Summary 1. We report on a 3‐year field study designed to monitor the detailed population dynamics of Anisantha sterilis in winter wheat, as well as to explore the consequences of changing broad‐scale patterns of management, in the form of reduced fertilizer inputs. 2. In the absence of herbicides, population dynamics were dominated by density‐dependent population growth. Unusually, this occurred mainly through density‐dependent recruitment. This was estimated to reduce population growth rates by 50‐fold, compared with the effects of density‐dependent competition between plants for resources. Density‐dependent recruitment also tended to buffer populations against year‐to‐year variations in emergence levels. 3. Little evidence for temporal variations in allometric seed production, the strength of competition between plants for resources or maximal mean plant performance was found in this study, or in comparison with previously published data. 4. No aspect of the life cycle was significantly affected by variation in the level of applied nitrogen fertilizer. In the case of competitive interactions we postulate that this lack of effect results from reduced intraspecific competitive effects as a consequence of decreased maximal plant size under low nitrogen conditions. The highly competitive nature of the environment in which A. sterilis occurs means that such changes tend to mask the effects of changing nitrogen levels. 5. Estimates of the effects of cultivation, on the other hand, indicated that seed germination, and hence population growth, was reduced by up to 90% when ploughing was employed rather than minimum tillage. While to some extent the effects of variation in the form of cultivation on population numbers may be buffered by density‐dependent recruitment, this effect outweighs any effects of nutrients or spatial or temporal variability in population dynamics. 6. Using previously published models for the dynamics of Alopecurus myosuroides, Avena sterilis and Avena fatua, we show that the response of populations of Anisantha sterilis to cultivation is very different from that of other grass weeds. In addition we show how single species models for population dynamics may be used to predict the responses of weed assemblages to changes in forms of management.

The linguistic profile of bilingual children is known to show areas of overlap with that of children affected by Developmental Language Disorder (DLD), creating a need to differentiate the profiles and provide clinicians with tools to evaluate bilingual speakers in both of their languages. Data from typical adult bilinguals provide a picture of the language of a bilingual speaker at the end of language development. The present work explores how clitic production and nonword repetition (NWR) behave in mature language systems in situations of bilingualism, aiming to provide initial data as a benchmark on Italian as a non-dominant language. Heritage speakers (HSs) of Italian were confronted with adult immigrants (AIs) who moved from Italy to an English-speaking country in adulthood. Clitic pronouns were found to be vulnerable in HSs, who produced approximately 35% of the target clitics against the 80% of Ais, suggesting that clitic pronouns may not be reliable structures to test language competence in heritage Italian. On the other hand, HSs were >97% correct in NWR, suggesting that this paradigm should be explored as a possible marker to test language competence in these populations.

This study is an investigation of both comprehension and production of Wh- questions in Malay-speaking children with a developmental language disorder (DLD). A total of 15 Malay children with DLD (ages 7;0–9;11 years) were tested on a set of Wh- questions (who subject and object, which subject and object), comparing their performance with two control groups [15 age-matched typically developing (TD) children and 15 younger TD language-matched children]. Malay children with DLD showed a clear asymmetry in comprehension of Wh- questions, with a selective impairment for which NP questions compared with who questions. Age-matched controls performed at ceiling in all Wh- questions, while the language-matched group reported a subject/object asymmetry selective for the which NP, as reported in other languages. In production, both children with DLD and younger children showed a preference for questions with in situ Wh- elements, a structure that is allowed in colloquial Malay, but which is not produced by the age-matched TD group. Several non-adult-like strategies were adopted particularly by the children with DLD to avoid complex sentences, including substitution with yes/no echo questions, production of the wrong Wh- question, and use of a generic Wh- element. The study provides an insight on the mastery of Wh- questions in both typical Malay children and children with DLD. Implications for the definition of a clinical marker for DLD in a free word order language with Wh- in situ option will be discussed.

No abstract

The grammar of bilingual children has been shown to be sensitive to linguistic markers for language impairment. These markers can detect similarities and differences between typical bilingual profiles and atypical monolingual profiles in children. In this chapter, we review a study exploring whether the same markers can detect differences in the grammatical patterns of adult bilingual speakers of Italian immersed in an English-speaking environment. Adult immigrants (AI) and heritage speakers (HS) of Italian are bilinguals who are native speakers of a language that is not dominant in their current environment. The study exploits language markers applied to the investigation of language-specific vulnerabilities in Italian children with language impairments, in particular the production of clitic pronouns and the task of sentence repetition. In both tasks, accuracy in HS is significantly worse than that in AI, showing that both linguistic markers are sensitive to a difference between AI and HS grammatical profiles. In sentence repetition both groups show high accuracy; in clitic production HS are considerably more affected than AI. Qualitatively, the markers show similarities, with most produced sentences being grammatically licit in both groups, but also important differences, with HS showing a selective and more severe disadvantage in the use of functional words modifying sentence structure (complementisers, clitics).