16, 2006. Cell division in the cambial zone of these trees started within the third week of May. In June and July the rate of xylem cell production was highest and around mid-August cell division ended. However, cell-wall formation was not yet completed around mid-September. The cell-division period appears to coincide with the time of highest monsoon precipitation and of above 0 °C daily minimum temperature. Moreover, the cambium activity period seems to be in agreement with the time of the highest number of sunshine hours/day. These preliminary results are important for dendroclimatic studies with Chinese pine in North China and can furthermore be used as a benchmark for future monitoring activities in ecologically similar areas.
Intra-annual density fluctuations (IADFs) in tree rings of Aleppo pine (Pinus halepensis) are considered to be among the most promising wood anatomical features in dendrochronological studies. They provide environmental information in addition to those obtained from tree-ring widths. We used a network of 35 sites in Spain, ranging from nearly desert to temperate climate. We analysed tree-ring series of 529 trees to study IADF frequencies, and their dependence on climatic factors and cambial age. The results showed that IADF frequency is age dependent, with its maximum at the cambial age of 27 years (evaluated at breast height). The frequencies varied across the network and at different sites we recorded that 0.3% to 33% of the analysed tree rings contained IADFs. They were more frequent where and when the temperatures were higher, summer drought was intense and autumn was the main precipitation season. IADF formation was particularly related to high minimum temperatures and wet conditions in late summer and autumn. These results suggest that IADF formation is not related to stressful conditions during summer but to favourable conditions during autumn. These conditions promote cambial reactivation and consequently formation of wider tree rings.
[German version] All Mediterranean countries have freezing temperatures in the winter (average minimumtemperature: Rome -9° C; central Turkey -18° C; southern France -11° C; Sicily -3° C; northern Algeria -2° C). Heat sources in residences were originally the hearthfire, wood or charcoal braziers
Predation pressure, food availability, and activity may be affected by level of moonlight and climatic conditions. While many nocturnal mammals reduce activity at high lunar illumination to avoid predators (lunarphobia), most visually-oriented nocturnal primates and birds increase activity in bright nights (lunarphilia) to improve foraging efficiency. Similarly, weather conditions may influence activity level and foraging ability. We examined the response of Javan slow lorises (Nycticebus javanicus Geoffroy, 1812) to moonlight and temperature. We radio-tracked 12 animals in West Java, Indonesia, over 1.5 years, resulting in over 600 hours direct observations. We collected behavioural and environmental data including lunar illumination, number of human observers, and climatic factors, and 185 camera trap nights on potential predators. Nycticebus javanicus reduced active behaviours in bright nights. Although this might be interpreted as a predator avoidance strategy, animals remained active when more observers were present. We did not find the same effect of lunar illumination on two potential predators. We detected an interactive effect of minimum temperature and moonlight, e.g. in bright nights slow lorises only reduce activity when it is cold. Slow lorises also were more active in higher humidity and when it was cloudy, whereas potential predators were equally active across conditions. As slow lorises are well-adapted to avoid/defend predators by crypsis, mimicry and the possession of venom, we argue that lunarphobia may be due to prey availability. In bright nights that are cold, the combined effects of high luminosity and low temperature favour reduced activity and even torpor. We conclude that Javan slow lorises are lunarphobic – just as the majority of mammals.