Bridging the explanatory gaps: What can we learn from a biological agency perspective?

We begin this article by delineating the explanatory gaps left by prevailing gene-focused approaches in our understanding of phenotype determination, inheritance, and the origin of novel traits. We aim not to diminish the value of these approaches but to highlight where their implementation, despite best efforts, has encountered persistent limitations. We then discuss how each of these explanatory gaps can be addressed by expanding research foci to take into account biological agency-the capacity of living systems at various levels to participate in their own development, maintenance, and function by regulating their structures and activities in response to conditions they encounter. Here we aim to define formally what agency and agents are and-just as importantly-what they are not, emphasizing that agency is an empirical property connoting neither intention nor consciousness. Lastly, we discuss how incorporating agency helps to bridge explanatory gaps left by conventional approaches, highlight scientific fields in which implicit agency approaches are already proving valuable, and assess the opportunities and challenges of more systematically incorporating biological agency into research programs.

The agential perspective: Countermapping the modern synthesis.

We compare and contrast two theoretical perspectives on adaptive evolution-the orthodox Modern Synthesis perspective, and the nascent Agential Perspective. To do so, we develop the idea from Rasmus Grønfeldt Winther of a 'countermap', as a means for comparing the respective ontologies of different scientific perspectives. We conclude that the modern Synthesis perspective achieves an impressively comprehensive view of a universal set of dynamical properties of populations, but at the considerable cost of radically distorting the nature of the biological processes that contribute to evolution. For its part, the Agential Perspective offers the prospect of representing the biological processes of evolution with much greater fidelity, but at the expense of generality. Trade-offs of this sort are endemic to science, and inevitable. Recognizing them helps us to avoid the pitfalls of 'illicit reification', i.e. the mistake of interpreting a feature of a scientific perspective as a feature of the non-perspectival world. We argue that much of the traditional Modern Synthesis representation of the biology of evolution commits this illicit reification.

First-time mothers' choice of birthplace: influencing factors, expectations of the midwife's role and perceived safety.

AIM: To explore first-time pregnant women's expectations and factors influencing their choice of birthplace. BACKGROUND: Although outcomes and advantages for low-risk childbearing women giving birth in midwifery-led units and home compared with obstetric units have been investigated previously, there is little information on the factors that influence women's choice of place of birth. DESIGN: A qualitative Straussian grounded theory methodology was adopted. Fourteen women expecting their first baby were recruited from three large National Health Service organizations that provided maternity services free at the point of care. The three organizations offered the following birthplace options: home, freestanding midwifery unit and obstetric unit. Ethical approvals were obtained and informed consent was gained from each participant. METHODS: Data collection was undertaken in 2013-2014. One tape-recorded face-to-face semistructured interview was conducted with each woman in the third trimester of pregnancy. FINDINGS: Findings are presented as three main themes: (i) influencing factors on the choice of birthplace; (ii) expectations on the midwife's 'being' and 'doing' roles; (iii) perceptions of safety. CONCLUSION: Midwives should consider each woman's expectations and approach to birth beyond the planned birthplace, as these are often influenced by the intersection of various influencing factors. Several birthplace options should be made available to women in each maternity service and the alternatives should be shared with women by healthcare professionals during pregnancy to allow an informed choice. Virtual tours or visits to the birth units could also be offered to women to help them familiarize with the chosen setting.

Midwives, gender equality and feminism.

Gender inequality and the harmful effects of patriarchy are sustaining the wide spread oppression of women across the world and this is also having an impact on maternity services with unacceptable rates of maternal mortality, the continued under investment in the midwifery profession and the limiting of women's place of birth options. However alongside these effects, the current zeitgeist is affirming an alignment of feminism and gender equality such that both have a high profile in public discourse. This presents a once in a generation opportunity for midwives to self-declare as feminists and commit to righting the wrongs of this most pernicious form of discrimination.

Naturalizing relevance realization: why agency and cognition are fundamentally not computational.

