摘要:

Cuttings were made from six‐year‐old seedlings ofPicea abiesL. (Karst.) that had been studied in the Stockholm phytotron. The seedlings belonged to four full‐sib families, one being of French origin, one of North‐Swedish origin and two being hybrids between parents of North‐Swedish and French origin. Nine clones from each family were included. After the rooting phase, the cuttings were exposed to the same cultivation regimes as the seedling ortets. Characteristics of growth rhythm, percentage free growth and leader length were recorded during the 2nd to the 5th growth period (GP). Plagiotropic growth habit was recorded in the 3rd to the 5th growth period, and, characteristics of the rooting phase were studied. A juvenile behaviour very similar to that characterizing growth periods 2–3 of the seedlings was observed for growth rhythm characteristics and for free growth capacity during GP2 of the cuttings. The absolute value of the differences between each observation of the seedling ortets in GP6 and the means of the cuttings in GP2 produced a new variable that quantified the degree of rejuvenation. This new variable was meaningfully calculated only for growth rhythm and growth pattern variables. A gradual reversion of the growth rhythm occurred for the cuttings, which corresponded to the change with increasing age for the seedlings. The capacity for free growth, on the contrary, disappeared already in GP3 for the cuttings, except for the French family. A large variation in the rejuvenation ability between families was observed. Furthermore, the rejuvenation ability was negatively correlated with the ability to grow plagiotropically.

ISSN:0282-7581    

DOI:10.1080/02827588709382481

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Vegetation changes caused by glyphosate application or hand cutting were evaluated on five experimental sites. Reactions on Norway spruce(Picea abiesL.) were also recorded.Betulaspp. andSorbus aucupariaappeared sensitive to glyphosate and the rate of recoverage of the canopy was related to the extent of control. Vegetative regeneration was stimulated by hand cutting and suppressed by glyphosate. Except for fems, which showed high sensitivity to glyphosate and slow regeneration, the great majority of species in the height level below 1 meter were classified as moderately tolerant. The successional development appeared relatively rapid. Glyphosate application caused an increase in the diversity of the plant community established after application. The release of Norway spruce from competition following glyphosate application caused a more rapid increase in the number of plants higher than 50 cm on glyphosate areas than on reference areas.

ISSN:0282-7581    

DOI:10.1080/02827588709382482

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The vegetation of four different forest soils in lysimeters was killed with glyphosate. New vegetation became established in some of the treated lysimeters the year after application. During this year, leachates from lysimeters without vegetation had nitrate concentrations up to 4.5 mM NO3−in the fall. A corresponding increase in leached cations was evident. The settlement of one raspberry or one willow herb in treated lysimeters effectively hindered nitrate leaching as soon as the plants were sufficiently large (in mid‐summer). As plants became established in treated lysimeters, the chemistry of these leachates approached those of untreated lysimeters. The absolute effect of even small plants in controlling water regime and water chemistry was evident.

ISSN:0282-7581    

DOI:10.1080/02827588709382483

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Chemical parameters of soil profiles of four different forest soils were investigated after glyphosate application in a lysimeter experiment lasting 28 months. Generally, there was hardly any effect found on the nutrient status of the soils due to glyphosate treatment. A slight increase in NO3−and a decrease in pH and extractable Na+were detected. The amounts of extractable NH4+and org.‐N, t‐N, extractable K+, Mg2+, Ca2+, Mn2+, Fen+and Aln+, CEC and BS in the soil profiles were not affected by glyphosate application. These results, taking into consideration the extreme treatment of the soils, justify the conclusion that no harmful ecological effects on forest soil chemical status due to glyphosate application are likely.

ISSN:0282-7581    

DOI:10.1080/02827588709382484

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The water quality of forest brooks was monitored after glyphosate application to two Norwegian forest areas. The application was done according to common forestry practice. The major effect on water quality of glyphosate is to increase the concentration of NO3−. The maximum concentration found was 80–90 μM NO3−the first and second winters after application. Without glyphosate application, the level was estimated to be 20–40 μM lower. Generally the increase in NO3−was smaller or undetectable. Only at the higher levels of NO3−was an increase in water acidity observed. This occurred the first summer after application and was in the range 1–3 μm H+. No other effects on the water quality resulting from glyphosate application were detected. Glyphosate application as part of common forestry management in Norway gives only small changes in the water quality of forest brooks. As long as small areas of the forest are treated the consequences of the changes in water quality appear nonsignificant.

ISSN:0282-7581    

DOI:10.1080/02827588709382485

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The water quality of forest brooks was monitored after manual clearing of forest plantations and in an area treated with glyphosate for two consecutive years. In both cases an increase in the concentration of NO3−was evident. Manual clearing gave concentrations of 20–60 μM NO3−during winter and less than 10 μM during the growth season, which is in the same range as usually found in glyphosate‐treated forests. The doubly‐treated glyphosate area showed increased leaching of NO3−during summer, giving 30–60 μM NO3−as the maximum value the first summer after the second application. The summer leaching decreased the following two years, giving brook water with 5–25 μM NO3−. No effect of the treatments was found for the other nutrients measured. Both manual clearing and glyphosate application in forest plantations give the same small effect on brook water quality. The effects appear not to be of ecological importance.

ISSN:0282-7581    

DOI:10.1080/02827588709382486

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In this article, an engineering approach is used to derive the access cost function for roundwood in northern Sweden. This approach can make use of detailed biological, technological and economic information and can give insights that cannot be gained with statistical methods. The engineering approach gives a reliable estimate of the whole cost function, so it avoids the difficulties of the statistical approaches in discriminating between different functional forms. The computations are based on data from the Swedish Forest Survey. Cost distributions are derived both at the roadside and at the mill and also with and without subsidies to forestry. Some applications to forest policy problems are mentioned. The elasticity of the cost curve near the current price level is the same as previously reported price elasticities.

ISSN:0282-7581    

DOI:10.1080/02827588709382487

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The variation in the basic‐density level of 45 stems of Sitka spruce from two Danish sites has been examined. It is shown that the basic‐density level, i.e. the basic density as a function of ring width, within the juvenile wood decreases with (1) increasing distance from the pith and (2) increasing height in the stem (same ring number from pith provided). Furthermore, the basic‐density level seems to decrease with increasing stand quality, which may affect the pattern of variation in basic‐density level if the stand quality class varies with age. The basic density of the juvenile wood is markedly higher in Sitka spruce than in Norway spruce, whereby the risk of stem cracks probably is reduced.

ISSN:0282-7581    

DOI:10.1080/02827588709382488

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0282-7581    

DOI:10.1080/02827588709382489

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor