Worldwide, multiple ecosystems are currently affected by global change because of important anthropogenic disturbances which have quickly increased levels of abiotic (e.g. climate) and biotic stress (e.g. diseases, pests, herbivory). In particular, oak-dominated systems have experienced a general decline as a consequence of habitat destruction, mismanagement and extreme climate events along with the aggressive root pathogen Phytophthora spp. Here, we investigated the effect of soil improvement through soil biological fertilizers on oak defense against tree decline symptoms associated with Phytophthora for two ontogenetic stages of oak trees: adults and recruits. We examined oak survival and crown defoliation status on 60 pairs of adult trees (a treated tree with biological fertilizers vs. non-treated tree) as well as the survival, growth and herbivory on 30 quartets of treated and non-treated recruits, with and without protection against large herbivores. We used two different liquid fertilizers: OptiPlus (a biological fertilizer with organic N, P, S, Ca, Mg, trace elements (Fe, Mn, B, Zn) and humic fulvic acids) and OptiFer (a biological trace element fertilizer with only Fe, Mn and Mg). Treated oak trees with fertilizers showed lower oak defoliation (0.33-fold difference) than non-treated trees. In addition, trees treated with OptiPlus liquid showed a significant reduction of crown defoliation compared to those trees that received OptiFer treatment (0.68-fold difference). Interestingly, this crown amelioration was more effective in steep slopes, revealing that OptiPlus may buffer the stress generated by shallower and poorer soils. Overall, fertilized plants (particularly OptiPlus) were more attractive to herbivores, probably as a result of the greater content in deficient minerals, increasing their palatability. This study has slightly visualized the importance of soil improvement against oak decline through biological fertilizers and the need to further explore different times and techniques of application. Managers should be cautious with the use of fertilizers as they may increase the browsing impact of livestock and wild herbivores on tree regeneration. It is therefore imperative to improve the resilience of oak trees against oak decline while minimizing the herbivory impact on oak recruits.

在全球范围内，由于重要的人为干扰，非生态系统（例如气候）和生物胁迫（例如疾病，害虫，草食动物）的数量迅速增加，目前全球范围内的多个生态系统都受到全球变化的影响。特别是，以橡树为主的系统由于生境破坏，管理不善和极端气候事件以及侵害性根病菌疫霉菌种而普遍下降。在这里，我们研究了通过土壤生物肥料改良土壤对橡树防御与疫霉病相关的树木衰弱症状的影响橡树的两个发育阶段：成年和新兵。我们检查了60对成年树木（用生物肥料处理过的树木与未处理过的树木）上橡树的存活率和树冠脱叶状态，以及经过处理的和未处理的新兵在30个四重木上的存活，生长和草食状况，分别使用没有针对大型食草动物的保护。我们使用了两种不同的液体肥料：OptiPlus（一种含有有机N，P，S，Ca，Mg，微量元素（Fe，Mn，B，Zn和腐殖酸黄腐酸）的生物肥料）和OptiFer（一种仅含有生物元素的生物微量元素肥料）。铁，锰和镁）。与未处理的树木相比，用肥料处理的橡树显示出较低的橡树落叶（相差0.33倍）。此外，与接受OptiFer处理的树木相比，经OptiPlus液体处理的树木显示出的树冠脱叶显着减少（相差0.68倍）。有趣的是，这种冠冕改善措施在陡坡上更为有效，这表明OptiPlus可以缓冲由较浅和较差的土壤产生的应力。总体而言，受精植物（特别是OptiPlus）对草食动物更具吸引力，这可能是由于缺乏矿物质的含量更高，增加了它们的适口性。这项研究稍微形象地表明了通过生物肥料改良土壤以防止橡树衰落的重要性，以及进一步探索不同时期和应用技术的需求。管理人员应谨慎使用化肥，因为化肥可能会增加牲畜和野生食草动物对树木再生的浏览影响。因此，必须在减少对橡树新兵的食草影响的同时，提高橡树的抗逆能力。