The oldest Pinus nigra plantations in the central Apennines: distribution and floristic-vegetational characterisation

This paper represents the first syntaxonomic study on the Pinus nigra subsp. nigra artificial stands in the Apennines. It refers exclusively to the mature Pinus nigra forest plantations in the central Apennines that were planted before the 1950s, and then not managed. The mature Pinus nigra forest plantations in the central Apennines are distributed within four National Parks, on limestone substrata, mainly with southern aspects and rugged slopes, and at elevations ranging from 655 m to 1670 m a.s.l.. Two new phytosociological associations are described here and classified in the alliance Junipero communis–Pinion nigrae: Orthilio secundae–Pinetum nigrae and Digitalidi micranthae–Pinetum nigrae. The association Orthilio secundae–Pinetum nigrae comprises the relative mesophilous mature pine forests of the supratemperate thermotype in the plant landscape context of the alliance Aremonio agrimonioidis–Fagion sylvaticae potential vegetation belt. The Digitalidi micranthae–Pinetum nigrae comprises the thermophilous pine forests occurring on rocky stands within mesotemperate and lower supratemperate thermotypes in the potential belt of alliance Carpinion orientalis woods. The comparison of these two new associations and the phytosociological literature concerning the natural communities of Pinus nigra in the Apennines highlights their floristic and coenological autonomy.

Nonuniform Late Pleistocene glacier fluctuations in tropical Eastern Africa

Today’s ice caps and glaciers in Africa are restricted to the highest peaks, but during the Pleistocene, several mountains on the continent were extensively glaciated. However, little is known about regional differences in the timing and extent of past glaciations and the impact of paleoclimatic changes on the afro-alpine environment and settlement history. Here, we present a glacial chronology for the Ethiopian Highlands in comparison with other East African Mountains. In the Ethiopian Highlands, glaciers reached their maximum 42 to 28 ka thousand years ago before the global Last Glacial Maximum. The local maximum was accompanied by a temperature depression of 4.4° to 6.0°C and a ~700-m downward shift of the afro-alpine vegetation belt, reshaping the human and natural habitats. The chronological comparison reveals that glaciers in Eastern Africa responded in a nonuniform way to past climatic changes, indicating a regionally varying influence of precipitation, temperature, and orography on paleoglacier dynamics.

European beech stem diameter grows better in mixed than in mono-specific stands at the edge of its distribution in mountain forests

Recent studies show that several tree species are spreading to higher latitudes and elevations due to climate change. European beech, presently dominating from the colline to the subalpine vegetation belt, is already present in upper montane subalpine forests and has a high potential to further advance to higher elevations in European mountain forests, where the temperature is predicted to further increase in the near future. Although essential for adaptive silviculture, it remains unknown whether the upward shift of beech could be assisted when it is mixed with Norway spruce or silver fir compared with mono-specific stands, as the species interactions under such conditions are hardly known. In this study, we posed the general hypotheses that the growth depending on age of European beech in mountain forests was similar in mono-specific and mixed-species stands and remained stable over time and space in the last two centuries. The scrutiny of these hypotheses was based on increment coring of 1240 dominant beech trees in 45 plots in mono-specific stands of beech and in 46 mixed mountain forests. We found that (i) on average, mean tree diameter increased linearly with age. The age trend was linear in both forest types, but the slope of the age–growth relationship was higher in mono-specific than in mixed mountain forests. (ii) Beech growth in mono-specific stands was stronger reduced with increasing elevation than that in mixed-species stands. (iii) Beech growth in mono-specific stands was on average higher than beech growth in mixed stands. However, at elevations > 1200 m, growth of beech in mixed stands was higher than that in mono-specific stands. Differences in the growth patterns among elevation zones are less pronounced now than in the past, in both mono-specific and mixed stands. As the higher and longer persisting growth rates extend the flexibility of suitable ages or size for tree harvest and removal, the longer-lasting growth may be of special relevance for multi-aged silviculture concepts. On top of their function for structure and habitat improvement, the remaining old trees may grow more in mass and value than assumed so far.

