Evergreen Hardwood Research Articles

Differences in nitrogen use efficiency between leaves from canopy and subcanopy trees

We examined the effects of increasing light availability along a vertical gradient within a forest community on the efficiency of leaf nitrogen (N) use in individual trees. The N contents of green and senescent leaves in canopy and subcanopy trees of an evergreen coniferous species, Podocarpus nagi, and an evergreen hardwood species, Neolitsea aciculata, were analyzed in a mixed forest community at Mt Mikasa, Nara City, Japan. The inverse of N concentration (NC) in senescent leaves was used as an index of N use efficiency (NUE) at the leaf‐level. The leaf‐level NUE was higher in canopy trees than in subcanopy trees in both P. nagi and N. aciculata, although soil N mineralization rates around canopy and subcanopy trees did not differ significantly. The NC in green leaves was lower in canopy trees than in subcanopy trees. The ratio of resorbed N in senescent leaves to the N content in green leaves was higher in canopy trees than in subcanopy trees. The higher leaf‐level NUE of canopy trees was partly a result of lower NC in living tissues and partly because of greater N resorption during senescence. The present study suggested that the leaf‐level NUE could be increased in response to an imbalance between soil N and light availability caused by spatial community structure.

Distribution of Lucidophyll Oak-Laurel Forest Formation in Asia and Other Areas.

Summer-rain warm-temperate, wet subtropical and tropical zones in East, South and Southeast Asia are widely covered by evergreen broad-leaved forests. These forests are dominated mainly by evergreen tree species of Fagaceae, Lauraceae, Theaceae, Magnoliaceae and Hamamelidaceae. Trees have leathery smooth leaves ready to reflect the sunshine and brighten, and Kira (1977) put forward a proposal of lucidophyll forest as a new nomenclature of this type of evergreen broad-leaved forest. It was fIrst reported as Lorbeerform by Griesebach (1872) in Canarias Islands. The lucidophyll oak-laurel forests are found in ranges among 85 and 180°C month of Kira’s warmth index, which corresponds to warm temperate zone and among 180 and 240°C month to subtropical zones in Japan. Such lucidophyll oak-laurel forests have a wide range of distribution in Asia, New Guinea, Macaronesia and southeastern United States. The northern limit of its distribution is at about 40°N of the seashore or islets of Northeast District of Japan in the PacifIc and at 39°N in Acres Islands in the Atlantic. The altitudinal limit goes up to about 1,000 m from sea shore in warm-temperate Japan, and upwards to about 3000 m in the wet tropical Asia. The constituent species of the forests becomes diversifIed as it goes to the tropics. In the area of northern limit the forest is dominated only by a laurel, Persea thunbergii, but forests are diversifIed with many species of a number of genera and families as shown in Appendix. In the tropics they are mixed with some tropical species such as climbing bamboos, screw pines, palms and climbing species of Araceae. On the other hand, some species of Lauraceae and Fagaceae are found in the lowland tropical rain forests, but they are minority of tall lowland rain forests. In Africa temperate and montane forests (afromontane forests) do not have lauraceous and fagaceous dominants but for Ocotea as a companion, and their species composition is not similar with the Asian lucidophyll oak-laurel forests. Southeastern evergreen hardwood forests of the United States are dominated by Quercus (Quercus) species under summer-rain climate with hot and humid summer and not so severe winter. As their leaves also reflect sunshine and brighten, this type of forest should be included into lucidophyll forest formation as well as Macaronesian laurel forests. The nomenclature of the lucidophyll oak-laurel forest is diversifIed, and a number of names have been used. They are largely classified into five groups of terms based on vertical zonation, climatic zone, leaf characters, species composition and plant sociology. The author thinks that it is desirable to give a standard name like summer green forest formation to the forest formation widely distributing in the lowland of warm-temperate, and montane areas of subtropical and tropical regions dominated by oaks and lor laurels. Lucidophyll oak-laurel forest formation is a recommendable name of the formation. Evergreen Nothofagus forests evolved and developed only in the southern hemisphere under similar climate to that of lucidophyll oak-laurel forest formations, could be included into the latter formation, because trees in evergreen southern beech forests are also lucid under humid climate and both forests assembled only in New Guinea and its adjacent islands. Discussion is carried out on other types of vegetation in the Middle and South America.