The way organismic agents come to know the world, and the way algorithms solve problems, are fundamentally different. The most sensible course of action for an organism does not simply follow from logical rules of inference. Before it can even use such rules, the organism must tackle the problem of relevance. It must turn ill-defined problems into well-defined ones, turn semantics into syntax. This ability to realize relevance is present in all organisms, from bacteria to humans. It lies at the root of organismic agency, cognition, and consciousness, arising from the particular autopoietic, anticipatory, and adaptive organization of living beings. In this article, we show that the process of relevance realization is beyond formalization. It cannot be captured completely by algorithmic approaches. This implies that organismic agency (and hence cognition as well as consciousness) are at heart not computational in nature. Instead, we show how the process of relevance is realized by an adaptive and emergent triadic dialectic (a trialectic), which manifests as a metabolic and ecological-evolutionary co-constructive dynamic. This results in a meliorative process that enables an agent to continuously keep a grip on its arena, its reality. To be alive means to make sense of one's world. This kind of embodied ecological rationality is a fundamental aspect of life, and a key characteristic that sets it apart from non-living matter.

Alternative versus conventional institutional settings for birth.

BACKGROUND: Alternative institutional settings have been established for the care of pregnant women who prefer little or no medical intervention. The settings may offer care throughout pregnancy and birth, or only during labour; they may be part of hospitals or freestanding entities. Specially designed labour rooms include bedroom-like rooms, ambient rooms, and Snoezelen rooms. OBJECTIVES: Primary: to assess the effects of care in an alternative institutional birth environment compared to care in a conventional setting. Secondary: to determine if the effects of birth settings are influenced by staffing, architectural features, organizational models or geographical location. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 March 2012). SELECTION CRITERIA: All randomized or quasi-randomized controlled trials which compared the effects of an alternative institutional birth setting to a conventional setting. DATA COLLECTION AND ANALYSIS: We used the standard methods of the Cochrane Collaboration Pregnancy and Childbirth Group. Two review authors evaluated methodological quality. We performed double data extraction and presented results using risk ratios (RR) and 95% confidence intervals (CI). MAIN RESULTS: Ten trials involving 11,795 women met the inclusion criteria. We found no trials of freestanding birth centres or Snoezelen rooms. Allocation to an alternative setting increased the likelihood of: no intrapartum analgesia/anesthesia (six trials, n = 8953; RR 1.18, 95% CI 1.05 to 1.33); spontaneous vaginal birth (eight trials; n = 11,202; RR 1.03, 95% CI 1.01 to 1.05); breastfeeding at six to eight weeks (one trial, n = 1147; RR 1.04, 95% CI 1.02 to 1.06); and very positive views of care (two trials, n = 1207; RR 1.96, 95% CI 1.78 to 2.15). Allocation to an alternative setting decreased the likelihood of epidural analgesia (eight trials, n = 10.931; RR 0.80, 95% CI 0.74 to 0.87); oxytocin augmentation of labour (eight trials, n = 11,131; RR 0.77, 95% CI 0.67 to 0.88); instrumental vaginal birth (eight trials, n = 11,202; RR 0.89, 95% CI 0.79 to 0.99), and episiotomy (eight trials, n = 11,055; RR 0.83, 95% CI 0.77 to 0.90). There was no apparent effect on other adverse maternal or neonatal outcomes. Care by the same or separate staff had no apparent effects. No conclusions could be drawn regarding the effects of continuity of caregiver or architectural characteristics. In several of the trials included in this review, the design features of the alternative setting were confounded by important differences in the organizational models for care (separate staff for the alternative setting, offering more continuity of caregiver), and thus it is difficult to draw inferences about the independent effects of the physical birth environment. AUTHORS' CONCLUSIONS: Hospital birth centres are associated with lower rates of medical interventions during labour and birth and higher levels of satisfaction, without increasing risk to mothers or babies.

A metasynthesis of midwife-led care.

The purpose of this metasynthesis is to describe and interpret qualitative research relating to midwife-led care to see if it sheds light on why low-risk women experience fewer birth interventions within this model of care. Eleven articles were included in the review. Three themes emerged: (a) relationally mediated benefits for women that resulted in increased agency and empathic care; (b) the problematic interface of midwife-led units with host maternity units, stemming from a clash of models and culture; and (c) greater agency for midwives within midwife-led models of care though bounded by the relationship with the host maternity unit. This metasynthesis suggests that lower rates of interventions could be linked to the greater agency experienced by women and midwives within midwife-led models, and that these effects are mediated, in part, by the smallness of scale in these settings.

Alternative versus conventional institutional settings for birth.

