Jonathan A. Moran

Pitcher Dimorphism, Prey Composition and the Mechanisms of Prey Attraction in the Pitcher Plant Nepenthes Rafflesiana in Borneo

1 The pitcher plant Nepenthes rafflesiana Jack produces dimorphic pitcher types. Upper pitchers catch more flying prey than lower pitchers. The most important single prey group in both pitcher forms was Formicidae. 2 Both pitcher forms possess ultraviolet (UV) patterns which were associated with the site of the major nectaries, causing it to stand out in contrast to the adjacent area. Manipulation of these patterns in upper pitchers confirmed their role in the attraction of prey. 3 Upper pitchers produce a fragrance which is attractive to flying prey. The combination of visual and olfactory cues accounted for the greater prey attraction of upper over lower pitchers. This is confirmed by the pitchers of N. rafflesiana var. elongata, which possess neither UV patterns nor fragrance, and catch significantly less prey than the typical form. 4 Lower pitchers resting at ground level, where densities of potential invertebrate prey are highest, are less than optimally attractive. This may reduce the amount of prey caught, thus preventing overloading and consequent putrefaction of the contents, and death of the pitchers.

Tree shrew lavatories: a novel nitrogen sequestration strategy in a tropical pitcher plant

Nepenthes pitcher plants are typically carnivorous, producing pitchers with varying combinations of epicuticular wax crystals, viscoelastic fluids and slippery peristomes to trap arthropod prey, especially ants. However, ant densities are low in tropical montane habitats, thereby limiting the potential benefits of the carnivorous syndrome. Nepenthes lowii, a montane species from Borneo, produces two types of pitchers that differ greatly in form and function. Pitchers produced by immature plants conform to the ‘typical’ Nepenthes pattern, catching arthropod prey. However, pitchers produced by mature N. lowii plants lack the features associated with carnivory and are instead visited by tree shrews, which defaecate into them after feeding on exudates that accumulate on the pitcher lid. We tested the hypothesis that tree shrew faeces represent a significant nitrogen (N) source for N. lowii, finding that it accounts for between 57 and 100 per cent of foliar N in mature N. lowii plants. Thus, N. lowii employs a diversified N sequestration strategy, gaining access to a N source that is not available to sympatric congeners. The interaction between N. lowii and tree shrews appears to be a mutualism based on the exchange of food sources that are scarce in their montane habitat.

Biomass relationships for tree species in regenerating semi-deciduous tropical moist forest in Cameroon

Abstract To enable carbon accumulation in regenerating tropical forest to be assessed, regression equations which permit the estimation of above and below ground biomass from measurements of stem diameter (D) and height (H) were derived from destructive harvests and dimensions of 14 trees distributed among five species in the moist tropical forest zone of Cameroon. Coarse root biomass (over 10 mm diameter) was assessed by complete excavation and fine root biomass (10 mm or less in diameter) by coring. Tree biomass (above and below ground) was linearly related to D2H and to cross-sectional area of the stem. Above ground biomass estimates predicted by the equations developed in this study were smaller than those predicted by published multi-species equations. However, adjusting the estimates to take account of differences in timber density, brought the predictions closer to those from existing equations. Root biomass found in this study was larger than in previous work. The root: shoot ratio was significantly (P Root shoot =0.223+0.0199× 2 h where D is stem diameter at breast height (m) and H is tree height (m). The mean root/shoot ratio based on this study and recalculation of other published studies from moist tropical forests was about 0.25. Fine root amounts increased as forests aged from less than 1 year to 30 years, but there were no significant differences in fine root biomass between forests aged 30 (about 9 t ha−1) and mature forest. Branch surface area was positively correlated (r2 = 0.95) with leaf area.

From Carnivore to Detritivore? Isotopic Evidence for Leaf Litter Utilization by the Tropical Pitcher Plant Nepenthes ampullaria

Nepenthes pitcher plants trap prey in specialized leaves formed into pitchers. Most lowland species live in open, sunny habitats and capture prey to obtain nutrients, principally nitrogen (N). Nepenthes ampullaria is commonly found under closed canopy forest and possesses morphological traits that indicate adaptation to trap leaf litter as a nutrient source. We tested this hypothesis by comparing foliar stable N isotope abundance (δ15N) between plants growing under forest canopy at 20 sites (litterfall present) and those growing in 20 open areas (no litterfall) in Borneo. Foliar δ15N values were significantly lower and total N concentrations were higher for the plants with access to litterfall. Using a mixing model, we estimated that N. ampullaria plants growing under forest canopy derived \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

The carnivorous syndrome in Nepenthes pitcher plants: Current state of knowledge and potential future directions

35.7\% \pm 0.1\%

A Carnivorous Plant Fed by Its Ant Symbiont: A Unique Multi-Faceted Nutritional Mutualism

\end{document} of their foliar N from leaf litter inputs.

Nepenthes baramensis (Nepenthaceae) – a new species from north-western Borneo

Pitcher plants of the genus Nepenthes trap invertebrate prey in pitchers formed from modified leaf tips. This study investigates the benefits of carnivory to Nepenthes rafflesiana, a common Bornean lowland species. Plants were denied prey capture in their natural habitat for 18 wk and were compared with a control group that was allowed to trap, digest, and assimilate prey as usual over the same period. Resource limitation was demonstrated in prey‐deprived plants, which produced significantly fewer and smaller pitchers than did control plants. Analysis of foliar spectral reflectance showed increased reflectance within part (608–738 nm) of the photosynthetically active wave band in the prey‐deprived plants, signifying a reduction in chlorophyll content. Decreased reflectance at 550 nm in the prey‐deprived plants also indicated increased production of anthocyanins, denoting possible nitrogen or phosphorus limitation. Although no difference was found in tissue concentrations of nitrogen or phosphorus between treatments, vector analysis identified a reduction in content of both elements as a result of reduced biomass production in prey‐deprived plants. Our findings demonstrate the key role carnivory plays in the nutrition of this species in its natural habitat.

Incorporating ecological context: a revised protocol for the preservation of Nepenthes pitcher plant specimens (Nepenthaceae)

Nepenthes is the largest genus of pitcher plants, with its centre of diversity in SE Asia. The plants grow in substrates that are deficient in N and offset this deficiency by trapping animal prey, primarily arthropods. Recent research has provided new insights into the function of the pitchers, particularly with regard to prey tapping and retention. Species examined to date use combinations of wettable peristomes, wax layers and viscoelastic fluid to trap and retain prey. In many respects, this has redefined our understanding of the functioning of Nepenthes pitchers. In addition, recent research has shown that several Nepenthes species target specific groups of prey animals, or are even evolving away from a strictly carnivorous mode of operation. Future research into nutrient sequestration strategies and mechanisms of prey attraction would no doubt further enhance our knowledge of the ecology of this remarkable genus.