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1.
Biol Rev Camb Philos Soc ; 98(4): 1003-1015, 2023 08.
Article in English | MEDLINE | ID: mdl-36808687

ABSTRACT

Forestry management worldwide has become increasingly effective at obtaining high timber yields from productive forests. In New Zealand, a focus on improving an increasingly successful and largely Pinus radiata plantation forestry model over the last 150 years has resulted in some of the most productive timber forests in the temperate zone. In contrast to this success, the full range of forested landscapes across New Zealand, including native forests, are impacted by an array of pressures from introduced pests, diseases, and a changing climate, presenting a collective risk of losses in biological, social and economic value. As the national government policies incentivise reforestation and afforestation, the social acceptability of some forms of newly planted forests is also being challenged. Here, we review relevant literature in the area of integrated forest landscape management to optimise forests as nature-based solutions, presenting 'transitional forestry' as a model design and management paradigm appropriate to a range of forest types, where forest purpose is placed at the heart of decision making. We use New Zealand as a case study region, describing how this purpose-led transitional forestry model can benefit a cross section of forest types, from industrialised forest plantations to dedicated conservation forests and a range of multiple-purpose forests in between. Transitional forestry is an ongoing multi-decade process of change from current 'business-as-usual' forest management to future systems of forest management, embedded across a continuum of forest types. This holistic framework incorporates elements to enhance efficiencies of timber production, improve overall forest landscape resilience, and reduce some potential negative environmental impacts of commercial plantation forestry, while allowing the ecosystem functioning of commercial and non-commercial forests to be maximised, with increased public and biodiversity conservation value. Implementation of transitional forestry addresses tensions that arise between meeting climate mitigation targets and improving biodiversity criteria through afforestation, alongside increasing demand for forest biomass feedstocks to meet the demands of near-term bioenergy and bioeconomy goals. As ambitious government international targets are set for reforestation and afforestation using both native and exotic species, there is an increasing opportunity to make such transitions via integrated thinking that optimises forest values across a continuum of forest types, while embracing the diversity of ways in which such targets can be reached.


Subject(s)
Ecosystem , Forestry , New Zealand , Forests , Biodiversity , Conservation of Natural Resources , Trees
2.
Environ Sci Pollut Res Int ; 15(4): 308-17, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18488261

ABSTRACT

BACKGROUND, AIM, AND SCOPE: Large quantities of biosolids (sewage sludge), which are produced from municipal wastewater treatment, are ever-increasing because of the commissioning of new treatment plants and continuous upgrades of the existing facilities. A large proportion of biosolids are currently landfilled. With increasing pressure from regulators and the general public, landfilling of biosolids is being phased out in many countries because of potential secondary pollution caused by leachate and the emission of methane, a potent greenhouse gas. Biosolids contain nutrients and energy that can be used beneficially. Significant efforts have been made recently to develop new technologies to manage biosolids and make useful products from them. In this paper, we provide a review of the technologies in biosolids management. MATERIALS AND METHODS: A survey of literature was conducted. RESULTS: At present, the most common beneficial use of biosolids is agricultural land application because of inherent fertilizer values found in biosolids. Expansion of land application, however, may be limited in the future because of more stringent regulatory requirements and public concern about food chain contamination in some countries. Perceived as a green energy source, the combustion of biosolids has received renewed interest. Anaerobic digestion is generally a more effective method than incineration for energy recovery, and digested biosolids are suitable for further beneficial use through land application. Although conventional incineration systems for biosolid management generally consume more energy than they produce because of the high moisture content in the biosolids, it is expected that more combustion systems, either monocombustion or cocombustion, will be built to cope with the increasing quantity of biosolids. DISCUSSION: Under the increasingly popular low-carbon economy policy, biosolids may be recognized as a renewable fuel and be eligible for 'carbon credits'. Because ash can be used to manufacture construction materials, combustion can provide a complete management for biosolids. A number of advanced thermal conversion technologies (e.g., supercritical water oxidation process and pyrolysis) are under development for biosolids management with a goal to generate useful products, such as higher quality fuels and recovery of phosphorus. With an ever-increasing demand for renewable energy, growing bioenergy crops and forests using biosolids as a fertilizer and soil amendment can not only contribute to the low-carbon economy but also maximize the nutrient and carbon value of the biosolids. CONCLUSIONS: Land application of biosolids achieves a complete reuse of its nutrients and organic carbon at a relatively low cost. Therefore, land application should become a preferred management option where there is available land, the quality of biosolids meet regulatory requirements, and it is socially acceptable. Intensive energy cropping and forest production using biosolids can help us meet the ever-increasing demand for renewable energy, which can eliminate the contamination potential for food sources, a common social concern about land application of biosolids. In recent years, increasing numbers of national and local governments have adopted more stringent regulations toward biosolid management. Under such a political climate, biosolids producers will have to develop multireuse strategies for biosolids to avoid being caught because a single route management practice might be under pressure at a short notice. Conventional incineration systems for biosolids management generally consume more energy than they produce and, although by-products may be used in manufacturing, this process cannot be regarded as a beneficial use of biosolids. However, biosolids are likely to become a source of renewable energy and produce 'carbon credits' under the increasingly popular, low-carbon economy policy. RECOMMENDATIONS AND PERSPECTIVES: To manage biosolids in a sustainable manner, there is a need for further research in the following areas: achieving a higher degree of public understanding and acceptance for the beneficial use of biosolids, developing cost-efficient and effective thermal conversions for direct energy recovery from biosolids, advancing technology for phosphorus recovery, and selecting or breeding crops for efficient biofuel production.


Subject(s)
Conservation of Natural Resources/methods , Gases/chemistry , Sewage/chemistry , Soil Pollutants/isolation & purification , Waste Disposal, Fluid/methods , Waste Management/methods , Anaerobiosis , Carbon/chemistry , Cities , Conservation of Natural Resources/economics , Crops, Agricultural , Energy-Generating Resources/economics , Fertilizers , Greenhouse Effect , Incineration , Methane/chemistry , Phosphorus/chemistry , Sewage/microbiology , Soil Pollutants/chemistry , Soil Pollutants/metabolism , Time Factors , Trees , Waste Disposal, Fluid/economics , Waste Management/economics
3.
Tree Physiol ; 19(8): 535-540, 1999 Jul.
Article in English | MEDLINE | ID: mdl-12651544

ABSTRACT

Magnesium (Mg) nutrition and photosynthesis were studied in clones of Pinus radiata D. Don grown in sand culture for 21 weeks at four Mg concentrations (0.008, 0.04, 0.2 and 0.4 mM) and three potassium (K) concentrations (0.25, 0.5 and 2.5 mM). We found significant clonal variation in Mg nutrition of P. radiata. Plants grown at 0.04 mM [Mg] or less showed pronounced visible symptoms of foliar Mg deficiency. Net photosynthetic rate and leaf conductance were closely related to shoot Mg concentrations below a concentration of 0.6 mg Mg g(DW) (-1). Potassium enhanced the development of visible symptoms of foliar Mg deficiency. At the lowest Mg concentration tested (0.008 mM), the severity of needle chlorosis and necrosis increased with increasing K concentration in the culture solution. With increasing Mg concentration, 2.5 mM [K] in the culture solution markedly increased root Mg concentration, but decreased shoot Mg concentration, suggesting that excessive K inhibited Mg mobilization from roots to shoots. Rates of growth and photosynthesis were both severely inhibited at 0.008 mM [Mg].

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