BACKGROUND: Alternative institutional settings have been established for the care of pregnant women who prefer and require little or no medical intervention. The settings may offer care throughout pregnancy and birth, or only during labour; they may be part of hospitals or freestanding entities. Specially designed labour rooms include bedroom-like rooms, ambient rooms, and Snoezelen rooms. OBJECTIVES: Primary: to assess the effects of care in an alternative institutional birth environment compared to care in a conventional institutional setting. Secondary: to determine if the effects of birth settings are influenced by staffing, architectural features, organizational models or geographical location. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2010). SELECTION CRITERIA: All randomized or quasi-randomized controlled trials which compared the effects of an alternative institutional maternity care setting to conventional hospital care. DATA COLLECTION AND ANALYSIS: We used standard methods of the Cochrane Collaboration Pregnancy and Childbirth Group. Two review authors evaluated methodological quality. We performed double data entry and have presented results using risk ratios (RR) and 95% confidence intervals (CI). MAIN RESULTS: Nine trials involving 10684 women met the inclusion criteria. We found no trials of freestanding birth centres or Snoezelen rooms. Allocation to an alternative setting increased the likelihood of: no intrapartum analgesia/anaesthesia (five trials, n = 7842; RR 1.17, 95% CI 1.01 to 1.35); spontaneous vaginal birth (eight trials; n = 10,218; RR 1.04, 95% CI 1.02 to 1.06); breastfeeding at six to eight weeks (one trial, n = 1147; RR 1.04, 95% CI 1.02 to 1.06); and very positive views of care (two trials, n = 1207; RR 1.96, 95% CI 1.78 to 2.15). Allocation to an alternative setting decreased the likelihood of epidural analgesia (seven trials, n = 9820; RR 0.82, 95% CI 0.75 to 0.89); oxytocin augmentation of labour (seven trials, n = 10,020; RR 0.78, 95% CI 0.66 to 0.91); and episiotomy (seven trials, n = 9944; RR 0.83, 95% CI 0.77 to 0.90). There was no apparent effect on serious perinatal or maternal morbidity/mortality, other adverse neonatal outcomes, or postpartum hemorrhage. No firm conclusions could be drawn regarding the effects of variations in staffing, organizational models, or architectural characteristics of the alternative settings. AUTHORS' CONCLUSIONS: When compared to conventional settings, hospital-based alternative birth settings are associated with increased likelihood of spontaneous vaginal birth, reduced medical interventions and increased maternal satisfaction.

Childbirth embodiment: problematic aspects of current understandings.

The experience of childbirth is one of the most corporeal of the human condition. Against a backdrop of profound change in the milieu of birthing over the past 30 years, especially in the developed world, a number of discourses now compete for the status of the safest, most fulfilling birth experience. Supporters of biomedical and 'natural' approaches make their respective claims to those, with obstetricians broadly aligning their professional interests with the former and midwives with the latter. There is mounting evidence that childbearing women's experiences of birth are often shaped in the uneasy space between the two. Within sociological discourse in health, embodiment is a dominant theme but, to date, research has concentrated mainly on new reproductive technologies, and there is a dearth of recent research and theorising around the act of parturition itself. This paper argues that because of this, there has been a polarising tendency in current discourses which is having a largely negative impact on women, professionals and the maternity services. A call is made for an integration of traditional childbirth embodiment theories, mediated through compassionate, relationally focused maternity care, especially when labour complications develop.

Factors influencing the utilisation of free-standing and alongside midwifery units in England: a qualitative research study.

OBJECTIVE: To identify factors influencing the provision, utilisation and sustainability of midwifery units (MUs) in England. DESIGN: Case studies, using individual interviews and focus groups, in six National Health Service (NHS) Trust maternity services in England. SETTING AND PARTICIPANTS: NHS maternity services in different geographical areas of England Maternity care staff and service users from six NHS Trusts: two Trusts where more than 20% of all women gave birth in MUs, two Trusts where less than 10% of all women gave birth in MUs and two Trusts without MUs. Obstetric, midwifery and neonatal clinical leaders, managers, service user representatives and commissioners were individually interviewed (n=57). Twenty-six focus groups were undertaken with midwives (n=60) and service users (n=52). MAIN OUTCOME MEASURES: Factors influencing MU use. FINDINGS: The study findings identify several barriers to the uptake of MUs. Within a context of a history of obstetric-led provision and lack of decision-maker awareness of the clinical and economic evidence, most Trust managers and clinicians do not regard their MU provision as being as important as their obstetric unit (OU) provision. Therefore, it does not get embedded as an equal and parallel component in the Trust's overall maternity package of care. The analysis illuminates how implementation of complex interventions in health services is influenced by a range of factors including the medicalisation of childbirth, perceived financial constraints, adequate leadership and institutional norms protecting the status quo. CONCLUSIONS: There are significant obstacles to MUs reaching their full potential, especially free-standing midwifery units. These include the lack of commitment by providers to embed MUs as an essential service provision alongside their OUs, an absence of leadership to drive through these changes and the capacity and willingness of providers to address women's information needs. If these remain unaddressed, childbearing women's access to MUs will continue to be restricted.

