Conceptualising the Global Forest Response to Liana Proliferation

Lianas are woody vines, rooted in the soil, and supported physically by trees. Lianas contribute to forest ecosystem functioning globally, but especially in the tropics and subtropics. However, prolific liana growth following heavy disturbance frequently affects subsequent recovery of forest tree diversity, biomass, structure, and function. Understanding this forest liana dynamic, and its sensitivity to climate and anthropogenic forces, is essential for worldwide forest restoration and climate change mitigation. Here, we synthesise the evidence for both positive and negative effects of lianas on forests and propose a framework that outlines the expected global response of forests to disturbance-induced liana proliferation. Emerging evidence suggests that lianas play a major role in both facilitating and delaying forest recovery following disturbance. At low levels of disturbance and/or where environmental conditions favour tree growth, lianas can facilitate forest recovery by protecting trees from extreme weather, fire, weed invasion and herbivory. However, under conditions where lianas proliferate beyond critical thresholds, positive feedbacks are expected to induce and sustain liana-dominated forest states that can endure for decades or even longer. We conceptualise alternative classes of forest recovery response to disturbance and describe measurement and modelling of liana thresholds.We identify four essential challenges for global change science relating to lianas: (1) incorporation of lianas and sapling stems into forest monitoring and tree stand measurements worldwide; (2) long-term experiments to determine variation in liana-tree competition, and potential drivers across forest successional gradients; (3) identification and prediction of liana thresholds and other alternative forest recovery response classes; and (4) dynamicmechanisticmodelling of forest recovery to determine regional and global variation within and among different recovery response classes, in relation to variation in potential drivers, liana feedbacks and their interactions. Addressing these challenges will determine the importance of lianas in shaping regional and global forest composition, recovery and dynamics

Allometric models for liana aboveground biomass in old-growth and secondary tropical forests of Tanzania

\ua9 2024 The AuthorsLianas are common in tropical forests, where they influence forest dynamics, thus impacting the global carbon sink, with implications for climate change mitigation. Despite their increasing competitiveness with trees at the global scale, robust measurements of liana aboveground biomass (AGB) have been limited. Here we use data from destructive sampling to develop two separate allometric equations for estimating liana AGB from stem diameter in old-growth (n = 15 lianas) and secondary forests (n = 22 lianas). We compared estimates of AGB using our equations for 3141 lianas (≥ 1 cm diameter) in Tanzania\u27s Kilombero Valley against estimates from previously published equations in other tropical regions. Our equations demonstrated stronger correlations between diameter and destructively measured AGB, than those from previously published equations (R2 = 0.86–0.89, versus R2 = 0.82–0.88). Across all stems, the average stem-level liana AGB estimated using the equation for old-growth forests was 52 % higher than that estimated by the equation for secondary forests, showing that lianas have lower biomass per unit diameter in forests impacted by disturbance. In such forests, liana stems are damaged, deformed, or cannot reach maximum height due to reduced structural support. At the scale of the forest stand, our equations estimated a mean liana AGB of 3.25 Mg ha−1 (95 % Confidence Interval: 1.52–6.96) in old-growth forests and 10.19 Mg ha−1 (5.91–17.64) in secondary forests. These estimates roughly aligned with estimates from other equations, although there was considerable variation. Depending on the equation used, mean stand-level estimates of liana AGB ranged from 2.49–9.76 Mg ha−1 in old-growth forests and 10.19–20.74 Mg ha−1 in secondary forests. Our findings show the variability in liana allometry and AGB with disturbance and successional stage, further underscoring a need for caution when comparing estimates of liana biomass across studies and regions

Inequitable Gains and Losses from Conservation in a Global Biodiversity Hotspot

A billion rural people live near tropical forests. Urban populations need them for water, energy and timber. Global society benefits from climate regulation and knowledge embodied in tropical biodiversity. Ecosystem service valuations can incentivise conservation, but determining costs and benefits across multiple stakeholders and interacting services is complex and rarely attempted. We report on a 10-year study, unprecedented in detail and scope, to determine the monetary value implications of conserving forests and woodlands in Tanzania’s Eastern Arc Mountains. Across plausible ranges of carbon price, agricultural yield and discount rate, conservation delivers net global benefits (+US$8.2B present value, 20-year central estimate). Crucially, however, net outcomes diverge widely across stakeholder groups. International stakeholders gain most from conservation (+US$10.1B), while local-rural communities bear substantial net costs (-US$1.9B), with greater inequities for more biologically important forests. Other Tanzanian stakeholders experience conflicting incentives: tourism, drinking water and climate regulation encourage conservation (+US$72M); logging, fuelwood and management costs encourage depletion (-US$148M). Substantial global investment in disaggregating and mitigating local costs (e.g., through boosting smallholder yields) is essential to equitably balance conservation and development objectives

Descripción de cuatro nuevas especies de Monodora e Isolona (Annonaceae) de Tanzania y una descripción general de la diversidad de Annonaceae de Tanzania

Se describen e ilustran cuatro nuevas especies de Annonaceae de Tanzania: Monodora carolinae, de la costa de Tanzania y el norte de Mozambique, con pétalos exteriores reflejos y pétalos internos que se conjugan por sus puntas; M. globiflora, endémica de los bosques montanos de las montañas de Udzungwa, con pétalos internos en total connivencia como un globo sobre el receptáculo; M. hastipetala, endémica del bosque de Kiwengoma (Matumbi Hills), con pétalos internos hastados y acuminados en los ápices; e Isolona linearis, endémica de la región de Iringa, con lóbulos de corola lineales. Se proporcionan claves para todas las especies de ambos géneros para África Oriental. La morfología del polen y la estructura del tectum están indicadas para cada nueva especie, y se discuten las tendencias evolutivas de Isolona. Finalmente, se ofrece una descripción general de las Annonaceae de Tanzania, con una lista de verificación de especies y mapas de distribución de especies y géneros, basado en datos recopilados de la literatura y las bases de datos de herbario MO y WAG. La mayor parte de la biodiversidad de las Annonaceae se limita al Arco Oriental y los Bosques Costeros, lo que subraya una vez más la importancia de estas regiones en peligro de extinción.Four new species of Annonaceae from Tanzania are described and illustrated: Monodora carolinae, from coastal Tanzania and northern Mozambique, with refl exed outer petals and inner petals connivent by their tips; M. globifl ora, endemic to the montane forests of the Udzungwa Mountains, with inner pet- als fully connivent as a globe over the receptacle; M. hastipetala, endemic to the Kiwengoma Forest (Matumbi Hills), with hastate inner petals acuminate at apices; and Isolona linearis, endemic to Iringa region, with linear corolla lobes. Keys are provided to all species of both genera for East Africa. PollenDescription de quatre nouvelles espèces de Monodora et Isolona (Annonaceae) de Tanzanie, et aperçu de la diversité des Annonaceae tanzaniennes. Quatre nouvelles espèces d’Annonaceae sont décrites et illustrées : Monodora carolinae, distribuée dans les forêts côtières de la Tanzanie et au nord du Mozambique, avec les pétales externes réfl échis et les internes connivents par leurs extrémités ; M. globifl ora, endémique des forêts montagneuses du Udzungwa, à pétales internes totalement connivents et formant un globe au-dessus du réceptacle ; M. hastipetala, endémique de la forêt de Kiwengoma (Matumbi Hills), à pétales internes hastés et acuminés au sommet ; et enfi n Isolona linearis, endémique de la région d’Iringa, avec les lobes de la corolle linéaires. Des clés de détermination sont données pour toutes les espèces de Monodora et Isolona croissant en Afrique orientale. Une étude palynologique de ces nouvelles espèces est présentée avec une discussion sur l’évolution d’Isolona. Un aperçu des Annonaceae de Tanzanie est donné ainsi qu’une liste exhaustive des espèces reconnues pour le pays. Des cartes de distribution aux niveaux spécifi que et générique ont été générées grâce à des données rassemblées dans la littérature et des bases de données des herbiers MO et WAG. Les « Eastern Arc » et « Coastal Forests » de la Tanzanie présentent la plus grande concentration d’espèces d’Annonaceae, ce qui souligne une fois encore l’importance de ces régions grandement menacées.

