Root Mass and Elemental Concentrations in an Irish Oak Woodland

Fine roots (< 2 mm diameter) are key for nutrient and carbon cycling in forests but less well studied for oak than other European trees. To better understand controls on root mass and nutrient concentrations in oak stands, a study was conducted at Glendalough in Ireland. Roots were removed from soils and measured for biomass, length and nutrient concentrations along with soil nutrients. Fine root mass was 360 gm-2 and comparable to other oak stands. Whilst root N concentrations were high, P concentrations were low and N, P, K, Mg, but not C or Ca were at greater concentrations in fine roots compared to coarse (2-5 mm) roots. The root Ca:Al ratio suggested Al toxicity although this was less marked in organic-rich soils. Neither root mass nor root nutrient concentrations showed particularly strong correlations with soil nutrients or pH. Whilst this data agrees well with other similar studies, improved analysis by separating live and dead roots will further advance our understanding of controls on forest fine root dynamics

Geo-ecological insights on the island of Inchcailloch in Loch Lomond, Scotland: a small serpentine outcrop in a mixed geological setting

Inchcailloch hosts a small serpentine (ultramafic) site in Loch Lomond that is unusual in the Scottish context in being covered with broad-leaved woodland; along with serpentinite, serpentine breccias and sandstones are also found. In order to look at plant-soil relationships in more detail here, I analysed soil and foliar chemistry from sampling locations on and around the ultramafic outcrop. Soils situated directly on the outcrop had elevated concentrations of metals such as Co, Cr, Mg, Mn, Ni and Zn and a lower Ca-to-Mg ratio. Foliar elemental composition was influenced more by species than sampling location although some metals (Ni and Mn) were at greater concentrations in plants on the ultramafic outcrop. Foxgloves (Digitalis purpurea) had the highest foliar Ni concentration as well as Al and Zn, indicating an ability to accumulate multiple metals. Overall, the high Ca-to-Mg ratio indicating the calcareous nature of the soils due to mixing of soils from contrasting geologies, the low metal concentrations, and the high soil P are all considered to act together to prevent this site from exhibiting some of the more extreme features, such as skeletal soils and sparse vegetation cover, found at other Scottish serpentine sites

Biomass and floristics of a secondary forest in West Kalimantan, Indonesia

To understand the biomass and floristics of secondary forests in Borneo better, we established a one-hectare plot on the lower slopes of Gunung Kelam in West Kalimantan, Indonesia. We recorded 683 stems (≥5 cm dbh) representing 50 species, 44 genera and 27 families; the five species with the greatest Importance Value were Artocarpus elasticus (IV＝81.5), Vitex pinnata (40.2), Cryptocarya ferrea (14.2), Polyscias elliptica (12.7) and Gordonia excelsa (10.7); stem dbh distributions differed among species indicating that succession was still occurring. The stand basal area was 29.0 m2. We estimated biomass with eight different allometric equations. Four equations (Chave, Hashimoto, Kenzo and Manuri-DGH9) showed very close agreement at around 137 Mg ha−1 suggesting they were all suitable for mid-aged secondary forest biomass estimation in this region. Despite tree diversity and biomass being lower than nearby primary forest, secondary forests will become increasingly prevalent in the future and this therefore necessitates their increased study and conservation

Below-ground secondary succession in tropical forests of Borneo

As the destruction and severe disturbance of primary tropical forest continues, it is important to understand how these forests may recover from perturbations. Considerable work has been done on above-ground recovery but below-ground processes are less well understood. To determine changes in root mass during tropical secondary succession in lowland forests of Central Borneo, samples were taken from stands of increasing ages since abandonment of agriculture (1, 3, 14 and 31 y) with a primary forest control (six plots from 1-y-old stands and three from all other ages). Root mass and elemental concentrations were determined and soils were chemically analysed. There was no increase in root mass with stand age for fine-root (< 2 mm diameter) or small-root (< 5 mm diameter) mass but there was a trend for coarse-root mass (5-10 mm diameter) to increase with stand age. Negative correlations were shown between root mass and soil nutrient status. Fine-root C concentrations increased with stand age but there was no clear effect of stand age on fine-root N or P. Fine-root mass did not increase significantly with stand age suggesting a rapid recovery; instead, soil nutrient status appeared to be the most important factor controlling root mass. Of the soil nutrients measured in this study, N had a stronger control over root mass than P suggesting that this element may be limiting during secondary succession in tropical lowland forests of Borneo. © 2011 Cambridge University Press

