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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Ontology-Guided Domain Entity Recognition in Environmental Texts: Evaluating Syntax-Driven and LLM Approaches Using BabelNet and GEMET</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Elisa Chierchiello</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Patricia Chiril</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Adriana Pagano</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Universidade Federal de Minas Gerais</institution>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Università degli Studi di Torino</institution>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>University of Chicago</institution>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2025</year>
      </pub-date>
      <abstract>
        <p>This paper investigates the identification and ontological classification of domain-specific entities to enable large-scale analysis of environmental discourse. While general-purpose Named Entity Recognition (NER) systems reliably detect standard categories such as persons, organizations, and locations, specialized domains like environmental communication require the recognition of additional, domain-relevant entities. These entities, often realized as common nouns, represent abstract, evolving concepts that are highly dependent on context and vary across languages. To address this challenge, we compare two pipelines for identifying domain-specific environmental entities in a bilingual corpus of WWF Living Planet Reports: (i) a traditional NLP pipeline that extracts noun phrases using dependency syntax parsing and matches them to BabelNet and GEMET, and (ii) a Large Language Model (LLM)-based pipeline that uses prompt-based instructions to both extract noun phrases and generate corresponding ontology matches. We evaluate the coverage of each approach and analyze the most frequent mapped entities to identify key environmental concepts emphasized in WWF discourse. To further assess the capabilities of LLMs in ontology-based annotation, we also prompted the LLM to generate GEMET-style definitions for phrases not found in the ontology. Our findings contribute practical insights for developing robust, ontology-enriched methods for environmental discourse analysis and knowledge extraction. Though tested on environmental texts, the framework can generalize to other domains via suitable ontologies and extraction rules.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;environmental discourse analysis</kwd>
        <kwd>domain entity recognition</kwd>
        <kwd>dependency syntax</kwd>
        <kwd>Large Language Models (LLMs)</kwd>
        <kwd>ontology mapping</kwd>
        <kwd>BabelNet</kwd>
        <kwd>GEMET</kwd>
        <kwd>cross-linguistic annotation</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>CLiC-it 2025: Eleventh Italian Conference on Computational
Linguistics, September 24 — 26, 2025, Cagliari, Italy
* Corresponding author.
† These authors contributed equally.
$ elisa.chierchiello@unito.it (E. Chierchiello);
pchiril@uchicago.edu (P. Chiril); apagano@ufmg.br (A. Pagano)
© 2025 Copyright for this paper by its authors. Use permitted under Creative Commons License adapted extensions show good performance to detect
Attribution 4.0 International (CC BY 4.0).</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related work</title>
      <p>domain mentions [3, 7, 8]. Hybrid architectures, such as
the Ontology-Attention Layer, demonstrate that coupling
LLMs with explicit ontology guidance further improves Generic NER has been extensively studied as a
foundaaccuracy in specialized contexts [9]. tional NLP task, with systems reliably detecting persons,</p>
      <p>Despite this progress, to the best of our knowledge, organizations, and locations [1, 2]. However, as Marrero
no study has systematically compared rule-based NLP et al. [4] and Zhang et al. [3] observe, such systems
perpipelines and LLM-based methods for domain entity form poorly when applied to specialized domains because
recognition in multilingual environmental discourse. Our domain-specific concepts are often expressed through
study addresses this gap by focusing exclusively on common noun phrases rather than proper names, and
domain-specific entities, with conventional named enti- thus lack the distinctive lexical or orthographic cues that
ties such as persons, organizations, and locations to be standard NER methods exploit.
examined in future work, and implementing two distinct To address these limitations, domain-specific NER has
pipelines for their identification and classification. by im- been pursued to handle technical and abstract
terminolplementing and comparing two pipelines on a bilingual ogy in specialized texts. In the biomedical field, for
incorpus of WWF Living Planet Report Executive Sum- stance, Zhang et al. [10] review biomedical entity
recogmaries (2014–2024). The first pipeline uses dependency nition as an example of domain-focused extraction,
highparsing to extract noun phrases and matches them to lighting the essential role of ontologies for semantic
preciBabelNet and GEMET using string-based similarity. The sion. In geosciences, Villacorta Chambi et al. [11] pursue
second pipeline uses a prompt-based LLM to both detect NER improvement through the use of specialized
geolognoun phrases and suggest ontology matches directly. We ical schemas.