Descripción de cuatro nuevas especies de Monodora e Isolona (Annonaceae) de Tanzania y una descripción general de la diversidad de Annonaceae de Tanzania

Se describen e ilustran cuatro nuevas especies de Annonaceae de Tanzania: Monodora carolinae, de la costa de Tanzania y el norte de Mozambique, con pétalos exteriores reflejos y pétalos internos que se conjugan por sus puntas; M. globiflora, endémica de los bosques montanos de las montañas de Udzungwa, con pétalos internos en total connivencia como un globo sobre el receptáculo; M. hastipetala, endémica del bosque de Kiwengoma (Matumbi Hills), con pétalos internos hastados y acuminados en los ápices; e Isolona linearis, endémica de la región de Iringa, con lóbulos de corola lineales. Se proporcionan claves para todas las especies de ambos géneros para África Oriental. La morfología del polen y la estructura del tectum están indicadas para cada nueva especie, y se discuten las tendencias evolutivas de Isolona. Finalmente, se ofrece una descripción general de las Annonaceae de Tanzania, con una lista de verificación de especies y mapas de distribución de especies y géneros, basado en datos recopilados de la literatura y las bases de datos de herbario MO y WAG. La mayor parte de la biodiversidad de las Annonaceae se limita al Arco Oriental y los Bosques Costeros, lo que subraya una vez más la importancia de estas regiones en peligro de extinción.Four new species of Annonaceae from Tanzania are described and illustrated: Monodora carolinae, from coastal Tanzania and northern Mozambique, with refl exed outer petals and inner petals connivent by their tips; M. globifl ora, endemic to the montane forests of the Udzungwa Mountains, with inner pet- als fully connivent as a globe over the receptacle; M. hastipetala, endemic to the Kiwengoma Forest (Matumbi Hills), with hastate inner petals acuminate at apices; and Isolona linearis, endemic to Iringa region, with linear corolla lobes. Keys are provided to all species of both genera for East Africa. PollenDescription de quatre nouvelles espèces de Monodora et Isolona (Annonaceae) de Tanzanie, et aperçu de la diversité des Annonaceae tanzaniennes. Quatre nouvelles espèces d’Annonaceae sont décrites et illustrées : Monodora carolinae, distribuée dans les forêts côtières de la Tanzanie et au nord du Mozambique, avec les pétales externes réfl échis et les internes connivents par leurs extrémités ; M. globifl ora, endémique des forêts montagneuses du Udzungwa, à pétales internes totalement connivents et formant un globe au-dessus du réceptacle ; M. hastipetala, endémique de la forêt de Kiwengoma (Matumbi Hills), à pétales internes hastés et acuminés au sommet ; et enfi n Isolona linearis, endémique de la région d’Iringa, avec les lobes de la corolle linéaires. Des clés de détermination sont données pour toutes les espèces de Monodora et Isolona croissant en Afrique orientale. Une étude palynologique de ces nouvelles espèces est présentée avec une discussion sur l’évolution d’Isolona. Un aperçu des Annonaceae de Tanzanie est donné ainsi qu’une liste exhaustive des espèces reconnues pour le pays. Des cartes de distribution aux niveaux spécifi que et générique ont été générées grâce à des données rassemblées dans la littérature et des bases de données des herbiers MO et WAG. Les « Eastern Arc » et « Coastal Forests » de la Tanzanie présentent la plus grande concentration d’espèces d’Annonaceae, ce qui souligne une fois encore l’importance de ces régions grandement menacées.