Autonomous and dependent-The dichotomy of birth: A feminist analysis of birth plans in Sweden.

OBJECTIVE: To elicit pregnant women's perceptions of childbirth as expressed in their birth plans, and through a feminist lens analyse their wishes, fears, values, and beliefs about childbirth, as well as their expectations on partner and midwife. DESIGN: This study used qualitative content analysis, identifying subcategories, categories, and an overall theme in data gathered from women's written birth plans. A feminist theoretical framework underpinned the research. SETTING: A middle-sized city in northern Sweden. PARTICIPANTS: 132 women who gave birth in an obstetrician-led hospital labour ward between March and June 2016 and consented to grant access to their birth plans and antenatal and intrapartum electronic medical records. FINDINGS: Three categories emerged: 'Keeping integrity intact through specific requests and continuous dialogue with the midwife', 'A preference towards a midwife-supported birth regardless of method of pain relief", and '"Help my partner help me" - Women anticipating partner involvement.' The overall theme linking the categories together was: 'Autonomous and dependent - The dichotomy of birth', portraying women's ambiguity before birth -expressing a wish to remain in control while simultaneously letting go of control by entrusting partner and midwifewith decision-making regarding their own bodies. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: Women primarily desired a natural, midwife-supported birth and favoured a relationship-based, woman-centred model of care, based on the close interaction between woman, partner, and midwife. Midwives need to be aware of women's ambiguous reliance on them and the power they have to influence women's birth choices and birth experiences. Feminist theory and values in midwifery practice may be useful to inspire a maternity care based on women's wishes and expectations, acknowledging and valuing women's voices, and embracing the sanctity of birth and of the birthing woman's body.

First-time mothers' expectations of the unknown territory of childbirth: Uncertainties, coping strategies and 'going with the flow'.

OBJECTIVE: To explore first-time mothers' expectations of labour and birth, coping strategies they adopt during pregnancy towards childbirth and coping strategies they expect to use during labour and birth. DESIGN: A qualitative Straussian grounded theory methodology was adopted, with data collected through semi-structured interviews in the third trimester of pregnancy. Ethical approval was gained. Data analysis included the processes of coding and conceptualising data, with constant comparison between data, literature and memos. SETTING: Three National Health Service (NHS) Trusts in England offering the choice of various birth settings including home, Freestanding Midwifery Unit (FMU) and Obstetric Unit (OU). PARTICIPANTS: Fourteen first-time pregnant women in good general health with a straightforward pregnancy (single fetus) and anticipating a normal birth. FINDINGS: Three themes were identified in regard to women's expectations of childbirth and coping strategies: (a) the unknown territory of labour and birth; (b) waiting for the unknown: coping strategies; (c) going with the flow. First-time mothers acknowledged labour and birth was an unknown territory, irrespective of the planned place of birth. While waiting for the unknown, the women put in place a number of coping strategies during pregnancy: preparing; avoiding; thinking about childbirth as a shared experience among women; relying on maternal instinct; relying on pharmacological pain relief; considering birth partner(s) as voice of reason. Overall, women were flexible in regard to their birth plan and open to change if needed, referring to this open-minded state as 'going with the flow'. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: Women and their families may appreciate receiving accurate and realistic information from caregivers starting in pregnancy and continuing during labour and birth to alleviate the state of uncertainty typical of the childbearing event. The midwife should address the woman's uncertainties and help her 'go with the flow' in the labour continuum. The birth plan should also be revised by the midwife and woman together if they can no longer adhere to the original one.

Mapping midwifery and obstetric units in England.