Floristic study and conservation value analysis of the Jordán river middle basin forest (Jujuy, Argentina)

The floristic study and the conservation value analysis of forest from the Jordan river middle basin are addressed in this research. This vegetation forms part of the subtropical mountain forests or Yungas, one of the most diverse ecosystems on Earth. Present forest species were surveyed, and the vegetation Interest Conservation index (INCON) was determined based on a series of conservation value criteria (Phytocenotic, Territorial, Mesological, Ethnobotanical, Perceptual and Didactics) recorded in the field. Available data on socio-cultural aspects of the area was also included in the study. All plants were identified up to genera and/or species. INCON was calculated from the sum of scoring assigned to each analyzed criterion. As a result, 42 forest species were identified; for each one, its conservation status was performed, including the altitudinal vegetation belt, biogeographical origin (at least for the genus), and their ethnobotanical value. The INCON obtained (135 points) showed the high natural, ethnocultural, landscape, and educational value of these forest vegetation according to the criteria analyzed. This information provides a useful tool to have a more precise knowledge of the diversity conservation status of Las Yungas. It also serves to recognize the biological and environmental relevance of this area, whose usefulness can be used for conservation purposes or decision making on protection plans.

Humboldt’sTableau Physiquerevisited

Alexander von Humboldt’sTableau Physique(1807) has been one of the most influential diagrams in the history of environmental sciences. In particular, detailed observations of the altitudinal distribution of plant species in the equatorial Andes, depicted on a cross-section of Mt. Chimborazo, allowed Humboldt to establish the concept of vegetation belt, thereby laying the foundations of biogeography. Surprisingly, Humboldt’s original data have never been critically revisited, probably due to the difficulty of gathering and interpreting dispersed archives. By unearthing and analyzing overlooked historical documents, we show that the top section of theTableau Physique, above the tree line, is an intuitive construct based on unverified and therefore partly false field data that Humboldt constantly tried to revise in subsequent publications. This finding has implications for the documentation of climate change effects in the tropical Andes. We found that Humboldt’s primary plant data above tree line were mostly collected on Mt. Antisana, not Chimborazo, which allows a comparison with current records. Our resurvey at Mt. Antisana revealed a 215- to 266-m altitudinal shift over 215 y. This estimate is about twice lower than previous estimates for the region but is consistent with the 10- to 12-m/decade upslope range shift observed worldwide. Our results show the cautious approach needed to interpret historical data and to use them as a resource for documenting environmental changes. They also profoundly renew our understanding of Humboldt’s scientific thinking, methods, and modern relevance.

Estimates and Analysis of the Reference Evapotranspiration in Gassol, Taraba State

Reference evapotranspiration is very important because it correlates with the amount of water required by crops and also plays very key role in the hydrological cycle. Evaporation is the process of water loss from the earth surface in which temperature effect is significant while transpiration is water loss from plants. Studying evapotranspiration is also important because of the link between climate change and water scarcity. The reference evapotranspiration for Gassol was estimated and analysis done to observe its trend and variation. In this paper, the FAO Penmann-Monteith model was used to estimate the reference evapotranspiration for Gassol town located in the Sudan Savannah vegetation belt of Nigeria. The annual monthly estimates show a generally recurring seasonal pattern of variation from 1985 to 1991. January through June had lower ET0 compared to July through December. The time series plot of the ET0 estimates from 1985 to 1991 in monthly renditions gives a cyclical pattern of variability with most of the years showing bimodal peaks. Also, an evenly spread data was presented by the normal distribution curve. The periodogram of the estimated reference evapotranspiration gave a dominant periodicity of 9.33 months cycle. The estimates of and the pattern of variation of the reference evapotranspiration as observed for Gassol in this study will very likely experience a continuous downward trend. For proper irrigation management, January to March and October to December should be properly planned.