Factors affecting performance of eucalyptus and other species

Firewood is the basic energy source for 60% of the urban population and most of the rural population of Maputo province (Mozambique). Accelerated forest degradation is further reducing the limited firewood supplies in the region. To fulfil fuel needs and exploit the existing resource in a sustainable way, plantations should be established in the area at a rate of 17000 ha/year. Areas for forestry activities are limited to the marginal soils remaining after agriculture or livestock activities. Thus, working in such soils (mainly sandy soils with a grassy vegetation cover) the selection^ appropriate species and provenances allied with the use of appropriate silvicultural techniques is essential to guarantee adequate yield. The studies described in this thesis have examined how growth of E.grandis and E.camaldulensis is affected by different silvicultural factors, initially in the field, and later with respect to the effects of water and weed competition, in glasshouse conditions, in Canberra. They revealed that: (i) Factors which affect performance of Eucalyptus were more marked in E.grandis (a more demanding species) and least in the E.camaldulensis provenance from Petford. The negative effect of weeds was strong as they reduced both survival and growth. Thus, better land preparation allied with good weed control was effective in improving performance of both species; (ii) The effect of weeds appeared to be a result of competition for water rather than for nutrient. Possible allelopathic effects could be investigated in further studies; (iii) Some differences among provenances of E.camaldulensis from different climatic regions may contribute to their successful establishment and performance in plantations: The provenance from the humid tropics (Petford) appeared to be the most suited to planting in a wide range of different environment conditions as it was the least affected by the adverse weed and low water treatments. There was evidence that it did not need to modify its root system to tolerate water stress; The three provenances from the dry tropics (Gilbert River, Manning Creek and Victoria River), had greater rootishoot ratios, yet were more affected by the stress treatments and so they may prefer areas with regular distribution of rainfall; The provenance from the temperate zone (Lake Albacutya), with the lowest rootishoot ratio, was not able to increase its root system in presence of weeds or with low water and, like the previous group, was adversely affected by such treatments. The results have shown that detailed species and provenance trials need to be integrated with silvicultural trials. This is especially important if stress conditions are to be encountered. V I I I LIST OF ABBREVIATIONS A.N. U. A ustralia N ational U niversity auxil. auxiliary carnal. cam aldulensis cu.m. cubic m eter CSIRO Com m onw ealth Scientific and Industrial dbhob Research O rganisation diam eter at breast height over bark D.N. F.F. B. N ational D irectorate of Forest and W ildlife euc. eucalypt Gilb. rv. G ilbert River grand. ha grandis hectare inhab inhab itan t Lake Albac. Lake Albacutya M ann. ck. M anning Creek M.O. organic m atter Mt. m o u n ta in N.C. Harb. N orth Coffs H arbour NSW New South W ales Petf. Petford P.N. R. N ational Reforestation Program m e proven. QLD. provenance Q ueensland rv. river Vic. V ictoria Vict.rv. Victoria River W. of W and. W est of W andecla wgt. weight yr year CONTENTS TITLE i STATEMENT OF ORIGINALITY iii ACKNOWLEDGEMENTS iv ABSTRACT v i LIST OF ABBREVIATIONS viii TABLE OF CONTENTS ix LIST OF TABLES xi LIST OF FIGURES xiv LIST OF APPENDICES xv TABLE OF CONTENTS INTRODUCTION 1 CHAPTER 1 3 1.1 LOCALIZATION AND GENERALITIES 3 1.1.2.Soils 10 1.1.3 Vegetation 13 1.1. 4 Existing stock 17 1.2. FORESTRY PRODUCTS DEMAND 20 1.2.1 Existing plantation programmes 23 1.2.2 The ideal plantation target 26 1.3 THE PROPOSED SPECIES 29 1.3.1 The needs for research programmes 29 1.3.2 Review of research programmes 29 1.3. 3 Summarized performance of the Eucalyptus spp. trials. 32 CHAPTER 2 34 2.1 OBJECTIVES. 34 2.2 MATERIAL 35 2.3 RESULTS 43 2.3.1 Survival 43 2.3.2 Height and diameter growth 46 2.3. 3 The health condition of the trees. 55 2.3. 4 Stem form quality of trees. 58 2.3. 5 Maturity stage of the trees. 61 2.4 DISCUSSION 63 2.5 CONCLUSIONS 73 CHAPTER 3 74 3.1 THE FINDINGS OF THE FIELD STUDY. 74 3.2 THE RATIONALE FOR FURTHER STUDY 75 CHAPTER 4 78 4.1 THE PROPOSED STUDY 78 4.2 MATERIAL AND METHODS 79 4.2.1 The first glasshouse experiment 79 4.2.2 The second glasshouse experiment 92 X 4.3 RESULTS 102 4.3.1 Results of the first glasshouse experiment 102 4.3.2 Results of the second glasshouse experiment 112 4.4 DISCUSSION 4.4.1 Seedling size 123 4.4.2 The production of leaves 127 4.4.3 Dry matter production 129 4.4.4 The partitioning of dry matter 131 4.4. 5 Allelopathy: a possible effect 136 CHAPTER 5 138 5.1 CONCLUSIONS 138 5.2 RECOMENDATIONS 140 REFERENCES 142 APPENDICES 153