Roosting ecology of endangered plant‐roosting bats on Okinawa Island: Implications for bat‐friendly forestry practices

Roosting information is crucial to guiding bat conservation and bat-friendly forestry practices. The Ryukyu tube-nosed bat Murina ryukyuana (Endangered) and Yanbaru whiskered bat Myotis yanbarensis (Critically Endangered) are forest-dwelling bats endemic to the central Ryukyu Archipelago, Japan. Despite their threatened status, little is known about the roosting ecology of these species and the characteristics of natural maternity roosts are unknown. To inform sustainable forestry practices and conservation management, we radio-tracked day roosts of both species in the subtropical forests of Okinawa's Kunigami Village District. We compared roost and roost site characteristics statistically between M. ryukyuana nonmaternity roosts (males or nonreproductive females), maternity roosts, and all M. yanbarensis roosts. Generalized linear models were used to investigate roost site selection by M. ryukyuana irrespective of sex and age class. Lastly, we compiled data on phenology from this and prior studies. Nonreproductive M. ryukyuana roosted alone and primarily in understory foliage. Murina ryukyuana maternity roosts were limited to stands >50 years old, and ~60% were in foliage. Myotis yanbarensis roosted almost entirely in cavities along gulch bottoms and only in stands >70 years old (~1/3 of Kunigami's total forest area). Murina ryukyuana maternity roosts were higher (4.3 ± 0.6 m) than conspecific nonmaternity roosts (2.3 ± 0.5 m; p <.001) and M. yanbarensis roosts (2.7 ± 0.5 m; not significant). Model results were inconclusive. Both species appear to be obligate plant roosters throughout their life cycle, but the less flexible roosting preferences of M. yanbarensis may explain its striking rarity. To conserve these threatened bats, we recommend the following forestry practices: (a) reduce clearing of understory vegetation, (b) refrain from removing trees along streams, (c) promote greater tree cavity densities by protecting old-growth forests and retaining snags, and (d) refrain from removing trees or understory between April and July, while bats are pupping.コウモリのねぐらに関する生態学的な情報はコウモリの保全とそれを考慮する森林の施業のために重要である。リュウキュウテングコウモリMurina ryukyuana（絶滅危惧）とヤンバルホオヒゲコウモリMyotis yanbarensis（絶滅寸前）は森林性コウモリで、日本の琉球列島中部における固有種である。絶滅の恐れがある種にもかかわらず、これらの種のねぐらに関する生態については情報が不足しており、自然条件下における母子集団のねぐらの特徴は明らかになっていない。持続可能な森林施業と保全に関わる情報を提供するために、沖縄島国頭村における亜熱帯林で両種の昼間のねぐらの場所や特徴を、ラジオテレメトリー法によって個体を追跡することによって調査した。リュウキュウテングコウモリの非母子集団ねぐら（雄または非繁殖雌）、母子集団ねぐら、及び全てのヤンバルホオヒゲコウモリのねぐらの間で、ねぐらとねぐらの場所の特徴を統計的に比較した。一般化線形モデルを用いて、性別や年齢階級を考慮しない条件でリュウキュウテングコウモリによるねぐら場所の選好性を調査した。最後に、本研究と先行研究から、ねぐらに関わるフェノロジーに関するデータを収集・整理した。非生殖のリュウキュウテングコウモリは単独で、主に下層植生の葉をねぐらとして利用した。リュウキュウテングコウモリの母子集団のねぐらとしての利用は林齢50年以上の林分に限定され、約60％が葉であった。ヤンバルホオヒゲコウモリはほぼ完全に谷底の樹洞をねぐらとして利用し、ねぐらの形成は林齢70年以上の林分に限られていた（国頭村における森林面積の約1／3）。リュウキュウテングコウモリの母子集団ねぐらは同種の非母子集団ねぐら（2.3 ± 0.5 m; p < .001）とヤンバルホオヒゲコウモリのねぐら（2.7 ± 0.5 m; not significant）より高い位置にあった（4.3 ± 0.6 m）。モデルによる推定結果は決定的ではなかった。両種はライフサイクルの間ずっと偏性的な植物性コウモリであるようだが、ヤンバルホオヒゲコウモリの選好は柔軟性が低く、このことが本種の際だった希少性を説明する可能性がある。これらの絶滅危惧種であるコウモリを保全するためには、以下の森林施業が提案できる：（a）下層植生の除去を少なくすること、（b）渓流沿いの樹木の伐採を控えること、（c）高林齢の森林を保存し、枯死木も除去せず、樹洞の密度を確保すること、（d）コウモリが子育てしている時期である4月〜7月の間に、樹木と下層植生の除去を控えることである

Nitrogen and oxygen isotope measurements of nitrate to survey the sources and transformation of nitrogen loads in rivers