then assess the coverage of each approach and qualita- Ontology-based approaches to domain-specific entity
tively examine the most frequent shared mapped entities recognition have been widely explored. García-Silva et
to highlight the core concepts that characterize WWF en- al. [5] proposed an ontology-based pipeline for
environvironmental discourse. To address these aims, this study mental data that uses dependency parsing to identify
investigates the following research questions: candidate terms and maps them to structured
environmental ontologies. Zhou and El-Gohary [6] developed
• How much coverage do a dependency syntax- a syntax-driven framework to extract provisions from
based pipeline and a prompt-based LLM pipeline environmental regulations and link them to a
complieach achieve when extracting and mapping noun ance ontology, demonstrating high precision for
domainphrases to BabelNet and GEMET in a bilingual specific phrases. Wei et al. [ 9] integrated an
ontologycorpus of WWF Living Planet Reports? attention mechanism within BERT to improve medical
• Which environmental concepts emerge as the entity recognition, while Dai et al. [12] emphasized the
most frequently mapped entities and what do combination of entity recognition and ontology linking
these frequent concepts reveal about thematic to build domain-specific knowledge graphs.
emphases in WWF environmental discourse? More recently, LLMs have emerged as powerful tools
for general and domain-specific entity recognition. These</p>
      <p>In order to answer these questions, we assess the two LLMs can complement ontology-based systems by
propipelines in terms of coverage — that is, the number viding contextual understanding for domain terms that
and proportion of extracted noun phrases that can be lack consistent surface forms.
mapped to domain concepts in BabelNet and GEMET — Cross-lingual and multilingual methods support
conand then examine the most frequently mapped entities sistent domain entity alignment across languages.
Navto highlight key environmental concepts emphasized in igli and Ponzetto [13] presented BabelNet, a
multilinWWF discourse. gual lexical network used for semantic linking. GEMET</p>
      <p>Finally, to explore how LLMs can contribute to ex- [14] serves as a domain-focused environmental thesaurus,
panding domain ontologies, we prompted the LLM to while Ryu et al. [15] and Zhao et al. [16] show how
generate GEMET-style definitions for entities that could such resources help maintain terminological coherence
not be matched in GEMET. in translation and cross-lingual NLP.</p>
      <p>By comparing these two pipelines, we highlight practi- A disciplinary field that directly benefits from precise
cal considerations for building ontology-based workflows domain entity recognition supported by
environmenfor semantic search and discourse analysis in environ- tal thesauri and ontologies is environmental discourse
mental texts. While applied here to environmental texts, analysis. Dryzek [17] and Doyle [18] examine how
lanthe general approach can be tested in other domains us- guage shapes environmental policy debates and public
ing suitable ontologies and tailored extraction strategies. narratives. Nerlich and Koteyko [19] explore competing
frames in climate change discourse, while recent
computational studies by Jørgensen et al. [20] and Chen et</p>
      <sec id="sec-2-1">
        <title>Drawing on the assumption that most entities are gram</title>
        <p>matically realized as noun phrases, we applied two
different methods to extract noun phrases from the corpus.
As described in the following sections, the first method
is rule-based and the second is LLM-based.
