Immature Trees Research Articles

Ground Flora and Its Control Under Rubber in South Thailand

Abstract A list of common weeds and their distribution in South Thailand is given. The methods used for weed control under mature and immature rubber trees, in nurseries, and the control of encroachment by leguminous cover crops are discussed.

The Growth of the Rubber Economy of Southern Thailand

In 1934 the Siamese Council of Ministers agreed to participate in an international rubber control scheme without understanding either the dynamics of the expansion process or the extensiveness of the planting of small stands of rubber trees in peninsular Siam. The area estimates and export statistics available in Bangkok caused the government to believe that the quota offered by the International Rubber Regulation Committee was generous, and they consequently signed agreements with the producers' organizations and cooperating countries subject only to the ratification of the People's Assembly. The State Councilors were so confident of perfunctory approval of what appeared to be a technical issue that they delayed submitting the proposal until three months after the effective date of the agreement. But when the debate opened the representatives from the South sharply challenged the government estimates for failing to account for the areas of immature trees or to recognize that low prices had depressed production below current capacity. Neither Premier Bahol's plea that negotiations with countries “which are already civilised require something substantial in the way of evidence, such as statistics,” nor the need to honor the government's commitment dissuaded them.1 A minor political crisis was precipitated as the Assembly rejected the proposal and Siam's first constitutional government resigned.

Correction Factors for Heights of Immature Trees Measured on Aerial Photographs

Correction Factors for Heights of Immature Trees Measured on Aerial Photographs

Variation in the Lignin laid down by Eucalyptus regnans at Different Stages of Growth

THE spectrum of softwood lignin shows an absorption maximum at about 280 mµ1; this is at the same position for various lignin preparations and for calcium lignosulphonates2. Hardwood lignin shows an absorption peak at 275 mµ1, which is the same as that shown by lignin extracted from the wood of a ten-year old specimen of Eucalyptus regnans with methanol at 150° C.3. We have recently observed that the absorption maximum for lignin prepared by the same method from extractive-free wood from the outer growth rings of heartwood of trees 30–100 years old was at an even shorter wavelength, usually below 270 mµ. The spectra of lignins from tension wood from immature trees of E. regnans and E. goniocalyx also showed maxima in the range 267–272 mµ.

FORMATION AND ROOTING OF ADVENTITIOUS SHOOTS IN HEVEA BRASILIENSIS

YOUNG PLANTS often differ both morphologically and physiologically from older plants of the same species. For example, immature trees of various species often have more thorns, greater vigor, and a more erect habit than mature plants (Furr et al., 1947) and different leaf shapes (Stoutemeyer, 1937). Numerous photoperiod-sensitive species do not respond to photoperiodic treatment when very young, and others which display marked sensitivity to day length when young, lose it with age (Naylor, 1953). Sometimes adventitious or juvenile shoots on older plants can be used for propagation, whereas cuttings from branches of mature trees root poorly if at all (Stoutemeyer, 1937; Dermen, 1948). The problem of juvenility is of particular interest in the Para rubber tree (Hevea brasiliensis (Wild. ex. Adr. Juss.) Muell. Arg.), in which cuttings from young trees regenerate roots readily, but cuttings from old trees do not root at all (Baptist, 1939; Muzik, 1953). The rubber tree generally is propagated by budding, but the effect of stock on yield is still unsettled (Dijkman, 1951). Stahel (1947) reported the rooting of cuttings from Hevea trees of seedling origin under a water spray. This paper describes methods to induce the development of adventitious shoots on seedlings and mature trees of Hevea brasiliensis and compares the rooting ability of these shoots to axillary shoots. Such studies are of fundamental interest in relation to the general phenomenon of juvenility in plants as well as of potential practical interest in developing uniform rootstocks for experimental purposes. The long first internode (epicotyl) in seedlings of Hevea brasiliensis has been described by Calvert (1887) and Petch (1911). The length of this internode is fairly constant within a population but mav vary from 12 to 23 cm. in mixed plantings. The buds at the first node are opposite but they are alternate on the rest of the stem, thus making it easy to distinguish this node. The first internode was very useful in the present study because any buds which sprouted in this region must necessarily be of adventitious origin. On ordinary stems it is often difficult to determine the exact origin of new sprouts. MATERIALS AND METHODS.-The stems of rubber seedlings from 3 weeks to 18 months of age were excised at various heights to stimulate bud sprouting. A similar study of grafted plants was also made. Mature clonal trees were laid horizontally

RECOMMENDED FOEEST PEACTICE FOR NEW ENGLAND

Without debating the question of public regulation of private timberlands, the Committee felt that a useful purpose would be served by reviewing and compiling existing information on desirable forest practices for New England and has undertaken to condense this information into simple workable rules which would keep the forests of this region continuously and economically productive.As a minimum requirement forest practice rules should aim to stop unnecessary forest destruction and deterioration and keep the land reasonably productive. Under certain conditions clear cutting may be undertaken without jeopardizing this objective but such cutting should be confined to harvesting mature stands containing satisfactory reproduction or in the nature of salvage. Partial or selective cutting should be the general rule and, so far as practicable, all desirable immature trees should be preserved for future growth.In the spruce-fir region the main effort should be toward keeping heavily stocked stands which are inadequately stocked with reproduction from being clear cut. Spruce-fir rules are designed to favor partial cutting where reproduction is lacking, yet prevent windfall due to excessive removal.In the northern hardwoods region a cleanup of the poorer old trees is urgently needed, with protection of stands under 60 years of age from heavy cutting except in aspen and paper birch which are considered mature at 30 and 40 years.In the white pine, pine-oak, and oak regions partial cutting should be the rule but clear cutting is permitted under certain conditions.