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P.R. van Gardingen

P.R. van Gardingen
Independent

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64
Publications
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2,147
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Publications

Publications (64)
Article
Full-text available
Abstract We analyse social demography, livelihood diversification and land tenure among the Maasai people inhabiting Kenya (three sites) and Tanzania (one site) with contrasting land tenure policies. In Kenya, land was communally owned in the rural Amboseli, fully privatized in the peri-urban Kitengela in Athi-Kaputiei and partially privatized and...
Article
Full-text available
We examine livestock-wealth inequality by gender and age of the household head among Maasai households located in areas of contrasting land tenure and land productivity in the Amboseli, Athi-Kaputiei and Maasai Mara regions of Kenya and Tarangire-Manyara Region of Tanzania. We also investigate whether livestock-poor households are more likely to di...
Preprint
Full-text available
Migration of ungulates is under pressure worldwide from range contraction, habitat loss and degradation, anthropogenic barriers and poaching. Here, we synthesize and compare the extent of historical migrations of the white-bearded wildebeest (Connochaetes taurinus) to their contemporary status, in five premier East African ecosystems, namely the Se...
Article
The large diversity of tree species of tropical moist forests relative to temperate zones and their biomass storage capacity and how these are maintained over extended periods of time have been subjects of particular interest. Simulation models of forest dynamics are increasingly used to gain insights regarding the long term effect of both direct a...
Article
Full-text available
A rapid review of the current literature on the links between climate change, ecosystem services (ES) and poverty alleviation has identified 41 papers. Of these, 19 were considered relevant as they specifically discussed the linkages between ES and poverty and the influence of climate change on that relationship. The papers reviewed focused on a li...
Technical Report
Full-text available
Summary of Key Points: - Ecosystem-based Adaptation (EbA) provides numerous opportunities for natural solutions to manage the impacts of climate change. - EbA interventions generate a range of significant social, economic, and environmental co-benefits by reducing society’s vulnerability to natural hazards, improving the availability of ecosyst...
Article
In this article, we discuss the drivers, causes, and impacts of land-use change in the Maasai Steppe of northern Tanzania. Remote sensing data were used to analyze land-use change, and Geographical Information Systems (GIS) was used to link-up with wildlife population dynamics and livestock distribution data derived from aerial censuses. Agricultur...
Article
Full-text available
The Biosphere II Experiment, started in 1991, tried and failed to generate sufficient breathable air, drinkable water and adequate food for just eight people, despite an expenditure of US$200 million. Even the most advanced space programmes such as those of NASA have to rely on very basic supplies from the Earth for astronauts to survive. In contra...
Article
Ecosystem Services for Poverty Alleviation (ESPA) is supporting a range of international research projects which are trying to do this in Sub-Saharan Africa, South Asia, China and the Amazon. A number of large ESPA research consortia will begin in 2011, joining 18 smaller projects. The large projects will address significant challenges like the inf...
Article
Full-text available
Spatially explicit models are becoming increasingly important tools for simulating land-use change. In this study, we formulated and tested models that incorporated spatial correlates of agricultural expansion and used them to predict local-and landscape-scale patterns of agricultural land-use change and its implications in the Maasai-Steppe of Nor...
Article
It is widely accepted that protected areas alone are not sufficient to conserve wildlife populations particularly for migratory or wide-ranging species. In this study, we assess the population density of migratory species in the Tarangire–Simanjiro Ecosystem by conducting a ground census using DISTANCE sampling. We focus on the Simanjiro Plains whi...
Article
Simulation models are increasingly used to gain insights regarding the long-term effect of both direct and indirect anthropogenic impacts on natural resources and to devise and evaluate policies that aim to minimize these effects. If the uncertainty from simulation model projections is not adequately quantified and reported, modeling results might...
Article
i Executive Summary This report is designed as one of a series of briefing papers prepared for NEPAD's Office of Science and Technology to inform debate on methods to implement Africa's Science and Technology Consolidated Plan of Action (CPA), as agreed by the 2005 African Ministerial Conference on Science and Technology (AMCOST). The report consid...
Article
Timber logging is one of the main land uses in the Brazilian Amazon. Despite its recognized potential as a sustainable activity, logging is generally conducted in an unsustainable or predatory manner, with significant negative environmental impact. There is increasing pressure to adopt more sustainable practices and reduced-impact logging (RIL) is...
Article
The sustainability of a range of forest management scenarios were evaluated for the Tapajós region of the Brazilian Amazon using the growth and yield simulation model, Simflora, a derivative of the model SYMFOR developed for application in Indonesia. A simulation of current management regulations based upon a maximum extracted volume of 35 m3 ha−1...
Article
The abundance and height of three common shrubs (bilberry Vaccinium myrtillus, cowberry V. vitis-idaea and heather Calluna vulgaris) in Scots pine Pinus sylvestris woodland in Scotland were studied in relation to irradiance and browsing by herbivores (deer). In particular, we were interested in how these variables could be manipulated in order to i...