al. [21] apply NLP and machine learning to large-scale
climate communication data.</p>
        <p>The aforementioned studies demonstrate the benefits
of combining NLP methods with structured ontologies
for domain-specific entity recognition across multiple
domains. However, comparative studies on these methods
in the context of multilingual environmental discourse
remain limited. This work builds on these foundations to
advance ontology-enriched environmental text analysis.</p>
        <sec id="sec-2-1-1">
          <title>Rule-based Noun Phrase Extraction. We per</title>
          <p>
            formed rule-based noun phrase extraction relying
on annotations following the Universal
Dependen3. Methodology cies (UD) guidelines.2 Sentences were annotated
morphologically and syntactically using a
neuThis section introduces the corpus and outlines the two ral state-of-the-art dependency parser [23] using
methodological pipelines, which combine noun phrase the language models english-gum-ud-2.15 and
extraction with ontology mapping. italian-isdt-ud-2.15. For each sentence in
CoNLL-U format, we identified head tokens tagged
3.1. Corpus as NOUN or PROPN and expanded them by recursively
including adjectival modifiers ( amod), compounds
The corpus used in this study is the English and Italian (compound), and nominal modifiers ( nmod). The
subcorpus of the TreEn corpus [22], which compiles en- extraction algorithm builds each noun phrase starting
vironmental discourse from the 2014 to 2024 editions of from the head and prepending modifiers according to
the WWF Living Planet Report.1 WWF typically pub- their dependency links. The lemma column in each
lishes a suite of documents tailored to diferent audiences, CoNLL-U representation was used in order to reduce
including a full report (a comprehensive publication con- lexical variation and support downstream concept
taining detailed data, methodology, case studies, visual- mapping. For instance, from the sample sentence:
izations, and policy analysis) and an executive summary,
which distills the key findings and recommendations for (
            <xref ref-type="bibr" rid="ref1">1</xref>
            ) Adequate funding mechanisms are needed if
protecpolicymakers and stakeholders. It is important to note tive area management is to be efective.
that for the Italian subcorpus, we were only able to
locate full reports for the 2022 and 2024 editions, while for the extracted noun phrases are: Adequate funding
mechthe other years under analysis, only the executive sum- anisms and protective area management, which according
maries were available. As such, to ensure comparability, to the UD guidelines have the same internal structure
the English subcorpus is based on the same type of docu- and are represented as shown in Figure 1:
ment (i.e., full reports for 2022 and 2024, and executive
summaries for the remaining years).
          </p>
          <p>Both the English and the Italian texts were man- amodcompoundroot
ually cleaned to retain only the plain text, with all
non-textual content — such as images, captions, info- Adequate funding mechanisms
graphics, footnotes, and bibliographic references — sys- ADJ NOUN NOUN
tematically removed to support syntactic and
semantic annotation. For each English and Italian edition amod root
of the WWF Living Planet Report published between compound
2014 and 2024, we computed the number of sentences, protective area management
words, and lemmas using a custom Python pipeline ADJ NOUN NOUN
built with pandas and language-specific spaCy models
({en,it}_core_web_sm). Table 1 presents the result- Figure 1: Dependency syntax annotation for sample noun
ing counts across reporting years. phrases.</p>
        </sec>
        <sec id="sec-2-1-2">
          <title>LLM-based Noun Phrase Extraction. Our second</title>
          <p>method of noun phrase extraction employed GPT-o3.3</p>
        </sec>
      </sec>
      <sec id="sec-2-2">
        <title>1The timeframe (2014–2024) reflects the period for which we were</title>
        <p>able to retrieve the Italian editions of the report, starting from the
earliest available publication up to the most recent: https://www. 2https://universaldependencies.org/guidelines.html
wwf.it/cosa-facciamo/pubblicazioni/living-planet-report/ 3https://platform.openai.com/docs/models/o3
sentences
tokens
unique words
lemmas
avg. sentence length
2014
2016
2018
2020
2022
2024</p>
        <p>
          Specific prompts were iteratively developed for each lan- Translate,4 and then applied basic normalization (e.g.,
guage under analysis (i.e., Italian and English), with in- lowercasing, removal of diacritics) before comparing it to
structions highlighting syntactic constraints, lemmati- the set of Italian noun phrases extracted from the aligned
zation, and complete modifier preservation in order to sentence using the same syntactic rules. If a match was
ensure consistency with the rule-based noun phrase ex- found, the corresponding GEMET concept was propagated
traction method. Figure 4 (see Appendix A) presents the to the Italian sentence. For example, in the English
senEnglish prompt used for this task. tence:
(
          <xref ref-type="bibr" rid="ref2">2</xref>
          ) “Around the world, many languages are used to
communicate science.”