Ecology of Nepenthes on Mount Talang, West Sumatra, Indonesia

Gunung (Mount) Talang is an active volcano in West Sumatra that has a number of Nepenthes species, including the endemic N. talangensis, but their ecology has been little been studied. This study found five species of Nepenthes growing in the protected forest area of Gunung Talang, namely N. bongso, N. inermis, N. pectinata, N. spathulata and N. talangensis. The population of N. talangensis is very small (23 individuals) and it grows sympatrically with N. bongso and N. inermis forming natural hybrids. Lithocarpus conocarpus, Camellia lanceolata, Syzygium acuminatissimum, Adinandra dumosa and Dehaasia sp. are the five most dominant tree species found in the Nepenthes habitat, while L. conocarpus and Podocarpus neriifolius had strong positive associations with N. talangensis. Growth rates of the five Nepenthes species were not significantly different, neither were foliar nitrogen (mean = 1.14%) or phosphorus concentrations (mean = 0.11%). We suggest that N. talangensis should be considered as Critically Endangered and outline some possible conservation actions

Status of ramin (Gonystylus spp.) in eastern Kalimantan, Indonesia

Peat swamp forests in Indonesia have been heavily logged in recent years, with Gonystylus bancanus, locally known as the ramin tree, being one of the main species of timber harvested. The potential for other Gonystylus species as timber trees is not known, as we have a poorer understanding of their distribution and regeneration patterns. In this study, the team explored the Gonystylus species diversity and distribution at five locations in East and North Kalimantan (Indonesia) in 2009. In total, we found six Gonystylus species – G. affinis, G. brunnescens, G. consanguineus, G. forbesii, G. keithii and G velutinus – in primary forest with flat to hilly topography up to 500 m a.s.l. on typical ultisol soils. Gonystylus brunnescens was the most abundant species and had the best natural regeneration, whilst the populations of the other five species were much smaller, with fewer than five individuals at each location, and their regeneration was poor. We present information on the autecology of these Gonystylus species and recommend further studies on their physiology and ecology, with the support of governments and concessionaires, in order to conserve ramin populations

DIVERSITY, ECOLOGY AND CONSERVATION STATUS OF NEPENTHES IN WEST SUMATRA PROVINCE, INDONESIA

Nepenthes is the largest carnivorous plant genus present in Indonesia. There are 39 species of Nepenthes pitcher plants recorded in Sumatra from lowland to montane forests, and 34 of them are endemic; this represents the greatest species diversity of Nepenthes after Borneo. Field studies were conducted in 2021 and 2022 to increase our knowledge of the diversity, habitats and distributions of Nepenthes in West Sumatra province. Twenty-three species of Nepenthes were recorded from the province, consisting of 15 highland species, 4 mid-elevation species and 4 lowland species. Ecophysiological studies conducted at Bukit Malalak showed clumped distributions of N. bongso, N. dubia, N. eustachya and N. rhombicaulis. Foliar and pitcher fluid nutrient concentrations were found to be similar to those cited in other recent studies although growth rates were slightly more rapid than at Gunung Talang. Bukit Malalak is a new locality for two threatened species, namely N. dubia (CR) and N. rhombicaulis (VU), enlarging their extents of occurrence. In total, nine species from West Sumatra are threatened and conservation actions are urgently needed for these and other Nepenthes species remaining on the island

Influence of species functional strategy on leaf stoichiometric responses to fertilizer in a Bornean heath forest