Article
Understanding the effects of logging activity on genetic diversity is an important aspect of establishing the sustainability of selective logging management operations in tropical forests. Genetic variation is affected by selective logging directly, through the removal of and damage to trees within the population, and indirectly, through a change i...
Article
A model to simulate the ecological processes of tree growth, mortality and recruitment, and the processes of forest management, in the terra firme forests of the eastern Amazon is described. It is implemented within the SYMFOR (http://www.symfor.org) framework. It is based on measurements of all trees that have a diameter greater than 5 cm from exp...
Article
We review some of the experience gained through experiments with participatory management of common pool resources (CPRs) in forests, with a view to developing lessons for policy and practice that can be applied in the management of CPRs in other contexts such as fisheries, water, and rangelands. We summarise lessons from experience in India, Nepal...
Article
Full-text available
This paper discusses the overall diameter growth of naturally regenerated Dryobalanops aromatica trees using results obtained from measurements taken for a period of 61 years (1915 till 1976). The plot was located at Kancing Forest Reserve, Selangor, Peninsular Malaysia. After 61 years, the achieved mean DBH was 61.4 ± 2.0 cm. The periodic annual d...
Article
The sustainable management of areas of logged-over tropical forests requires an understanding of the potential yield from the forest and likely financial performance of the management system. This paper describes an analytical approach that involves the linkage of a simulation model of forest growth and yield to a financial model based on data from...
Article
The study focused on the growth of 50- to 70-year-old planted Dryobalanops aromatica, potential yield and factors affecting its growth within the research area of the Bukit Lagong Forest Reserve at the Forest Research Institute Malaysia (FRIM). Trees were evaluated on periodic annual diameter increment over a period of four years (1997-2000) consis...
Article
A model of ecological processes that determine the behaviour of individual trees, and thus the overall characteristics of forest stands, is described, evaluated and discussed. The purpose of the model is to simulate individual trees as part of the SYMFOR framework for modelling the effects of silviculture on the growth and yield of tropical forests...
Article
The management, conservation and theoretical understanding of mixed tropical forests rely heavily on the interpretation of data collected from those forests. Data-derived quantities that are averaged over all species often hide important descriptors of the forest, whereas quantities based on individual species are difficult to interpret due to the...
Article
Full-text available
This document is an output from a project funded through the Forestry Research Programme of the UK Department for International Development (DFID) for the benefit of developing countries. The views expressed are not necessarily those of DFID. R6915 Forestry Research Programme.
Article
This study examined the photosynthetic acclimation of pre-existing Shorea johorensis (Dipterocarpaceae) seedlings to the change in conditions that occurs at the time of logging in Central Kalimantan, Indonesia. The hypothesis was that the seedlings would be unable to acclimate beyond partially open conditions after canopy disturbance caused by logg...
Article
Hemispherical canopy photographs are now widely used to estimate the proportion of above canopy PPFD (photosynthetic photon flux density) that is transmitted to the forest understorey. Some studies have obtained good results, while others have found that predictions are not always independent of forest type or condition, and that errors are sometim...
Article
A method has been developed to improve estimates of leaf area index determined from hemispherical images of plant canopies. The approach used has been to modify existing techniques for analysis of gap fraction at a range of zenith angles. Conventional analytical techniques determine the gap fraction for a number of concentric annuli and then calcul...
Article
The growth structure and yield of three Dryobalanops aromatica stands established in the forest area of the Forest Research Institute Malaysia in the 1930s are discussed. The species when grown in plantation can grow to merchantable size in about 50 years. It exhibits rapid height and diameter growth. The study is a first assessment of the stands w...
Article
The effect of logging practices on rainfall interception loss has been investigated in a humid tropical rainforest of central Kalimantan. The traditional volume balance method was used to measure throughfall, stemflow and interception loss. The evaporation rate during and after rainfall has ceased in canopy-saturated conditions was calculated by an...
Article
Research into the impacts of logging on the regeneration of lowland dipterocarp forests has been carried out in Central Kalimantan (Indonesian Borneo) as part of the UK Department for International Development funded Indonesian Tropical Forest Management Programme. The paper describes the impact of logging on the radiation environment, dipterocarp...
Article
Full-text available
Rainfall interception losses were monitored for twelve months and related to vegetation and rainfall characteristics at the Wanariset Sangai on the upper reaches of the Mentaya river, Central Kalimantan. The rainfall interception losses were quantified for one hectare each of unlogged and logged humid tropical rainforests. The results show that int...
Article
Rainfall interception losses were monitored for 12 months, and related to vegetation and rainfall characteristics at the BPK-ECTF research site (Wanariset Sangai) on the upper reaches of the Mentaya river, Central Kalimantan. The rainfall interception losses were quantified, based on the records of 55 selected rainfall events within the range of 8....