3.3. Ontology Mapping
        </p>
        <sec id="sec-2-2-1">
          <title>3.3.1. Ontology String Matching</title>
          <p>the noun phrases science and world were mapped to
Following the extraction of candidate noun phrases, we GEMET concepts. Their Italian equivalents, scienza and
performed concept-level mapping using two distinct on- mondo, appeared among the extracted noun phrases in
tologies: GEMET and BabelNet. The objective was to the aligned Italian sentence “In tutto il mondo si usano
link each phrase to an unique identifier representing an molte lingue per comunicare la scienza”. In this way, we
environmentally relevant concept within a structured could propagate the annotations to the Italian side, even
semantic resource. though the GEMET concept is originally linked to the
En</p>
          <p>Our multilingual setting required diferent strategies glish noun phrase.
for the two resources. For GEMET, which is primarily In contrast, BabelNet provides multilingual support
designed around English entries and ofers more lim- by design. Therefore, we queried noun phrases directly in
ited multilingual coverage, we relied on aligned sentence both English and Italian, allowing us to retrieve
languagepairs in English and Italian to propagate annotations. specific senses without relying on sentence alignment.
Specifically, we used an alignment file where each English This approach enabled broader coverage and avoided the
sentence was paired with its Italian equivalent. Once need for cross-lingual projection.</p>
          <p>GEMET concepts were identified in the English sentence,
we transferred them to the Italian version whenever the GEMET. We queried GEMET via its public REST API.5
same noun phrase (or a direct translation) was present. For each noun phrase, we attempted an exact string
This allowed us to enrich the Italian portion of the corpus match using the getConceptsMatchingKeyword
endeven when direct GEMET matches were not available in point. To maximize recall, we also applied fallback
strateItalian. To support this transfer, we first checked whether gies by decomposing multiword expressions and
querythe same noun phrase annotated in English occurred ver- ing each component token separately (e.g., climate
vulbatim in the aligned Italian sentence. If no exact match nerability → climate, vulnerability). Concept URIs
(Uniwas found, we used automatic translation to bridge the form Resource Identifier) returned from GEMET were
gap between the two languages. Specifically, we
translated the English noun phrase into Italian using Google
4https://cloud.google.com/translate/docs/reference/rest
5https://www.eionet.europa.eu/gemet/en/webservices/
stored along with the original phrase to support later
semantic grouping and analysis. In addition, we
retrieved the semantic group associated with each concept
using the getAllConceptRelatives endpoint (with
relation group), allowing us to categorize entities into
high-level thematic domains (e.g., BIOSPHERE, SOCIETY,
WASTES).</p>
          <p>Figure 2 shows the GEMET entry for climate change6and
all the fields we extract: concept URI, label, definition,
related terms, and group. These fields were stored to
facilitate both downstream semantic analysis and
explainability of the mappings.</p>
        </sec>
      </sec>
      <sec id="sec-2-3">
        <title>The extracted noun phrases are: scientist, Holocene, new</title>
        <p>geological epoch, Anthropocene. Figure 3 shows the
BabelNet entry for Anthropocene, highlighting the fields
we extract, namely, definition, categories, relations,
synonyms, and semantically related terms.</p>
      </sec>
      <sec id="sec-2-4">
        <title>BabelNet. In parallel, we integrated mappings from</title>
        <p>BabelNet. We accessed BabelNet via its getSenses
and getSynsetIds endpoints,7 querying each noun
phrase both in Italian and in English. This bilingual
querying strategy was adopted to maximize coverage and
mitigate cases where a concept might be present only
in one of the two languages. Unlike GEMET, BabelNet
returns disambiguated senses associated with synset
identifiers. We retained only senses with part-of-speech NOUN 3.3.2. LLM-based Ontology Mapping
and applied a filtering step to discard irrelevant or
ambiguous senses based on glosses and semantic domains. Our second method for performing the concept-level
In multiword expressions that failed to return a direct mapping of the extracted noun phrases relies on GPT-o3
match, we again decomposed the phrase into component through prompts with expected output. Upon extraction,
tokens and aggregated partial matches when available. a manual analysis of the concept-level mapping process
As an example, consider the following sentence: (cf. Table 2) revealed that several (multi-word) noun
phrases were not found in either GEMET or BabelNet.</p>
        <p>For example, in the following sentence:</p>
      </sec>
      <sec id="sec-2-5">
        <title>No GEMET concept was found matching any of these</title>
        <p>noun phrases, highlighting the wider lexical and
multilingual coverage of BabelNet. This example also
demonstrates the complementary nature of the two resources:
GEMET provides high precision within the environmental
domain, while BabelNet ensures broader recall across
a wider conceptual space.</p>
        <p>
          This dual mapping strategy enabled both
domainspecific grounding (via GEMET) and broader lexical
disambiguation (via BabelNet), intensifying the robustness of
concept alignment across heterogeneous texts.
