One basic weakness in a conservation system based wholly

on economic motives is that most members of the land community

have no economic value.  Wildflowers and songbirds are examples.

Of the 22,000 higher plants and animals native to Wisconsin, it

is doubtful whether more than 5 per cent can be sold, fed, eaten,

or otherwise put to economic use.  Yet these creatures are

members of the biotic community, and if (as I believe) its

stability depends on its integrity, they are entitled to

continuance.

         When one of these non-economic categories is threatened,

and if we happen to love it, we invent subterfuges to Lyive it

economic importance, At the beginning of the century songbirds

were supposed to be disappearing.  Ornithologists jumped to the

rescue with some distinctly shaky evidence to the effect that

insects would eat us up if birds failed to control them.  The

evidence had to be economic in order to be valid.

         It is painful to read these circumlocutions today.  We

have no land ethic yet, but we have at least drawn nearer point

of admitting that birds'should continue as a matter of biotic

right, regardless of the presence or absence of economic

advantage to us.

         A parallel situation exists in respect of predatory mam

mals, raptorial birds, and fish-eating birds.  Time was whe

biologists somewhat overworked the evidence that thes creatures

preserve the health of game by killing weaklings or that they

control rodents for the farmer, or that they prey only on

'worthless' species.  Here again, the evidence had to be economic

in order to be valid.  It is only in recent year that we hear the

more honest argument that predators are members of the community,

and that no special interest has the right to exterminate them

for the sake of a benefit, real or fancied, to itself.

Unfortunately this enlightened view is still in the talk stage.

In the field the extermination of predators goes merrily on:

witness the impending erasure of the timber wolf by flat of

Congress, the Conservation Bureaus, and many state legislatures.

         Some species of trees have been 'read out of the party'

by economics-minded foresters because they grow too slowly, or

have too low a sale value to pay as timber crops: white cedar,,

tamarack, cypress, beech, and hemlock are examples.  In Europe,

where forestry is ecologically more advanced, the non-commercial

tree species are recognized as membe

To sum up: a system of conservation based solely on economic

self-interest is hopelessly lopsided.  It tends to ignore, and

thus eventually to eliminate, many elements in the land community

that lack commercial value, but that are (as far as we know)

essential to its healthy functioning.  It assumes, falsely, I

think, that the economic parts of the biotic clock will function

without the uneconomic parts, It tends to relegate to government

many functions eventually too large, too complex, or too widely

dispersed to be performed by government.

         An ethical obligation on the part of the private owner is the

only visible remedy for these situations.

　46.科学家们赶紧拿出某些明显站不住脚的证据前来救驾，大致说的是如果鸟儿不能控制害虫的话，害虫就会把我们吃掉。

　　47.但是我们至少已经几乎承认了这样一种观点：那就是鸟儿的生存是它们的固有权利，不管它对我们是否有经济利益。

　　48.曾几何时，生物学家总是重述以下的这条证据：这些生物是为了维持食物链的正常运行去捕食弱小的生物或“没有价值的物种”。

　　49.在生态林业较为先进的欧洲，没有成为商业化对象的树种被视为原始森林群落的成员适当地加以保护。

　　50他容易忽视并最终消灭很多缺乏商业价值的物种，然而这些物种对于整个生物群落的健康运行是至关重要的。