Nick D Brown
University of Oxford, Plant Sciences, Emeritus
Although sacred groves are important for conservation in India, the landscape that surrounds them has a vital influence on biodiversity within them. Research has focused on tree diversity inside these forest patches. In a coffee-growing... more
Although sacred groves are important for conservation in India, the landscape that surrounds them has a vital influence on biodiversity within them. Research has focused on tree diversity inside these forest patches. In a coffee-growing region of the Western Ghats, however, landscape outside sacred groves is also tree covered because planters have retained native trees to provide shade for coffee plants. We examined the diversity of trees, birds, and macrofungi at 58 sites—10 forest-reserve sites, 25 sacred groves, and 23 coffee plantations— in Kodagu district. We measured landscape composition and configuration around each site with a geographic information system. To identify factors associated with diversity we constructed multivariate models by using a decision-tree technique. The conventional measures of landscape fragmentation such as patch size did not influence species richness. Distance of sacred groves from the forest reserve had a weak influence. The measures of landscape...
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Water availability has frequently been linked to seasonal leaf display in seasonally dry ecosystems, but there have been few ecohydrological investigations of this link. Miombo woodland is a dominant seasonally dry tropical forest... more
Water availability has frequently been linked to seasonal leaf display in seasonally dry ecosystems, but there have been few ecohydrological investigations of this link. Miombo woodland is a dominant seasonally dry tropical forest ecosystem type in southern Africa; however, there are few data on the relationship between seasonal dynamics in plant-water relations and patterns of leaf display for Miombo woodland. Here we investigate this relationship among nine key Miombo woodland tree species differing in drought tolerance ability and leaf phenology. Results of this study showed that seasonal patterns of leaf phenology varied significantly with seasonal changes in stem water relations among the nine species. Leaf shedding coincided with the attainment of seasonal minimum stem water potential. Leaf flush occurred following xylem rehydration at the peak of the dry season suggesting that endogenous plant factors play a pivotal role in seasonal leaf display in this forest type. Drought-t...
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... Title Community structure and the demography of primary species in tropical rainforest. ... and their spatial distribution may maintain themselves in the community at different population size distributions, which represent different... more
... Title Community structure and the demography of primary species in tropical rainforest. ... and their spatial distribution may maintain themselves in the community at different population size distributions, which represent different pathways towards successful regeneration. ...
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Research Interests: Forest Ecology And Management, Geostatistics, Forest Ecology, Biological Sciences, Spatial autocorrelation, and 12 moreGrowth, Environmental Sciences, Forest Management, Light, Secondary Forest, Spatial Variation, Canopy Gap, Spatial structure, Understory, Spatial Relationships, Forest Canopy, and Seedling Growth
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ABSTRACT Cited By (since 1996): 14
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Page 1. -3----- Degeneration versus regeneration - logging in tropical rain forests ... Francis Bacon 3.1 REGENERATION OF TROPICAL RAIN FORESTS Tropical rain forests are widely regarded as being very ancient climax ecosystems composed of... more
Page 1. -3----- Degeneration versus regeneration - logging in tropical rain forests ... Francis Bacon 3.1 REGENERATION OF TROPICAL RAIN FORESTS Tropical rain forests are widely regarded as being very ancient climax ecosystems composed of highly specialized organisms. ...
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Rhododendron ponticum is a constant problem on the island of Lundy. We present the results of an experiment investigating the lasting legacy of Rhododendron following manual clearance, and the time needed for natural regeneration of the... more
Rhododendron ponticum is a constant problem on the island of Lundy. We present the results of an experiment investigating the lasting legacy of Rhododendron following manual clearance, and the time needed for natural regeneration of the plants and fungi in cleared areas. These results are discussed with particular reference to their implications for management and clearance on Lundy and in other areas in the future.