OBJECTIVE: to describe the configuration of midwifery units, both alongside&free-standing, and obstetric units in England. DESIGN: national survey amongst Heads of Midwifery in English Maternity Services SETTING: National Health Service (NHS) in England PARTICIPANTS: English Maternity Services Measurements descriptive statistics of Alongside Midwifery Units and Free-standing Midwifery Units and Obstetric Units and their annual births/year in English Maternity Services FINDINGS: alongside midwifery units have nearly doubled since 2010 (n = 53-97); free-standing midwifery units have increased slightly (n = 58-61). There has been a significant reduction in maternity services without either an alongside or free-standing midwifery unit (75-32). The percentage of all births in midwifery units has trebled, now representing 14% of all births in England. This masks significant differences in percentage of all births in midwifery units between different maternity services with a spread of 4% to 31%. KEY CONCLUSIONS: In some areas of England, women have no access to a local midwifery unit, despite the National Institute for Health&Clinical Excellence (NICE) recommending them as an important place of birth option for low risk women. The numbers of midwifery units have increased significantly in England since 2010 but this growth is almost exclusively in alongside midwifery units. The percentage of women giving birth in midwifery units varies significantly between maternity services suggesting that many midwifery units are underutilised. IMPLICATIONS FOR PRACTICE: Both the availability and utilisation of midwifery units in England could be improved.

Understanding tree growth responses after partial cuttings: A new approach.

Forest ecosystem management heads towards the use of partial cuttings. However, the wide variation in growth response of residual trees remains unexplained, preventing a suitable prediction of forest productivity. The aim of the study was to assess individual growth and identify the driving factors involved in the responses of residual trees. Six study blocks in even-aged black spruce [Picea mariana (Mill.) B.S.P.] stands of the eastern Canadian boreal forest were submitted to experimental shelterwood and seed-tree treatments. Individual-tree models were applied to 1039 trees to analyze their patterns of radial growth during the 10 years after partial cutting by using the nonlinear Schnute function on tree-ring series. The trees exhibited different growth patterns. A sigmoid growth was detected in 32% of trees, mainly in control plots of older stands. Forty-seven percent of trees located in the interior of residual strips showed an S-shape, which was influenced by stand mortality, harvested intensity and dominant height. Individuals showing an exponential pattern produced the greatest radial growth after cutting and were edge trees of younger stands with higher dominant height. A steady growth decline was observed in 4% of trees, represented by the individuals suppressed and insensitive to the treatment. The analyses demonstrated that individual nonlinear models are able to assess the variability in growth within the stand and the factors involved in the occurrence of the different growth patterns, thus improving understanding of the tree responses to partial cutting. This new approach can sustain forest management strategies by defining the best conditions to optimize the growth yield of residual trees.

Subverting the assembly-line: childbirth in a free-standing birth centre.

Across the world, concern is being expressed about the rising rates of birth interventions. As a result, there is growing interest in alternative organisational models of maternity care. Most of the research to date on these models has examined clinical outcomes. This paper, discussing key findings from an ethnographic study of a free-standing birth centre in the UK, explores organisational dimensions to care. It suggests that the advantages of scale have been under-recognised by policy makers to date. The birth centre displays organisational characteristics that contrast with the dominant Fordist/Taylorist model of large maternity units. These characteristics allow for greater temporal flexibility in labour care and tend to privilege relational, 'being' care over task-orientated, 'doing' care. In addition, features of a bureaucracy are much less in evidence, enabling entrepreneurial activity to flourish. There may be lessons here for other heath services as well as maternity services in optimising the advantages of small-scale provision.

'Nesting' and 'Matrescence' as distinctive features of a free-standing birth centre in the UK.

OBJECTIVE: To explore the culture, beliefs, values, customs and practices around the birth process within a free-standing birth centre (FSBC). DESIGN: Ethnography. SETTING: A birth centre situated in the midlands of England. PARTICIPANTS: Women attending the centre, midwives and maternity-care assistants (MCAs) working at the centre. FINDINGS: Women in the study seemed to invoke intuitive nesting-related behaviours in their assessment of the suitability of the birth centre. In addition, the birth centre staff's focus on creating the right ambience for birth may also emanate from nesting concerns. Birth-centre staff assisted women through the 'becoming mother' transition, which is conceptualised as 'matrescent' care. KEY CONCLUSIONS: The birth-centre environment elicited nesting-like behaviours from both women and staff. This formed part of a nurturing orientation that was conceptualised as 'matrescent' (becoming mother) care. 'Matrescence' does not seem to be grounded in clinical skills but is relationally mediated. IMPLICATIONS FOR PRACTICE: Nesting-like behaviours and 'matrescent' care in this context challenge maternity services to review traditional conceptualisations of safety and traditional expressions of clinical intrapartum care.

Appraising the quality of qualitative research.