This paper reviews the studies on evaluation of river environments in terms of water pollution, ecosystem disturbances, excess nutrient (nitrogen) loads, and developments in the isotopic measurements of nitrate and present an update and future perspectives regarding the application of nitrate isotopes to river nutrient assessments. Then, we present the advantages of simultaneous measurement of the nitrogen and oxygen isotopes of nitrate in streamwaters.Dual isotope measurement has recently been used to identify the sources and paths of nitrogen loading in several stream systems. The most recently developed high-resolution denitrifier method is a promising tool with which to investigate the detailed spatial and temporal variation and mechanisms of nitrogen loading and transformation in rivers

Transformation as Praxis: Responding to Climate Change Uncertainties in Marginal Environments in South Asia

This paper provides some of the conceptual and methodological underpinnings being developed in the ongoing TAPESTRY project which is part of the Transformations to Sustainability (T2S) Programme. We debate how the notion of transformation may be conceptualized from ‘below’ in marginal environments that are especially marked by high levels of climate-related uncertainties. We propose the notion of transformation as praxis — where the focus is on bottom-up change, identities, wellbeing and the recovery of agency by marginalized people and explore how ‘patches’ and the ‘marginal’ offer critical conceptual templates to examine whether and how systemic transformative changes are being assembled and effected on the ground by hybrid and transformative alliances. The article concludes by discussing potential challenges of such engagements, alongside pursuing a normative and political approach to T2S

Striped catfish (Pangasianodon hypophthalmus) exploit food sources across anaerobic decomposition- and primary photosynthetic production-based food chains

Dietary information from aquatic organisms is instrumental in predicting biological interactions and understanding ecosystem functionality. In freshwater habitats, generalist fish species can access a diverse array of food sources from multiple food chains. These may include primary photosynthetic production and detritus derived from both oxic and anoxic decomposition. However, the exploitation of anoxic decomposition products by fish remains insufficiently explored. This study examines feeding habits of striped catfish (Pangasianodon hypophthalmus) at both adult and juvenile stages within a tropical reservoir, using stable carbon, nitrogen, and sulfur isotope ratios (δ¹³C, δ¹⁵N, and δ³⁴S, respectively) and fatty acid (FA) analyses. The adult catfish exhibited higher δ¹⁵N values compared to primary consumers that feed on primary photosynthetic producers, which suggests ingestion of food sources originating from primary photosynthetic production-based food chains. On the other hand, juvenile catfish demonstrated lower δ¹⁵N values than primary consumers, correlating with low δ³⁴S value and large proportions of bacterial FA but contained small proportions of polyunsaturated FA. This implies that juveniles utilize food sources from both anoxic decomposition and primary photosynthetic production-based food chains. Our results indicate that food chains based on anoxic decomposition can indeed contribute to the dietary sources of tropical fish species

MULTI-PARAMETER SENSITIVITY ANALYSIS AND OPTIMIZATION OF THE ALPINE HYDROCHEMICAL MODEL

The University of Arizona's Alpine Hydrochemical Model (AHM) is an integrated set of algorithms for water and chemical balances that describes hydrologic and chemical processes in a headwater catchment. We developed AHM for use both as a research tool and as a predictive model for estimating effects of natural and anthropogenic changes in climate or in atmospheric -pollutant loading on alpine watersheds. We initially applied AHM to Emerald Lake watershed in the southern Sierra Nevada, and estimated model parameters by trial and error using a single water year of data and process -level studies. Using the same parameters, AHM successfully reproduced stream chemistry and discharge for a second water year. We have extended that empirical analysis by doing a systematic analysis of parameter sensitivity and an automatic optimization of model parameters. In the sensitivity analysis, a large number of Monte -Carlo simulations done on the multi -dimensional function field were used to identify the sensitive parameters and to set an appropriate range for each parameter. These results were then used to reduce the computational load in the automatic optimization, which is based on the downhill simplex method in multiple dimensions; we estimate the global optimum parameter set according to the fluctuation of the sum of squared errors between observed and modeled stream discharge and chemistry. Sensitive physical and chemical parameters were identified, including those describing evapotranspiration, hydraulic conductivity and soil depth or porosity; and those describing mineral weathering, ion release from the snow - pack, ion exchange, soil CO2 and nitrogen reactions. The automatic optimization method succeeded in estimating a global optimum parameter set from a single water year of data that improved the fitting compared to the set from trial and error manipulation.Partial support for this work was provided through a grant from the U.S. National Aeronautics and Space Administration's Earth Observing System program. V. Gupta provided helpful comments on setting up the optimization procedure. R. Brice assisted in manuscript preparation.This title from the Hydrology & Water Resources Technical Reports collection is made available by the Department of Hydrology & Atmospheric Sciences and the University Libraries, University of Arizona. If you have questions about titles in this collection, please contact [email protected]