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Tropical and subtropical forests. RW Pearcy, RH Robichaux 1985. In the present chapter, the authors briefly review the distributions of tropical and subtropical forests and the limited information available on the physicological ecology... more
Tropical and subtropical forests. RW Pearcy, RH Robichaux 1985. In the present chapter, the authors briefly review the distributions of tropical and subtropical forests and the limited information available on the physicological ecology of their component species. ...
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Cyclotrichiids are of ecological and evolutionary interest by virtue of their importance in red tide formation, their highly divergent small subunit (SSU) ribosomal RNA (rRNA) genes, kleptoplastidy, and utility as indicators of... more
Cyclotrichiids are of ecological and evolutionary interest by virtue of their importance in red tide formation, their highly divergent small subunit (SSU) ribosomal RNA (rRNA) genes, kleptoplastidy, and utility as indicators of eutrophication. However, only seven strains have had their SSU rRNA genes sequenced and their environmental diversity and distribution are largely unknown. We probed 67 globally dispersed freshwater column/sediment and soil DNA samples (eDNAs) and constructed 24 environmental gene libraries using polymerase chain reaction primers specific to an uncharacterised cyclotrichiid subgroup. We reveal a novel, globally ubiquitous freshwater clade comprising 25 genetically distinct SSU ribosomal DNA (rDNA) sequences (SSU-types). Some identical SSU-types were detected at globally widely distributed sites. The SSU-types form four distinct phylogenetic clusters according to marine or non-marine provenance, suggesting at least one major marine-freshwater evolutionary transition within the cyclotrichiids. We used the same primers to sample intensively 18 sampling points in 13 closely situated lakes, each characterised by 14 environmental variables, and showed that molecular detection or non-detection of cyclotrichiids was most significantly influenced by levels of total phosphorus, dissolved organic carbon, and chlorophyll a. Within the subset of lakes in which cyclotrichiids were detected, closely related SSU-types differed in their ecological preferences to pH, total phosphorus, and sample depth.
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Fungi are the principal degraders of biomass in most terrestrial ecosystems. In contrast to surface environments, deep-sea environmental gene libraries have suggested that fungi are rare and non-diverse in high-pressure marine... more
Fungi are the principal degraders of biomass in most terrestrial ecosystems. In contrast to surface environments, deep-sea environmental gene libraries have suggested that fungi are rare and non-diverse in high-pressure marine environments. Here, we report the diversity of fungi from 11 deep-sea samples from around the world representing depths from 1500 to 4000 m (146–388 atm) and two shallower water column samples (250 and 500 m). We sequenced 239 clones from 10 fungal-specific 18S rRNA gene libraries constructed from these samples, from which we detected only 18 fungal 18S-types in deep-sea samples. Our phylogenetic analyses show that a total of only 32 fungal 18S-types have so far been recovered from deep-sea habitats, and our results suggest that fungi, in general, are relatively rare in the deep-sea habitats we sampled. The fungal diversity detected suggests that deep-sea environments host an evolutionarily diverse array of fungi dominated by groups of distantly related yeasts...
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Research Interests: Phytochemistry, Metabolism, Carbon Dioxide, Kinetics, Multivariate Analysis, and 15 moreArabidopsis thaliana, Biological Sciences, Growth, Metabolic Flux Analysis, Glucose, Glucose Metabolism, Carbon Isotopes, Arabidopsis, CHEMICAL SCIENCES, Kinetic Isotope Effect, Plant extracts, Carbon Metabolism, Culture Media, Cell Suspension Culture, and Medical and Health Sciences
The theory of gap regeneration dynamics proposes that different species of tree partition canopy gaps because they are preferentially adapted to a particular gap size class. A variety of gap sizes would therefore favour the regeneration... more
The theory of gap regeneration dynamics proposes that different species of tree partition canopy gaps because they are preferentially adapted to a particular gap size class. A variety of gap sizes would therefore favour the regeneration of a range of species. The theory has been used to explain the extraordinarily high tree species diversity of tropical rain forests. A test was mounted in lowland evergreen dipterocarp rain forest in the Danum Valley, Sabah, East Malaysia by the creation of ten, artificial canopy gaps ranging in size from 10 m 2 to 1500 m 2 (6 to 30% canopy openness). The responses of established populations of seedlings of three dipterocarp species ( Hopea nervosa , Parashorea malaanonan and Shorea johorensis ) with contrasting silvicultural reputations were monitored for 40 months in these gaps and under closed forest. There were significant differences in survival and growth under closed forest between these three species. However, in gaps, the most important dete...