(
          <xref ref-type="bibr" rid="ref3">3</xref>
          ) Scientists suggest that we have transitioned from the
Holocene into a new geological epoch, calling it the
’Anthropocene’.
        </p>
      </sec>
      <sec id="sec-2-6">
        <title>6http://www.eionet.europa.eu/gemet/concept/1471 7https://babelnet.org/guide</title>
        <p>
          (
          <xref ref-type="bibr" rid="ref4">4</xref>
          )
        </p>
        <p>We need nature positive by 2030 – which, in simple
terms, means more nature by the end of this decade
than at its start.</p>
        <p>
          To conduct a diachronic analysis of concepts mapped
with GEMET and BabelNet across the 2014–2024 corpus,
we identified concepts that appear in all WWF report
editions and analysed their frequency per report to gather
insights into the evolution of environmental discourse.
(
          <xref ref-type="bibr" rid="ref5">5</xref>
          ) At the Rio+20 conference in 2012, the world’s
governments afirmed their commitment to an “economically,
socially and environmentally sustainable future for
our planet and for present and future generations”.
3.4. Thematic analysis
nature positive is one of the noun phrases both syntac- “accesso a quantità senza precedente di dato da sensore su
tically and semantically relevant to environmental dis- satellite smartphone e dispositivo” 9 illustrate the model’s
course. While the phrase is made up of a NOUN and ADJ, tendency to extract the full extent of some noun phrases
it is used as a NOUN and has a distinct meaning in cur- which have several nested ones.
rent environmental discourse. Both the rule– and LLM- In terms of coverage, the Italian noun phrases extracted
based methods correctly identified nature positive as a using GPT-o3 show a notable increase in GEMET exact
noun phrase, and it was successfully matched to a corre- matches, nearly doubling the coverage compared to the
sponding concept in BabelNet. The concept, however, rule-based approach. Partial matches also increase across
is notably absent in GEMET. To address such coverage both ontologies, indicating a broader semantic reach.
Ingap due to GEMET’s limitations and explore the poten- terestingly, exact matches to BabelNet decline sharply
tial of using LLMs for ontology-based annotation, we for noun phrases extracted using the LLM-based method
used GPT-o3 to generate GEMET-style annotations for after 2016, even when partial BabelNet coverage
inunmatched phrases in the first output. The prompt used creases. As noted above, GPT-o3 tends to extract longer
for this task is shown in Figure 4 (see Appendix A). and more contextually rich noun phrases that partially
align with BabelNet entries. For instance, in the
sentence:
9Original in English: “access to unprecedented amounts of data from
sensors on satellites, smartphones and in situ devices”.
one of the noun phrases extracted by GPT-o3 is
economically socially environmentally sustainable future. While
4. Results conceptually accurate, this phrase does not match any
exact entry in BabelNet, whereas a shorter variant such
Following the extraction of candidate noun phrases and as sustainable future does. This seems to suggest that
their subsequent concept-label annotation using GEMET GPT-o3 extracts entire noun phrases including all
modiand BabelNet, Table 2 and Table 3 (see Appendix A) fiers (economically socially environmentally), when
ontolpresent the coverage of noun phrases by the rule– and ogy entries typically include noun phrases made up of
LLM-based methods across the English and Italian cor- classifiers and a few epithets, in this case, sustainable.
pora, as well as the number of phrases matched either Regarding the capabilities of LLMs in ontology-based
fully or partially in the two ontologies. A full (exact) annotation, our manual analysis of the quality of the
match refers to cases in which the entire noun phrase (e.g., definitions generated by GPT-o3 for phrases not found
vertebrate species) was found in the ontology, while a par- in GEMET provided relevant insights into the potential
tial match refers to instances in which only a component for using LLMs for scaling semantic resources.
