---

Coronaviruses were discovered in the 1960s, and continued to be studied until the mid-1980s. The virus is naturally prevalent in mammals and birds, yet seven human-transmitted coronaviruses have been discovered so far; the most important of these, SARS Acute Respiratory Syndrome or acute respiratory syndrome, was a dangerous viral respiratory disease of genetic origin caused by coronavirus and from November 2002 to July 2003, the outbreak in Southern China caused 8098 cases. Possible disease and death of 774 people in 17 countries, and now since December 2019, another and more dangerous type called COVID-19 has spread with the human epidemic in Wuhan, China and in a short time has spread all over the world. China was the source of the virus, as well as the first country to stop it's spread to a large extent, but other countries failed to contain the virus despite their ability to contain it. Why? The answer is simple: "It is a matter of policy and approach, not power"! Another issue is "change"; as cities begin to recede and move toward recovery, the consequences of the epidemic will lead to new norms. In this article, we have tried to study the process of crisis management in several countries of the world is facing this virus and the extent of damages to the citizens of these countries until April 30, 2021.

---

Tensions between the Kurds and the Iraqi central government have continued throughout the country's contemporary history. The imposed geopolitics of the trans-regional powers in Iraq for more than half a century has led to violent ethnic resistance. To begin with, Iraq is an outcome of trans-regional geopolitical policy. Its leaders have always struggled to create an inclusive national identity and have used only violent means.
One of Iraq's problems for political stability and the creation of a coherent structure is the agreement with the Iraqi Kurdistan Federal Government on the disputed issues. Among these, one of the most contentious factors between the central government and the Kurds is the issues related to the disputed areas which its settlement is widely reflected in the Iraqi constitution and Security Council resolutions and a variety of solutions has been offered. This article uses a descriptive-analytical method to study and explain the territorial dispute between the Kurds and the central government of Iraq. The results of the research show that the settlement of territorial disputes is affected by geopolitical competition and the best solution to this crisis is to use a good governance model for the development and stability of those areas.

---

Aims: In this study, the response of individual trees and the stand structure to windstorm damage were investigated in a mixed broad-leaf forest stands located in Darabkola Forest, Sari, northern Iran. A field survey was conducted over an area of 2612 ha of the given stands.
Material & Methods: A full inventory was performed for all trees with diameter at breast height≥ 10cm and all damaged (i.e., snapped, snags, branch loss, broken trunk or uprooted) trees were identified within the study area. Tree height was measured using Laser Distance Meter for trees more than 10 m high and a Clinometer for all trees <10m. The percentage of trees damaged was the dependent variable; but, independent variables included number, mean height (m), total basal area (m²) and volume trees (m³). Independent t-test was performed to compare the mean of trees based on diameter classes. Also, the affection of height on susceptibility to windstorm effects was tested by comparing mean trees height within each class.
Findings: The number of the damaged trees varied with species, ranging from 0.04 % (2 individuals) in Tilia begonifolia Stev to 53.7 % (2709 individuals) in Fagus orientalis L. Among the damaged trees 5054 recorded, 2231 (44.20 %) had been snapped and 787 (15.6 %) uprooted, and 2028 (40.20 %) were snags. Among the species, Fagus orientalis L. (47.7 %), Alnus subcordata C. A. Mey. (19.7 %) and Carpinus betulus L. (18.8 %) were most susceptible to uprooting, whereas Populus caspica Bornm, Quercus castaneifolia C. A. Mey. and Ulmus glabra Huds. were the least susceptible to uprooting. The species differed significantly in their susceptibility to snapping. Trees ≥60cm dbh were more likely to be snapped (78 %) or snags (69 %), whereas trees <60 cm dbh were more presumably to be uprooted (50 %). Also, about one third (33 %) of total trees larger than 60 cm (D.B.H) have showed distinct effects and individual trees >20 m were more commonly uprooted. The number of snapped trees, snags and uprooted trees had a sharp increase in trees taller than 20m.
Conclusion: Our finding showed that Oriental beech and Common hornbeam to be species that were most susceptible to both being snapped and snagged, whereas Caucasian alder had the most uprooting damage among the other species. Overall, features like species, D.B.H, height and height to diameter ratio (H/D.B.H), were intensively related with the type and severity of windstorm damage. The findings showed that windstorms cause substantial structural effects in mixed stands of beech and hornbeam.