The distribution of Bornean heath forest on white sand soils is believed to be due to element limitation and soil acidity. To determine the impact of both element limitation and soil acidity on tropical heath forest, we established a soil fertilization experiment to investigate the impact that increased soil N availability and reduced soil pH (using lime/CaCO3) had on a range of elements in tree leaves. We hypothesized that alterations in soil resource availability would cause changes in the tree leaf N:P ratio and concentrations of other elements and these changes would be influenced by species' functional strategies. The experiment was carried out in a Bornean heath forest on infertile soil over a 2-year period. We selected 10 common tree species, spanning acquisitive to conservative strategies and tested whether tree species functional strategies influenced tree leaf elemental concentrations after the fertilization. Leaf N:P ratios showed considerable differences among co-occurring species. Overall, we found that soil N addition treatments increased leaf N concentration, although leaf N:P ratios were not affected. Changes in leaf Al, Fe and S concentrations were correlated with species functional strategy: conservative species showed a greater increase in leaf Fe compared with acquisitive species, whereas acquisitive species showed a greater increase in leaf Al but a decrease in leaf S compared with conservative species. Synthesis. We show that soil elements uptake differs between acquisitive and conservative species and that acquisitive species may not take up soil elemental resources more effectively than conservative species. We suggest that the greater Fe acquisition by conservative species, in comparison to acquisitive species, might be due to a stress tolerance strategy. The overall increase in leaf N showed that, in this nutrient-poor forest, N is a fundamental requirement irrespective of species functional strategies. Given the increased leaf Al and Fe concentration after liming, we also suggest that these elements are important, and possibly limiting (Fe), in this heath forest

Assessment of human exposure to food crops contaminated with lead and cadmium in Owerri, South-eastern Nigeria

Background: Food safety and security have remained an emerging global challenge amidst increasing human activities that potentially contaminate the food chain. With the rapid population growth, urbanisation and unrestrained emission of toxic substances, urban-dwelling Nigerians are particularly vulnerable to consuming contaminated food crops. Materials and method: This study presents a framework for critical analysis of human exposure patterns to potentially contaminated food crops using the city of Owerri (Nigeria) as case study. It systematically assessed the metal burden of soil and staple food crops and the potential health risk associated with dietary exposure of humans to contaminated food crops. Samples of soil, cassava (Manihot esculenta) tubers and fluted pumpkin (Telfairia occidentalis) leaves were collected from household gardens and analysed for concentration of selected metals (Al, As, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb and Zn) using ICP-OES. A risk assessment of human exposure to Pb contamination using both the Target Hazard Quotient (THQ) and Hazard Index (HI) was estimated. Results: The majority of metals measured below the respective health-based maximum concentration limits of the Nigerian Department of Petroleum Resources target value, except for Pb in soil, which was above the limit of 85 µg g−1 in 0.9 % of sampled soils. However, Pb measured above the threshold of 0.3 µg g−1 stipulated by the FAO/WHO Codex Alimentarius in 46 % of sampled pumpkin leaves with no correlation established with soil Pb concentrations. This suggests possible Pb contamination via atmospheric deposition, and that human ingestion of pumpkin leaves presents the greatest health risks. Conclusion: The findings revealed that children and toddlers are more prone to Pb contamination via food crop ingestion than adults based on the THQ and HI evaluations; hence need for relevant policies to ensure food safety. This study provides background data for epidemiological investigation of relationships between contaminated food crop ingestion and blood Pb

Plant community composition and carbon stocks of a community reserve forest in north-east India

Anthropogenic activities are altering the structure and functioning of forests and their services to society. However, we know little about the degree to which such activities are changing the health of forests through edge effects in fragmented forests in different regions of the world. The present study was carried out in Minkong Community Reserve Forest of Nagaland (North-east India) with the aim to determine the effects of anthropogenic activities on floristic composition and diversity, population structure, and biomass and carbon (C) stocks in the core zone (CZ) and buffer zone (BZ) of the forest. We established 15 plots of 0.04 ha each in the two forest zones. We identified 31 trees, 18 shrubs, and 22 herbs in the CZ, and 22 trees, 25 shrubs, and 24 herbs in the BZ; tree species diversity was greater in the CZ whereas the diversity of shrubs and herbs was greater in the BZ. The values for tree density and basal area in the CZ and BZ were 303 and 197 individuals ha−1 and 32.6 and 22.2 m2 ha−1, respectively; in contrast, the shrub and herb density increased in the BZ (4470 and 50,200 individuals ha−1) compared to that of the CZ (2530 and 35,500 individuals ha−1). The total stand biomass (including that below-ground) was 327 Mg ha−1 in the CZ and 224 Mg ha−1 in the BZ. Similarly, the total ecosystem C stocks in the CZ and BZ were 224 Mg C ha−1 and 173 Mg C ha−1, indicating that the overall ecosystem C pool including soil in the CZ was approximately 30% greater than the BZ. These results show how fragmentation and anthropogenic disturbance can reduce forest diversity and C stocks and that community forest management can play a role in conserving biodiversity and act as an ecosystem management tool to mitigate climate change