(substring) of the phrase (e.g., vertebrate or species) was For instance, going back to example (
          <xref ref-type="bibr" rid="ref4">4</xref>
          ), the term
nafound. For example, in GEMET, while vertebrate species ture positive, while absent from GEMET, is present in
was not found, both vertebrate and species were matched BabelNet, which defines it as “outcomes which are net
individually, resulting in a partial match. positive for biodiversity, directly and measurably
increas
        </p>
        <p>Across the 2014–2024 WWF reports, the LLM-based ing in the health, abundance, diversity and resilience of
method extracts a number of unique noun phrases com- species, ecosystems and processes”. GPT-o3, on the other
parable to the rule-based method. However, for the hand, generates the following definition: “a future state
2022 Italian edition, the LLM extracts substantially more in which nature—biodiversity, ecosystem services and
natuphrases. This diference appears to result from the way ral capital—is restored and enhanced relative to its current
nested structures were handled: the LLM returned entire condition”. While both definitions are valid, the
LLMnoun phrases with several nested noun phrases. This pat- generated one captures more accurately the
forwardtern is especially evident in Italian, where nested noun looking, goal-oriented nature of the nature positive
conand prepositional phrases are common. For instance, cept. Unlike BabelNet’s definition, which frames the
extracted spans such as “negoziato internazionale della concept mainly as a set of measurable biodiversity
outconvenzione quadro delle Nazioni Unite sul cambiamento comes, the LLM definition presents it as a “future state”
climatico e della convenzione sulla diversità biologica” 8 or in which nature is restored and enhanced. This
distinction is significant, as BabelNet treats the concept as a
8Original in English: “international negotiations under the United
Nations Framework Convention on Climate Change and the Convention
on Biological Diversity”.
10https://wwf.panda.org/nature_positive/
11Acronym for Sustainable Development Goals.
5. Discussion
result, while the LLM version treats it as a
trajectory/vision, which aligns more closely with how the term is
currently used in WWF discourse (e.g., WWF defines
nature positive as a goal to “halt and reverse nature loss by
2030” ).10 This suggests a promising direction for scaling
these semantic resources, with domain-relevant entities
extracted from domain-specific literature. However, as
highlighted above, given the nuanced conceptual
distinctions, expert validation remains crucial in order to
ensure accuracy and to account for the subtle semantic
distinctions that such models may overlook.</p>
      </sec>
      <sec id="sec-2-7">
        <title>Our findings shed light on both the strengths and limita</title>
        <p>tions of rule-based and LLM-based pipelines for
ontologyoriented entity annotation in environmental discourse,
aligning with insights from previous work on
domainspecific NLP [3, 4, 5, 6].</p>
        <p>First, in terms of extraction, the LLM-based approach
demonstrated coverage comparable to the rule-based
method in line with recent research highlighting LLMs’
strong performance for entity detection [7, 8]. However,
the LLM’s tendency to generate longer, contextually rich
Temporal analysis of concept dynamics. Our di- noun phrases — particularly in Italian, where nesting is
achronic analysis of the concepts mapped via GEMET and frequent — resulted in both higher phrase counts and
BabelNet across the six-year corpus (2014–2024) yielded a greater proportion of partial matches. This confirms
the following results. observations by Marrero et al. [4] that domain-relevant</p>
        <p>For GEMET, we identified 59 English concepts that concepts often appear as complex, nested noun phrases
appeared consistently in all years, including domain- that challenge standard NER boundaries.
specific terms such as climate change, biodiversity, ecosys- Second, our results show that while GEMET provides
tem, and habitat loss, reflecting the controlled and envi- reliable coverage for core environmental concepts,
conronmentally focused nature of the thesaurus. A parallel sistent with its controlled and domain-focused design,
analysis of the Italian portion revealed a partially over- BabelNet ofers a wider conceptual coverage. This
lapping core set, with terms such as ambiente (environ- aligns with prior findings that general-purpose lexical
ment), specie (species), and risorsa (resource) persistently networks like BabelNet can capture more entities, but
appearing. at the same time can include discourse or general entities</p>
        <p>In contrast, BabelNet yielded a smaller set of consis- not so relevant to characterize a domain [13, 15].
