在全球范围内绘制树木密度图
T W Crowther1, H B Glick1, K R Covey1
1Yale School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA.
Nature
|September 3, 2015
概括
全球森林树木数量约为3.04万亿, 自人类文明开始以来, 森林砍伐导致树木数量下降了46%.
科学领域:
- 生态学
- 森林管理
- 环境科学
背景情况:
- 了解森林树木的分布对于全球生物圈研究至关重要.
- 之前的估计全球树木数量显著下降.
研究的目的:
- 创建森林树密度的第一个空间连续全球地图.
- 提供全球树木总数的最新估计.
主要方法:
- 使用地面数据和空间建模的组合.
- 气候,地形和人类影响的综合数据.
主要成果:
- 估计全球树木数量约为3.04万亿.
- 已确定热带和亚热带森林树木密度最高 (1.39万亿).
- 发现人类活动使全球树木数量自文明开始以来大幅减少了46%.
结论:
- 气候和地形影响当地树木密度.
- 人类影响是影响全球树木密度的主要因素.
- 估计每年有15亿棵树因为森林砍伐而消失.
相关概念视频
Survival Tree
497
Survival trees are a non-parametric method used in survival analysis to model the relationship between a set of covariates and the time until an event of interest occurs, often referred to as the "time-to-event" or "survival time." This method is particularly useful when dealing with censored data, where the event has not occurred for some individuals by the end of the study period, or when the exact time of the event is unknown.
Building a Survival Tree
Constructing a...
Building a Survival Tree
Constructing a...
497
Phylogenetic Trees
52.0K
Phylogenetic trees come in many forms. It matters in which sequence the organisms are arranged from the bottom to the top of the tree, but the branches can rotate at their nodes without altering the information. The lines connecting individual nodes can be straight, angled, or even curved.
52.0K
Phylogenetic Trees
6.8K
6.8K
Density
21.0K
Density is an important characteristic of substances, crucial in determining whether an object sinks or floats in a fluid. Its SI unit is kg/m3, and its cgs unit is g/cm3. The density of an object helps in identifying its composition, and also reveals information about the phase of the matter and its substructure. The densities of liquids and solids are roughly comparable, consistent with the fact that their atoms are in close contact. However, gases have much lower densities than liquids and...
21.0K
Evolutionary Relationships through Genome Comparisons
7.3K
Genome comparison is one of the excellent ways to interpret the evolutionary relationships between organisms. The basic principle of genome comparison is that if two species share a common feature, it is likely encoded by the DNA sequence conserved between both species. The advent of genome sequencing technologies in the late 20th century enabled scientists to understand the concept of conservation of domains between species and helped them to deduce evolutionary relationships across diverse...
7.3K
Plotting of Topographic Maps
744
Topographic maps represent the Earth's surface features using contour lines, which connect points of equal elevation to create a two-dimensional representation of three-dimensional terrain. Creating a topographic map requires a systematic approach.Begin by plotting a scaled grid and marking intersections corresponding to the survey's elevation data points. Assign elevation values at these intersections to build the base map. Next, determine contour levels using a consistent contour interval,...
744


