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But experts say that trees can start looking sick before any sign of Bell-miner Associated Dieback.
但专家表示，在矿吸蜜鸟枯梢病迹象出现之前，树木可能就开始看起来生病了。
So it looks as if the problem might have another explanation.
因此，看起来这个问题可能有另一种解释。
One possibility is that it's to do with the huge bushfires that we have in Australia.
一种可能性是，这与澳大利亚发生的丛林大火有关。
A theory proposed over 40 years ago by ecologist William Jackson is that the frequency of bushfires in a particular region affects the type of vegetation that grows there.
生态学家威廉·杰克逊40多年前提出的一种理论是，特定地区丛林大火的发生频率会影响那里生长的植被类型。
If there are very frequent bushfires in a region, this encourages grass to grow afterwards, while if the bushfires are rather less frequent, this results in the growth of eucalyptus forests.
如果一个地区经常发生丛林大火，这就会促进草的生长，而如果丛林大火的发生频率相对较低，这就会导致桉树林的生长。
So why is this? Why do fairly frequent bushfires actually support the growth of eucalyptus?
为什么会这样呢？为什么相当频繁的丛林大火实际上支持了桉树的生长？
Well, one reason is that the fire stops the growth of other species which would consume water needed by eucalyptus trees.
其中一个原因是，大火阻止了其他物种的生长，这些物种会消耗桉树所需的水分。
And there's another reason.
还有另一个原因。
If these other quick-growing species of bushes and plants are allowed to proliferate, they harm the eucalyptus in another way, by affecting the composition of the soil, and removing nutrients from it.
如果允许其他快速生长的灌木和植被繁殖，它们就会以另一种方式伤害桉树，即影响土壤的构成，并从土壤中去除养分。
So some bushfires are actually essential for the eucalyptus to survive as long as they are not too frequent.
因此，一些丛林大火实际上对桉树的生存至关重要，只要它们不太频繁发生就好。
In fact there's evidence that Australia's indigenous people practised regular burning of bush land for thousands of years before the arrival of the Europeans.
事实上，有证据表明，在欧洲人到来之前，澳大利亚的土著居民几千年来经常焚烧灌木丛林。
But since Europeans arrived on the continent, the number of bushfires has been strictly controlled.
但自从欧洲人抵达这片大陆以来，森林大火的数量受到了严格控制。
Now scientists believe that this reduced frequency of bushfires to low levels has led to what's known as 'dry rainforest', which seems an odd name as usually we associate tropical rainforest with wet conditions.
如今，科学家认为，这种将丛林大火发生频率降低到低水平的做法导致了所谓的“干燥雨林”，这似乎是一个奇怪的名字，因为我们通常会将热带雨林与潮湿的环境联系在一起。
And what's special about this type of rainforest?
这种类型的雨林有什么特别之处？
Well, unlike tropical rainforest which is a rich ecosystem, this type of ecosystem is usually a simple one.
与热带雨林丰富的生态系统不同，这种类型的生态系统通常很简单。
It has very thick, dense vegetation, but not much variety of species.
那里的植被非常茂密，但物种种类不多。
The vegetation provides lots of shade, so one species that does find it ideal is the bell-miner bird, which builds its nests in the undergrowth there.
植被提供了大量的荫凉，所以矿吸蜜鸟发现那里的环境很理想，于是就在那里的灌木丛中筑巢。
But again that's not helpful for the eucalyptus tree.
但这却对桉树没有帮助。