tently recurring concepts, such as biodiversity, consump- Third, the quality of LLM-generated definitions for
untion, and development, but also revealed a much broader mapped phrases suggests potential for semi-automated
and more dynamic tail of emerging concepts (i.e., less fre- ontology enrichment. For instance, for the concept
naquent terms that vary widely across documents and cap- ture positive, the LLM produced a forward-looking
definiture context-dependent discourse). Notably, BabelNet tion more aligned with current environmental discourse
annotations surfaced many general-purpose or discourse- framing than the existing BabelNet entry. This supports
driven terms (e.g., ambition, alarm, goal, confidence limit), recent arguments for integrating LLMs into domain
onoften reflecting the rhetorical framing of environmental tology extension workflows [ 9], but also highlights the
narratives in the source texts. importance of expert validation, given possible subtleties</p>
        <p>We also tracked emerging and declining concepts in sense distinctions.
across both resources. For GEMET, emergent concepts Finally, our diachronic analysis, though conducted on
since 2018 include soil biodiversity, plastic, ocean acidifi- a very low scale, showed interesting aspects about how
cation, and urbanisation, many of which correspond to sustainability narratives evolve rhetorically, in line with
increasingly salient ecological issues. Conversely, con- work by Dryzek [17] and Nerlich and Koteyko [19] on
cepts such as ammonia, energy consumption, and ozone shifting environmental frames.
peaked before 2018 and gradually disappeared, suggest- Taken together, our results demonstrate that
combining shifting topical focus in environmental discourse. ing rule-based and LLM-based pipelines may provide
Similar trends were found in BabelNet, where contem- complementary strengths for environmental concept
anporary discourse introduced terms like sdg,11 carbon se- notation: the rule-based method ensures syntactic
preciquestration, and digital storytelling, while older narrative sion and consistent granularity, while the LLM broadens
anchors like anthropocene, habitat loss, and even ocean semantic reach and can supply draft definitions for novel
saw relative decline. A detailed overview of the five most or evolving terms. However, consistent ontology
covfrequent concepts per year, derived from both GEMET and erage remains an issue, as a substantial proportion of
BabelNet annotations, is provided in Tables 4 and 5 (see relevant phrases were not found in either resource,
unAppendix A). derscoring the need for ongoing ontology expansion and
domain adaptation, as stressed in recent surveys [10, 24].</p>
        <p>Future work should explore refining LLM prompts
to better constrain phrase boundaries, integrating
syntactic cues during generation, and developing
semiautomatic curation workflows to incorporate validated
LLM-generated definitions into existing ontologies. This
is a promising path for scaling high-quality,
domainadapted semantic annotation in support of environmental
discourse analysis.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>6. Conclusion and Future Work</title>
      <sec id="sec-3-1">
        <title>In this study, we presented a pipeline for extract</title>
        <p>ing and semantically annotating noun phrases in
multilingual environmental texts using both GEMET and
BabelNet ontological frameworks. The two resources
were used in complementary ways: GEMET provided
structured domain-specific knowledge, while BabelNet
contributed broader lexical coverage and multilingual
lfexibility. Through a combination of ontology
matching, fallback decomposition strategies, and cross-lingual
projection, we achieved wide and meaningful
semantic enrichment across languages. Looking ahead, the
approach we propose could also support the ongoing
evolution of domain ontologies themselves. For instance,
GEMET is periodically updated with new concepts and
definitions. 12 Automatically extracting candidate terms
and associating them with existing or missing concepts,
especially through LLM-based suggestion and contextual
generalization, might provide curators looking to add to
the thesaurus with insightful information.</p>
        <p>Several directions can be pursued for the future
development of this work. For instance, alternative approaches
to named entity propagation — such as alignment-based
techniques [25, 26] — can be tested, and additional
inventories for entities and concepts can be explored, such as
[27].</p>
        <p>Finally, it is important to note that our study focused
on the task as performed by LLMs. In future work, we
will compare these results with human annotations
provided by domain experts in order to examine whether
more or diferent entities are extracted from the texts.
This comparison will help determine whether more
finegrained analyses are necessary (e.g., to resolve partial
matches involving nested entities or syntactically
complex modifier structures). Moreover, incorporating expert
judgment will allow us to account for diverse disciplinary
perspectives (e.g., biology, ecology, chemistry, physics,
geography) on environmental issues.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Acknowledgments</title>
      <sec id="sec-4-1">
        <title>This research is supported by the University of Turin and</title>
        <p>the TreEn project team. Special thanks to the
collaborators who contributed to the treebank annotation.