Coarse woody debris in old-growth temperate beech (Nothofagus) forests of New Zealand

The volume, biomass, and carbon and nitrogen content of coarse woody debris were measured on three 1-ha reference plots in old-growth Nothofagusfusca (Hook. f.) Oerst.–Nothofagusmenziesii (Hook. f.) Oerst. forest on the South Island of New Zealand. Two decay sequences for logs and one for standing dead trees (snags) were recognised from two-way indicator species analysis (TWINSPAN) of up to 30 variables related to physical characteristics and structural integrity. Wood volume (up to 800 m3•ha−1) and biomass were high (up to 300 Mg•ha−1), and the inside-out decay sequence from heartwood to sapwood was unusual compared with that of other temperate hardwood forests. Coarse woody debris represented significant carbon and nitrogen pools, with ca. 150 Mg•ha−1 and 370 kg•ha−1, respectively, in one stand. The coarse woody debris component of these broad-leaved evergreen hardwood forests was much higher than that reported for other temperate hardwood forests and approaches that of many northern hemisphere conifer forests. The large coarse woody debris pools are discussed in relation to live stand biomass, natural disturbances and tree mortality, and decomposition processes.

Land-Use Change and the Structural Dynamics of Pinus kesiya in a Hill Evergreen Forest in Northern Thailand

This study describes changes occurring in a stand of Pinus kesiya in hill evergreen forest adjacent to a new settlement of tribal people in the Doi Inthanon mountain region of northern Thailand. These forests are increasingly experiencing chronic human impacts as tribal people are settled permanently at one site by government programs which encourage the cultivation of cash crops in place of opium. Results from age stand structure analysis suggest that two factors, human-set fires and kindling stick harvesting, are now severely affecting the age distribution of Pinus kesiya in the mixed pine and evergreen hardwood forest.

Dynamics of the boreal forest south of James Bay

Ordination models of approximate environmental and dynamic relationship between eight boreal tree species were constructed based upon principal components analysis and Kruskal's nonmetric multidimensional scaling. The assumptions inherent in these models are stated and discussed. The data consisted of 152 forest stands from the closed-crown boreal forest zone of Ontario and Quebec south of James Bay. Sequential forest succession, as demonstrated by similar techniques for a section of the Wisconsin evergreen–hardwood forest, is not common in the region of boreal forest studied. However, for those species in common between this and the Wisconsin study, similar dynamic pathways are indicated despite differences in sample size and field technique. Tree species developmental pathways, as indicated by 'succession vectors' on the ordination models are, for the most part, short and circular with the exception of Abies balsamea (balsam fir). This reflects the reestablishment of similar, relatively monospecific forest stands following catastrophic forest destruction by fire and (or) other agencies. Where catastrophe does not intervene, deciduous primary forest species may be succeeded by an understory of A. balsamea or by Picea mariana (black spruce). Equally, some forest stands of primary establishment may become decadent with little or no subsequent tree growth. These observations are discussed with respect to the general notion of forest succession.

VEGETATION ON THE ADRIATIC COAST OF YUGOSLAVIA

The vegetation distribution on the Adrratic coast from Rijeka to Dubrovnik and on the five islands, Krk, Cres, Losinj, Rab and Pag, was studied in relation to the climatic conditions, especially to the local wind, bora. The climax vegetation in this region is the Mediterranean evergreen hard wood forests and deciduous broad leaved forests. The vegetation shows the Mediterranean type on the Adriatic slopes of the Velebit Mts., but, in contrast, the continental type on the inland-facing slopes. The deterioration of vegetation is the most serious on the slopes up to 500 m above the sea level on the coastal region. It looks like a land almost without vegetation. The evergreen oak forests re-main in restricted areas on the Rab island and their degradation types, maquis and garrigue, were found along the coast and on the islands south of Zadar. The poor-vegetation landscape prevails on the windward slopes, but, on the contrary, the forests or the ever-green vegetations on the lee side slopes on the islands.The degree of density of the vegetation was studied for determining quantitatively the effect of the winds in this region. The rough density is found in the coastal and island regions from the north of Senj to the north of Zadar. This region coincides perfectly with the strong bora regions, which was revealed through an intensive investi-gation on the wind-shaped trees. The effect of wind, however, might be in a following way : (i) the original vegetation was destroyed first by human activity, (ii) the strong bora winds hindered the vegetation from restoration, and (iii) overgrazing of goat and sheep and felling of trees for fire-wood intensified the effect of hinderance by the winds.

A New Basic Chromosome Number in the Family Fagaceae

CHROMOSOME numbers have been determined previously for some 58 species in the family Fagaceae, covering the three genera of the northern temperate zone, Quercus, Castanea and Fagw1–3. These determinations are uniformly 2n = 24, the Fagaceae resembling many other families of woody angiosperms in this stability of chromosome number. The southern beech genus, Nothofagus, with some 20 species distributed in temperate South America, New Zealand and Australia and extending up into New Guinea and New Caledonia, was at one time included in Fagus, and it is more closely allied in features of floral and pollen morphology to Fagus than to any of the other genera in the family4–6. The four New Zealand species are all endemic and are the principal evergreen hardwoods in much of the indigenous forest. They include representatives of two of the sections into which the genus is divided: in the fusca section, N.fusca, N.truncata and N.solandri, all of which hybridize freely in the wild, and in the menziesii section, N.menziesii, which is not known to cross with any of the other species.