In the process of undertaking a meta-synthesis of qualitative studies of free-standing midwife-led units, the authors of this paper encountered a number of methodologically and epistemologically unresolved issues. One of these related to the assessment of the quality of qualitative research. In an iterative approach to scoping this issue, we identified eight existing checklists and summary frameworks. Some of these publications were opinion based, and some involved a synthesis of pre-existing frameworks. None of them provide a clear map of the criteria used in all their reviewed papers, and of the commonalities and differences between them. We critically review these frameworks and conclude that, although they are epistemologically and theoretically dense, they are excessively detailed for most uses. In order to reach a workable solution to the problem of the quality assessment of qualitative research, the findings from these frameworks and checklists were mapped together. Using a technique we have termed a 'redundancy approach' to eliminate non-essential criteria, we developed our own summary framework. The final synthesis was achieved through reflexive debate and discussion. Aspects of this discussion are detailed here. The synthesis is clearly rooted in a subjectivist epistemology, which views knowledge as constructed and hermeneutic in intent, encompassing individual, cultural and structural representations of reality.

The kaleidoscopic midwife: A conceptual metaphor illustrating first-time mothers' perspectives of a good midwife during childbirth. A grounded theory study.

BACKGROUND: The literature review reveals general information about a good midwife from a range of perspectives and what childbearing women generally value in a midwife, but there is a lack of information around mothers' perspectives of what makes a good midwife specifically during labour and birth, and even less in the context of different places of birth. AIM: To conceptualise first-time mothers' expectations and experiences of a good midwife during childbirth in the context of different birthplaces. DESIGN: Qualitative Straussian grounded theory methodology. SETTING: Three National Health Service Trusts in England providing maternity care that offered women the possibility of giving birth in different settings (home, freestanding midwifery unit and obstetric unit). PARTICIPANTS: Fourteen first-time mothers in good general health with a straightforward singleton pregnancy anticipating a normal birth. METHODS: Ethical approval was gained. Data were collected through two semi-structured interviews for each participant (before and after birth). Data analysis included the processes of coding and conceptualising data, with constant comparison between data, literature and memos. FINDINGS: The model named 'The kaleidoscopic midwife: a conceptual metaphor illustrating first-time mothers' perspectives of a good midwife during childbirth' was developed. The model is dynamic and woman-centred, and is operationalised as the midwife adapts to each woman's individual needs in the context of each specific labour. Four pillars of intrapartum care were identified for a good midwife in the labour continuum: promoting individuality; supporting embodied limbo; helping to go with the flow; providing information and guidance. The metaphor of a kaleidoscopic figure is used to describe a midwife who is 'multi-coloured' and ever changing in the light of the woman's individual needs, expectations and labour journey, in order to create an environment that enables her to move forward despite the uncertainty and the expectations-experiences gap. The following elements are harmonised by the kaleidoscopic midwife: relationship-mediated being; knowledgeable doing; physical presence; immediately available presence. CONCLUSION: The model presented has relevance to contemporary debates about quality of care and place of birth and can be used by midwives to pursue excellence in caring for labouring mothers. Independently from the place of birth, when the woman is cared for by a midwife demonstrating the above characteristics, she is likely to have an optimum experience of birth. Future research is necessary to tease out individual components of the model in a variety of practice settings.

A 6-Year-Long Manipulation with Soil Warming and Canopy Nitrogen Additions does not Affect Xylem Phenology and Cell Production of Mature Black Spruce.

The predicted climate warming and increased atmospheric inorganic nitrogen deposition are expected to have dramatic impacts on plant growth. However, the extent of these effects and their interactions remains unclear for boreal forest trees. The aim of this experiment was to investigate the effects of increased soil temperature and nitrogen (N) depositions on stem intra-annual growth of two mature stands of black spruce [Picea mariana (Mill.) BSP] in Québec, QC, Canada. During 2008-2013, the soil around mature trees was warmed up by 4°C with heating cables during the growing season and precipitations containing three times the current inorganic N concentration were added by frequent canopy applications. Xylem phenology and cell production were monitored weekly from April to October. The 6-year-long experiment performed in two sites at different altitude showed no substantial effect of warming and N-depositions on xylem phenological phases of cell enlargement, wall thickening and lignification. Cell production, in terms of number of tracheids along the radius, also did not differ significantly and followed the same patterns in control and treated trees. These findings allowed the hypothesis of a medium-term effect of soil warming and N depositions on the growth of mature black spruce to be rejected.