Modulation of hippocampal synaptic transmission by the kynurenine pathway member xanthurenic acid and other VGLUT inhibitors

Xanthurenic acid (XA), an endogenous kynurenine, is a known vesicular glutamate transport (VGLUT) inhibitor and has also been proposed as an mGlu2/3 receptor agonist. Changes in these systems have been implicated in the pathophysiology of schizophrenia and other psychiatric disorders; however, little is known of how XA affects synaptic transmission. We therefore investigated the effects of XA on synaptic transmission at two hippocampal glutamatergic pathways and evaluated the ability of XA to bind to mGlu2/3 receptors. Field excitatory postsynaptic potentials (fEPSPs) were recorded from either the dentate gyrus (DG) or CA1 region of mouse hippocampal slices in vitro. Addition of XA to the bathing medium (1–10 mM) resulted in a dose-related reduction of fEPSP amplitudes (up to 52% reduction) in both hippocampal regions. In the DG, the VGLUT inhibitors Congo Red and Rose Bengal, and the mGlu2/3 agonist LY354740, also reduced fEPSPs (up to 80% reduction). The mGlu2/3 antagonist LY341495 reversed the LY354740 effect, but not the XA effect. LY354740, but not XA, also reduced DG paired-pulse depression. XA had no effect on specific binding of 1 nM [3H]LY341495 to membranes with human mGlu2 receptors. We conclude that XA can modulate synaptic transmission via a mechanism that may involve VGLUT inhibition rather than activation of mGlu2/3 receptors. This could be important in the pathophysiology of nervous system disorders including schizophrenia and might represent a target for developing novel pharmacological therapies

Pharmacological and Anatomical Evidence for an Interaction Between mGluR5- and GABAA α1-Containing Receptors in the Discriminative Stimulus Effects of Ethanol

The discriminative stimulus properties of ethanol are mediated in part by positive modulation of GABA(A) receptors. Recent evidence indicates that metabotropic glutamate receptor subtype 5 (mGluR5) activity can influence GABA(A) receptor function. Therefore, the purpose of this work was to examine the potential involvement of mGluR5 in the discriminative stimulus effects of ethanol. In rats trained to discriminate ethanol (1 g/kg, intragastric gavage (i.g.)) from water, 2-methyl-6-(phenylethyl)-pyridine (MPEP) (1–50 mg/kg, i.p.) a selective noncompetitive antagonist of the mGlu5 receptor did not produce ethanol-like stimulus properties. However, pretreatment with MPEP (30 mg/kg) reduced the stimulus properties of ethanol as indicated by significant reductions in ethanol-appropriate responding, specifically at 0.5 and 1 g/kg ethanol, and a failure of ethanol test doses (1 and 2 g/kg) to fully substitute for the ethanol training dose. To test whether mGluR5 antagonism altered the GABA(A) receptor component of the ethanol stimulus, the ability of MPEP to modulate pentobarbital and diazepam substitution for ethanol was assessed. Pentobarbital substitution (1–10 mg/kg, i.p.) for ethanol was not altered by MPEP pretreatment. However, MPEP pretreatment inhibited the ethanol-like stimulus properties of diazepam (5 mg/kg, i.p.). To examine a potential anatomical basis for these pharmacological findings, expression patterns of mGluR5- and benzodiazepine-sensitive GABA(A) α1-containing receptors were examined by dual-label fluorescent immunohistochemistry with visualization by confocal microscopy. Results indicated that mGluR5- and GABA(A) α1-containing receptors were both coexpressed in limbic brain regions and colocalized on the same cells in specific brain regions including the amygdala, hippocampus, globus pallidus, and ventral pallidum. Together, these findings suggest an interaction between mGluR5- and benzodiazepine-sensitive GABA(A) receptors in mediating ethanol discrimination