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:The direct removal of adult trees by logging affects tree recruitment in tropical rain forests. However, secondary effects of logging, such as loss of vertebrate seed dispersers may also affect tree recruitment. We studied the... more
:The direct removal of adult trees by logging affects tree recruitment in tropical rain forests. However, secondary effects of logging, such as loss of vertebrate seed dispersers may also affect tree recruitment. We studied the recruitment and spatial distribution of five tree species namely Balanites wilsoniana, Celtis zenkeri, Chrysophyllum albidum, Cordia millenii and Ricinodendron heudelotii in Kibale, Budongo and Mabira Forests in Uganda. These forests have been subjected to varying degrees of disturbance leading to changes in their vertebrate seed dispersers. Vertebrate frugivores of the five tree species were identified. Three 1-ha plots were established around adult trees of the same five species in each forest and the distance from the juveniles to the nearest adult conspecific was measured to generate a recruitment curve. Frugivore visitation rates were high in the less disturbed Budongo and Kibale (2.2 and 1.6 individuals h−1 respectively) compared with the highly disturbed Mabira (0.9 individuals h−1). In the frugivore-impoverished forest, 70–90% of juveniles established beneath adult conspecifics, whereas in the less-disturbed forests juveniles were established up to 80 m from adult conspecifics. Shade-tolerant species capable of recruiting beneath adult conspecifics appeared to maintain their populations without dispersal. Consequently, disturbances leading to significant loss of vertebrates may alter tree recruitment and spatial distribution with consequences for long-term population viability of shade-intolerant tropical trees.
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The influence of herbivory on dipterocarp seedling growth and survival in Bornean primary lowland forest understorey during and after the 1997–8 El Niño-Southern Oscillation was investigated. During the drought, a coleopteran (Scolytidae)... more
The influence of herbivory on dipterocarp seedling growth and survival in Bornean primary lowland forest understorey during and after the 1997–8 El Niño-Southern Oscillation was investigated. During the drought, a coleopteran (Scolytidae) root borer attacked dipterocarp seedlings, primarily of the genus Parashorea. Infestation was spatially heterogeneous on a large (c. 100 m) scale. Attack rate decreased with plant vigour within infested areas. Experiments showed that root damage was fatal under drought conditions, but not after rain. Defoliation and apical meristem removal did not increase mortality. The spatio-temporal heterogeneity of herbivore outbreaks and difficulties involved in experimenting with root herbivores limit the power of such short-term investigations. However, the study shows that herbivores can cause differential mortality between species, and can therefore influence dipterocarp regeneration dynamics. The effect of herbivory depends on the plant organ attacked an...
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ABSTRACTPresent theories of tropical rain forest regeneration dynamics suggest that different tree species specialize on the microclimates of different sizes of canopy gap. A detailed analysis of the microclimates of closed forest and 10... more
ABSTRACTPresent theories of tropical rain forest regeneration dynamics suggest that different tree species specialize on the microclimates of different sizes of canopy gap. A detailed analysis of the microclimates of closed forest and 10 canopy gaps of different sizes was carried out in lowland dipterocarp rain forest, Sabah, Malaysian Borneo. It reveals that gaps exhibit considerable spatial and temporal variation in microclimate. As a consequence the relationship between microclimate and gap sizes is not simple. Gaps of the same size do not necessarily have the same microclimate and may favour the growth of different seedling species. Chance location and timing of gap creation play an important role in regeneration dynamics.