Species extinction following habitat loss is well documented. However, these extinctions do not happen immediately. The biodiversity surplus (extinction debt) declines with some delay through the process of relaxation. Estimating the time constants of relaxation, mainly the expected time to first extinction and the commonly used time for half the extinction debt to be paid off (half-life), is crucial for conservation purposes. Currently, there is no agreement on the rate of relaxation and the factors that it depends on. Here we find that half-life increases with area for all groups examined in a large meta-analysis of extinction data. A common pattern emerges if we use average number of individuals per species before habitat loss as an area index: for mammals, birds, reptiles and plants, the relationship has an exponent close to a half. We also find that the time to first determined extinction is short and increases slowly with area.

The olive tree (Olea europaea L.) is an emblematic, long-living fruit tree species of profound economic and environmental importance. This study is a literature review of articles published during the last 10 years about the role of beneficial microbes [Arbuscular Mycorrhizal Fungi (AMF), Plant Growth Promoting Rhizobacteria (PGPR), Plant Growth Promoting Fungi (PGPF), and Endophytes] on olive tree plant growth and productivity, pathogen control, and alleviation from abiotic stress. The majority of the studies examined the AMF effect using mostly Rhizophagus irregularis and Glomus mosseae species. These AMF species stimulate the root growth improving the resistance of olive plants to environmental and transplantation stresses. Among the PGPR, the nitrogen-fixing bacteria Azospirillum sp. and potassium- and phosphorous-solubilizing Bacillus sp. species were studied extensively. These PGPR species were combined with proper cultural practices and improved considerably olive plant’s growth. The endophytic bacterial species Pseudomonas fluorescens and Bacillus sp., as well as the fungal species Trichoderma sp. were identified as the most effective biocontrol agents against olive tree diseases (e.g., Verticillium wilt, root rot, and anthracnose).

The Meloidogyne genus is widely recognized for its significant economic and scientific importance within the group of plant-parasitic nematodes. The chemical management of nematodes presents its challenges and heavily depends on employing soil fumigants containing toxic and costly nematicides. However, plant-derived essential oils offer promising alternatives, demonstrating a wide range of biological activities that affect nematodes through a range of mechanisms, including disrupting their nervous systems, inducing detrimental effects on plasma membrane permeability, penetrating the gelatinous matrix of nematode eggs, and disturbing intracellular redox status. Most of the extracted essential oils were predominantly sourced from the Lamiaceae family (32%), followed by Asteraceae (11%), Apiaceae (9%), and Poaceae (8%), and with genera Thymus, Mentha, Ocimum, Artemisia, Cymbopogon being the most common. The nematicidal activity of EOs primarily arises from their chemical groups, such as terpenes, phenylpropanoids, and organosulfur compounds. Among these, geraniol, carvacrol, limonene, eugenol, thymol, and pinene demonstrate the strongest nematicidal potential. The assessed EO efficacy was evaluated against 6 species belonging to the genus Meloidogyne. This review also provides knowledge of synergistic and antagonistic interactions of EO components. Synergistic interactions were identified between carvacrol and geraniol, as well as geraniol and eugenol, whereas binary combinations of carvacrol, γ-terpinene, and o-cymene exhibited reduced efficacy. Understanding how specific compounds interact can lead to the development of more potent and effective final products.