12https://www.eionet.europa.eu/gemet/en/about/</p>
      </sec>
      <sec id="sec-4-2">
        <title>The work of Elisa Chierchiello is funded by the Interna</title>
        <p>tional project CN-HPC-Spoke1-Future HPC &amp; Big Data,
PNRR MUR-M4C2. Adriana Pagano has a grant from
Brazil’s National Council for Scientific and Technological
Development (CNPq 404722/2024-5; 313103/2021-6) and
Minas Gerais State Agency for Research and
Development (FAPEMIG) to conduct research in collaboration
with the University of Turin.
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        <p>
          WWF report
ecosystem (20), world (20), species (18), energy (18), resource (16)
specie (18), ecosistema (14), energia (13), mondo (13), biodiversità (12)
ecosystem (31), species (27), resource (22), food (22), energy (18)
ecosistema (26), specie (25), risorsa (23), habitat (15), consumo (15)
biodiversity (56), species (35), loss (26), indicator (15), land (14)
biodiversità (39), specie (26), perdita (20), indicatore (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), conservazione (
          <xref ref-type="bibr" rid="ref9">9</xref>
          )
species (58), biodiversity (55), ecosystem (25), climate (24), world (23)
specie (55), biodiversità (53), ecosistema (23), perdita (21), mondo (20)
species (72), climate (67), biodiversity (58), loss (38), climate change (30)
specie (62), biodiversità (41), perdita (23), cambiamento climatico (23), foresta (21)
climate (145), ecosystem (102), species (96), food (92), energy (91)
specie (90), ecosistema (90), biodiversità (74), cambiamento climatico (66), clima (64)
        </p>
        <p>
          Top five BabelNet Concepts (with frequency)
earth (11), country (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), lpi (
          <xref ref-type="bibr" rid="ref9">9</xref>
          ), development (
          <xref ref-type="bibr" rid="ref8">8</xref>
          ), biodiversity (
          <xref ref-type="bibr" rid="ref6">6</xref>
          )
acqua (18), ambientale (15), alto (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), declino (
          <xref ref-type="bibr" rid="ref8">8</xref>
          ), anno (
          <xref ref-type="bibr" rid="ref8">8</xref>
          )
lpi (15), earth (12), anthropocene (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), area (
          <xref ref-type="bibr" rid="ref9">9</xref>
          ), consumption (
          <xref ref-type="bibr" rid="ref9">9</xref>
          )
ambientale (11), altro (11), anno (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), acqua (
          <xref ref-type="bibr" rid="ref9">9</xref>
          ), antropocene (
          <xref ref-type="bibr" rid="ref8">8</xref>
          )
biodiversity (23), index (11), earth (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), lpi (
          <xref ref-type="bibr" rid="ref9">9</xref>
          ), abundance (
          <xref ref-type="bibr" rid="ref8">8</xref>
          )
biodiversità (23), altro (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), anno (
          <xref ref-type="bibr" rid="ref8">8</xref>
          ), accordo (
          <xref ref-type="bibr" rid="ref7">7</xref>
          ), agricoltura (
          <xref ref-type="bibr" rid="ref7">7</xref>
          )
biodiversity (27), change (13), index (11), earth (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), action (
          <xref ref-type="bibr" rid="ref8">8</xref>
          )
biodiversità (16), acqua (12), agricolo (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ), alimentare (
          <xref ref-type="bibr" rid="ref9">9</xref>
          ), abbondanza (
          <xref ref-type="bibr" rid="ref9">9</xref>
          )
biodiversity (40), action (24), amazon (21), change (20), area (18)
biodiversità (49), acqua (34), abbondanza (28), acqua dolce (24), approccio (20)
change (38), area (31), action (29), biodiversity (26), lpi (22)
acqua (42), alimentare (40), altro (32), area (32), acqua dolce (29)
        </p>
        <p>Declaration on Generative AI
During the preparation of this work, the author(s) did not use any generative AI tools or services.</p>
      </sec>
    </sec>
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