Chapter
The rise in the concentration of CO2 in the atmosphere since the start of industrialization, and the global warming associated with this greenhouse gas, has stimulated research into the response of plants to elevated levels of CO2. Much of this work has been carried out in controlled environments which provide limited information about long-term ef...
Chapter
The rise in the concentration of CO2 in the atmosphere since the start of industrialization, and the global warming associated with this greenhouse gas, has stimulated research into the response of plants to elevated levels of CO2. Much of this work has been carried out in controlled environments which provide limited information about long-term ef...
Article
Full-text available
La conductancia aerodinámica a escala de copa en dos especies dominantes del área de Rambla Honda (Almería), Retama sphaerocarpa L. Boiss y Stipa tenacissima L., ha sido calculada en condiciones naturales a partir de la medida de la evaporación directa de copas saturadas de agua. R. sphaerocarpa es un arbusto perenne de copa abierta, con cladodios...
Article
Leaf boundary layer conductance was measured in the field using heated leaf replicas placed in the canopies of two of the three main semi-arid species found in the Rambla Honda (Almería, South East of Spain), Retama sphaerocarpa (L.) Boiss, and Stipa tenacissima L. R. sphaerocarpa is a woody perennial bush with approximately cylindrical cladodes ar...
Article
The geometry of tree branches can have considerable effect on their efficiency in terms of carbon export per unit carbon investment in structure. The purpose of this study was to evaluate different design criteria using data describing the form of Picea sitchensis branches. Allometric analysis of the data suggests that resources are distributed to...
Article
Emissions of carbon dioxide from vents at the Bossoleto mineral spring in Central Italy have been calculated to exceed 12 t day−1. This emission leads to enhanced atmospheric concentrations of CO2 over an area of more than 3000 m2. The vent gas is over 99% pure CO2, with a characteristic isotopic signature that is totally depleted in 14C. At night,...
Article
Full-text available
One of the major concerns about the effect of increasing carbon dioxide concentration in the atmosphere is for the long-term response of photosynthesis and biomass accumulation in natural vegetation. Knowledge about this response is critical while attempting to predict the effect of global change on primary production, on vegetation spatial distrib...
Article
SummaryA cryo‐specimen storage system for low‐temperature scanning electron microscopy (LTSEM) specimens is described, which: liberates multi‐specimen experiments from sampling restrictions imposed by the rate at which LTSEM specimens can be examined in the SEM; provides security against experiment loss resulting from breakdown of the SEM or cryo‐s...
Article
The cuticular conductance (gc) of the astomatous adaxial surface of Fagus sylvatica L. leaves was determined under varying vapour pressure deficits at a constant temperature of 20 °C. Cuticular conductance was determined from the weight loss of detached leaves after both the stomatous abaxial surface and the cut end of the petiole had been sealed u...
Chapter
The interaction between air flow and exchange processes in the canopy is currently being re-examined. This has been prompted by a general disillusionment with the classical technique for evaluating heat and mass transfer from micrometeorological profiles (the one-dimensional flux-gradient approach). Not only is the technique inapplicable to non-hom...
Article
. After a period of one week at 11m s−1 in a wind tunnel, the leaf surface of Picea sitchensis and Pinus sylvestris had undergone structural modification. Low-temperature scanning electron microscopy was used to examine these changes. Picea showed flattening and smearing of wax crystals, as well as cracks in some of the wax structures filling the s...
Article
. A novel technique to record the variability of stomatal aperture over the leaf surface is described. This combines observations of leaf surfaces using low-temperature scanning electron microscopy (LTSEM), with digital image analysis to produce the most accurate aperture measurements obtained to date. Leaf samples are rapidly immobilized by cryo-f...
Article
Alternative formulae have been derived from those of Kuppers (1984) to compute transpiration and stomatal conductance for the Li-Cor LI-6000 portable photosynthesis system. Analysis shows that the LI-6000 tends to underestimate these parameters with the largest errors occurring when using small chambers, with high flow rates through the water vapou...
Article
SYMFOR is a software framework allowing forest managers and policy makers to simulate the effects of silvicultural treatments on mixed tropi-cal forests. The framework is designed to use Permanent Sample Plot data and house individual-based, spatially explicit models of silvicultural treatments and ecological processes. The framework and models are...
Article
For sustainable forest management, information is required on the long-term consequences of current logging practises for tree species composition and future timber yields. Yet, little is known about these long-term effects of logging on species composition and forest recovery. We used a simulation model of forest dynamics to study the effects of l...
Article
SYMFOR is a framework used to simulate the effects of silviculture on the growth and future yield of tropical forests. The framework is made up of models of the natural processes in the forest (ecology) and the management of forest (silviculture) The ecological model describes the natural forest processes in terms of the behaviour of individual tre...

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