防护林

Windbreaks loblolly pine.Windbreaks not only protect land and crops from the wind.* Surplus trees can be cut down and used to provide wood.

防护林不仅仅能保护大风中的土地和庄稼，多余的树还可以砍下当作木材。

The methods for the same researches of wood borers, such as the simple and convenient workable methods of investigation insect enemy and studying life table of the longicorn, have been provided in this paper.

这对在防护林、非食用经济林中大面积应用此不育剂，以克服其它防治法难以大面积推广的问题，有着重要意义。

Tall California cypress endemic on Monterey Bay; widely used for ornament as well as reforestation and shelterbelt planting.

蒙特里杰克湾的地方树种，是一种高大的加州柏木；用于装饰、重新造林和建造防护林。

Therefore,the studies on pastureland shelterbelt have been begun since 1900's,especially ecological ...

因此 ，2 0世纪以来对草牧场防护林的研究就已开始，特别是进入 2 0世纪 80年代之后，随着草原生态环境的急剧恶化，其研究日趋活跃。

The objective of the paper is to state the necessity of introducing Pinus pinaster Ait. in China. Firstly, generalize the biological and ecological characteristic of P. pinaster, and its utilization value. Secondly, after analyzing the natural distributions of P. pinaster and natural conditions of these areas, comparing the climate attributes of the introduced regions in our country and other countries, the possibility of introducing this species are discussed.

概括了沙地海岸松的生物学、生态学特性及其推广利用价值；通过了解沙地海岸松在国外自然分布区以及引种地区的自然概况，总结中国沿海防护林建设中出现的问题和亟待引进优良品种的迫切性，并对中国沿海地区的气候特点进行了对比分析得出，中国引进沙地海岸松的必要性和可行性。

Since 1998, China has worked on projects to protect natural forest reserves, to reforest cultivated land, to build shelterbelts in northern, northeastern and northwestern China and in the Yangtze River basin, to control the sources of duststorms in the Beijing-Tianjin area, to build wild animal and plant reserves and other types of nature reserves, as well as fast-growing, high-yielding timber bases in some key areas.

从1998年起，中国开展了天然林资源保护工程、退耕还林工程、"三北"及长江流域等防护林体系建设工程、京津风沙源治理工程、野生动植物保护及自然保护区建设工程和重点地区速生丰产用材林基地建设工程等。

All measured heavy metal concentrations in roadside soils of Beiyan road,which had sparse protection forest,decreased exponentially with the increase of distance from the road; the maximum heavy metal value appeared within the distance of 15 m from Beiyan road.

公路防护林体系较差的北沿公路路侧土壤纵向剖面重金属含量随距路肩距离增加呈指数下降，土壤重金属重污染区在距路肩15 m范围内。

So, does shelter-forest have much big effect to agricultural increase production after all?

那么，防护林到底对农业增产起多大作用呢？

The afforested area jumped from 868 ha in 1990 to 19,069 ha in 2007, registering a more than 20-fold increase. The area of shelter-forest, which plays an important role in ecological protection, rose from 440 ha in 1990 to 13,132 ha in 2007, an increase of nearly 30-fold see Fig.

造林面积从1990年的868公顷增长到2007年的19069公顷，增长了20多倍，其中对生态环境保护具有重要作用的防护林面积由1990年的440公顷增长到2007年的13132公顷，增长了近30倍（注24）。

North shelter-forest the 4th period the project is started formally already.

三北防护林第四期工程已正式启动。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。